Version: 0.8.69

Co-authored-by: metalgearsloth <metalgearsloth@gmail.com>

MSBuild/Robust.Engine.Version.props

@@ -1,4 +1,4 @@
 <Project>
     <!-- This file automatically reset by Tools/version.py -->
-    <PropertyGroup><Version>0.8.52</Version></PropertyGroup>
+    <PropertyGroup><Version>0.8.69</Version></PropertyGroup>
 </Project>

Robust.Client/BaseClient.cs

@@ -26,7 +26,6 @@ namespace Robust.Client
         [Dependency] private readonly IPlayerManager _playMan = default!;
         [Dependency] private readonly INetConfigurationManager _configManager = default!;
         [Dependency] private readonly IClientEntityManager _entityManager = default!;
-        [Dependency] private readonly IEntityLookup _entityLookup = default!;
         [Dependency] private readonly IMapManager _mapManager = default!;
         [Dependency] private readonly IDiscordRichPresence _discord = default!;
         [Dependency] private readonly IGameTiming _timing = default!;
@@ -213,7 +212,6 @@ namespace Robust.Client
         {
             _entityManager.Startup();
             _mapManager.Startup();
-            _entityLookup.Startup();
 
             _timing.ResetSimTime();
             _timing.Paused = false;
@@ -224,7 +222,6 @@ namespace Robust.Client
             IoCManager.Resolve<INetConfigurationManager>().FlushMessages();
             _gameStates.Reset();
             _playMan.Shutdown();
-            _entityLookup.Shutdown();
             _entityManager.Shutdown();
             _mapManager.Shutdown();
             _discord.ClearPresence();

Robust.Client/ClientIoC.cs

@@ -47,7 +47,6 @@ namespace Robust.Client
             IoCManager.Register<IMapManagerInternal, NetworkedMapManager>();
             IoCManager.Register<INetworkedMapManager, NetworkedMapManager>();
             IoCManager.Register<IEntityManager, ClientEntityManager>();
-            IoCManager.Register<IEntityLookup, EntityLookup>();
             IoCManager.Register<IReflectionManager, ClientReflectionManager>();
             IoCManager.Register<IConsoleHost, ClientConsoleHost>();
             IoCManager.Register<IClientConsoleHost, ClientConsoleHost>();
@@ -72,7 +71,6 @@ namespace Robust.Client
             IoCManager.Register<IStateManager, StateManager>();
             IoCManager.Register<IUserInterfaceManager, UserInterfaceManager>();
             IoCManager.Register<IUserInterfaceManagerInternal, UserInterfaceManager>();
-            IoCManager.Register<IDebugDrawing, DebugDrawing>();
             IoCManager.Register<ILightManager, LightManager>();
             IoCManager.Register<IDiscordRichPresence, DiscordRichPresence>();
             IoCManager.Register<IMidiManager, MidiManager>();

Robust.Client/Console/ClientConsoleHost.cs

@@ -109,13 +109,13 @@ namespace Robust.Client.Console
             if (AvailableCommands.ContainsKey(commandName))
             {
                 var playerManager = IoCManager.Resolve<IPlayerManager>();
-
+#if !DEBUG
                 if (!_conGroup.CanCommand(commandName) && playerManager.LocalPlayer?.Session.Status > SessionStatus.Connecting)
                 {
                     WriteError(null, $"Insufficient perms for command: {commandName}");
                     return;
                 }
-
+#endif
                 var command1 = AvailableCommands[commandName];
                 args.RemoveAt(0);
                 var shell = new ConsoleShell(this, null);

Robust.Client/Console/Commands/Debug.cs

@@ -168,7 +168,7 @@ namespace Robust.Client.Console.Commands
 
         public void Execute(IConsoleShell shell, string argStr, string[] args)
         {
-            var mgr = IoCManager.Resolve<IDebugDrawing>();
+            var mgr = EntitySystem.Get<DebugDrawingSystem>();
             mgr.DebugPositions = !mgr.DebugPositions;
         }
     }
@@ -861,7 +861,7 @@ namespace Robust.Client.Console.Commands
             var chunkIndex = grid.LocalToChunkIndices(grid.MapToGrid(mousePos));
             var chunk = internalGrid.GetChunk(chunkIndex);
 
-            shell.WriteLine($"worldBounds: {chunk.CalcWorldAABB()} localBounds: {chunk.CalcLocalBounds()}");
+            shell.WriteLine($"worldBounds: {internalGrid.CalcWorldAABB(chunk)} localBounds: {chunk.CachedBounds}");
         }
     }
 

Robust.Client/Debugging/DebugDrawingSystem.cs

@@ -6,17 +6,21 @@ using Robust.Shared.Maths;
 
 namespace Robust.Client.Debugging
 {
-    /// <inheritdoc />
-    public sealed class DebugDrawing : IDebugDrawing
+    /// <summary>
+    /// A collection of visual debug overlays for the client game.
+    /// </summary>
+    public sealed class DebugDrawingSystem : EntitySystem
     {
         [Dependency] private readonly IOverlayManager _overlayManager = default!;
         [Dependency] private readonly IEyeManager _eyeManager = default!;
-        [Dependency] private readonly IEntityLookup _lookup = default!;
         [Dependency] private readonly IEntityManager _entityManager = default!;
+        [Dependency] private readonly EntityLookupSystem _lookup = default!;
 
         private bool _debugPositions;
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Toggles the visual overlay of the local origin for each entity on screen.
+        /// </summary>
         public bool DebugPositions
         {
             get => _debugPositions;
@@ -42,13 +46,13 @@ namespace Robust.Client.Debugging
 
         private sealed class EntityPositionOverlay : Overlay
         {
-            private readonly IEntityLookup _lookup;
+            private readonly EntityLookupSystem _lookup;
             private readonly IEyeManager _eyeManager;
             private readonly IEntityManager _entityManager;
 
             public override OverlaySpace Space => OverlaySpace.WorldSpace;
 
-            public EntityPositionOverlay(IEntityLookup lookup, IEyeManager eyeManager, IEntityManager entityManager)
+            public EntityPositionOverlay(EntityLookupSystem lookup, IEyeManager eyeManager, IEntityManager entityManager)
             {
                 _lookup = lookup;
                 _eyeManager = eyeManager;
@@ -61,13 +65,11 @@ namespace Robust.Client.Debugging
 
                 var worldHandle = (DrawingHandleWorld) args.DrawingHandle;
                 var viewport = _eyeManager.GetWorldViewport();
+                var xformQuery = _entityManager.GetEntityQuery<TransformComponent>();
 
                 foreach (var entity in _lookup.GetEntitiesIntersecting(_eyeManager.CurrentMap, viewport))
                 {
-                    var transform = _entityManager.GetComponent<TransformComponent>(entity);
-
-                    var center = transform.WorldPosition;
-                    var worldRotation = transform.WorldRotation;
+                    var (center, worldRotation) = xformQuery.GetComponent(entity).GetWorldPositionRotation();
 
                     var xLine = worldRotation.RotateVec(Vector2.UnitX);
                     var yLine = worldRotation.RotateVec(Vector2.UnitY);

Robust.Client/Debugging/IDebugDrawing.cs

@@ -1,13 +0,0 @@
-namespace Robust.Client.Debugging
-{
-    /// <summary>
-    /// A collection of visual debug overlays for the client game.
-    /// </summary>
-    public interface IDebugDrawing
-    {
-        /// <summary>
-        /// Toggles the visual overlay of the local origin for each entity on screen.
-        /// </summary>
-        bool DebugPositions { get; set; }
-    }
-}

Robust.Client/GameController/GameController.cs

@@ -50,7 +50,6 @@ namespace Robust.Client
         [Dependency] private readonly IClientConsoleHost _console = default!;
         [Dependency] private readonly ITimerManager _timerManager = default!;
         [Dependency] private readonly IClientEntityManager _entityManager = default!;
-        [Dependency] private readonly IEntityLookup _lookup = default!;
         [Dependency] private readonly IPlacementManager _placementManager = default!;
         [Dependency] private readonly IClientGameStateManager _gameStateManager = default!;
         [Dependency] private readonly IOverlayManagerInternal _overlayManager = default!;
@@ -455,6 +454,7 @@ namespace Robust.Client
         private void Tick(FrameEventArgs frameEventArgs)
         {
             _modLoader.BroadcastUpdate(ModUpdateLevel.PreEngine, frameEventArgs);
+            _console.CommandBufferExecute();
             _timerManager.UpdateTimers(frameEventArgs);
             _taskManager.ProcessPendingTasks();
 
@@ -470,7 +470,6 @@ namespace Robust.Client
                 // The last real tick is the current tick! This way we won't be in "prediction" mode.
                 _gameTiming.LastRealTick = _gameTiming.CurTick;
                 _entityManager.TickUpdate(frameEventArgs.DeltaSeconds, noPredictions: false);
-                _lookup.Update();
             }
 
             _modLoader.BroadcastUpdate(ModUpdateLevel.PostEngine, frameEventArgs);
@@ -510,7 +509,7 @@ namespace Robust.Client
             logManager.GetSawmill("discord").Level = LogLevel.Warning;
             logManager.GetSawmill("net.predict").Level = LogLevel.Info;
             logManager.GetSawmill("szr").Level = LogLevel.Info;
-            logManager.GetSawmill("loc").Level = LogLevel.Error;
+            logManager.GetSawmill("loc").Level = LogLevel.Warning;
 
 #if DEBUG_ONLY_FCE_INFO
 #if DEBUG_ONLY_FCE_LOG
@@ -575,7 +574,6 @@ namespace Robust.Client
 
             _networkManager.Shutdown("Client shutting down");
             _midiManager.Shutdown();
-            IoCManager.Resolve<IEntityLookup>().Shutdown();
             _entityManager.Shutdown();
             _clyde.Shutdown();
             _clydeAudio.Shutdown();

Robust.Client/GameObjects/Components/Light/ClientOccluderComponent.cs

@@ -8,7 +8,7 @@ using Robust.Shared.ViewVariables;
 namespace Robust.Client.GameObjects
 {
     [ComponentReference(typeof(OccluderComponent))]
-    internal sealed class ClientOccluderComponent : OccluderComponent
+    public sealed class ClientOccluderComponent : OccluderComponent
     {
         [Dependency] private readonly IMapManager _mapManager = default!;
         [Dependency] private readonly IEntityManager _entityManager = default!;
@@ -71,13 +71,29 @@ namespace Robust.Client.GameObjects
         {
             Occluding = OccluderDir.None;
 
-            if (Deleted || !_entityManager.GetComponent<TransformComponent>(Owner).Anchored)
+            if (Deleted)
+                return;
+
+            // Content may want to override the default behavior for occlusion.
+            var xform = _entityManager.GetComponent<TransformComponent>(Owner);
+            var ev = new OccluderDirectionsEvent
             {
+                Component = xform,
+            };
+
+            _entityManager.EventBus.RaiseLocalEvent(Owner, ref ev);
+
+            if (ev.Handled)
+            {
+                Occluding = ev.Directions;
                 return;
             }
 
-            var grid = _mapManager.GetGrid(_entityManager.GetComponent<TransformComponent>(Owner).GridID);
-            var position = _entityManager.GetComponent<TransformComponent>(Owner).Coordinates;
+            if (!xform.Anchored)
+                return;
+
+            var grid = _mapManager.GetGrid(xform.GridID);
+            var position = xform.Coordinates;
             void CheckDir(Direction dir, OccluderDir oclDir)
             {
                 foreach (var neighbor in grid.GetInDir(position, dir))
@@ -90,7 +106,7 @@ namespace Robust.Client.GameObjects
                 }
             }
 
-            var angle = _entityManager.GetComponent<TransformComponent>(Owner).LocalRotation;
+            var angle = xform.LocalRotation;
             var dirRolling = angle.GetCardinalDir();
             // dirRolling starts at effective south
 
@@ -105,15 +121,28 @@ namespace Robust.Client.GameObjects
 
             CheckDir(dirRolling, OccluderDir.East);
         }
+    }
 
-        [Flags]
-        internal enum OccluderDir : byte
-        {
-            None = 0,
-            North = 1,
-            East = 1 << 1,
-            South = 1 << 2,
-            West = 1 << 3,
-        }
+    [Flags]
+    public enum OccluderDir : byte
+    {
+        None = 0,
+        North = 1,
+        East = 1 << 1,
+        South = 1 << 2,
+        West = 1 << 3,
+    }
+
+    /// <summary>
+    /// Raised by occluders when trying to get occlusion directions.
+    /// </summary>
+    [ByRefEvent]
+    public struct OccluderDirectionsEvent
+    {
+        public bool Handled = false;
+        public OccluderDir Directions = OccluderDir.None;
+        public TransformComponent Component = default!;
+
+        public OccluderDirectionsEvent() {}
     }
 }

Robust.Client/GameObjects/Components/Renderable/ISpriteComponent.cs

@@ -119,7 +119,8 @@ namespace Robust.Client.GameObjects
         ///     This is useful to allow layer map configs to be defined in prototypes,
         ///     while still allowing code to create configs if they're absent.
         /// </remarks>
-        void LayerMapReserveBlank(object key);
+        /// <returns>Index of the new layer.</returns>
+        int LayerMapReserveBlank(object key);
 
         /// <summary>
         ///     Adds a layer without texture (thus falling back to the error texture).
@@ -145,8 +146,8 @@ namespace Robust.Client.GameObjects
         void RemoveLayer(int layer);
         void RemoveLayer(object layerKey);
 
-        void LayerSetShader(int layer, ShaderInstance shader);
-        void LayerSetShader(object layerKey, ShaderInstance shader);
+        void LayerSetShader(int layer, ShaderInstance shader, string? prototype = null);
+        void LayerSetShader(object layerKey, ShaderInstance shader, string? prototype = null);
         void LayerSetShader(int layer, string shaderName);
         void LayerSetShader(object layerKey, string shaderName);
 
@@ -217,8 +218,8 @@ namespace Robust.Client.GameObjects
         int GetLayerDirectionCount(ISpriteLayer layer);
 
         /// <summary>
-        ///     Calculate sprite bounding box in world-space coordinates.
+        ///     Calculate the rotated sprite bounding box in world-space coordinates.
         /// </summary>
-        Box2 CalculateBoundingBox(Vector2 worldPos);
+        Box2Rotated CalculateRotatedBoundingBox(Vector2 worldPosition, Angle worldRotation, IEye? eye = null);
     }
 }

Robust.Client/GameObjects/Components/Renderable/ISpriteLayer.cs

@@ -25,8 +25,6 @@ namespace Robust.Client.GameObjects
 
         RSI.State.Direction EffectiveDirection(Angle worldRotation);
 
-        Vector2 LocalToLayer(Vector2 localPos);
-
         /// <summary>
         ///     Layer size in pixels.
         ///     Don't account layer scale or sprite world transform.
@@ -37,6 +35,6 @@ namespace Robust.Client.GameObjects
         ///     Calculate layer bounding box in sprite local-space coordinates.
         /// </summary>
         /// <returns>Bounding box in sprite local-space coordinates.</returns>
-        Box2 CalculateBoundingBox();
+        Box2 CalculateBoundingBox(Angle worldAngle);
     }
 }

Robust.Client/GameObjects/Components/Renderable/SpriteBoundsOverlay.cs

@@ -84,10 +84,16 @@ namespace Robust.Client.GameObjects
 
                 foreach (var sprite in comp.SpriteTree.QueryAabb(localAABB))
                 {
-                    var worldPos = _entityManager.GetComponent<TransformComponent>(sprite.Owner).WorldPosition;
-                    var bounds = sprite.CalculateBoundingBox(worldPos);
+                    var (worldPos, worldRot) = _entityManager.GetComponent<TransformComponent>(sprite.Owner).GetWorldPositionRotation();
+                    var bounds = sprite.CalculateRotatedBoundingBox(worldPos, worldRot);
+
+                    // Get scaled down bounds used to indicate the "south" of a sprite.
+                    var localBound = bounds.Box;
+                    var smallLocal = localBound.Scale(0.2f).Translated(-new Vector2(0f, localBound.Extents.Y));
+                    var southIndicator = new Box2Rotated(smallLocal, bounds.Rotation, bounds.Origin);
+
                     handle.DrawRect(bounds, Color.Red.WithAlpha(0.2f));
-                    handle.DrawRect(bounds.Scale(0.2f).Translated(-new Vector2(0f, bounds.Extents.Y)), Color.Blue.WithAlpha(0.5f));
+                    handle.DrawRect(southIndicator, Color.Blue.WithAlpha(0.5f));
                 }
             }
         }

Robust.Client/GameObjects/Components/Renderable/SpriteComponent.cs

@@ -20,6 +20,7 @@ using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom;
 using Robust.Shared.Utility;
 using Robust.Shared.ViewVariables;
 using DrawDepthTag = Robust.Shared.GameObjects.DrawDepth;
+using RSIDirection = Robust.Client.Graphics.RSI.State.Direction;
 
 namespace Robust.Client.GameObjects
 {
@@ -31,6 +32,8 @@ namespace Robust.Client.GameObjects
         [Dependency] private readonly IResourceCache resourceCache = default!;
         [Dependency] private readonly IPrototypeManager prototypes = default!;
         [Dependency] private readonly IEntityManager entities = default!;
+        [Dependency] private readonly IReflectionManager reflection = default!;
+        [Dependency] private readonly IEyeManager eyeManager = default!;
 
         [DataField("visible")]
         private bool _visible = true;
@@ -72,7 +75,11 @@ namespace Robust.Client.GameObjects
         public Vector2 Scale
         {
             get => scale;
-            set => scale = value;
+            set
+            {
+                scale = value;
+                UpdateLocalMatrix();
+            }
         }
 
         [DataField("rotation")]
@@ -83,7 +90,11 @@ namespace Robust.Client.GameObjects
         public Angle Rotation
         {
             get => rotation;
-            set => rotation = value;
+            set
+            {
+                rotation = value;
+                UpdateLocalMatrix();
+            }
         }
 
         [DataField("offset")]
@@ -97,12 +108,18 @@ namespace Robust.Client.GameObjects
         public Vector2 Offset
         {
             get => offset;
-            set => offset = value;
+            set
+            {
+                offset = value;
+                UpdateLocalMatrix();
+            }
         }
 
         [DataField("color")]
         private Color color = Color.White;
 
+        public Matrix3 LocalMatrix = Matrix3.Identity;
+
         [Animatable]
         [ViewVariables(VVAccess.ReadWrite)]
         public Color Color
@@ -134,113 +151,7 @@ namespace Robust.Client.GameObjects
                 Layers.Clear();
                 foreach (var layerDatum in value)
                 {
-                    var anyTextureAttempted = false;
-                    var layer = new Layer(this);
-                    if (!string.IsNullOrWhiteSpace(layerDatum.RsiPath))
-                    {
-                        var path = TextureRoot / layerDatum.RsiPath;
-
-                        if (IoCManager.Resolve<IResourceCache>().TryGetResource(path, out RSIResource? resource))
-                        {
-                            layer.RSI = resource.RSI;
-                        }
-                        else
-                        {
-                            Logger.ErrorS(LogCategory, "Unable to load layer RSI '{0}'.", path);
-                        }
-                    }
-
-                    if (!string.IsNullOrWhiteSpace(layerDatum.State))
-                    {
-                        anyTextureAttempted = true;
-                        var theRsi = layer.RSI ?? BaseRSI;
-                        if (theRsi == null)
-                        {
-                            Logger.ErrorS(LogCategory,
-                                "Layer has no RSI to load states from. Cannot use 'state' property. ({0})",
-                                layerDatum.State);
-                        }
-                        else
-                        {
-                            var stateid = new RSI.StateId(layerDatum.State);
-                            layer.State = stateid;
-                            if (theRsi.TryGetState(stateid, out var state))
-                            {
-                                // Always use south because this layer will be cached in the serializer.
-                                layer.AnimationTimeLeft = state.GetDelay(0);
-                            }
-                            else
-                            {
-                                Logger.ErrorS(LogCategory,
-                                    $"State '{stateid}' not found in RSI: '{theRsi.Path}'.",
-                                    stateid);
-                            }
-                        }
-                    }
-
-                    if (!string.IsNullOrWhiteSpace(layerDatum.TexturePath))
-                    {
-                        anyTextureAttempted = true;
-                        if (layer.State.IsValid)
-                        {
-                            Logger.ErrorS(LogCategory,
-                                "Cannot specify 'texture' on a layer if it has an RSI state specified."
-                            );
-                        }
-                        else
-                        {
-                            layer.Texture =
-                                IoCManager.Resolve<IResourceCache>().GetResource<TextureResource>(TextureRoot / layerDatum.TexturePath);
-                        }
-                    }
-
-                    if (!string.IsNullOrWhiteSpace(layerDatum.Shader))
-                    {
-                        if (IoCManager.Resolve<IPrototypeManager>().TryIndex<ShaderPrototype>(layerDatum.Shader, out var prototype))
-                        {
-                            layer.Shader = prototype.Instance();
-                        }
-                        else
-                        {
-                            Logger.ErrorS(LogCategory,
-                                "Shader prototype '{0}' does not exist.",
-                                layerDatum.Shader);
-                        }
-                    }
-
-                    layer.Color = layerDatum.Color;
-                    layer.Rotation = layerDatum.Rotation;
-                    layer._offset = layerDatum.Offset;
-                    // If neither state: nor texture: were provided we assume that they want a blank invisible layer.
-                    layer.Visible = anyTextureAttempted && layerDatum.Visible;
-                    layer.Scale = layerDatum.Scale;
-
-                    Layers.Add(layer);
-
-                    if (layerDatum.MapKeys != null)
-                    {
-                        var index = Layers.Count - 1;
-                        foreach (var keyString in layerDatum.MapKeys)
-                        {
-                            object key;
-                            if (IoCManager.Resolve<IReflectionManager>().TryParseEnumReference(keyString, out var @enum))
-                            {
-                                key = @enum;
-                            }
-                            else
-                            {
-                                key = keyString;
-                            }
-
-                            if (LayerMap.ContainsKey(key))
-                            {
-                                Logger.ErrorS(LogCategory, "Duplicate layer map key definition: {0}", key);
-                                continue;
-                            }
-
-                            LayerMap.Add(key, index);
-                        }
-                    }
+                    AddLayer(layerDatum);
                 }
 
                 _layerMapShared = true;
@@ -336,11 +247,13 @@ namespace Robust.Client.GameObjects
 
         void ISerializationHooks.AfterDeserialization()
         {
+            IoCManager.InjectDependencies(this);
+
             {
                 if (!string.IsNullOrWhiteSpace(rsi))
                 {
                     var rsiPath = TextureRoot / rsi;
-                    if(IoCManager.Resolve<IResourceCache>().TryGetResource(rsiPath, out RSIResource? resource))
+                    if(resourceCache.TryGetResource(rsiPath, out RSIResource? resource))
                     {
                         BaseRSI = resource.RSI;
                     }
@@ -373,6 +286,8 @@ namespace Robust.Client.GameObjects
                 LayerMap.Clear();
                 LayerDatums = layerDatums;
             }
+
+            UpdateLocalMatrix();
         }
 
         /// <summary>
@@ -390,6 +305,7 @@ namespace Robust.Client.GameObjects
             offset = other.offset;
             rotation = other.rotation;
             scale = other.scale;
+            UpdateLocalMatrix();
             drawDepth = other.drawDepth;
             _screenLock = other._screenLock;
             _overrideDirection = other._overrideDirection;
@@ -415,9 +331,14 @@ namespace Robust.Client.GameObjects
             RenderOrder = other.RenderOrder;
         }
 
+        internal void UpdateLocalMatrix()
+        {
+            LocalMatrix = Matrix3.CreateTransform(in offset, in rotation, in scale);
+        }
+
         public Matrix3 GetLocalMatrix()
         {
-            return Matrix3.CreateTransform(in offset, in rotation, in scale);
+            return LocalMatrix;
         }
 
         /// <inheritdoc />
@@ -462,14 +383,17 @@ namespace Robust.Client.GameObjects
             _layerMapShared = false;
         }
 
-        public void LayerMapReserveBlank(object key)
+        public int LayerMapReserveBlank(object key)
         {
-            if (LayerMapTryGet(key, out var _))
+            if (LayerMapTryGet(key, out var index))
             {
-                return;
+                return index;
             }
 
-            LayerMapSet(key, AddBlankLayer());
+            index = AddBlankLayer();
+            LayerMapSet(key, index);
+
+            return index;
         }
 
         public int AddBlankLayer(int? newIndex = null)
@@ -478,6 +402,19 @@ namespace Robust.Client.GameObjects
             return AddLayer(layer, newIndex);
         }
 
+        /// <summary>
+        ///     Add a new layer based on some <see cref="PrototypeLayerData"/>.
+        /// </summary>
+        public int AddLayer(PrototypeLayerData layerDatum, int? newIndex = null)
+        {
+            var layer = new Layer(this);
+
+            var index = AddLayer(layer, newIndex);
+
+            LayerSetData(index, layerDatum);
+            return index;
+        }
+
         public int AddLayer(string texturePath, int? newIndex = null)
         {
             return AddLayer(new ResourcePath(texturePath), newIndex);
@@ -653,7 +590,144 @@ namespace Robust.Client.GameObjects
             RemoveLayer(layer);
         }
 
-        public void LayerSetShader(int layer, ShaderInstance? shader)
+        /// <summary>
+        ///     Fills in a layer's values using some <see cref="PrototypeLayerData"/>.
+        /// </summary>
+        public void LayerSetData(int index, PrototypeLayerData layerDatum)
+        {
+            if (Layers.Count <= index)
+            {
+                Logger.ErrorS(LogCategory, "Layer with index '{0}' does not exist, cannot set layer data! Trace:\n{1}",
+                    index, Environment.StackTrace);
+                return;
+            }
+
+            var layer = Layers[index];
+
+            var anyTextureAttempted = false;
+
+            if (!string.IsNullOrWhiteSpace(layerDatum.RsiPath))
+            {
+                var path = TextureRoot / layerDatum.RsiPath;
+
+                if (resourceCache.TryGetResource(path, out RSIResource? resource))
+                {
+                    layer.RSI = resource.RSI;
+                }
+                else
+                {
+                    Logger.ErrorS(LogCategory, "Unable to load layer RSI '{0}'.", path);
+                }
+            }
+
+            if (!string.IsNullOrWhiteSpace(layerDatum.State))
+            {
+                anyTextureAttempted = true;
+                var theRsi = layer.RSI ?? BaseRSI;
+                if (theRsi == null)
+                {
+                    Logger.ErrorS(LogCategory,
+                        "Layer has no RSI to load states from. Cannot use 'state' property. ({0})",
+                        layerDatum.State);
+                }
+                else
+                {
+                    var stateid = new RSI.StateId(layerDatum.State);
+                    layer.State = stateid;
+                    if (theRsi.TryGetState(stateid, out var state))
+                    {
+                        // Always use south because this layer will be cached in the serializer.
+                        layer.AnimationTimeLeft = state.GetDelay(0);
+                    }
+                    else
+                    {
+                        Logger.ErrorS(LogCategory,
+                            $"State '{stateid}' not found in RSI: '{theRsi.Path}'.",
+                            stateid);
+                    }
+                }
+            }
+
+            if (!string.IsNullOrWhiteSpace(layerDatum.TexturePath))
+            {
+                anyTextureAttempted = true;
+                if (layer.State.IsValid)
+                {
+                    Logger.ErrorS(LogCategory,
+                        "Cannot specify 'texture' on a layer if it has an RSI state specified."
+                    );
+                }
+                else
+                {
+                    layer.Texture =
+                        resourceCache.GetResource<TextureResource>(TextureRoot / layerDatum.TexturePath);
+                }
+            }
+
+            if (!string.IsNullOrWhiteSpace(layerDatum.Shader))
+            {
+                if (prototypes.TryIndex<ShaderPrototype>(layerDatum.Shader, out var prototype))
+                {
+                    layer.ShaderPrototype = layerDatum.Shader;
+                    layer.Shader = prototype.Instance();
+                }
+                else
+                {
+                    Logger.ErrorS(LogCategory,
+                        "Shader prototype '{0}' does not exist.",
+                        layerDatum.Shader);
+                }
+            }
+
+            if (layerDatum.MapKeys != null)
+            {
+                foreach (var keyString in layerDatum.MapKeys)
+                {
+                    object key;
+                    if (reflection.TryParseEnumReference(keyString, out var @enum))
+                    {
+                        key = @enum;
+                    }
+                    else
+                    {
+                        key = keyString;
+                    }
+
+                    if (LayerMap.TryGetValue(key, out var mappedIndex))
+                    {
+                        if (mappedIndex != index)
+                            Logger.ErrorS(LogCategory, "Duplicate layer map key definition: {0}", key);
+                        continue;
+                    }
+
+                    _layerMapEnsurePrivate();
+                    LayerMap[key] = index;
+                }
+            }
+
+            layer.Color = layerDatum.Color;
+            layer._rotation = layerDatum.Rotation;
+            layer._offset = layerDatum.Offset;
+            layer._scale = layerDatum.Scale;
+            layer.UpdateLocalMatrix();
+
+            // If neither state: nor texture: were provided we assume that they want a blank invisible layer.
+            layer.Visible = anyTextureAttempted && layerDatum.Visible;
+        }
+
+        public void LayerSetData(object layerKey, PrototypeLayerData data)
+        {
+            if (!LayerMapTryGet(layerKey, out var layer))
+            {
+                Logger.ErrorS(LogCategory, "Layer with key '{0}' does not exist, cannot set shader! Trace:\n{1}",
+                    layerKey, Environment.StackTrace);
+                return;
+            }
+
+            LayerSetData(layer, data);
+        }
+
+        public void LayerSetShader(int layer, ShaderInstance? shader, string? prototype = null)
         {
             if (Layers.Count <= layer)
             {
@@ -664,9 +738,10 @@ namespace Robust.Client.GameObjects
 
             var theLayer = Layers[layer];
             theLayer.Shader = shader;
+            theLayer.ShaderPrototype = prototype;
         }
 
-        public void LayerSetShader(object layerKey, ShaderInstance shader)
+        public void LayerSetShader(object layerKey, ShaderInstance shader, string? prototype = null)
         {
             if (!LayerMapTryGet(layerKey, out var layer))
             {
@@ -675,7 +750,7 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            LayerSetShader(layer, shader);
+            LayerSetShader(layer, shader, prototype);
         }
 
         public void LayerSetShader(int layer, string shaderName)
@@ -684,10 +759,12 @@ namespace Robust.Client.GameObjects
             {
                 Logger.ErrorS(LogCategory, "Shader prototype '{0}' does not exist. Trace:\n{1}", shaderName,
                     Environment.StackTrace);
+
+                LayerSetShader(layer, null, null);
+                return;
             }
 
-            // This will set the shader to null if it does not exist.
-            LayerSetShader(layer, prototype?.Instance());
+            LayerSetShader(layer, prototype.Instance(), shaderName);
         }
 
         public void LayerSetShader(object layerKey, string shaderName)
@@ -1148,7 +1225,7 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            Layers[layer].SetOffset(layerOffset);
+            Layers[layer].Offset = layerOffset;
         }
 
         public void LayerSetOffset(object layerKey, Vector2 layerOffset)
@@ -1230,25 +1307,6 @@ namespace Robust.Client.GameObjects
             RenderInternal(drawingHandle, eyeRotation, worldRotation, worldPosition, overrideDir);
         }
 
-        private void CalcModelMatrix(int numDirs, Angle eyeRotation, Angle worldRotation, Vector2 worldPosition, out Matrix3 modelMatrix)
-        {
-            Angle angle;
-
-            if (_screenLock)
-            {
-                // Negate the eye rotation in the model matrix, so that later when the view matrix is applied the
-                // sprite will be locked upright to the screen
-                angle = new Angle(-eyeRotation.Theta);
-            }
-            else
-            {
-                angle = CalcRectWorldAngle(worldRotation + eyeRotation, numDirs) - eyeRotation;
-            }
-
-            var sWorldRotation = angle;
-            modelMatrix = Matrix3.CreateTransform(in worldPosition, in sWorldRotation);
-        }
-
         private void RenderInternal(DrawingHandleWorld drawingHandle, Angle eyeRotation, Angle worldRotation, Vector2 worldPosition, Direction? overrideDirection)
         {
             // Reduce the angles to fix math shenanigans
@@ -1257,56 +1315,16 @@ namespace Robust.Client.GameObjects
             if (worldRotation.Theta < 0)
                 worldRotation = new Angle(worldRotation.Theta + Math.Tau);
 
-            // sprite matrix, WITHOUT offset.
-            // offset is applied after sprite numDirs snapping/rotation correction
-            // --> apply at same time as layer offset
-            var spriteMatrix = Matrix3.CreateTransform(Vector2.Zero, rotation, scale);
+            // worldRotation + eyeRotation should be the angle of the entity on-screen. If no-rot is enabled this is just set to zero.
+            // However, at some point later the eye-matrix is applied separately, so we subtract -eye rotation for now:
+            var entityMatrix = Matrix3.CreateTransform(worldPosition, NoRotation ? -eyeRotation : worldRotation);
 
+            Matrix3.Multiply(ref LocalMatrix, ref entityMatrix, out var transform);
+
+            var angle = worldRotation + eyeRotation; // angle on-screen. Used to decide the direction of 4/8 directional RSIs
             foreach (var layer in Layers)
             {
-                if (!layer.Visible)
-                {
-                    continue;
-                }
-
-                var numDirs = GetLayerDirectionCount(layer);
-                var layerRotation = worldRotation + layer.Rotation;
-                var layerPosition = worldPosition + layerRotation.RotateVec(layer._offset + offset);
-
-                CalcModelMatrix(numDirs, eyeRotation, layerRotation, layerPosition, out var modelMatrix);
-                Matrix3.Multiply(ref spriteMatrix, ref modelMatrix, out var transformMatrix);
-                drawingHandle.SetTransform(in transformMatrix);
-
-                RenderLayer(drawingHandle, layer, eyeRotation, layerRotation, overrideDirection);
-            }
-        }
-
-        private void RenderLayer(DrawingHandleWorld drawingHandle, Layer layer, Angle eyeRotation, Angle worldRotation, Direction? overrideDirection)
-        {
-            var texture = GetRenderTexture(layer, worldRotation + eyeRotation, overrideDirection);
-
-            if (layer.Shader != null)
-            {
-                drawingHandle.UseShader(layer.Shader);
-            }
-
-            var layerColor = color * layer.Color;
-
-            var position = -(Vector2)texture.Size / (2f * EyeManager.PixelsPerMeter);
-            var textureSize = texture.Size / (float)EyeManager.PixelsPerMeter;
-            var quad = Box2.FromDimensions(position, textureSize);
-
-            // TODO: Implement layer-specific rotation and scale.
-            // Apply these directly to the box.
-            // Oh and when you do update Layer.LocalToLayer so content doesn't break.
-
-            // handle.Modulate changes the color
-            // drawingHandle.SetTransform() is set above, turning the quad into local space vertices
-            drawingHandle.DrawTextureRectRegion(texture, quad, layerColor);
-
-            if (layer.Shader != null)
-            {
-                drawingHandle.UseShader(null);
+                layer.Render(drawingHandle, ref transform, angle, overrideDirection);
             }
         }
 
@@ -1342,27 +1360,6 @@ namespace Robust.Client.GameObjects
             };
         }
 
-        private Texture GetRenderTexture(Layer layer, Angle worldRotation, Direction? overrideDirection)
-        {
-            var texture = layer.Texture;
-
-            if (layer.State.IsValid)
-            {
-                // Pull texture from RSI state instead.
-                var rsi = layer.RSI ?? BaseRSI;
-                if (rsi == null || !rsi.TryGetState(layer.State, out var state))
-                {
-                    state = GetFallbackState(resourceCache);
-                }
-
-                var layerSpecificDir = layer.EffectiveDirection(state, worldRotation, overrideDirection);
-                texture = state.GetFrame(layerSpecificDir, layer.AnimationFrame);
-            }
-
-            texture ??= resourceCache.GetFallback<TextureResource>().Texture;
-            return texture;
-        }
-
         public void FrameUpdate(float delta)
         {
             foreach (var t in Layers)
@@ -1417,12 +1414,14 @@ namespace Robust.Client.GameObjects
 
             Visible = thestate.Visible;
             DrawDepth = thestate.DrawDepth;
-            Scale = thestate.Scale;
-            Rotation = thestate.Rotation;
-            Offset = thestate.Offset;
+            scale = thestate.Scale;
+            rotation = thestate.Rotation;
+            offset = thestate.Offset;
+            UpdateLocalMatrix();
             Color = thestate.Color;
             RenderOrder = thestate.RenderOrder;
 
+
             if (thestate.BaseRsiPath != null && BaseRSI != null)
             {
                 if (resourceCache.TryGetResource<RSIResource>(TextureRoot / thestate.BaseRsiPath, out var res))
@@ -1438,43 +1437,8 @@ namespace Robust.Client.GameObjects
                 }
             }
 
-            // Maybe optimize this to NOT full clear.
-            Layers.Clear();
-            for (var i = 0; i < thestate.Layers.Count; i++)
-            {
-                var netlayer = thestate.Layers[i];
-                var layer = new Layer(this)
-                {
-                    // These are easy so do them here.
-                    Scale = netlayer.Scale,
-                    Rotation = netlayer.Rotation,
-                    Visible = netlayer.Visible,
-                    Color = netlayer.Color
-                };
-                Layers.Add(layer);
-
-                // Using the public API to handle errors.
-                // Probably slow as crap.
-                // Who am I kidding, DEFINITELY.
-                if (netlayer.Shader != null)
-                {
-                    LayerSetShader(i, netlayer.Shader);
-                }
-
-                if (netlayer.RsiPath != null)
-                {
-                    LayerSetRSI(i, netlayer.RsiPath);
-                }
-
-                if (netlayer.TexturePath != null)
-                {
-                    LayerSetTexture(i, netlayer.TexturePath);
-                }
-                else if (netlayer.State != null)
-                {
-                    LayerSetState(i, netlayer.State);
-                }
-            }
+            // Maybe optimize this to NOT fully clear the layers. (see LayerDatums setter function)
+            LayerDatums = thestate.Layers;
         }
 
         private void QueueUpdateIsInert()
@@ -1553,35 +1517,61 @@ namespace Robust.Client.GameObjects
         }
 
         /// <inheritdoc/>
-        public Box2 CalculateBoundingBox(Vector2 worldPos)
+        public Box2Rotated CalculateRotatedBoundingBox(Vector2 worldPosition, Angle worldRotation, IEye? eye = null)
         {
             // fast check for empty sprites
-            if (Layers.Count == 0)
-                return new Box2(worldPos, worldPos);
+            if (!Visible || Layers.Count == 0)
+            {
+                return new Box2Rotated(new Box2(worldPosition, worldPosition), Angle.Zero, worldPosition);
+            }
+
+            // We need to modify world rotation so that it lies between 0 and 2pi.
+            // This matters for 4 or 8 directional sprites deciding which quadrant (octant?) they lie in.
+            // the 0->2pi convention is set by the sprite-rendering code that selects the layers.
+            // See RenderInternal().
+
+            worldRotation = worldRotation.Reduced();
+            if (worldRotation.Theta < 0)
+                worldRotation = new Angle(worldRotation.Theta + Math.Tau);
+
+            eye ??= eyeManager.CurrentEye;
+
+            // Need relative angle on screen for determining the sprite rsi direction.
+            Angle relativeRotation = NoRotation
+                ? Angle.Zero
+                : worldRotation + eye.Rotation;
 
             // we need to calculate bounding box taking into account all nested layers
-            // because layers can have offsets, scale or rotation we need to calculate a new BB
-            // based on lowest bottomLeft and hightest topRight points from all layers
-            var box = Layers[0].CalculateBoundingBox();
+            // because layers can have offsets, scale or rotation, we need to calculate a new BB
+            // based on lowest bottomLeft and highest topRight points from all layers
+            var box = Layers[0].CalculateBoundingBox(relativeRotation);
 
             for (int i = 1; i < Layers.Count; i++)
             {
                 var layer = Layers[i];
-                var layerBB = layer.CalculateBoundingBox();
+                if (!layer.Visible) continue;
+                var layerBB = layer.CalculateBoundingBox(relativeRotation);
 
                 box = box.Union(layerBB);
             }
 
-            // apply sprite transformations and calculate sprite bounding box
-            // we can optimize it a bit, if sprite doesn't have rotation
-            var spriteBox = box.Scale(Scale);
-            var spriteHasRotation = !Rotation.EqualsApprox(Angle.Zero);
-            var spriteBB = spriteHasRotation ?
-                new Box2Rotated(spriteBox, Rotation).CalcBoundingBox() : spriteBox;
+            // Next, what we do is take the box2 and apply the sprite's transform, and then the entity's transform. We
+            // could do this via Matrix3.TransformBox, but that only yields bounding boxes. So instead we manually
+            // transform our box by the combination of these matrices:
 
-            // move it all to world transform system (with sprite offset)
-            var worldBB = spriteBB.Translated(Offset + worldPos);
-            return worldBB;
+            if (Scale != Vector2.One)
+                box = box.Scale(Scale);
+
+            var adjustedOffset = NoRotation
+                ? (-eye.Rotation).RotateVec(Offset)
+                : worldRotation.RotateVec(Offset);
+
+            Vector2 position = adjustedOffset + worldPosition;
+            Angle finalRotation = NoRotation
+                ? Rotation - eye.Rotation
+                : Rotation + worldRotation;
+
+            return new Box2Rotated(box.Translated(position), finalRotation, position);
         }
 
         internal void UpdateBounds()
@@ -1615,10 +1605,11 @@ namespace Robust.Client.GameObjects
             Flip = 3,
         }
 
-        public sealed class Layer : ISpriteLayer
+        public sealed class Layer : ISpriteLayer, ISerializationHooks
         {
             [ViewVariables] private readonly SpriteComponent _parent;
 
+            [ViewVariables] public string? ShaderPrototype;
             [ViewVariables] public ShaderInstance? Shader;
             [ViewVariables] public Texture? Texture;
 
@@ -1628,11 +1619,37 @@ namespace Robust.Client.GameObjects
             [ViewVariables] public float AnimationTime;
             [ViewVariables] public int AnimationFrame;
 
-            [ViewVariables(VVAccess.ReadWrite)]
-            public Vector2 Scale { get; set; } = Vector2.One;
+            public Matrix3 LocalMatrix = Matrix3.Identity;
 
             [ViewVariables(VVAccess.ReadWrite)]
-            public Angle Rotation { get; set; }
+            public Vector2 Scale
+            {
+                get => _scale;
+                set
+                {
+                    if (_scale.EqualsApprox(value)) return;
+
+                    _scale = value;
+                    UpdateLocalMatrix();
+                    _parent.UpdateBounds();
+                }
+            }
+            internal Vector2 _scale = Vector2.One;
+
+            [ViewVariables(VVAccess.ReadWrite)]
+            public Angle Rotation
+            {
+                get => _rotation;
+                set
+                {
+                    if (_rotation.EqualsApprox(value)) return;
+
+                    _rotation = value;
+                    UpdateLocalMatrix();
+                    _parent.UpdateBounds();
+                }
+            }
+            internal Angle _rotation = Angle.Zero;
 
             [ViewVariables(VVAccess.ReadWrite)]
             public bool Visible = true;
@@ -1652,6 +1669,7 @@ namespace Robust.Client.GameObjects
                     if (_offset.EqualsApprox(value)) return;
 
                     _offset = value;
+                    UpdateLocalMatrix();
                     _parent.UpdateBounds();
                 }
             }
@@ -1675,6 +1693,7 @@ namespace Robust.Client.GameObjects
                 if (toClone.Shader != null)
                 {
                     Shader = toClone.Shader.Mutable ? toClone.Shader.Duplicate() : toClone.Shader;
+                    ShaderPrototype = toClone.ShaderPrototype;
                 }
                 Texture = toClone.Texture;
                 RSI = toClone.RSI;
@@ -1682,14 +1701,26 @@ namespace Robust.Client.GameObjects
                 AnimationTimeLeft = toClone.AnimationTimeLeft;
                 AnimationTime = toClone.AnimationTime;
                 AnimationFrame = toClone.AnimationFrame;
-                Scale = toClone.Scale;
-                Rotation = toClone.Rotation;
+                _scale = toClone.Scale;
+                _rotation = toClone.Rotation;
+                _offset = toClone.Offset;
+                UpdateLocalMatrix();
                 Visible = toClone.Visible;
                 Color = toClone.Color;
                 DirOffset = toClone.DirOffset;
                 AutoAnimated = toClone.AutoAnimated;
             }
 
+            void ISerializationHooks.AfterDeserialization()
+            {
+                UpdateLocalMatrix();
+            }
+
+            internal void UpdateLocalMatrix()
+            {
+                LocalMatrix = Matrix3.CreateTransform(in _offset, in _rotation, in _scale);
+            }
+
             RSI? ISpriteLayer.Rsi { get => RSI; set => SetRsi(value); }
             RSI.StateId ISpriteLayer.RsiState { get => State; set => SetState(value); }
             Texture? ISpriteLayer.Texture { get => Texture; set => SetTexture(value); }
@@ -1701,7 +1732,7 @@ namespace Robust.Client.GameObjects
                     Color = Color,
                     Rotation = Rotation,
                     Scale = Scale,
-                    //todo Shader = Shader,
+                    Shader = ShaderPrototype,
                     State = State.Name,
                     Visible = Visible,
                     RsiPath = RSI?.Path?.ToString(),
@@ -1730,7 +1761,7 @@ namespace Robust.Client.GameObjects
                 set => SetAutoAnimated(value);
             }
 
-            public RSI.State.Direction EffectiveDirection(Angle worldRotation)
+            public RSIDirection EffectiveDirection(Angle worldRotation)
             {
                 if (State == default)
                 {
@@ -1751,22 +1782,16 @@ namespace Robust.Client.GameObjects
                 return default;
             }
 
-            public Vector2 LocalToLayer(Vector2 localPos)
-            {
-                // TODO: scale & rotation for layers is currently unimplemented.
-                return localPos;
-            }
-
-            public RSI.State.Direction EffectiveDirection(RSI.State state, Angle worldRotation,
+            public RSIDirection EffectiveDirection(RSI.State state, Angle worldRotation,
                 Direction? overrideDirection)
             {
                 if (state.Directions == RSI.State.DirectionType.Dir1)
                 {
-                    return RSI.State.Direction.South;
+                    return RSIDirection.South;
                 }
                 else
                 {
-                    RSI.State.Direction dir;
+                    RSIDirection dir;
                     if (overrideDirection != null)
                     {
                         dir = overrideDirection.Value.Convert(state.Directions);
@@ -1849,7 +1874,7 @@ namespace Robust.Client.GameObjects
                     }
                     else
                     {
-                        Logger.ErrorS(LogCategory, "State '{0}' does not exist in set RSI. Trace:\n{1}", State,
+                        Logger.ErrorS(LogCategory, "State '{0}' does not exist in set RSI ({1}). Trace:\n{2}", State, rsi?.Path?.ToString() ?? "null",
                             Environment.StackTrace);
                         Texture = null;
                     }
@@ -1898,11 +1923,6 @@ namespace Robust.Client.GameObjects
                 _parent.QueueUpdateIsInert();
             }
 
-            public void SetOffset(Vector2 offset)
-            {
-                Offset = offset;
-            }
-
             /// <inheritdoc/>
             public Vector2i PixelSize
             {
@@ -1923,10 +1943,121 @@ namespace Robust.Client.GameObjects
             }
 
             /// <inheritdoc/>
-            public Box2 CalculateBoundingBox()
+            public Box2 CalculateBoundingBox(Angle angle)
             {
-                // TODO: scale & rotation for layers is currently unimplemented.
-                return Box2.CenteredAround(Offset, PixelSize / EyeManager.PixelsPerMeter);
+                // Other than some special cases for simple layers, this will basically just apply the matrix obtained
+                // via GetLayerDrawMatrix() to this layer's bounding box.
+
+                var rsiState = GetActualState();
+
+                var dir = (rsiState == null || rsiState.Directions == RSI.State.DirectionType.Dir1)
+                    ? RSIDirection.South
+                    : angle.ToRsiDirection(rsiState.Directions);
+
+                // special case for simple layers. The vast majority of layers are like this.
+                if (_rotation == Angle.Zero)
+                {
+                    var textureSize = PixelSize / EyeManager.PixelsPerMeter;
+
+                    // this switch block is basically an explicit version of the `rsiDirectionMatrix` in `GetLayerDrawMatrix()`.
+                    var box = dir switch
+                    {
+                        // No rotation:
+                        RSIDirection.South or RSIDirection.North => Box2.CenteredAround(Offset, textureSize),
+                        // rotate 90 degrees:
+                        RSIDirection.East or RSIDirection.West => Box2.CenteredAround(Offset, (textureSize.Y, textureSize.X)),
+                        // rotated 45 degrees (any 45 degree rotated rectangle has a square bounding box with sides of length (x+y)/sqrt(2) )
+                        _ => Box2.CenteredAround(Offset, Vector2.One * (textureSize.X + textureSize.Y) / MathF.Sqrt(2))
+                    };
+
+                    return _scale == Vector2.One ? box : box.Scale(_scale);
+                }
+
+                // Welp we have some non-zero _rotation, so lets just apply the generalized layer transform and get the bounding box from where;
+                GetLayerDrawMatrix(dir, out var layerDrawMatrix);
+                return layerDrawMatrix.TransformBox(Box2.CentredAroundZero(PixelSize / EyeManager.PixelsPerMeter));
+            }
+
+            internal RSI.State? GetActualState()
+            {
+                if (!State.IsValid)
+                    return null;
+
+                // Pull texture from RSI state
+                var rsi = RSI ?? _parent.BaseRSI;
+                if (rsi == null || !rsi.TryGetState(State, out var rsiState))
+                {
+                    rsiState = GetFallbackState(_parent.resourceCache);
+                }
+
+                return rsiState;
+            }
+
+            /// <summary>
+            ///     Given the apparent rotation of an entity on screen (world + eye rotation), get layer's matrix for drawing &
+            ///     relevant RSI direction.
+            /// </summary>
+            public void GetLayerDrawMatrix(RSIDirection dir, out Matrix3 layerDrawMatrix)
+            {
+                if (_parent.NoRotation)
+                    layerDrawMatrix = LocalMatrix;
+                else
+                {
+                    var rsiDirectionMatrix = Matrix3.CreateTransform(Vector2.Zero, -dir.Convert().ToAngle());
+                    Matrix3.Multiply(ref rsiDirectionMatrix, ref LocalMatrix, out layerDrawMatrix);
+                }
+            }
+
+            internal void Render(DrawingHandleWorld drawingHandle, ref Matrix3 spriteMatrix, Angle angle, Direction? overrideDirection)
+            {
+                if (!Visible)
+                    return;
+
+                var rsiState = GetActualState();
+
+                var dir = (rsiState == null || rsiState.Directions == RSI.State.DirectionType.Dir1)
+                    ? RSIDirection.South
+                    : angle.ToRsiDirection(rsiState.Directions);
+
+                // Set the drawing transform for this  layer
+                GetLayerDrawMatrix(dir, out var layerMatrix);
+                Matrix3.Multiply(ref layerMatrix, ref spriteMatrix, out var transformMatrix);
+                drawingHandle.SetTransform(in transformMatrix);
+
+                // The direction used to draw the sprite can differ from the one that the angle would naively suggest,
+                // due to direction overrides or offsets.
+                if (overrideDirection != null && rsiState != null)
+                    dir = overrideDirection.Value.Convert(rsiState.Directions);
+                dir = dir.OffsetRsiDir(DirOffset);
+
+                // Get the correct directional texture from the state, and draw it!
+                var texture = GetRenderTexture(rsiState, dir);
+                RenderTexture(drawingHandle, texture);
+            }
+
+            private void RenderTexture(DrawingHandleWorld drawingHandle, Texture texture)
+            {
+                if (Shader != null)
+                    drawingHandle.UseShader(Shader);
+
+                var layerColor = _parent.color * Color;
+
+                var position = -(Vector2)texture.Size / (2f * EyeManager.PixelsPerMeter);
+                var textureSize = texture.Size / (float)EyeManager.PixelsPerMeter;
+                var quad = Box2.FromDimensions(position, textureSize);
+
+                drawingHandle.DrawTextureRectRegion(texture, quad, layerColor);
+
+                if (Shader != null)
+                    drawingHandle.UseShader(null);
+            }
+
+            private Texture GetRenderTexture(RSI.State? state, RSIDirection dir)
+            {
+                if (state == null)
+                    return Texture ?? _parent.resourceCache.GetFallback<TextureResource>().Texture;
+
+                return state.GetFrame(dir, AnimationFrame);
             }
         }
 
@@ -2034,6 +2165,7 @@ namespace Robust.Client.GameObjects
             return results;
         }
 
+        [Obsolete("Use SpriteSystem")]
         public static IRsiStateLike GetPrototypeIcon(EntityPrototype prototype, IResourceCache resourceCache)
         {
             var icon = IconComponent.GetPrototypeIcon(prototype, resourceCache);

Robust.Client/GameObjects/EntitySystems/AppearanceSystem.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
@@ -6,7 +7,7 @@ using Robust.Shared.GameStates;
 namespace Robust.Client.GameObjects
 {
     [UsedImplicitly]
-    internal sealed class AppearanceSystem : SharedAppearanceSystem
+    public sealed class AppearanceSystem : SharedAppearanceSystem
     {
         private readonly Queue<ClientAppearanceComponent> _queuedUpdates = new();
 
@@ -50,10 +51,33 @@ namespace Robust.Client.GameObjects
 
             if (!stateDiff) return;
 
-            component.AppearanceData = actualState.Data;
+            component.AppearanceData = CloneAppearanceData(actualState.Data);
             MarkDirty(component);
         }
 
+        /// <summary>
+        ///     Take in an appearance data dictionary and attempt to clone it.
+        /// </summary>
+        /// <remarks>
+        ///     As some appearance data values are not simple value-type objects, this is not just a shallow clone.
+        /// </remarks>
+        private Dictionary<object, object> CloneAppearanceData(Dictionary<object, object> data)
+        {
+            Dictionary<object, object> newDict = new(data.Count);
+
+            foreach (var (key, value) in data)
+            {
+                if (value.GetType().IsValueType)
+                    newDict[key] = value;
+                else if (value is ICloneable cloneable)
+                    newDict[key] = cloneable.Clone();
+                else
+                    throw new NotSupportedException("Invalid object in appearance data dictionary. Appearance data must be cloneable");
+            }
+
+            return newDict;
+        }
+
         public override void MarkDirty(AppearanceComponent component)
         {
             if (component.AppearanceDirty)
@@ -107,7 +131,7 @@ namespace Robust.Client.GameObjects
     [ByRefEvent]
     public struct AppearanceChangeEvent
     {
-        public AppearanceComponent Component = default!;
-        public IReadOnlyDictionary<object, object> AppearanceData = default!;
+        public AppearanceComponent Component;
+        public IReadOnlyDictionary<object, object> AppearanceData;
     }
 }

Robust.Client/GameObjects/EntitySystems/ContainerSystem.cs

@@ -168,7 +168,7 @@ namespace Robust.Client.GameObjects
                 // This container is expecting an entity... but it got parented to some other entity???
                 // Ah well, the sever should send a new container state that updates expected entities so just ignore it for now.
                 return;
-            }    
+            }
 
             RemoveExpectedEntity(message.Entity);
 
@@ -210,68 +210,101 @@ namespace Robust.Client.GameObjects
         public override void FrameUpdate(float frameTime)
         {
             base.FrameUpdate(frameTime);
+            var pointQuery = EntityManager.GetEntityQuery<PointLightComponent>();
+            var spriteQuery = EntityManager.GetEntityQuery<SpriteComponent>();
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
 
             foreach (var toUpdate in _updateQueue)
             {
-                if (EntityManager.Deleted(toUpdate))
-                {
+                if (Deleted(toUpdate))
                     continue;
-                }
 
-                UpdateEntityRecursively(toUpdate);
+                UpdateEntityRecursively(toUpdate, xformQuery, pointQuery, spriteQuery);
             }
 
             _updateQueue.Clear();
         }
 
-        private void UpdateEntityRecursively(EntityUid entity)
+        private void UpdateEntityRecursively(
+            EntityUid entity,
+            EntityQuery<TransformComponent> xformQuery,
+            EntityQuery<PointLightComponent> pointQuery,
+            EntityQuery<SpriteComponent> spriteQuery)
         {
-            // TODO: Since we are recursing down,
-            // we could cache ShowContents data here to speed it up for children.
-            // Am lazy though.
-            UpdateEntity(entity);
+            // Recursively go up parents and containers to see whether both sprites and lights need to be occluded
+            // Could maybe optimise this more by checking nearest parent that has sprite / light and whether it's container
+            // occluded but this probably isn't a big perf issue.
+            var xform = xformQuery.GetComponent(entity);
+            var parent = xform.ParentUid;
+            var child = entity;
+            var spriteOccluded = false;
+            var lightOccluded = false;
 
-            foreach (var child in EntityManager.GetComponent<TransformComponent>(entity).Children)
+            while (parent.IsValid() && !spriteOccluded && !lightOccluded)
             {
-                UpdateEntityRecursively(child.Owner);
+                var parentXform = xformQuery.GetComponent(parent);
+                if (TryComp<ContainerManagerComponent>(parent, out var manager) && manager.TryGetContainer(child, out var container))
+                {
+                    spriteOccluded = spriteOccluded || !container.ShowContents;
+                    lightOccluded = lightOccluded || container.OccludesLight;
+                }
+
+                child = parent;
+                parent = parentXform.ParentUid;
             }
+
+            // Alright so
+            // This is the CBT bit.
+            // The issue is we need to go through the children and re-check whether they are or are not contained.
+            // if they are contained then the occlusion values may need updating for all those children
+            UpdateEntity(entity, xform, xformQuery, pointQuery, spriteQuery, spriteOccluded, lightOccluded);
         }
 
-        private void UpdateEntity(EntityUid entity)
+        private void UpdateEntity(
+            EntityUid entity,
+            TransformComponent xform,
+            EntityQuery<TransformComponent> xformQuery,
+            EntityQuery<PointLightComponent> pointQuery,
+            EntityQuery<SpriteComponent> spriteQuery,
+            bool spriteOccluded,
+            bool lightOccluded)
         {
-            if (EntityManager.TryGetComponent(entity, out SpriteComponent? sprite))
+            if (spriteQuery.TryGetComponent(entity, out var sprite))
             {
-                sprite.ContainerOccluded = false;
-
-                // We have to recursively scan for containers upwards in case of nested containers.
-                var tempParent = entity;
-                while (tempParent.TryGetContainer(out var container))
-                {
-                    if (!container.ShowContents)
-                    {
-                        sprite.ContainerOccluded = true;
-                        break;
-                    }
-
-                    tempParent = container.Owner;
-                }
+                sprite.ContainerOccluded = spriteOccluded;
             }
 
-            if (EntityManager.TryGetComponent(entity, out PointLightComponent? light))
+            if (pointQuery.TryGetComponent(entity, out var light))
             {
-                light.ContainerOccluded = false;
+                light.ContainerOccluded = lightOccluded;
+            }
 
-                // We have to recursively scan for containers upwards in case of nested containers.
-                var tempParent = entity;
-                while (tempParent.TryGetContainer(out var container))
+            var childEnumerator = xform.ChildEnumerator;
+
+            // Try to avoid TryComp if we already know stuff is occluded.
+            if ((!spriteOccluded || !lightOccluded) && TryComp<ContainerManagerComponent>(entity, out var manager))
+            {
+                while (childEnumerator.MoveNext(out var child))
                 {
-                    if (container.OccludesLight)
+                    // Thank god it's by value and not by ref.
+                    var childSpriteOccluded = spriteOccluded;
+                    var childLightOccluded = lightOccluded;
+
+                    // We already know either sprite or light is not occluding so need to check container.
+                    if (manager.TryGetContainer(child.Value, out var container))
                     {
-                        light.ContainerOccluded = true;
-                        break;
+                        childSpriteOccluded = childSpriteOccluded || !container.ShowContents;
+                        childLightOccluded = childLightOccluded || container.OccludesLight;
                     }
 
-                    tempParent = container.Owner;
+                    UpdateEntity(child.Value, xformQuery.GetComponent(child.Value), xformQuery, pointQuery, spriteQuery, childSpriteOccluded, childLightOccluded);
+                }
+            }
+            else
+            {
+                while (childEnumerator.MoveNext(out var child))
+                {
+                    UpdateEntity(child.Value, xformQuery.GetComponent(child.Value), xformQuery, pointQuery, spriteQuery, spriteOccluded, lightOccluded);
                 }
             }
         }

Robust.Client/GameObjects/EntitySystems/DebugLightTreeSystem.cs

@@ -25,7 +25,7 @@ namespace Robust.Client.GameObjects
                 if (_enabled)
                 {
                     _lightOverlay = new DebugLightOverlay(
-                        IoCManager.Resolve<IEntityLookup>(),
+                        EntitySystem.Get<EntityLookupSystem>(),
                         IoCManager.Resolve<IEyeManager>(),
                         IoCManager.Resolve<IMapManager>(),
                         Get<RenderingTreeSystem>());
@@ -44,7 +44,7 @@ namespace Robust.Client.GameObjects
 
         private sealed class DebugLightOverlay : Overlay
         {
-            private IEntityLookup _lookup;
+            private EntityLookupSystem _lookup;
             private IEyeManager _eyeManager;
             private IMapManager _mapManager;
 
@@ -52,7 +52,7 @@ namespace Robust.Client.GameObjects
 
             public override OverlaySpace Space => OverlaySpace.WorldSpace;
 
-            public DebugLightOverlay(IEntityLookup lookup, IEyeManager eyeManager, IMapManager mapManager, RenderingTreeSystem tree)
+            public DebugLightOverlay(EntityLookupSystem lookup, IEyeManager eyeManager, IMapManager mapManager, RenderingTreeSystem tree)
             {
                 _lookup = lookup;
                 _eyeManager = eyeManager;
@@ -72,7 +72,7 @@ namespace Robust.Client.GameObjects
                 {
                     foreach (var light in tree.LightTree)
                     {
-                        var aabb = _lookup.GetWorldAabbFromEntity(light.Owner);
+                        var aabb = _lookup.GetWorldAABB(light.Owner);
                         if (!aabb.Intersects(worldBounds)) continue;
 
                         args.WorldHandle.DrawRect(aabb, Color.Green.WithAlpha(0.1f));

Robust.Client/GameObjects/EntitySystems/EffectSystem.cs

@@ -323,7 +323,7 @@ namespace Robust.Client.GameObjects
         {
             private readonly IPlayerManager _playerManager;
 
-            public override OverlaySpace Space => OverlaySpace.WorldSpace;
+            public override OverlaySpace Space => OverlaySpace.WorldSpaceBelowFOV;
 
             private readonly ShaderInstance _unshadedShader;
             private readonly EffectSystem _owner;

Robust.Client/GameObjects/EntitySystems/GridRenderingSystem.cs

@@ -0,0 +1,19 @@
+using Robust.Client.Graphics;
+using Robust.Shared.GameObjects;
+
+namespace Robust.Client.GameObjects;
+
+internal class GridRenderingSystem : EntitySystem
+{
+    private readonly IClydeInternal _clyde;
+
+    public GridRenderingSystem(IClydeInternal clyde)
+    {
+        _clyde = clyde;
+    }
+
+    public override void Initialize()
+    {
+        _clyde.RegisterGridEcsEvents();
+    }
+}

Robust.Client/GameObjects/EntitySystems/InputSystem.cs

@@ -4,11 +4,15 @@ using Robust.Client.Input;
 using Robust.Client.Player;
 using Robust.Shared;
 using Robust.Shared.Configuration;
+using Robust.Shared.Console;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Input;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
 using Robust.Shared.Players;
+using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 
 namespace Robust.Client.GameObjects
@@ -21,6 +25,8 @@ namespace Robust.Client.GameObjects
         [Dependency] private readonly IInputManager _inputManager = default!;
         [Dependency] private readonly IPlayerManager _playerManager = default!;
         [Dependency] private readonly IClientGameStateManager _stateManager = default!;
+        [Dependency] private readonly IConsoleHost _conHost = default!;
+        [Dependency] private readonly IGameTiming _timing = default!;
 
         private readonly IPlayerCommandStates _cmdStates = new PlayerCommandStates();
 
@@ -108,6 +114,43 @@ namespace Robust.Client.GameObjects
         public override void Initialize()
         {
             SubscribeLocalEvent<PlayerAttachSysMessage>(OnAttachedEntityChanged);
+
+            _conHost.RegisterCommand("incmd",
+                "Inserts an input command into the simulation",
+                "incmd <KeyFunction> <d|u KeyState> <wxPos> <wyPos>",
+                GenerateInputCommand);
+        }
+
+        public override void Shutdown()
+        {
+            base.Shutdown();
+
+            _conHost.UnregisterCommand("incmd");
+        }
+
+        private void GenerateInputCommand(IConsoleShell shell, string argstr, string[] args)
+        {
+            var localPlayer = _playerManager.LocalPlayer;
+            if(localPlayer is null)
+                return;
+
+            var pent = localPlayer.ControlledEntity;
+            if(pent is null)
+                return;
+
+            BoundKeyFunction keyFunction = new BoundKeyFunction(args[0]);
+            BoundKeyState state = args[1] == "u" ? BoundKeyState.Up: BoundKeyState.Down;
+
+            var pxform = Transform(pent.Value);
+            var wPos = pxform.WorldPosition + new Vector2(float.Parse(args[2]), float.Parse(args[3]));
+            var coords = EntityCoordinates.FromMap(EntityManager, pent.Value, new MapCoordinates(wPos, pxform.MapID));
+
+            var funcId = _inputManager.NetworkBindMap.KeyFunctionID(keyFunction);
+
+            var message = new FullInputCmdMessage(_timing.CurTick, _timing.TickFraction, funcId, state,
+                coords, new ScreenCoordinates(0, 0, default), EntityUid.Invalid);
+
+            HandleInputCommand(localPlayer.Session, keyFunction, message);
         }
 
         private void OnAttachedEntityChanged(PlayerAttachSysMessage message)

Robust.Client/GameObjects/EntitySystems/RenderingTreeSystem.cs

@@ -70,8 +70,9 @@ namespace Robust.Client.GameObjects
             UpdatesAfter.Add(typeof(TransformSystem));
             UpdatesAfter.Add(typeof(PhysicsSystem));
 
-            _mapManager.MapCreated += MapManagerOnMapCreated;
-            _mapManager.OnGridCreated += MapManagerOnGridCreated;
+            SubscribeLocalEvent<MapChangedEvent>(MapManagerOnMapCreated);
+
+            SubscribeLocalEvent<GridInitializeEvent>(MapManagerOnGridCreated);
 
             // Due to how recursion works, this must be done.
             SubscribeLocalEvent<MoveEvent>(AnythingMoved);
@@ -113,12 +114,18 @@ namespace Robust.Client.GameObjects
 
         private void AnythingMoved(ref MoveEvent args)
         {
-            var xforms = EntityManager.GetEntityQuery<TransformComponent>();
+            var pointQuery = EntityManager.GetEntityQuery<PointLightComponent>();
+            var spriteQuery = EntityManager.GetEntityQuery<SpriteComponent>();
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
 
-            AnythingMovedSubHandler(args.Sender, xforms);
+            AnythingMovedSubHandler(args.Sender, xformQuery, pointQuery, spriteQuery);
         }
 
-        private void AnythingMovedSubHandler(EntityUid uid, EntityQuery<TransformComponent> xforms)
+        private void AnythingMovedSubHandler(
+            EntityUid uid,
+            EntityQuery<TransformComponent> xformQuery,
+            EntityQuery<PointLightComponent> pointQuery,
+            EntityQuery<SpriteComponent> spriteQuery)
         {
             // To avoid doing redundant updates (and we don't need to update a grid's children ever)
             if (!_checkedChildren.Add(uid) || EntityManager.HasComponent<RenderingTreeComponent>(uid)) return;
@@ -127,17 +134,19 @@ namespace Robust.Client.GameObjects
             // WHATEVER YOU DO, DON'T REPLACE THIS WITH SPAMMING EVENTS UNLESS YOU HAVE A GUARANTEE IT WON'T LAG THE GC.
             // (Struct-based events ok though)
             // Ironically this was lagging the GC lolz
-            if (EntityManager.TryGetComponent(uid, out SpriteComponent? sprite))
+            if (spriteQuery.TryGetComponent(uid, out var sprite))
                 QueueSpriteUpdate(sprite);
 
-            if (EntityManager.TryGetComponent(uid, out PointLightComponent? light))
+            if (pointQuery.TryGetComponent(uid, out var light))
                 QueueLightUpdate(light);
 
-            if (!xforms.TryGetComponent(uid, out var xform)) return;
+            if (!xformQuery.TryGetComponent(uid, out var xform)) return;
 
-            foreach (var child in xform.ChildEntities)
+            var childEnumerator = xform.ChildEnumerator;
+
+            while (childEnumerator.MoveNext(out var child))
             {
-                AnythingMovedSubHandler(child, xforms);
+                AnythingMovedSubHandler(child.Value, xformQuery, pointQuery, spriteQuery);
             }
         }
 
@@ -212,13 +221,6 @@ namespace Robust.Client.GameObjects
         }
         #endregion
 
-        public override void Shutdown()
-        {
-            base.Shutdown();
-            _mapManager.MapCreated -= MapManagerOnMapCreated;
-            _mapManager.OnGridCreated -= MapManagerOnGridCreated;
-        }
-
         private void OnTreeRemove(EntityUid uid, RenderingTreeComponent component, ComponentRemove args)
         {
             foreach (var sprite in component.SpriteTree)
@@ -235,9 +237,9 @@ namespace Robust.Client.GameObjects
             component.LightTree.Clear();
         }
 
-        private void MapManagerOnMapCreated(object? sender, MapEventArgs e)
+        private void MapManagerOnMapCreated(MapChangedEvent e)
         {
-            if (e.Map == MapId.Nullspace)
+            if (e.Destroyed || e.Map == MapId.Nullspace)
             {
                 return;
             }
@@ -245,9 +247,9 @@ namespace Robust.Client.GameObjects
             EntityManager.EnsureComponent<RenderingTreeComponent>(_mapManager.GetMapEntityId(e.Map));
         }
 
-        private void MapManagerOnGridCreated(MapId mapId, GridId gridId)
+        private void MapManagerOnGridCreated(GridInitializeEvent ev)
         {
-            EntityManager.EnsureComponent<RenderingTreeComponent>(_mapManager.GetGrid(gridId).GridEntityId);
+            EntityManager.EnsureComponent<RenderingTreeComponent>(_mapManager.GetGrid(ev.GridId).GridEntityId);
         }
 
         private RenderingTreeComponent? GetRenderTree(EntityUid entity, EntityQuery<TransformComponent> xforms)
@@ -369,13 +371,10 @@ namespace Robust.Client.GameObjects
         private Box2 SpriteAabbFunc(in SpriteComponent value)
         {
             var xforms = EntityManager.GetEntityQuery<TransformComponent>();
-
             var xform = xforms.GetComponent(value.Owner);
             var (worldPos, worldRot) = xform.GetWorldPositionRotation();
-            var bounds = new Box2Rotated(value.CalculateBoundingBox(worldPos), worldRot, worldPos);
-            var tree = GetRenderTree(value.Owner, xforms);
 
-            return tree == null ? bounds.CalcBoundingBox() : xforms.GetComponent(tree.Owner).InvWorldMatrix.TransformBox(bounds);
+            return SpriteAabbFunc(value, worldPos, worldRot, xforms);
         }
 
         private Box2 LightAabbFunc(in PointLightComponent value)
@@ -392,7 +391,7 @@ namespace Robust.Client.GameObjects
 
         private Box2 SpriteAabbFunc(SpriteComponent value, Vector2 worldPos, Angle worldRot, EntityQuery<TransformComponent> xforms)
         {
-            var bounds = new Box2Rotated(value.CalculateBoundingBox(worldPos), worldRot, worldPos);
+            var bounds = value.CalculateRotatedBoundingBox(worldPos, worldRot);
             var tree = GetRenderTree(value.Owner, xforms);
 
             return tree == null ? bounds.CalcBoundingBox() : xforms.GetComponent(tree.Owner).InvWorldMatrix.TransformBox(bounds);

Robust.Client/GameObjects/EntitySystems/SpriteSystem.Specifier.cs

@@ -0,0 +1,84 @@
+using System;
+using JetBrains.Annotations;
+using Robust.Client.Graphics;
+using Robust.Client.ResourceManagement;
+using Robust.Client.Utility;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Log;
+using Robust.Shared.Map;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Utility;
+
+namespace Robust.Client.GameObjects;
+
+public sealed partial class SpriteSystem
+{
+    [Dependency] private readonly IPrototypeManager _proto = default!;
+    [Dependency] private readonly IResourceCache _resourceCache = default!;
+
+    [Pure]
+    public Texture Frame0(SpriteSpecifier specifier)
+    {
+        return RsiStateLike(specifier).Default;
+    }
+
+    [Pure]
+    public IRsiStateLike RsiStateLike(SpriteSpecifier specifier)
+    {
+        switch (specifier)
+        {
+            case SpriteSpecifier.Texture tex:
+                return tex.GetTexture(_resourceCache);
+
+            case SpriteSpecifier.Rsi rsi:
+                return GetState(rsi);
+
+            case SpriteSpecifier.EntityPrototype prototypeIcon:
+                if (!_proto.TryIndex<EntityPrototype>(prototypeIcon.EntityPrototypeId, out var prototype))
+                {
+                    Logger.Error("Failed to load PrototypeIcon {0}", prototypeIcon.EntityPrototypeId);
+                    return SpriteComponent.GetFallbackState(_resourceCache);
+                }
+
+                return SpriteComponent.GetPrototypeIcon(prototype, _resourceCache);
+
+            default:
+                throw new NotSupportedException();
+        }
+    }
+
+    [Pure]
+    public IRsiStateLike GetPrototypeIcon(EntityPrototype prototype, IResourceCache resourceCache)
+    {
+        var icon = IconComponent.GetPrototypeIcon(prototype, _resourceCache);
+        if (icon != null) return icon;
+
+        if (!prototype.Components.ContainsKey("Sprite"))
+        {
+            return SpriteComponent.GetFallbackState(resourceCache);
+        }
+
+        var dummy = Spawn(prototype.ID, MapCoordinates.Nullspace);
+        var spriteComponent = EnsureComp<SpriteComponent>(dummy);
+        var result = spriteComponent.Icon ?? SpriteComponent.GetFallbackState(resourceCache);
+        Del(dummy);
+
+        return result;
+    }
+
+    [Pure]
+    public RSI.State GetState(SpriteSpecifier.Rsi rsiSpecifier)
+    {
+        if (_resourceCache.TryGetResource<RSIResource>(
+                SharedSpriteComponent.TextureRoot / rsiSpecifier.RsiPath,
+                out var theRsi) &&
+            theRsi.RSI.TryGetState(rsiSpecifier.RsiState, out var state))
+        {
+            return state;
+        }
+
+        Logger.Error("Failed to load RSI {0}", rsiSpecifier.RsiPath);
+        return SpriteComponent.GetFallbackState(_resourceCache);
+    }
+}

Robust.Client/GameObjects/EntitySystems/SpriteSystem.cs

@@ -11,7 +11,7 @@ namespace Robust.Client.GameObjects
     /// Updates the layer animation for every visible sprite.
     /// </summary>
     [UsedImplicitly]
-    public sealed class SpriteSystem : EntitySystem
+    public sealed partial class SpriteSystem : EntitySystem
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly RenderingTreeSystem _treeSystem = default!;

Robust.Client/GameStates/ClientGameStateManager.cs

@@ -45,7 +45,6 @@ namespace Robust.Client.GameStates
 
         [Dependency] private readonly IComponentFactory _compFactory = default!;
         [Dependency] private readonly IClientEntityManagerInternal _entities = default!;
-        [Dependency] private readonly IEntityLookup _lookup = default!;
         [Dependency] private readonly IPlayerManager _players = default!;
         [Dependency] private readonly IClientNetManager _network = default!;
         [Dependency] private readonly IBaseClient _client = default!;
@@ -332,8 +331,6 @@ namespace Robust.Client.GameStates
             }
 
             _entities.TickUpdate((float) _timing.TickPeriod.TotalSeconds, noPredictions: !IsPredictionEnabled);
-
-            _lookup.Update();
         }
 
         private void ResetPredictedEntities(GameTick curTick)

Robust.Client/Graphics/Clyde/Clyde.GridRendering.cs

@@ -18,8 +18,8 @@ namespace Robust.Client.Graphics.Clyde
         private readonly Dictionary<GridId, Dictionary<Vector2i, MapChunkData>> _mapChunkData =
             new();
 
-        private int _verticesPerChunk(IMapChunk chunk) => chunk.ChunkSize * chunk.ChunkSize * 4;
-        private int _indicesPerChunk(IMapChunk chunk) => chunk.ChunkSize * chunk.ChunkSize * GetQuadBatchIndexCount();
+        private int _verticesPerChunk(MapChunk chunk) => chunk.ChunkSize * chunk.ChunkSize * 4;
+        private int _indicesPerChunk(MapChunk chunk) => chunk.ChunkSize * chunk.ChunkSize * GetQuadBatchIndexCount();
 
         private void _drawGrids(Viewport viewport, Box2Rotated worldBounds, IEye eye)
         {
@@ -78,7 +78,7 @@ namespace Robust.Client.Graphics.Clyde
             }
         }
 
-        private void _updateChunkMesh(IMapGrid grid, IMapChunk chunk)
+        private void _updateChunkMesh(IMapGrid grid, MapChunk chunk)
         {
             var data = _mapChunkData[grid.Index];
 
@@ -91,25 +91,36 @@ namespace Robust.Client.Graphics.Clyde
             Span<Vertex2D> vertexBuffer = stackalloc Vertex2D[_verticesPerChunk(chunk)];
 
             var i = 0;
-            foreach (var tile in chunk)
+            var cSz = grid.ChunkSize;
+            var cScaled = chunk.Indices * cSz;
+            for (ushort x = 0; x < cSz; x++)
             {
-                var regionMaybe = _tileDefinitionManager.TileAtlasRegion(tile.Tile);
-                if (regionMaybe == null)
+                for (ushort y = 0; y < cSz; y++)
                 {
-                    continue;
+                    var tile = chunk.GetTile(x, y);
+                    if (tile.IsEmpty)
+                        continue;
+
+                    var regionMaybe = _tileDefinitionManager.TileAtlasRegion(tile.TypeId);
+                    if (regionMaybe == null)
+                    {
+                        continue;
+                    }
+
+                    var region = regionMaybe.Value;
+                    var gx = x + cScaled.X;
+                    var gy = y + cScaled.Y;
+
+                    var vIdx = i * 4;
+                    vertexBuffer[vIdx + 0] = new Vertex2D(gx, gy, region.Left, region.Bottom);
+                    vertexBuffer[vIdx + 1] = new Vertex2D(gx + 1, gy, region.Right, region.Bottom);
+                    vertexBuffer[vIdx + 2] = new Vertex2D(gx + 1, gy + 1, region.Right, region.Top);
+                    vertexBuffer[vIdx + 3] = new Vertex2D(gx, gy + 1, region.Left, region.Top);
+                    var nIdx = i * GetQuadBatchIndexCount();
+                    var tIdx = (ushort)(i * 4);
+                    QuadBatchIndexWrite(indexBuffer, ref nIdx, tIdx);
+                    i += 1;
                 }
-
-                var region = regionMaybe.Value;
-
-                var vIdx = i * 4;
-                vertexBuffer[vIdx + 0] = new Vertex2D(tile.X, tile.Y, region.Left, region.Bottom);
-                vertexBuffer[vIdx + 1] = new Vertex2D(tile.X + 1, tile.Y, region.Right, region.Bottom);
-                vertexBuffer[vIdx + 2] = new Vertex2D(tile.X + 1, tile.Y + 1, region.Right, region.Top);
-                vertexBuffer[vIdx + 3] = new Vertex2D(tile.X, tile.Y + 1, region.Left, region.Top);
-                var nIdx = i * GetQuadBatchIndexCount();
-                var tIdx = (ushort) (i * 4);
-                QuadBatchIndexWrite(indexBuffer, ref nIdx, tIdx);
-                i += 1;
             }
 
             GL.BindVertexArray(datum.VAO);
@@ -122,7 +133,7 @@ namespace Robust.Client.Graphics.Clyde
             datum.TileCount = i;
         }
 
-        private MapChunkData _initChunkBuffers(IMapGrid grid, IMapChunk chunk)
+        private MapChunkData _initChunkBuffers(IMapGrid grid, MapChunk chunk)
         {
             var vao = GenVertexArray();
             BindVertexArray(vao);
@@ -159,7 +170,7 @@ namespace Robust.Client.Graphics.Clyde
             return datum;
         }
 
-        private bool _isChunkDirty(IMapGrid grid, IMapChunk chunk)
+        private bool _isChunkDirty(IMapGrid grid, MapChunk chunk)
         {
             var data = _mapChunkData[grid.Index];
             return !data.TryGetValue(chunk.Indices, out var datum) || datum.Dirty;
@@ -175,7 +186,7 @@ namespace Robust.Client.Graphics.Clyde
             // Don't need to set it if we don't have an entry since lack of an entry is treated as dirty.
         }
 
-        private void _updateOnGridModified(object? sender, GridChangedEventArgs args)
+        private void _updateOnGridModified(GridModifiedEvent args)
         {
             foreach (var (pos, _) in args.Modified)
             {
@@ -185,21 +196,23 @@ namespace Robust.Client.Graphics.Clyde
             }
         }
 
-        private void _updateTileMapOnUpdate(object? sender, TileChangedEventArgs args)
+        private void _updateTileMapOnUpdate(TileChangedEvent args)
         {
             var grid = _mapManager.GetGrid(args.NewTile.GridIndex);
             var chunk = grid.GridTileToChunkIndices(new Vector2i(args.NewTile.X, args.NewTile.Y));
             _setChunkDirty(grid, chunk);
         }
 
-        private void _updateOnGridCreated(MapId mapId, GridId gridId)
+        private void _updateOnGridCreated(GridStartupEvent ev)
         {
+            var gridId = ev.GridId;
             Logger.DebugS("grid", $"Adding {gridId} to grid renderer");
             _mapChunkData.Add(gridId, new Dictionary<Vector2i, MapChunkData>());
         }
 
-        private void _updateOnGridRemoved(MapId mapId, GridId gridId)
+        private void _updateOnGridRemoved(GridRemovalEvent ev)
         {
+            var gridId = ev.GridId;
             Logger.DebugS("grid", $"Removing {gridId} from grid renderer");
 
             var data = _mapChunkData[gridId];

Robust.Client/Graphics/Clyde/Clyde.HLR.cs

@@ -24,11 +24,17 @@ namespace Robust.Client.Graphics.Clyde
     {
         public ClydeDebugLayers DebugLayers { get; set; }
 
-        private readonly RefList<(SpriteComponent sprite, Matrix3 worldMatrix, Angle worldRotation, float yWorldPos)>
+        private readonly RefList<(SpriteComponent sprite, Vector2 worldPos, Angle worldRotation, Box2 spriteScreenBB)>
             _drawingSpriteList
                 =
                 new();
 
+        // TODO allow this scale to be passed with PostShader as variable
+        /// <summary>
+        ///     Some shaders that enlarge the final sprite, like emission or highlight effects, need to use a slightly larger render target.
+        /// </summary>
+        public static float PostShadeScale = 1.25f;
+
         public void Render()
         {
             CheckTransferringScreenshots();
@@ -217,9 +223,8 @@ namespace Robust.Client.Graphics.Clyde
             RenderOverlays(viewport, OverlaySpace.WorldSpaceBelowEntities, worldAABB, worldBounds);
 
             var screenSize = viewport.Size;
-            eye.GetViewMatrix(out var eyeMatrix, eye.Scale);
 
-            ProcessSpriteEntities(mapId, eyeMatrix, worldBounds, _drawingSpriteList);
+            ProcessSpriteEntities(mapId, viewport, eye, worldBounds, _drawingSpriteList);
 
             var worldOverlays = new List<Overlay>();
 
@@ -276,30 +281,12 @@ namespace Robust.Client.Graphics.Clyde
                     break;
                 }
 
-                var matrix = entry.worldMatrix;
-                var worldPosition = new Vector2(matrix.R0C2, matrix.R1C2);
-
                 RenderTexture? entityPostRenderTarget = null;
                 Vector2i roundedPos = default;
                 if (entry.sprite.PostShader != null)
                 {
-                    // calculate world bounding box
-                    var spriteBB = entry.sprite.CalculateBoundingBox(worldPosition);
-                    var spriteLB = spriteBB.BottomLeft;
-                    var spriteRT = spriteBB.TopRight;
-
-                    // finally we can calculate screen bounding in pixels
-                    var screenLB = viewport.WorldToLocal(spriteLB);
-                    var screenRT = viewport.WorldToLocal(spriteRT);
-
-                    // we need to scale RT a for effects like emission or highlight
-                    // scale can be passed with PostShader as variable in future
-                    var postShadeScale = 1.25f;
-                    var screenSpriteSize = (Vector2i) ((screenRT - screenLB) * postShadeScale).Rounded();
-
-                    // Rotate the vector by the eye angle, otherwise the bounding box will be incorrect
-                    screenSpriteSize = (Vector2i) eye.Rotation.RotateVec(screenSpriteSize).Rounded();
-                    screenSpriteSize.Y = -screenSpriteSize.Y;
+                    // get the size of the sprite on screen, scaled slightly to allow for shaders that increase the final sprite size.
+                    var screenSpriteSize = (Vector2i) (entry.spriteScreenBB.Size * PostShadeScale).Rounded();
 
                     // I'm not 100% sure why it works, but without it post-shader
                     // can be lower or upper by 1px than original sprite depending on sprite rotation or scale
@@ -322,16 +309,14 @@ namespace Robust.Client.Graphics.Clyde
                         // Calculate viewport so that the entity thinks it's drawing to the same position,
                         // which is necessary for light application,
                         // but it's ACTUALLY drawing into the center of the render target.
-                        var spritePos = spriteBB.Center;
-                        var screenPos = viewport.WorldToLocal(spritePos);
-                        var (roundedX, roundedY) = roundedPos = (Vector2i) screenPos;
-                        var flippedPos = new Vector2i(roundedX, screenSize.Y - roundedY);
+                        roundedPos = (Vector2i) entry.spriteScreenBB.Center;
+                        var flippedPos = new Vector2i(roundedPos.X, screenSize.Y - roundedPos.Y);
                         flippedPos -= entityPostRenderTarget.Size / 2;
                         _renderHandle.Viewport(Box2i.FromDimensions(-flippedPos, screenSize));
                     }
                 }
 
-                entry.sprite.Render(_renderHandle.DrawingHandleWorld, eye.Rotation, in entry.worldRotation, in worldPosition);
+                entry.sprite.Render(_renderHandle.DrawingHandleWorld, eye.Rotation, in entry.worldRotation, in entry.worldPos);
 
                 if (entry.sprite.PostShader != null && entityPostRenderTarget != null)
                 {
@@ -369,17 +354,26 @@ namespace Robust.Client.Graphics.Clyde
         }
 
         [MethodImpl(MethodImplOptions.NoInlining)]
-        private void ProcessSpriteEntities(MapId map, Matrix3 eyeMatrix, Box2Rotated worldBounds,
-            RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> list)
+        private void ProcessSpriteEntities(MapId map, Viewport view, IEye eye, Box2Rotated worldBounds,
+            RefList<(SpriteComponent sprite, Vector2 worldPos, Angle worldRot, Box2 spriteScreenBB)> list)
         {
             var xforms = _entityManager.GetEntityQuery<TransformComponent>();
 
+            // Construct a matrix equivalent for Viewport.WorldToLocal()
+            eye.GetViewMatrix(out var viewMatrix, view.RenderScale);
+            var uiProjmatrix = Matrix3.Identity;
+            uiProjmatrix.R0C0 = EyeManager.PixelsPerMeter;
+            uiProjmatrix.R1C1 = -EyeManager.PixelsPerMeter;
+            uiProjmatrix.R0C2 = view.Size.X / 2f;
+            uiProjmatrix.R1C2 = view.Size.Y / 2f;
+            var worldToLocal = viewMatrix * uiProjmatrix;
+
             foreach (var comp in _entitySystemManager.GetEntitySystem<RenderingTreeSystem>().GetRenderTrees(map, worldBounds))
             {
                 var bounds = xforms.GetComponent(comp.Owner).InvWorldMatrix.TransformBox(worldBounds);
 
                 comp.SpriteTree.QueryAabb(ref list, (
-                    ref RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> state,
+                    ref RefList<(SpriteComponent sprite, Vector2 worldPos, Angle worldRot, Box2 spriteScreenBB)> state,
                     in SpriteComponent value) =>
                 {
                     var entity = value.Owner;
@@ -387,12 +381,10 @@ namespace Robust.Client.Graphics.Clyde
 
                     ref var entry = ref state.AllocAdd();
                     entry.sprite = value;
-                    Vector2 worldPos;
-                    (worldPos, entry.worldRot, entry.matrix) = transform.GetWorldPositionRotationMatrix();
-                    var eyePos = eyeMatrix.Transform(worldPos);
-                    // Didn't use the bounds from the query as that has to be re-calculated (and is probably more expensive than this).
-                    var bounds = value.CalculateBoundingBox(eyePos);
-                    entry.yWorldPos = eyePos.Y - bounds.Extents.Y;
+                    (entry.worldPos, entry.worldRot) = transform.GetWorldPositionRotation();
+
+                    var spriteWorldBB = value.CalculateRotatedBoundingBox(entry.worldPos, entry.worldRot, eye);
+                    entry.spriteScreenBB = worldToLocal.TransformBox(spriteWorldBB);
                     return true;
 
                 }, bounds, true);

Robust.Client/Graphics/Clyde/Clyde.LightRendering.cs

@@ -514,14 +514,14 @@ namespace Robust.Client.Graphics.Clyde
             var enlargedBounds = worldAABB.Enlarged(renderingTreeSystem.MaxLightRadius);
 
             // Use worldbounds for this one as we only care if the light intersects our actual bounds
-            var state = (this, worldAABB, count: 0);
+            var state = (this, worldAABB, count: 0, shadowCastingCount: 0);
             var xforms = _entityManager.GetEntityQuery<TransformComponent>();
 
             foreach (var comp in renderingTreeSystem.GetRenderTrees(map, enlargedBounds))
             {
                 var bounds = xforms.GetComponent(comp.Owner).InvWorldMatrix.TransformBox(worldBounds);
 
-                comp.LightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldAABB, int count) state, in PointLightComponent light) =>
+                comp.LightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldAABB, int count, int shadowCastingCount) state, in PointLightComponent light) =>
                 {
                     if (state.count >= LightsToRenderListSize)
                     {
@@ -543,6 +543,9 @@ namespace Robust.Client.Graphics.Clyde
                         return true;
                     }
 
+                    // If the light is a shadow casting light, keep a separate track of that
+                    if (light.CastShadows) state.shadowCastingCount++;
+
                     float distanceSquared = (state.worldAABB.Center - lightPos).LengthSquared;
                     state.clyde._lightsToRenderList[state.count++] = (light, lightPos, distanceSquared);
 
@@ -550,17 +553,29 @@ namespace Robust.Client.Graphics.Clyde
                 }, bounds);
             }
 
-            if (state.count > _maxLightsPerScene)
+            if (state.shadowCastingCount > _maxLightsPerScene)
             {
-                // There are too many lights to fit in the scene.
+                // There are too many lights casting shadows to fit in the scene.
                 // This check must occur before occluder expansion, or else bad things happen.
-                // Sort lights by distance.
+
+                // First, partition the array based on whether the lights are shadow casting or not
+                // (non shadow casting lights should be the first partition, shadow casting lights the second)
                 Array.Sort(_lightsToRenderList, 0, state.count, Comparer<(PointLightComponent light, Vector2 pos, float distanceSquared)>.Create((x, y) =>
+                {
+                    if (x.light.CastShadows && !y.light.CastShadows) return 1;
+                    else if (!x.light.CastShadows && y.light.CastShadows) return -1;
+                    else return 0;
+                }));
+
+                // Next, sort just the shadow casting lights by distance.
+                Array.Sort(_lightsToRenderList, state.count - state.shadowCastingCount, state.shadowCastingCount, Comparer<(PointLightComponent light, Vector2 pos, float distanceSquared)>.Create((x, y) =>
                 {
                     return x.distanceSquared.CompareTo(y.distanceSquared);
                 }));
-                // Then effectively delete the furthest lights.
-                state.count = _maxLightsPerScene;
+
+                // Then effectively delete the furthest lights, by setting the end of the array to exclude N
+                // number of shadow casting lights (where N is the number above the max number per scene.)
+                state.count -= state.shadowCastingCount - _maxLightsPerScene;
             }
 
             // When culling occluders later, we can't just remove any occluders outside the worldBounds.

Robust.Client/Graphics/Clyde/Clyde.Rendering.cs

@@ -994,9 +994,9 @@ namespace Robust.Client.Graphics.Clyde
 
         private sealed class SpriteDrawingOrderComparer : IComparer<int>
         {
-            private readonly RefList<(SpriteComponent, Matrix3, Angle, float)> _drawList;
+            private readonly RefList<(SpriteComponent, Vector2, Angle, Box2)> _drawList;
 
-            public SpriteDrawingOrderComparer(RefList<(SpriteComponent, Matrix3, Angle, float)> drawList)
+            public SpriteDrawingOrderComparer(RefList<(SpriteComponent, Vector2, Angle, Box2)> drawList)
             {
                 _drawList = drawList;
             }
@@ -1019,7 +1019,8 @@ namespace Robust.Client.Graphics.Clyde
                     return cmp;
                 }
 
-                cmp = _drawList[y].Item4.CompareTo(_drawList[x].Item4);
+                // compare the top of the sprite's BB for y-sorting. Because screen coordinates are flipped, the "top" of the BB is actually the "bottom".
+                cmp = _drawList[x].Item4.Top.CompareTo(_drawList[y].Item4.Top);
 
                 if (cmp != 0)
                 {

Robust.Client/Graphics/Clyde/Clyde.cs

@@ -22,7 +22,7 @@ namespace Robust.Client.Graphics.Clyde
     /// <summary>
     ///     Responsible for most things rendering on OpenGL mode.
     /// </summary>
-    internal sealed partial class Clyde : IClydeInternal, IPostInjectInit
+    internal sealed partial class Clyde : IClydeInternal, IPostInjectInit, IEntityEventSubscriber
     {
         [Dependency] private readonly IClydeTileDefinitionManager _tileDefinitionManager = default!;
         [Dependency] private readonly IEyeManager _eyeManager = default!;
@@ -134,16 +134,19 @@ namespace Robust.Client.Graphics.Clyde
 
         public void PostInject()
         {
-            _mapManager.TileChanged += _updateTileMapOnUpdate;
-            _mapManager.OnGridCreated += _updateOnGridCreated;
-            _mapManager.OnGridRemoved += _updateOnGridRemoved;
-            _mapManager.GridChanged += _updateOnGridModified;
-
             // This cvar does not modify the actual GL version requested or anything,
             // it overrides the version we detect to detect GL features.
             RegisterBlockCVars();
         }
 
+        public void RegisterGridEcsEvents()
+        {
+            _entityManager.EventBus.SubscribeEvent<TileChangedEvent>(EventSource.Local, this, _updateTileMapOnUpdate);
+            _entityManager.EventBus.SubscribeEvent<GridStartupEvent>(EventSource.Local, this, _updateOnGridCreated);
+            _entityManager.EventBus.SubscribeEvent<GridRemovalEvent>(EventSource.Local, this, _updateOnGridRemoved);
+            _entityManager.EventBus.SubscribeEvent<GridModifiedEvent>(EventSource.Local, this, _updateOnGridModified);
+        }
+
         private void GLInitBindings(bool gles)
         {
             _glBindingsContext = _glContext!.BindingsContext;

Robust.Client/Graphics/Clyde/ClydeHeadless.cs

@@ -76,6 +76,11 @@ namespace Robust.Client.Graphics.Clyde
             return null;
         }
 
+        public void RegisterGridEcsEvents()
+        {
+            // Nada.
+        }
+
         public void SetWindowTitle(string title)
         {
             // Nada.

Robust.Client/Graphics/IClydeInternal.cs

@@ -61,5 +61,7 @@ namespace Robust.Client.Graphics
 
         /// <returns>Null if not running on X11.</returns>
         uint? GetX11WindowId();
+
+        void RegisterGridEcsEvents();
     }
 }

Robust.Client/Map/ClydeTileDefinitionManager.cs

@@ -24,9 +24,16 @@ namespace Robust.Client.Map
 
         private readonly Dictionary<ushort, Box2> _tileRegions = new();
 
+        /// <inheritdoc />
         public Box2? TileAtlasRegion(Tile tile)
         {
-            if (_tileRegions.TryGetValue(tile.TypeId, out var region))
+            return TileAtlasRegion(tile.TypeId);
+        }
+
+        /// <inheritdoc />
+        public Box2? TileAtlasRegion(ushort tileType)
+        {
+            if (_tileRegions.TryGetValue(tileType, out var region))
             {
                 return region;
             }

Robust.Client/Map/IClydeTileDefinitionManager.cs

@@ -19,5 +19,11 @@ namespace Robust.Client.Map
         /// </summary>
         /// <returns>If null, do not draw the tile at all.</returns>
         Box2? TileAtlasRegion(Tile tile);
+
+        /// <summary>
+        ///     Gets the region inside the texture atlas to use to draw a tile type.
+        /// </summary>
+        /// <returns>If null, do not draw the tile at all.</returns>
+        Box2? TileAtlasRegion(ushort tileType);
     }
 }

Robust.Client/Physics/PhysicsSystem.cs

@@ -37,7 +37,7 @@ namespace Robust.Client.Physics
             SimulateWorld((float) diff.TotalSeconds, true);
         }
 
-        protected override void HandleMapCreated(object? sender, MapEventArgs eventArgs)
+        protected override void HandleMapCreated(MapChangedEvent eventArgs)
         {
             if (eventArgs.Map == MapId.Nullspace) return;
             var mapUid = MapManager.GetMapEntityId(eventArgs.Map);

Robust.Client/Placement/Modes/AlignSimilar.cs

@@ -31,7 +31,7 @@ namespace Robust.Client.Placement.Modes
 
             var mapId = MouseCoords.GetMapId(pManager.EntityManager);
 
-            var snapToEntities = IoCManager.Resolve<IEntityLookup>().GetEntitiesInRange(MouseCoords, SnapToRange)
+            var snapToEntities = EntitySystem.Get<EntityLookupSystem>().GetEntitiesInRange(MouseCoords, SnapToRange)
                 .Where(entity => pManager.EntityManager.GetComponent<MetaDataComponent>(entity).EntityPrototype == pManager.CurrentPrototype && pManager.EntityManager.GetComponent<TransformComponent>(entity).MapID == mapId)
                 .OrderBy(entity => (pManager.EntityManager.GetComponent<TransformComponent>(entity).WorldPosition - MouseCoords.ToMapPos(pManager.EntityManager)).LengthSquared)
                 .ToList();

Robust.Client/Placement/Modes/AlignTileEmpty.cs

@@ -53,7 +53,7 @@ namespace Robust.Client.Placement.Modes
             var topRight = new Vector2(CurrentTile.X + 0.99f, CurrentTile.Y + 0.99f);
             var box = new Box2(bottomLeft, topRight);
 
-            return !IoCManager.Resolve<IEntityLookup>().AnyEntitiesIntersecting(map, box);
+            return !EntitySystem.Get<EntityLookupSystem>().AnyEntitiesIntersecting(map, box);
         }
     }
 }

Robust.Client/Placement/PlacementManager.cs

@@ -22,7 +22,7 @@ using Robust.Shared.Utility;
 
 namespace Robust.Client.Placement
 {
-    public sealed partial class PlacementManager : IPlacementManager, IDisposable
+    public sealed partial class PlacementManager : IPlacementManager, IDisposable, IEntityEventSubscriber
     {
         [Dependency] private readonly IClientNetManager NetworkManager = default!;
         [Dependency] public readonly IPlayerManager PlayerManager = default!;
@@ -185,7 +185,7 @@ namespace Robust.Client.Placement
                 _modeDictionary.Add(type.Name, type);
             }
 
-            MapManager.TileChanged += HandleTileChanged;
+            EntityManager.EventBus.SubscribeEvent<TileChangedEvent>(EventSource.Local, this, HandleTileChanged);
 
             _drawOverlay = new PlacementOverlay(this);
             _overlayManager.AddOverlay(_drawOverlay);
@@ -328,7 +328,7 @@ namespace Robust.Client.Placement
             }
         }
 
-        private void HandleTileChanged(object? sender, TileChangedEventArgs args)
+        private void HandleTileChanged(TileChangedEvent args)
         {
             var coords = MapManager.GetGrid(args.NewTile.GridIndex).GridTileToLocal(args.NewTile.GridIndices);
             _pendingTileChanges.RemoveAll(c => c.Item1 == coords);

Robust.Client/ResourceManagement/ResourceTypes/RSIResource.cs

@@ -230,7 +230,7 @@ namespace Robust.Client.ResourceManagement
 
             using (var manifestFile = cache.ContentFileRead(manifestPath))
             {
-                if (manifestFile.Length <= 4096)
+                if (manifestFile.CanSeek && manifestFile.Length <= 4096)
                 {
                     // Most RSIs are actually tiny so if that's the case just load them into a stackalloc buffer.
                     // Avoids a ton of allocations with stream reader etc

Robust.Client/Robust.Client.csproj

@@ -53,6 +53,7 @@
     <Compile Update="UserInterface\CustomControls\DefaultWindow.xaml.cs">
       <DependentUpon>DefaultWindow.xaml</DependentUpon>
     </Compile>
+    <Compile Remove="Debugging\IDebugDrawing.cs" />
   </ItemGroup>
   <Import Project="..\MSBuild\Robust.Engine.targets" />
   <PropertyGroup>

Robust.Client/Utility/SpriteSpecifierExt.cs

@@ -22,6 +22,7 @@ namespace Robust.Client.Utility
                 .Texture;
         }
 
+        [Obsolete("Use SpriteSystem")]
         public static RSI.State GetState(this SpriteSpecifier.Rsi rsiSpecifier, IResourceCache cache)
         {
             if (cache.TryGetResource<RSIResource>(
@@ -36,6 +37,7 @@ namespace Robust.Client.Utility
             return SpriteComponent.GetFallbackState(cache);
         }
 
+        [Obsolete("Use SpriteSystem")]
         public static Texture Frame0(this SpriteSpecifier specifier)
         {
             return specifier.RsiStateLike().Default;
@@ -80,6 +82,7 @@ namespace Robust.Client.Utility
             return specifier.RsiStateLike();
         }
 
+        [Obsolete("Use SpriteSystem")]
         public static IRsiStateLike RsiStateLike(this SpriteSpecifier specifier)
         {
             var resC = IoCManager.Resolve<IResourceCache>();

Robust.Server/BaseServer.cs

@@ -66,18 +66,17 @@ namespace Robust.Server
 
         [Dependency] private readonly IConfigurationManagerInternal _config = default!;
         [Dependency] private readonly IServerEntityManager _entityManager = default!;
-        [Dependency] private readonly IEntityLookup _lookup = default!;
         [Dependency] private readonly ILogManager _log = default!;
         [Dependency] private readonly IRobustSerializer _serializer = default!;
         [Dependency] private readonly IGameTiming _time = default!;
         [Dependency] private readonly IResourceManagerInternal _resources = default!;
         [Dependency] private readonly IMapManager _mapManager = default!;
-        [Dependency] private readonly ITimerManager timerManager = default!;
+        [Dependency] private readonly ITimerManager _timerManager = default!;
         [Dependency] private readonly IServerGameStateManager _stateManager = default!;
         [Dependency] private readonly IServerNetManager _network = default!;
         [Dependency] private readonly ISystemConsoleManager _systemConsole = default!;
         [Dependency] private readonly ITaskManager _taskManager = default!;
-        [Dependency] private readonly IRuntimeLog runtimeLog = default!;
+        [Dependency] private readonly IRuntimeLog _runtimeLog = default!;
         [Dependency] private readonly IModLoaderInternal _modLoader = default!;
         [Dependency] private readonly IWatchdogApi _watchdogApi = default!;
         [Dependency] private readonly HubManager _hubManager = default!;
@@ -127,7 +126,7 @@ namespace Robust.Server
             else
                 Logger.InfoS("srv", $"{reason}, shutting down...");
 
-            _shutdownReason = reason;
+            _shutdownReason = reason ?? "Shutting down";
 
             if (_mainLoop != null) _mainLoop.Running = false;
             if (_logHandler != null)
@@ -344,7 +343,6 @@ namespace Robust.Server
             _consoleHost.Initialize();
             _entityManager.Startup();
             _mapManager.Startup();
-            IoCManager.Resolve<IEntityLookup>().Startup();
             _stateManager.Initialize();
 
             var reg = _entityManager.ComponentFactory.GetRegistration<TransformComponent>();
@@ -603,7 +601,6 @@ namespace Robust.Server
             _network.Shutdown($"Server shutting down: {_shutdownReason}");
 
             // shutdown entities
-            IoCManager.Resolve<IEntityLookup>().Shutdown();
             _entityManager.Cleanup();
 
             if (_config.GetCVar(CVars.LogRuntimeLog))
@@ -614,7 +611,7 @@ namespace Robust.Server
                 Directory.CreateDirectory(relPath);
                 var pathToWrite = Path.Combine(relPath,
                     "Runtime-" + DateTime.Now.ToString("yyyy-MM-dd-THH-mm-ss") + ".txt");
-                File.WriteAllText(pathToWrite, runtimeLog.Display(), EncodingHelpers.UTF8);
+                File.WriteAllText(pathToWrite, _runtimeLog.Display(), EncodingHelpers.UTF8);
             }
 
             AppDomain.CurrentDomain.ProcessExit -= ProcessExiting;
@@ -659,7 +656,8 @@ namespace Robust.Server
 
             using (TickUsage.WithLabels("Timers").NewTimer())
             {
-                timerManager.UpdateTimers(frameEventArgs);
+                _consoleHost.CommandBufferExecute();
+                _timerManager.UpdateTimers(frameEventArgs);
             }
 
             using (TickUsage.WithLabels("AsyncTasks").NewTimer())
@@ -670,8 +668,6 @@ namespace Robust.Server
             // Pass Histogram into the IEntityManager.Update so it can do more granular measuring.
             _entityManager.TickUpdate(frameEventArgs.DeltaSeconds, noPredictions: false, TickUsage);
 
-            _lookup.Update();
-
             using (TickUsage.WithLabels("PostEngine").NewTimer())
             {
                 _modLoader.BroadcastUpdate(ModUpdateLevel.PostEngine, frameEventArgs);

Robust.Server/Bql/BqlQuerySelector.Builtin.cs

@@ -311,7 +311,7 @@ namespace Robust.Server.Bql
         public override IEnumerable<EntityUid> DoSelection(IEnumerable<EntityUid> input, IReadOnlyList<object> arguments, bool isInverted, IEntityManager entityManager)
         {
             var radius = (float)(double)arguments[0];
-            var entityLookup = IoCManager.Resolve<IEntityLookup>();
+            var entityLookup = EntitySystem.Get<EntityLookupSystem>();
 
             // TODO: Make this a foreach and reduce LINQ chain because it'll allocate a LOT
             //BUG: GetEntitiesInRange effectively uses manhattan distance. This is not intended, near is supposed to be circular.

Robust.Server/Console/Commands/MapCommands.cs

@@ -29,14 +29,13 @@ namespace Robust.Server.Console.Commands
             var mapId = new MapId(int.Parse(args[0]));
 
             var mapMgr = IoCManager.Resolve<IMapManager>();
-            var pauseMgr = IoCManager.Resolve<IPauseManager>();
 
             if (!mapMgr.MapExists(mapId))
             {
                 mapMgr.CreateMap(mapId);
                 if (args.Length >= 2 && args[1] == "false")
                 {
-                    pauseMgr.AddUninitializedMap(mapId);
+                    mapMgr.AddUninitializedMap(mapId);
                 }
 
                 shell.WriteLine($"Map with ID {mapId} created.");
@@ -219,7 +218,11 @@ namespace Robust.Server.Console.Commands
             }
 
             IoCManager.Resolve<IMapLoader>().LoadMap(mapId, args[1]);
-            shell.WriteLine($"Map {mapId} has been loaded from {args[1]}.");
+
+            if (mapManager.MapExists(mapId))
+                shell.WriteLine($"Map {mapId} has been loaded from {args[1]}.");
+            else
+                shell.WriteError($"Error while loading map from {args[1]}.");
         }
     }
 
@@ -318,7 +321,6 @@ namespace Robust.Server.Console.Commands
             }
 
             var mapManager = IoCManager.Resolve<IMapManager>();
-            var pauseManager = IoCManager.Resolve<IPauseManager>();
 
             var arg = args[0];
             var mapId = new MapId(int.Parse(arg, CultureInfo.InvariantCulture));
@@ -329,13 +331,13 @@ namespace Robust.Server.Console.Commands
                 return;
             }
 
-            if (pauseManager.IsMapInitialized(mapId))
+            if (mapManager.IsMapInitialized(mapId))
             {
                 shell.WriteError("Map is already initialized!");
                 return;
             }
 
-            pauseManager.DoMapInitialize(mapId);
+            mapManager.DoMapInitialize(mapId);
         }
     }
 
@@ -348,17 +350,16 @@ namespace Robust.Server.Console.Commands
         public void Execute(IConsoleShell shell, string argStr, string[] args)
         {
             var mapManager = IoCManager.Resolve<IMapManager>();
-            var pauseManager = IoCManager.Resolve<IPauseManager>();
 
             var msg = new StringBuilder();
 
             foreach (var mapId in mapManager.GetAllMapIds().OrderBy(id => id.Value))
             {
                 msg.AppendFormat("{0}: init: {1}, paused: {2}, ent: {3}, grids: {4}\n",
-                    mapId, pauseManager.IsMapInitialized(mapId),
-                    pauseManager.IsMapPaused(mapId),
-                    string.Join(",", mapManager.GetAllMapGrids(mapId).Select(grid => grid.Index)),
-                    mapManager.GetMapEntityId(mapId));
+                    mapId, mapManager.IsMapInitialized(mapId),
+                    mapManager.IsMapPaused(mapId),
+                    mapManager.GetMapEntityId(mapId),
+                    string.Join(",", mapManager.GetAllMapGrids(mapId).Select(grid => grid.Index)));
             }
 
             shell.WriteLine(msg.ToString());
@@ -380,7 +381,7 @@ namespace Robust.Server.Console.Commands
             foreach (var grid in mapManager.GetAllGrids().OrderBy(grid => grid.Index.Value))
             {
                 msg.AppendFormat("{0}: map: {1}, ent: {2}, pos: {3} \n",
-                    grid.Index, grid.ParentMapId, grid.WorldPosition, grid.GridEntityId);
+                    grid.Index, grid.ParentMapId, grid.GridEntityId, grid.WorldPosition);
             }
 
             shell.WriteLine(msg.ToString());

Robust.Server/Console/Commands/TestbedCommand.cs

@@ -109,9 +109,8 @@ namespace Robust.Server.Console.Commands
         private void SetupPlayer(MapId mapId, IConsoleShell shell, IPlayerSession? player, IMapManager mapManager)
         {
             if (mapId == MapId.Nullspace) return;
-            var pauseManager = IoCManager.Resolve<IPauseManager>();
-            pauseManager.SetMapPaused(mapId, false);
-            var mapUid = IoCManager.Resolve<IMapManager>().GetMapEntityIdOrThrow(mapId);
+            mapManager.SetMapPaused(mapId, false);
+            var mapUid = mapManager.GetMapEntityIdOrThrow(mapId);
             IoCManager.Resolve<IEntityManager>().GetComponent<SharedPhysicsMapComponent>(mapUid).Gravity = new Vector2(0, -9.8f);
 
             return;

Robust.Server/GameObjects/EntitySystems/AppearanceSystem.cs

@@ -3,7 +3,7 @@ using Robust.Shared.GameStates;
 
 namespace Robust.Server.GameObjects;
 
-internal sealed class AppearanceSystem : SharedAppearanceSystem
+public sealed class AppearanceSystem : SharedAppearanceSystem
 {
     public override void Initialize()
     {

Robust.Server/GameObjects/EntitySystems/PhysicsSystem.cs

@@ -1,4 +1,4 @@
-using JetBrains.Annotations;
+using JetBrains.Annotations;
 using Robust.Server.Physics;
 using Robust.Shared;
 using Robust.Shared.Configuration;
@@ -37,7 +37,7 @@ namespace Robust.Server.GameObjects
             collideComp.BodyType = BodyType.Static;
         }
 
-        protected override void HandleMapCreated(object? sender, MapEventArgs eventArgs)
+        protected override void HandleMapCreated(MapChangedEvent eventArgs)
         {
             if (eventArgs.Map == MapId.Nullspace) return;
             var mapUid = MapManager.GetMapEntityIdOrThrow(eventArgs.Map);

Robust.Server/GameStates/ChunkIndicesEnumerator.cs

@@ -5,30 +5,31 @@ namespace Robust.Server.GameStates;
 
 public struct ChunkIndicesEnumerator
 {
-    private Vector2i _topLeft;
-    private Vector2i _bottomRight;
+    private Vector2i _bottomLeft;
+    private Vector2i _topRight;
 
     private int _x;
     private int _y;
 
-    public ChunkIndicesEnumerator(Box2 viewBox, float chunkSize)
+    public ChunkIndicesEnumerator(Vector2 viewPos, float range, float chunkSize)
     {
-        _topLeft = (viewBox.TopLeft / chunkSize).Floored();
-        _bottomRight = (viewBox.BottomRight / chunkSize).Floored();
+        _bottomLeft = ((viewPos - range) / chunkSize).Floored();
+        // Also floor this as we get the whole chunk anyway.
+        _topRight = ((viewPos + range) / chunkSize).Floored();
 
-        _x = _topLeft.X;
-        _y = _bottomRight.Y;
+        _x = _bottomLeft.X;
+        _y = _bottomLeft.Y;
     }
 
     public bool MoveNext([NotNullWhen(true)] out Vector2i? chunkIndices)
     {
-        if (_y > _topLeft.Y)
+        if (_y > _topRight.Y)
         {
             _x++;
-            _y = _bottomRight.Y;
+            _y = _bottomLeft.Y;
         }
 
-        if (_x > _bottomRight.X)
+        if (_x > _topRight.X)
         {
             chunkIndices = null;
             return false;

Robust.Server/GameStates/PVSCollection.cs

@@ -37,7 +37,6 @@ public interface IPVSCollection
 public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : IComparable<TIndex>, IEquatable<TIndex>
 {
     [Shared.IoC.Dependency] private readonly IEntityManager _entityManager = default!;
-    [Shared.IoC.Dependency] private readonly IMapManager _mapManager = default!;
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static Vector2i GetChunkIndices(Vector2 coordinates)
@@ -81,14 +80,14 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
     private readonly List<(GameTick tick, TIndex index)> _deletionHistory = new();
 
     /// <summary>
-    /// An index containing the <see cref="IndexLocation"/>s of all <see cref="TIndex"/>.
+    /// An index containing the <see cref="IIndexLocation"/>s of all <see cref="TIndex"/>.
     /// </summary>
-    private readonly Dictionary<TIndex, IndexLocation> _indexLocations = new();
+    private readonly Dictionary<TIndex, IIndexLocation> _indexLocations = new();
 
     /// <summary>
     /// Buffer of all locationchanges since the last process call
     /// </summary>
-    private readonly Dictionary<TIndex, IndexLocation> _locationChangeBuffer = new();
+    private readonly Dictionary<TIndex, IIndexLocation> _locationChangeBuffer = new();
     /// <summary>
     /// Buffer of all indexremovals since the last process call
     /// </summary>
@@ -103,7 +102,7 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
     {
         var changedIndices = new HashSet<TIndex>(_locationChangeBuffer.Keys);
 
-        var changedChunkLocations = new HashSet<IndexLocation>();
+        var changedChunkLocations = new HashSet<IIndexLocation>();
         foreach (var (index, tick) in _removalBuffer)
         {
             //changes dont need to be computed if we are removing the index anyways
@@ -154,7 +153,7 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
 
     public HashSet<TIndex>.Enumerator GetElementsForSession(ICommonSession session) => _localOverrides[session].GetEnumerator();
 
-    private void AddIndexInternal(TIndex index, IndexLocation location)
+    private void AddIndexInternal(TIndex index, IIndexLocation location)
     {
         switch (location)
         {
@@ -186,7 +185,7 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
         _indexLocations.Add(index, location);
     }
 
-    private IndexLocation? RemoveIndexInternal(TIndex index)
+    private IIndexLocation? RemoveIndexInternal(TIndex index)
     {
         // the index might be gone due to disconnects/grid-/map-deletions
         if (!_indexLocations.TryGetValue(index, out var location))
@@ -352,14 +351,14 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
         var gridId = coordinates.GetGridId(_entityManager);
         if (gridId != GridId.Invalid)
         {
-            var gridIndices = GetChunkIndices(_mapManager.GetGrid(gridId).LocalToGrid(coordinates));
+            var gridIndices = GetChunkIndices(coordinates.Position);
             UpdateIndex(index, gridId, gridIndices, true); //skip overridecheck bc we already did it (saves some dict lookups)
             return;
         }
 
-        var mapId = coordinates.GetMapId(_entityManager);
-        var mapIndices = GetChunkIndices(coordinates.ToMapPos(_entityManager));
-        UpdateIndex(index, mapId, mapIndices, true); //skip overridecheck bc we already did it (saves some dict lookups)
+        var mapCoordinates = coordinates.ToMap(_entityManager);
+        var mapIndices = GetChunkIndices(coordinates.Position);
+        UpdateIndex(index, mapCoordinates.MapId, mapIndices, true); //skip overridecheck bc we already did it (saves some dict lookups)
     }
 
     /// <summary>
@@ -392,7 +391,7 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
         RegisterUpdate(index, new MapChunkLocation(mapId, chunkIndices));
     }
 
-    private void RegisterUpdate(TIndex index, IndexLocation location)
+    private void RegisterUpdate(TIndex index, IIndexLocation location)
     {
         if(_indexLocations.TryGetValue(index, out var oldLocation) && oldLocation == location) return;
 
@@ -400,14 +399,78 @@ public sealed class PVSCollection<TIndex> : IPVSCollection where TIndex : ICompa
     }
 
     #endregion
-
-    #region IndexLocations
-
-    private abstract record IndexLocation;
-    private record MapChunkLocation(MapId MapId, Vector2i ChunkIndices) : IndexLocation;
-    private record GridChunkLocation(GridId GridId, Vector2i ChunkIndices) : IndexLocation;
-    private record GlobalOverride : IndexLocation;
-    private record LocalOverride(ICommonSession Session) : IndexLocation;
-
-    #endregion
 }
+
+#region IndexLocations
+
+public interface IIndexLocation {};
+
+public interface IChunkIndexLocation{ };
+
+public struct MapChunkLocation : IIndexLocation, IChunkIndexLocation, IEquatable<MapChunkLocation>
+{
+    public MapChunkLocation(MapId mapId, Vector2i chunkIndices)
+    {
+        MapId = mapId;
+        ChunkIndices = chunkIndices;
+    }
+
+    public MapId MapId { get; init; }
+    public Vector2i ChunkIndices { get; init; }
+
+    public bool Equals(MapChunkLocation other)
+    {
+        return MapId.Equals(other.MapId) && ChunkIndices.Equals(other.ChunkIndices);
+    }
+
+    public override bool Equals(object? obj)
+    {
+        return obj is MapChunkLocation other && Equals(other);
+    }
+
+    public override int GetHashCode()
+    {
+        return HashCode.Combine(MapId, ChunkIndices);
+    }
+}
+
+public struct GridChunkLocation : IIndexLocation, IChunkIndexLocation, IEquatable<GridChunkLocation>
+{
+    public GridChunkLocation(GridId gridId, Vector2i chunkIndices)
+    {
+        GridId = gridId;
+        ChunkIndices = chunkIndices;
+    }
+
+    public GridId GridId { get; init; }
+    public Vector2i ChunkIndices { get; init; }
+
+    public bool Equals(GridChunkLocation other)
+    {
+        return GridId.Equals(other.GridId) && ChunkIndices.Equals(other.ChunkIndices);
+    }
+
+    public override bool Equals(object? obj)
+    {
+        return obj is GridChunkLocation other && Equals(other);
+    }
+
+    public override int GetHashCode()
+    {
+        return HashCode.Combine(GridId, ChunkIndices);
+    }
+}
+
+public struct GlobalOverride : IIndexLocation { }
+
+public struct LocalOverride : IIndexLocation
+{
+    public LocalOverride(ICommonSession session)
+    {
+        Session = session;
+    }
+
+    public ICommonSession Session { get; init; }
+}
+
+#endregion

Robust.Server/GameStates/PVSSystem.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
+using System.Composition;
 using System.Runtime.CompilerServices;
 using Microsoft.Extensions.ObjectPool;
 using NetSerializer;
@@ -23,7 +25,9 @@ internal sealed partial class PVSSystem : EntitySystem
     [Shared.IoC.Dependency] private readonly IMapManager _mapManager = default!;
     [Shared.IoC.Dependency] private readonly IPlayerManager _playerManager = default!;
     [Shared.IoC.Dependency] private readonly IConfigurationManager _configManager = default!;
+    [Shared.IoC.Dependency] private readonly IServerEntityManager _serverEntManager = default!;
     [Shared.IoC.Dependency] private readonly IServerGameStateManager _stateManager = default!;
+    [Shared.IoC.Dependency] private readonly SharedTransformSystem _transform = default!;
 
     public const float ChunkSize = 8;
 
@@ -35,7 +39,7 @@ internal sealed partial class PVSSystem : EntitySystem
     /// <summary>
     /// Is view culling enabled, or will we send the whole map?
     /// </summary>
-    private bool _cullingEnabled;
+    public bool CullingEnabled { get; private set; }
 
     /// <summary>
     /// How many new entities we can send per tick (dont wanna nuke the clients mailbox).
@@ -52,34 +56,62 @@ internal sealed partial class PVSSystem : EntitySystem
     /// </summary>
     private float _viewSize;
 
+    /// <summary>
+    /// If PVS disabled then we'll track if we've dumped all entities on the player.
+    /// This way any future ticks can be orders of magnitude faster as we only send what changes.
+    /// </summary>
+    public HashSet<ICommonSession> SeenAllEnts = new();
+
     /// <summary>
     /// All <see cref="Robust.Shared.GameObjects.EntityUid"/>s a <see cref="ICommonSession"/> saw last iteration.
     /// </summary>
     private readonly Dictionary<ICommonSession, Dictionary<EntityUid, PVSEntityVisiblity>> _playerVisibleSets = new();
+    /// <summary>
+    /// All <see cref="Robust.Shared.GameObjects.EntityUid"/>s a <see cref="ICommonSession"/> saw along its entire connection.
+    /// </summary>
     private readonly Dictionary<ICommonSession, HashSet<EntityUid>> _playerSeenSets = new();
 
     private PVSCollection<EntityUid> _entityPvsCollection = default!;
     public PVSCollection<EntityUid> EntityPVSCollection => _entityPvsCollection;
     private readonly List<IPVSCollection> _pvsCollections = new();
 
-    private readonly ObjectPool<Dictionary<EntityUid, PVSEntityVisiblity>> _visSetPool =
-        new DefaultObjectPool<Dictionary<EntityUid, PVSEntityVisiblity>>(
-            new DefaultPooledObjectPolicy<Dictionary<EntityUid, PVSEntityVisiblity>>(), MaxVisPoolSize);
-    private readonly ObjectPool<HashSet<EntityUid>> _viewerEntsPool
-        = new DefaultObjectPool<HashSet<EntityUid>>(new DefaultPooledObjectPolicy<HashSet<EntityUid>>(), MaxVisPoolSize);
+    private readonly ObjectPool<Dictionary<EntityUid, PVSEntityVisiblity>> _visSetPool
+        = new DefaultObjectPool<Dictionary<EntityUid, PVSEntityVisiblity>>(
+            new DictPolicy<EntityUid, PVSEntityVisiblity>(), MaxVisPoolSize);
+
+    private readonly ObjectPool<HashSet<EntityUid>> _uidSetPool
+        = new DefaultObjectPool<HashSet<EntityUid>>(new SetPolicy<EntityUid>(), MaxVisPoolSize);
+
+    private readonly ObjectPool<Dictionary<EntityUid, MetaDataComponent>> _chunkCachePool =
+        new DefaultObjectPool<Dictionary<EntityUid, MetaDataComponent>>(
+            new DictPolicy<EntityUid, MetaDataComponent>(), MaxVisPoolSize);
+
+    private readonly ObjectPool<HashSet<int>> _playerChunkPool =
+        new DefaultObjectPool<HashSet<int>>(new SetPolicy<int>(), MaxVisPoolSize);
+
+    private readonly ObjectPool<RobustTree<EntityUid>> _treePool =
+        new DefaultObjectPool<RobustTree<EntityUid>>(new TreePolicy<EntityUid>());
 
     public override void Initialize()
     {
         base.Initialize();
 
         _entityPvsCollection = RegisterPVSCollection<EntityUid>();
-        _mapManager.MapCreated += OnMapCreated;
-        _mapManager.MapDestroyed += OnMapDestroyed;
-        _mapManager.OnGridCreated += OnGridCreated;
-        _mapManager.OnGridRemoved += OnGridRemoved;
+
+        SubscribeLocalEvent<MapChangedEvent>(ev =>
+        {
+            if (ev.Created)
+                OnMapCreated(ev);
+            else
+                OnMapDestroyed(ev);
+        });
+
+        SubscribeLocalEvent<GridInitializeEvent>(OnGridCreated);
+        SubscribeLocalEvent<GridRemovalEvent>(OnGridRemoved);
+
         _playerManager.PlayerStatusChanged += OnPlayerStatusChanged;
         SubscribeLocalEvent<MoveEvent>(OnEntityMove);
-        SubscribeLocalEvent<TransformComponent, ComponentInit>(OnTransformInit);
+        SubscribeLocalEvent<TransformComponent, ComponentStartup>(OnTransformStartup);
         EntityManager.EntityDeleted += OnEntityDeleted;
 
         _configManager.OnValueChanged(CVars.NetPVS, SetPvs, true);
@@ -100,10 +132,6 @@ internal sealed partial class PVSSystem : EntitySystem
         base.Shutdown();
 
         UnregisterPVSCollection(_entityPvsCollection);
-        _mapManager.MapCreated -= OnMapCreated;
-        _mapManager.MapDestroyed -= OnMapDestroyed;
-        _mapManager.OnGridCreated -= OnGridCreated;
-        _mapManager.OnGridRemoved -= OnGridRemoved;
         _playerManager.PlayerStatusChanged -= OnPlayerStatusChanged;
         EntityManager.EntityDeleted -= OnEntityDeleted;
 
@@ -121,7 +149,7 @@ internal sealed partial class PVSSystem : EntitySystem
 
     private void SetPvs(bool value)
     {
-        _cullingEnabled = value;
+        CullingEnabled = value;
     }
 
     private void OnNewEntityBudgetChanged(int obj)
@@ -139,7 +167,21 @@ internal sealed partial class PVSSystem : EntitySystem
 
     public void Cleanup(IEnumerable<IPlayerSession> sessions)
     {
-        CleanupDirty(sessions);
+        var playerSessions = sessions.ToArray();
+
+        if (!CullingEnabled)
+        {
+            foreach (var player in playerSessions)
+            {
+                SeenAllEnts.Add(player);
+            }
+        }
+        else
+        {
+            SeenAllEnts.Clear();
+        }
+
+        CleanupDirty(playerSessions);
     }
 
     public void CullDeletionHistory(GameTick oldestAck)
@@ -170,29 +212,36 @@ internal sealed partial class PVSSystem : EntitySystem
 
     private void OnEntityMove(ref MoveEvent ev)
     {
-        UpdateEntityRecursive(ev.Sender, ev.Component);
+        var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+        var coordinates = _transform.GetMoverCoordinates(ev.Component);
+        UpdateEntityRecursive(ev.Sender, ev.Component, coordinates, xformQuery, false);
     }
 
-    private void OnTransformInit(EntityUid uid, TransformComponent component, ComponentInit args)
+    private void OnTransformStartup(EntityUid uid, TransformComponent component, ComponentStartup args)
     {
-        UpdateEntityRecursive(uid, component);
+        // use Startup because GridId is not set during the eventbus init yet!
+        var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+        var coordinates = _transform.GetMoverCoordinates(component);
+        UpdateEntityRecursive(uid, component, coordinates, xformQuery, false);
     }
 
-    private void UpdateEntityRecursive(EntityUid uid, TransformComponent? transformComponent = null)
+    private void UpdateEntityRecursive(EntityUid uid, TransformComponent xform, EntityCoordinates coordinates, EntityQuery<TransformComponent> xformQuery, bool mover)
     {
-        if(!Resolve(uid, ref transformComponent))
-            return;
+        if (mover && !xform.LocalPosition.Equals(Vector2.Zero))
+        {
+            coordinates = _transform.GetMoverCoordinates(xform);
+        }
 
-        _entityPvsCollection.UpdateIndex(uid, transformComponent.Coordinates);
+        _entityPvsCollection.UpdateIndex(uid, coordinates);
 
         // since elements are cached grid-/map-relative, we dont need to update a given grids/maps children
         if(_mapManager.IsGrid(uid) || _mapManager.IsMap(uid)) return;
 
-        var children = transformComponent.ChildEnumerator;
+        var children = xform.ChildEnumerator;
 
         while (children.MoveNext(out var child))
         {
-            UpdateEntityRecursive(child.Value);
+            UpdateEntityRecursive(child.Value, xformQuery.GetComponent(child.Value), coordinates, xformQuery, true);
         }
     }
 
@@ -209,8 +258,9 @@ internal sealed partial class PVSSystem : EntitySystem
         }
         else if (e.NewStatus == SessionStatus.Disconnected)
         {
-            _visSetPool.Return(_playerVisibleSets[e.Session]);
+            var playerVisSet = _playerVisibleSets[e.Session];
             _playerVisibleSets.Remove(e.Session);
+            _visSetPool.Return(playerVisSet);
             _playerSeenSets.Remove(e.Session);
             foreach (var pvsCollection in _pvsCollections)
             {
@@ -219,16 +269,17 @@ internal sealed partial class PVSSystem : EntitySystem
         }
     }
 
-    private void OnGridRemoved(MapId mapId, GridId gridId)
+    private void OnGridRemoved(GridRemovalEvent ev)
     {
         foreach (var pvsCollection in _pvsCollections)
         {
-            pvsCollection.RemoveGrid(gridId);
+            pvsCollection.RemoveGrid(ev.GridId);
         }
     }
 
-    private void OnGridCreated(MapId mapId, GridId gridId)
+    private void OnGridCreated(GridInitializeEvent ev)
     {
+        var gridId = ev.GridId;
         foreach (var pvsCollection in _pvsCollections)
         {
             pvsCollection.AddGrid(gridId);
@@ -238,7 +289,7 @@ internal sealed partial class PVSSystem : EntitySystem
         _entityPvsCollection.UpdateIndex(euid);
     }
 
-    private void OnMapDestroyed(object? sender, MapEventArgs e)
+    private void OnMapDestroyed(MapChangedEvent e)
     {
         foreach (var pvsCollection in _pvsCollections)
         {
@@ -246,7 +297,7 @@ internal sealed partial class PVSSystem : EntitySystem
         }
     }
 
-    private void OnMapCreated(object? sender, MapEventArgs e)
+    private void OnMapCreated(MapChangedEvent e)
     {
         foreach (var pvsCollection in _pvsCollections)
         {
@@ -260,114 +311,219 @@ internal sealed partial class PVSSystem : EntitySystem
 
     #endregion
 
-    public (List<EntityState>? updates, List<EntityUid>? deletions) CalculateEntityStates(ICommonSession session,
-        GameTick fromTick, GameTick toTick)
+    public (List<(uint, IChunkIndexLocation)> , HashSet<int>[], EntityUid[][] viewers) GetChunks(IPlayerSession[] sessions)
     {
-        DebugTools.Assert(session.Status == SessionStatus.InGame);
-        var newEntitiesSent = 0;
-        var entitiesSent = 0;
-
-        var deletions = _entityPvsCollection.GetDeletedIndices(fromTick);
-        if (!_cullingEnabled)
-        {
-            var allStates = GetAllEntityStates(session, fromTick, toTick);
-            return (allStates, deletions);
-        }
-
-        var playerVisibleSet = _playerVisibleSets[session];
-        var visibleEnts = _visSetPool.Get();
-        var seenSet = _playerSeenSets[session];
-
-        visibleEnts.Clear();
-
+        var chunkList = new List<(uint, IChunkIndexLocation)>();
+        var playerChunks = new HashSet<int>[sessions.Length];
         var eyeQuery = EntityManager.GetEntityQuery<EyeComponent>();
         var transformQuery = EntityManager.GetEntityQuery<TransformComponent>();
-        var metadataQuery = EntityManager.GetEntityQuery<MetaDataComponent>();
+        var viewerEntities = new EntityUid[sessions.Length][];
 
-        var globalOverridesEnumerator = _entityPvsCollection.GlobalOverridesEnumerator;
-        while(globalOverridesEnumerator.MoveNext())
+        // Keep track of the index of each chunk we use for a faster index lookup.
+        var mapIndices = new Dictionary<uint, Dictionary<MapChunkLocation, int>>(4);
+        var gridIndices = new Dictionary<uint, Dictionary<GridChunkLocation, int>>(4);
+
+        for (int i = 0; i < sessions.Length; i++)
         {
-            var uid = globalOverridesEnumerator.Current;
-            //todo paul reenable budgetcheck here once you fix mapmanager
-            TryAddToVisibleEnts(
-                in uid,
-                seenSet,
-                playerVisibleSet,
-                visibleEnts,
-                fromTick,
-                ref newEntitiesSent,
-                ref entitiesSent,
-                metadataQuery,
-                transformQuery,
-                dontSkip: true);
-        }
-        globalOverridesEnumerator.Dispose();
+            var session = sessions[i];
+            playerChunks[i] = _playerChunkPool.Get();
 
-        var localOverridesEnumerator = _entityPvsCollection.GetElementsForSession(session);
-        while (localOverridesEnumerator.MoveNext())
-        {
-            var uid = localOverridesEnumerator.Current;
-            //todo paul reenable budgetcheck here once you fix mapmanager
-            TryAddToVisibleEnts(in uid, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent, ref entitiesSent, metadataQuery, transformQuery, dontSkip: true);
-        }
-        localOverridesEnumerator.Dispose();
+            var viewers = GetSessionViewers(session);
+            viewerEntities[i] = new EntityUid[viewers.Count];
+            viewers.CopyTo(viewerEntities[i]);
 
-        var expandEvent = new ExpandPvsEvent((IPlayerSession) session, new List<EntityUid>());
-        RaiseLocalEvent(ref expandEvent);
-        foreach (var entityUid in expandEvent.Entities)
-        {
-            TryAddToVisibleEnts(in entityUid, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent, ref entitiesSent, metadataQuery, transformQuery);
-        }
-
-        var viewers = GetSessionViewers(session);
-
-        foreach (var eyeEuid in viewers)
-        {
-            var (viewBox, mapId) = CalcViewBounds(in eyeEuid, transformQuery);
-
-            uint visMask = EyeComponent.DefaultVisibilityMask;
-            if (eyeQuery.TryGetComponent(eyeEuid, out var eyeComp))
-                visMask = eyeComp.VisibilityMask;
-
-            //todo at some point just register the viewerentities as localoverrides
-            TryAddToVisibleEnts(in eyeEuid, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent, ref entitiesSent, metadataQuery, transformQuery, visMask, dontSkip: true);
-
-            var mapChunkEnumerator = new ChunkIndicesEnumerator(viewBox, ChunkSize);
-
-            while (mapChunkEnumerator.MoveNext(out var chunkIndices))
+            foreach (var eyeEuid in viewers)
             {
-                if(_entityPvsCollection.TryGetChunk(mapId, chunkIndices.Value, out var chunk))
+                var (viewPos, range, mapId) = CalcViewBounds(in eyeEuid, transformQuery);
+
+                uint visMask = EyeComponent.DefaultVisibilityMask;
+                if (eyeQuery.TryGetComponent(eyeEuid, out var eyeComp))
+                    visMask = eyeComp.VisibilityMask;
+
+                // Get the nyoom dictionary for index lookups.
+                if (!mapIndices.TryGetValue(visMask, out var mapDict))
                 {
-                    foreach (var index in chunk)
+                    mapDict = new Dictionary<MapChunkLocation, int>(32);
+                    mapIndices[visMask] = mapDict;
+                }
+
+                var mapChunkEnumerator = new ChunkIndicesEnumerator(viewPos, range, ChunkSize);
+
+                while (mapChunkEnumerator.MoveNext(out var chunkIndices))
+                {
+                    var chunkLocation = new MapChunkLocation(mapId, chunkIndices.Value);
+                    var entry = (visMask, chunkLocation);
+
+                    if (mapDict.TryGetValue(chunkLocation, out var indexOf))
                     {
-                        TryAddToVisibleEnts(in index, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent, ref entitiesSent, metadataQuery, transformQuery, visMask);
+                        playerChunks[i].Add(indexOf);
+                    }
+                    else
+                    {
+                        playerChunks[i].Add(chunkList.Count);
+                        mapDict.Add(chunkLocation, chunkList.Count);
+                        chunkList.Add(entry);
                     }
                 }
-            }
 
-            _mapManager.FindGridsIntersectingEnumerator(mapId, viewBox, out var gridEnumerator, true);
-            while (gridEnumerator.MoveNext(out var mapGrid))
-            {
-                var gridXform = transformQuery.GetComponent(mapGrid.GridEntityId);
-
-                var gridChunkEnumerator =
-                    new ChunkIndicesEnumerator(gridXform.InvWorldMatrix.TransformBox(viewBox), ChunkSize);
-
-                while (gridChunkEnumerator.MoveNext(out var gridChunkIndices))
+                // Get the nyoom dictionary for index lookups.
+                if (!gridIndices.TryGetValue(visMask, out var gridDict))
                 {
-                    if (_entityPvsCollection.TryGetChunk(mapGrid.Index, gridChunkIndices.Value, out var chunk))
+                    gridDict = new Dictionary<GridChunkLocation, int>(32);
+                    gridIndices[visMask] = gridDict;
+                }
+
+                _mapManager.FindGridsIntersectingEnumerator(mapId, new Box2(viewPos - range, viewPos + range), out var gridEnumerator, true);
+                while (gridEnumerator.MoveNext(out var mapGrid))
+                {
+                    var localPos = transformQuery.GetComponent(mapGrid.GridEntityId).InvWorldMatrix.Transform(viewPos);
+
+                    var gridChunkEnumerator =
+                        new ChunkIndicesEnumerator(localPos, range, ChunkSize);
+
+                    while (gridChunkEnumerator.MoveNext(out var gridChunkIndices))
                     {
-                        foreach (var index in chunk)
+                        var chunkLocation = new GridChunkLocation(mapGrid.Index, gridChunkIndices.Value);
+                        var entry = (visMask, chunkLocation);
+
+                        if (gridDict.TryGetValue(chunkLocation, out var indexOf))
                         {
-                            TryAddToVisibleEnts(in index, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent, ref entitiesSent, metadataQuery, transformQuery, visMask);
+                            playerChunks[i].Add(indexOf);
+                        }
+                        else
+                        {
+                            playerChunks[i].Add(chunkList.Count);
+                            gridDict.Add(chunkLocation, chunkList.Count);
+                            chunkList.Add(entry);
                         }
                     }
                 }
             }
+
+            _uidSetPool.Return(viewers);
         }
 
-        viewers.Clear();
-        _viewerEntsPool.Return(viewers);
+        return (chunkList, playerChunks, viewerEntities);
+    }
+
+    public (Dictionary<EntityUid, MetaDataComponent> mData, RobustTree<EntityUid> tree)? CalculateChunk(IChunkIndexLocation chunkLocation, uint visMask, EntityQuery<TransformComponent> transform, EntityQuery<MetaDataComponent> metadata)
+    {
+        var chunk = chunkLocation switch
+        {
+            GridChunkLocation gridChunkLocation => _entityPvsCollection.TryGetChunk(gridChunkLocation.GridId,
+                gridChunkLocation.ChunkIndices, out var gridChunk)
+                ? gridChunk
+                : null,
+            MapChunkLocation mapChunkLocation => _entityPvsCollection.TryGetChunk(mapChunkLocation.MapId,
+                mapChunkLocation.ChunkIndices, out var mapChunk)
+                ? mapChunk
+                : null
+        };
+        if (chunk == null) return null;
+        var chunkSet = _chunkCachePool.Get();
+        var tree = _treePool.Get();
+        foreach (var uid in chunk)
+        {
+            AddToChunkSetRecursively(in uid, visMask, tree, chunkSet, transform, metadata);
+        }
+
+        return (chunkSet, tree);
+    }
+
+    public void ReturnToPool((Dictionary<EntityUid, MetaDataComponent> metadata, RobustTree<EntityUid> tree)?[] chunkCache, HashSet<int>[] playerChunks)
+    {
+        foreach (var chunk in chunkCache)
+        {
+            if(!chunk.HasValue) continue;
+            _chunkCachePool.Return(chunk.Value.metadata);
+            _treePool.Return(chunk.Value.tree);
+        }
+
+        foreach (var playerChunk in playerChunks)
+        {
+            _playerChunkPool.Return(playerChunk);
+        }
+    }
+
+    private bool AddToChunkSetRecursively(in EntityUid uid, uint visMask, RobustTree<EntityUid> tree, Dictionary<EntityUid, MetaDataComponent> set, EntityQuery<TransformComponent> transform,
+        EntityQuery<MetaDataComponent> metadata)
+    {
+        //are we valid?
+        //sometimes uids gets added without being valid YET (looking at you mapmanager) (mapcreate & gridcreated fire before the uids becomes valid)
+        if (!uid.IsValid()) return false;
+
+        if (set.ContainsKey(uid)) return true;
+
+        var mComp = metadata.GetComponent(uid);
+
+        // TODO: Don't need to know about parents so no longer need to use bool for this method.
+        // If the eye is missing ANY layer this entity or any of its parents belongs to, it is considered invisible.
+        if ((visMask & mComp.VisibilityMask) != mComp.VisibilityMask)
+            return false;
+
+        var parent = transform.GetComponent(uid).ParentUid;
+
+        if (parent.IsValid() && //is it not a worldentity?
+            !set.ContainsKey(parent) && //was the parent not yet added to toSend?
+            !AddToChunkSetRecursively(in parent, visMask, tree, set, transform, metadata)) //did we just fail to add the parent?
+            return false; //we failed? suppose we dont get added either
+
+        //todo paul i want it to crash here if it gets added double bc that shouldnt happen and will add alot of unneeded cycles, make this a simpl assignment at some point maybe idk
+        tree.Set(uid, parent);
+        set.Add(uid, mComp);
+        return true;
+    }
+
+    public (List<EntityState>? updates, List<EntityUid>? deletions) CalculateEntityStates(IPlayerSession session,
+        GameTick fromTick, GameTick toTick,
+        (Dictionary<EntityUid, MetaDataComponent> metadata, RobustTree<EntityUid> tree)?[] chunkCache,
+        HashSet<int> chunkIndices, EntityQuery<MetaDataComponent> mQuery, EntityQuery<TransformComponent> tQuery,
+        EntityUid[] viewerEntities)
+    {
+        DebugTools.Assert(session.Status == SessionStatus.InGame);
+        var newEntitiesSent = 0;
+        var entitiesSent = 0;
+        var playerVisibleSet = _playerVisibleSets[session];
+        var visibleEnts = _visSetPool.Get();
+        var seenSet = _playerSeenSets[session];
+        var deletions = _entityPvsCollection.GetDeletedIndices(fromTick);
+
+        foreach (var i in chunkIndices)
+        {
+            var cache = chunkCache[i];
+            if(!cache.HasValue) continue;
+            var rootNodes = cache.Value.tree.GetRootNodes();
+            foreach (var rootNode in rootNodes)
+            {
+                RecursivelyAddTreeNode(in rootNode, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent,
+                        ref entitiesSent, cache.Value.metadata);
+            }
+            cache.Value.tree.ReturnRootNodes(rootNodes);
+        }
+
+        var globalEnumerator = _entityPvsCollection.GlobalOverridesEnumerator;
+        while (globalEnumerator.MoveNext())
+        {
+            var uid = globalEnumerator.Current;
+            RecursivelyAddOverride(in uid, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent,
+                ref entitiesSent, mQuery, tQuery);
+        }
+        globalEnumerator.Dispose();
+
+        var localEnumerator = _entityPvsCollection.GetElementsForSession(session);
+        while (localEnumerator.MoveNext())
+        {
+            var uid = localEnumerator.Current;
+            RecursivelyAddOverride(in uid, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent,
+                ref entitiesSent, mQuery, tQuery);
+        }
+        localEnumerator.Dispose();
+
+        foreach (var viewerEntity in viewerEntities)
+        {
+            RecursivelyAddOverride(in viewerEntity, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent,
+                ref entitiesSent, mQuery, tQuery);
+        }
 
         var entityStates = new List<EntityState>();
 
@@ -377,8 +533,7 @@ internal sealed partial class PVSSystem : EntitySystem
                 continue;
 
             var @new = visiblity == PVSEntityVisiblity.Entered;
-
-            var state = GetEntityState(session, entityUid, @new ? GameTick.Zero : fromTick);
+            var state = GetEntityState(session, entityUid, @new ? GameTick.Zero : fromTick, mQuery.GetComponent(entityUid).Flags);
 
             //this entity is not new & nothing changed
             if(!@new && state.Empty) continue;
@@ -411,7 +566,42 @@ internal sealed partial class PVSSystem : EntitySystem
     }
 
     [MethodImpl(MethodImplOptions.AggressiveOptimization)]
-    private bool TryAddToVisibleEnts(
+    private void RecursivelyAddTreeNode(
+        in RobustTree<EntityUid>.TreeNode node,
+        HashSet<EntityUid> seenSet,
+        Dictionary<EntityUid, PVSEntityVisiblity> previousVisibleEnts,
+        Dictionary<EntityUid, PVSEntityVisiblity> toSend,
+        GameTick fromTick,
+        ref int newEntitiesSent,
+        ref int totalEnteredEntities,
+        Dictionary<EntityUid, MetaDataComponent> metaDataCache)
+    {
+        //are we valid?
+        //sometimes uids gets added without being valid YET (looking at you mapmanager) (mapcreate & gridcreated fire before the uids becomes valid)
+
+        // As every map is parented to uid 0 in the tree we still need to get their children, plus because we go top-down
+        // we may find duplicate parents with children we haven't encountered before
+        // on different chunks (this is especially common with direct grid children)
+        if (node.Value.IsValid() && !toSend.ContainsKey(node.Value))
+        {
+            //are we new?
+            var (entered, budgetFail) = ProcessEntry(in node.Value, seenSet, previousVisibleEnts, ref newEntitiesSent,
+                ref totalEnteredEntities);
+
+            if (budgetFail) return;
+
+            AddToSendSet(in node.Value, metaDataCache[node.Value], toSend, fromTick, entered);
+        }
+
+        //our children are important regardless! iterate them!
+        foreach (var child in node.Children)
+        {
+            RecursivelyAddTreeNode(in child, seenSet, previousVisibleEnts, toSend, fromTick, ref newEntitiesSent,
+                ref totalEnteredEntities, metaDataCache);
+        }
+    }
+
+    public bool RecursivelyAddOverride(
         in EntityUid uid,
         HashSet<EntityUid> seenSet,
         Dictionary<EntityUid, PVSEntityVisiblity> previousVisibleEnts,
@@ -419,50 +609,39 @@ internal sealed partial class PVSSystem : EntitySystem
         GameTick fromTick,
         ref int newEntitiesSent,
         ref int totalEnteredEntities,
-        EntityQuery<MetaDataComponent> metadataQuery,
-        EntityQuery<TransformComponent> transformQuery,
-        uint? visMask = null,
-        bool dontSkip = false,
-        bool trustParent = false)
+        EntityQuery<MetaDataComponent> metaQuery,
+        EntityQuery<TransformComponent> transQuery)
     {
-        //are we valid yet?
+        //are we valid?
         //sometimes uids gets added without being valid YET (looking at you mapmanager) (mapcreate & gridcreated fire before the uids becomes valid)
         if (!uid.IsValid()) return false;
 
         //did we already get added?
         if (toSend.ContainsKey(uid)) return true;
 
-        var metadata = metadataQuery.GetComponent(uid);
+        var parent = transQuery.GetComponent(uid).ParentUid;
+        if (parent.IsValid() && !RecursivelyAddOverride(in parent, seenSet, previousVisibleEnts, toSend, fromTick,
+                ref newEntitiesSent, ref totalEnteredEntities, metaQuery, transQuery))
+            return false;
 
-        // if we are invisible, we are not going into the visSet, so don't worry about parents, and children are not going in
-        if (visMask != null)
-        {
-            // TODO: Don't need to know about parents so no longer need to use bool for this method.
+        var (entered, _) = ProcessEntry(in uid, seenSet, previousVisibleEnts, ref newEntitiesSent, ref totalEnteredEntities);
 
-            // If the eye is missing ANY layer this entity or any of its parents belongs to, it is considered invisible.
-            if ((visMask & metadata.VisibilityMask) != metadata.VisibilityMask)
-                return false;
-        }
+        AddToSendSet(in uid, metaQuery.GetComponent(uid), toSend, fromTick, entered);
+        return true;
+    }
 
-        var parent = transformQuery.GetComponent(uid).ParentUid;
-
-        if (!trustParent && //do we have it on good authority the parent exists?
-            parent.IsValid() && //is it not a worldentity?
-            !toSend.ContainsKey(parent) && //was the parent not yet added to toSend?
-            !TryAddToVisibleEnts(in parent, seenSet, previousVisibleEnts, toSend, fromTick, ref newEntitiesSent, ref totalEnteredEntities, metadataQuery, transformQuery, visMask)) //did we just fail to add the parent?
-            return false; //we failed? suppose we dont get added either
-
-        //did we already get added through the parent call?
-        if (toSend.ContainsKey(uid)) return true;
-
-        //are we new?
+    private (bool entered, bool budgetFail) ProcessEntry(in EntityUid uid, HashSet<EntityUid> seenSet,
+        Dictionary<EntityUid, PVSEntityVisiblity> previousVisibleEnts,
+        ref int newEntitiesSent,
+        ref int totalEnteredEntities)
+    {
         var @new = !seenSet.Contains(uid);
         var entered = @new | !previousVisibleEnts.Remove(uid);
 
         if (entered)
         {
-            if (!dontSkip && totalEnteredEntities >= _entityBudget)
-                return false;
+            if (totalEnteredEntities >= _entityBudget)
+                return (entered, true);
 
             totalEnteredEntities++;
         }
@@ -470,81 +649,110 @@ internal sealed partial class PVSSystem : EntitySystem
         if (@new)
         {
             //we just entered pvs, do we still have enough budget to send us?
-            if(!dontSkip && newEntitiesSent >= _newEntityBudget)
-                return false;
+            if(newEntitiesSent >= _newEntityBudget)
+                return (entered, true);
 
             newEntitiesSent++;
             seenSet.Add(uid);
         }
 
+        return (entered, false);
+    }
+
+    private void AddToSendSet(in EntityUid uid, MetaDataComponent metaDataComponent, Dictionary<EntityUid, PVSEntityVisiblity> toSend, GameTick fromTick, bool entered)
+    {
         if (entered)
         {
             toSend.Add(uid, PVSEntityVisiblity.Entered);
-            return true;
+            return;
         }
 
-        if (metadata.EntityLastModifiedTick < fromTick)
+        if (metaDataComponent.EntityLastModifiedTick < fromTick)
         {
             //entity has been sent before and hasnt been updated since
             toSend.Add(uid, PVSEntityVisiblity.StayedUnchanged);
-            return true;
+            return;
         }
 
         //add us
         toSend.Add(uid, PVSEntityVisiblity.StayedChanged);
-        return true;
     }
 
     /// <summary>
     ///     Gets all entity states that have been modified after and including the provided tick.
     /// </summary>
-    private List<EntityState>? GetAllEntityStates(ICommonSession player, GameTick fromTick, GameTick toTick)
+    public (List<EntityState>? updates, List<EntityUid>? deletions) GetAllEntityStates(ICommonSession player, GameTick fromTick, GameTick toTick)
     {
-        List<EntityState> stateEntities;
+        var deletions = _entityPvsCollection.GetDeletedIndices(fromTick);
+        // no point sending an empty collection
+        if (deletions.Count == 0) deletions = default;
 
-        stateEntities = new List<EntityState>();
+        var stateEntities = new List<EntityState>();
         var seenEnts = new HashSet<EntityUid>();
         var slowPath = false;
         var metadataQuery = EntityManager.GetEntityQuery<MetaDataComponent>();
 
-        for (var i = fromTick.Value; i <= toTick.Value; i++)
+        if (!SeenAllEnts.Contains(player))
         {
-            var tick = new GameTick(i);
-            if (!TryGetTick(tick, out var add, out var dirty))
+            // Give them E V E R Y T H I N G
+            stateEntities = new List<EntityState>(EntityManager.EntityCount);
+
+            // This is the same as iterating every existing entity.
+            foreach (var md in EntityManager.EntityQuery<MetaDataComponent>(true))
             {
-                slowPath = true;
-                break;
+                DebugTools.Assert(md.EntityLifeStage >= EntityLifeStage.Initialized);
+                stateEntities.Add(GetEntityState(player, md.Owner, GameTick.Zero, md.Flags));
             }
 
-            foreach (var uid in add)
+            return (stateEntities.Count == 0 ? default : stateEntities, deletions);
+        }
+
+        // Just get the relevant entities that have been dirtied
+        // This should be extremely fast.
+        if (!slowPath)
+        {
+            for (var i = fromTick.Value; i <= toTick.Value; i++)
             {
-                if (!seenEnts.Add(uid)) continue;
-                // This is essentially the same as IEntityManager.EntityExists, but returning MetaDataComponent.
-                if (!metadataQuery.TryGetComponent(uid, out MetaDataComponent? md)) continue;
+                // Fallback to dumping every entity on them.
+                var tick = new GameTick(i);
+                if (!TryGetTick(tick, out var add, out var dirty))
+                {
+                    slowPath = true;
+                    break;
+                }
 
-                DebugTools.Assert(md.EntityLifeStage >= EntityLifeStage.Initialized);
+                foreach (var uid in add)
+                {
+                    if (!seenEnts.Add(uid)) continue;
+                    // This is essentially the same as IEntityManager.EntityExists, but returning MetaDataComponent.
+                    if (!metadataQuery.TryGetComponent(uid, out var md)) continue;
 
-                if (md.EntityLastModifiedTick >= fromTick)
-                    stateEntities.Add(GetEntityState(player, uid, GameTick.Zero));
-            }
+                    DebugTools.Assert(md.EntityLifeStage >= EntityLifeStage.Initialized);
 
-            foreach (var uid in dirty)
-            {
-                DebugTools.Assert(!add.Contains(uid));
+                    if (md.EntityLastModifiedTick >= fromTick)
+                        stateEntities.Add(GetEntityState(player, uid, GameTick.Zero, md.Flags));
+                }
 
-                if (!seenEnts.Add(uid)) continue;
-                if (!metadataQuery.TryGetComponent(uid, out MetaDataComponent? md)) continue;
+                foreach (var uid in dirty)
+                {
+                    DebugTools.Assert(!add.Contains(uid));
 
-                DebugTools.Assert(md.EntityLifeStage >= EntityLifeStage.Initialized);
+                    if (!seenEnts.Add(uid)) continue;
+                    if (!metadataQuery.TryGetComponent(uid, out var md)) continue;
 
-                if (md.EntityLastModifiedTick >= fromTick)
-                    stateEntities.Add(GetEntityState(player, uid, fromTick));
+                    DebugTools.Assert(md.EntityLifeStage >= EntityLifeStage.Initialized);
+
+                    if (md.EntityLastModifiedTick >= fromTick)
+                        stateEntities.Add(GetEntityState(player, uid, fromTick, md.Flags));
+                }
             }
         }
 
         if (!slowPath)
         {
-            return stateEntities.Count == 0 ? default : stateEntities;
+            if (stateEntities.Count == 0) stateEntities = default;
+
+            return (stateEntities, deletions);
         }
 
         stateEntities = new List<EntityState>(EntityManager.EntityCount);
@@ -555,11 +763,13 @@ internal sealed partial class PVSSystem : EntitySystem
             DebugTools.Assert(md.EntityLifeStage >= EntityLifeStage.Initialized);
 
             if (md.EntityLastModifiedTick >= fromTick)
-                stateEntities.Add(GetEntityState(player, md.Owner, fromTick));
+                stateEntities.Add(GetEntityState(player, md.Owner, fromTick, md.Flags));
         }
 
         // no point sending an empty collection
-        return stateEntities.Count == 0 ? default : stateEntities;
+        if (stateEntities.Count == 0) stateEntities = default;
+
+        return (stateEntities, deletions);
     }
 
     /// <summary>
@@ -568,11 +778,16 @@ internal sealed partial class PVSSystem : EntitySystem
     /// <param name="player">The player to generate this state for.</param>
     /// <param name="entityUid">Uid of the entity to generate the state from.</param>
     /// <param name="fromTick">Only provide delta changes from this tick.</param>
+    /// <param name="flags">Any applicable metadata flags</param>
     /// <returns>New entity State for the given entity.</returns>
-    private EntityState GetEntityState(ICommonSession player, EntityUid entityUid, GameTick fromTick)
+    private EntityState GetEntityState(ICommonSession player, EntityUid entityUid, GameTick fromTick, MetaDataFlags flags)
     {
         var bus = EntityManager.EventBus;
         var changed = new List<ComponentChange>();
+        // Whether this entity has any component states that are only for a specific session.
+        // TODO: This GetComp is probably expensive, less expensive than before, but ideally we'd cache it somewhere or something from a previous getcomp
+        // Probably still needs tweaking but checking for add / changed states up front should do most of the work.
+        var specificStates = (flags & MetaDataFlags.EntitySpecific) == MetaDataFlags.EntitySpecific;
 
         foreach (var (netId, component) in EntityManager.GetNetComponents(entityUid))
         {
@@ -587,10 +802,22 @@ internal sealed partial class PVSSystem : EntitySystem
 
             DebugTools.Assert(component.LastModifiedTick >= component.CreationTick);
 
-            if (!EntityManager.CanGetComponentState(bus, component, player))
+            var addState = false;
+            var changeState = false;
+
+            // We'll check the properties first; if we ever have specific states then doing the struct event is expensive.
+            if (component.CreationTick != GameTick.Zero && component.CreationTick >= fromTick && !component.Deleted)
+                addState = true;
+            else if (component.NetSyncEnabled && component.LastModifiedTick != GameTick.Zero && component.LastModifiedTick >= fromTick)
+                changeState = true;
+
+            if (!addState && !changeState)
                 continue;
 
-            if (component.CreationTick != GameTick.Zero && component.CreationTick >= fromTick && !component.Deleted)
+            if (specificStates && !EntityManager.CanGetComponentState(bus, component, player))
+                continue;
+
+            if (addState)
             {
                 ComponentState? state = null;
                 if (component.NetSyncEnabled && component.LastModifiedTick != GameTick.Zero &&
@@ -601,14 +828,14 @@ internal sealed partial class PVSSystem : EntitySystem
                 // ReSharper disable once PossibleInvalidOperationException
                 changed.Add(ComponentChange.Added(netId, state));
             }
-            else if (component.NetSyncEnabled && component.LastModifiedTick != GameTick.Zero &&
-                     component.LastModifiedTick >= fromTick)
+            else
             {
+                DebugTools.Assert(changeState);
                 changed.Add(ComponentChange.Changed(netId, EntityManager.GetComponentState(bus, component)));
             }
         }
 
-        foreach (var netId in ((IServerEntityManager)EntityManager).GetDeletedComponents(entityUid, fromTick))
+        foreach (var netId in _serverEntManager.GetDeletedComponents(entityUid, fromTick))
         {
             changed.Add(ComponentChange.Removed(netId));
         }
@@ -618,7 +845,7 @@ internal sealed partial class PVSSystem : EntitySystem
 
     private HashSet<EntityUid> GetSessionViewers(ICommonSession session)
     {
-        var viewers = _viewerEntsPool.Get();
+        var viewers = _uidSetPool.Get();
         if (session.Status != SessionStatus.InGame)
             return viewers;
 
@@ -638,14 +865,69 @@ internal sealed partial class PVSSystem : EntitySystem
     }
 
     // Read Safe
-    private (Box2 view, MapId mapId) CalcViewBounds(in EntityUid euid, EntityQuery<TransformComponent> transformQuery)
+    private (Vector2 worldPos, float range, MapId mapId) CalcViewBounds(in EntityUid euid, EntityQuery<TransformComponent> transformQuery)
     {
         var xform = transformQuery.GetComponent(euid);
+        return (xform.WorldPosition, _viewSize / 2f, xform.MapID);
+    }
 
-        var view = Box2.UnitCentered.Scale(_viewSize).Translated(xform.WorldPosition);
-        var map = xform.MapID;
+    public sealed class SetPolicy<T> : PooledObjectPolicy<HashSet<T>>
+    {
+        public override HashSet<T> Create()
+        {
+            return new HashSet<T>();
+        }
 
-        return (view, map);
+        public override bool Return(HashSet<T> obj)
+        {
+            obj.Clear();
+            return true;
+        }
+    }
+
+    public sealed class ListPolicy<T> : PooledObjectPolicy<List<T>>
+    {
+        public override List<T> Create()
+        {
+            return new();
+        }
+
+        public override bool Return(List<T> obj)
+        {
+            obj.Clear();
+            return true;
+        }
+    }
+
+    public sealed class DictPolicy<T1, T2> : PooledObjectPolicy<Dictionary<T1, T2>> where T1 : notnull
+    {
+        public override Dictionary<T1, T2> Create()
+        {
+            return new Dictionary<T1, T2>();
+        }
+
+        public override bool Return(Dictionary<T1, T2> obj)
+        {
+            obj.Clear();
+            return true;
+        }
+    }
+
+    public sealed class TreePolicy<T> : PooledObjectPolicy<RobustTree<T>> where T : notnull
+    {
+        private readonly ObjectPool<HashSet<RobustTree<T>.TreeNode>> _treeNodeSetPool =
+            new DefaultObjectPool<HashSet<RobustTree<T>.TreeNode>>(new SetPolicy<RobustTree<T>.TreeNode>());
+
+        public override RobustTree<T> Create()
+        {
+            return new RobustTree<T>(_treeNodeSetPool.Get, _treeNodeSetPool.Return);
+        }
+
+        public override bool Return(RobustTree<T> obj)
+        {
+            obj.Clear();
+            return true;
+        }
     }
 }
 

Robust.Server/GameStates/RobustTree.cs

@@ -0,0 +1,167 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Robust.Server.GameStates;
+
+public sealed class RobustTree<T> where T : notnull
+{
+    private Dictionary<T, TreeNode> _nodeIndex = new();
+
+    private Dictionary<T, T> _parents = new();
+    private HashSet<T> _rootNodes = new();
+
+    private Func<HashSet<TreeNode>> _setProvider;
+    private Action<HashSet<TreeNode>> _setConsumer;
+
+    public RobustTree(Func<HashSet<TreeNode>>? setProvider = null, Action<HashSet<TreeNode>>? setConsumer = null)
+    {
+        _setProvider = setProvider ?? (static () => new());
+        _setConsumer = setConsumer ?? (static (_) => {});
+    }
+
+    public void Clear()
+    {
+        // TODO: This is hella expensive
+        foreach (var value in _nodeIndex.Values)
+        {
+            _setConsumer(value.Children);
+        }
+        _nodeIndex.Clear();
+        _parents.Clear();
+        _rootNodes.Clear();
+    }
+
+    public void Remove(T value, bool mend = false)
+    {
+        if (!_nodeIndex.TryGetValue(value, out var node))
+            throw new InvalidOperationException("Node doesnt exist.");
+
+        if (_rootNodes.Contains(value))
+        {
+            foreach (var child in node.Children)
+            {
+                _parents.Remove(child.Value);
+                _rootNodes.Add(child.Value);
+            }
+            _setConsumer(node.Children);
+            _rootNodes.Remove(value);
+            _nodeIndex.Remove(value);
+            return;
+        }
+
+        if (_parents.TryGetValue(value, out var parent))
+        {
+            foreach (var child in node.Children)
+            {
+                if (mend)
+                {
+                    _parents[child.Value] = parent;
+                    _nodeIndex[parent].Children.Add(child);
+                }
+                else
+                {
+                    _parents.Remove(child.Value);
+                    _rootNodes.Add(child.Value);
+                }
+            }
+
+            _setConsumer(node.Children);
+            _parents.Remove(value);
+            _nodeIndex.Remove(value);
+        }
+
+        throw new InvalidOperationException("Node neither had a parent nor was a RootNode.");
+    }
+
+    public TreeNode Set(T rootNode)
+    {
+        //root node, for now
+        if (_nodeIndex.TryGetValue(rootNode, out var node))
+        {
+            if(!_rootNodes.Contains(rootNode))
+                throw new InvalidOperationException("Node already exists as non-root node.");
+            return node;
+        }
+
+        node = new TreeNode(rootNode, _setProvider());
+        _nodeIndex.Add(rootNode, node);
+        _rootNodes.Add(rootNode);
+        return node;
+    }
+
+    public TreeNode Set(T child, T parent)
+    {
+        if (!_nodeIndex.TryGetValue(parent, out var parentNode))
+            parentNode = Set(parent);
+
+        if (_nodeIndex.TryGetValue(child, out var existingNode))
+        {
+            if (_rootNodes.Contains(child))
+            {
+                parentNode.Children.Add(existingNode);
+                _rootNodes.Remove(child);
+                _parents.Add(child, parent);
+                return existingNode;
+            }
+
+            if (!_parents.TryGetValue(child, out var previousParent) || _nodeIndex.TryGetValue(previousParent, out var previousParentNode))
+                throw new InvalidOperationException("Could not find old parent for non-root node.");
+
+            previousParentNode.Children.Remove(existingNode);
+            parentNode.Children.Add(existingNode);
+            _parents[child] = parent;
+            return existingNode;
+        }
+
+        existingNode = new TreeNode(child, _setProvider());
+        _nodeIndex.Add(child, existingNode);
+        parentNode.Children.Add(existingNode);
+        _parents.Add(child, parent);
+        return existingNode;
+    }
+
+    // todo paul optimize this maybe as its basically all this is used for.
+    public HashSet<TreeNode> GetRootNodes()
+    {
+        var nodes = _setProvider();
+        foreach (var node in _rootNodes)
+        {
+            nodes.Add(_nodeIndex[node]);
+        }
+
+        return nodes;
+    }
+
+    public void ReturnRootNodes(HashSet<TreeNode> rootNodes)
+    {
+        _setConsumer(rootNodes);
+    }
+
+    public readonly struct TreeNode : IEquatable<TreeNode>
+    {
+        public readonly T Value;
+        public readonly HashSet<TreeNode> Children;
+
+        public TreeNode(T value, HashSet<TreeNode> children)
+        {
+            Value = value;
+            Children = children;
+        }
+
+        public bool Equals(TreeNode other)
+        {
+            return Value.Equals(other.Value) && Children.Equals(other.Children);
+        }
+
+        public override bool Equals(object? obj)
+        {
+            return obj is TreeNode other && Equals(other);
+        }
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(Value, Children);
+        }
+    }
+}

Robust.Server/GameStates/ServerGameStateManager.cs

@@ -1,9 +1,12 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using JetBrains.Annotations;
+using Microsoft.CodeAnalysis;
+using Microsoft.Extensions.ObjectPool;
 using Robust.Server.GameObjects;
 using Robust.Server.Player;
 using Robust.Shared.Enums;
@@ -125,6 +128,37 @@ namespace Robust.Server.GameStates
             // people not in the game don't get states
             var players = _playerManager.ServerSessions.Where(o => o.Status == SessionStatus.InGame).ToArray();
 
+            //todo paul oh my god make this less shit
+            EntityQuery<MetaDataComponent> metadataQuery = default!;
+            EntityQuery<TransformComponent> transformQuery = default!;
+            HashSet<int>[] playerChunks = default!;
+            EntityUid[][] viewerEntities = default!;
+            (Dictionary<EntityUid, MetaDataComponent> metadata, RobustTree<EntityUid> tree)?[] chunkCache = default!;
+
+            if (_pvs.CullingEnabled)
+            {
+                List<(uint, IChunkIndexLocation)> chunks;
+                (chunks, playerChunks, viewerEntities) = _pvs.GetChunks(players);
+                const int ChunkBatchSize = 2;
+                var chunksCount = chunks.Count;
+                var chunkBatches = (int) MathF.Ceiling((float) chunksCount / ChunkBatchSize);
+                chunkCache =
+                    new (Dictionary<EntityUid, MetaDataComponent> metadata, RobustTree<EntityUid> tree)?[chunksCount];
+                transformQuery = _entityManager.GetEntityQuery<TransformComponent>();
+                metadataQuery = _entityManager.GetEntityQuery<MetaDataComponent>();
+                Parallel.For(0, chunkBatches, i =>
+                {
+                    var start = i * ChunkBatchSize;
+                    var end = Math.Min(start + ChunkBatchSize, chunksCount);
+
+                    for (var j = start; j < end; ++j)
+                    {
+                        var (visMask, chunkIndexLocation) = chunks[j];
+                        chunkCache[j] = _pvs.CalculateChunk(chunkIndexLocation, visMask, transformQuery, metadataQuery);
+                    }
+                });
+            }
+
             const int BatchSize = 2;
             var batches = (int) MathF.Ceiling((float) players.Length / BatchSize);
 
@@ -135,11 +169,9 @@ namespace Robust.Server.GameStates
 
                 for (var j = start; j < end; ++j)
                 {
-                    var session = players[j];
-
                     try
                     {
-                        SendStateUpdate(session);
+                        SendStateUpdate(j);
                     }
                     catch (Exception e) // Catch EVERY exception
                     {
@@ -148,8 +180,10 @@ namespace Robust.Server.GameStates
                 }
             });
 
-            void SendStateUpdate(IPlayerSession session)
+            void SendStateUpdate(int sessionIndex)
             {
+                var session = players[sessionIndex];
+
                 // KILL IT WITH FIRE
                 if(mainThread != Thread.CurrentThread)
                     IoCManager.InitThread(new DependencyCollection(parentDeps), true);
@@ -161,7 +195,10 @@ namespace Robust.Server.GameStates
                     DebugTools.Assert("Why does this channel not have an entry?");
                 }
 
-                var (entStates, deletions) = _pvs.CalculateEntityStates(session, lastAck, _gameTiming.CurTick);
+                var (entStates, deletions) = _pvs.CullingEnabled
+                    ? _pvs.CalculateEntityStates(session, lastAck, _gameTiming.CurTick, chunkCache,
+                        playerChunks[sessionIndex], metadataQuery, transformQuery, viewerEntities[sessionIndex])
+                    : _pvs.GetAllEntityStates(session, lastAck, _gameTiming.CurTick);
                 var playerStates = _playerManager.GetPlayerStates(lastAck);
                 var mapData = _mapManager.GetStateData(lastAck);
 
@@ -194,6 +231,8 @@ namespace Robust.Server.GameStates
                 _networkManager.ServerSendMessage(stateUpdateMessage, channel);
             }
 
+            if(_pvs.CullingEnabled)
+                _pvs.ReturnToPool(chunkCache, playerChunks);
             _pvs.Cleanup(_playerManager.ServerSessions);
             var oldestAck = new GameTick(oldestAckValue);
 

Robust.Server/Maps/MapLoader.cs

@@ -24,7 +24,6 @@ using Robust.Shared.Serialization.Markdown.Mapping;
 using Robust.Shared.Serialization.Markdown.Validation;
 using Robust.Shared.Serialization.Markdown.Value;
 using Robust.Shared.Serialization.TypeSerializers.Interfaces;
-using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 using YamlDotNet.Core;
 using YamlDotNet.RepresentationModel;
@@ -44,7 +43,6 @@ namespace Robust.Server.Maps
         [Dependency] private readonly IMapManagerInternal _mapManager = default!;
         [Dependency] private readonly ITileDefinitionManager _tileDefinitionManager = default!;
         [Dependency] private readonly IServerEntityManagerInternal _serverEntityManager = default!;
-        [Dependency] private readonly IPauseManager _pauseManager = default!;
         [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
 
         public event Action<YamlStream, string>? LoadedMapData;
@@ -54,7 +52,7 @@ namespace Robust.Server.Maps
         {
             var grid = _mapManager.GetGrid(gridId);
 
-            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _pauseManager, _prototypeManager);
+            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _prototypeManager);
             context.RegisterGrid(grid);
             var root = context.Serialize();
             var document = new YamlDocument(root);
@@ -100,7 +98,7 @@ namespace Robust.Server.Maps
                     throw new InvalidDataException("Cannot instance map with multiple grids as blueprint.");
                 }
 
-                var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _pauseManager,
+                var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager,
                     _prototypeManager, (YamlMappingNode) data.RootNode, mapId, options);
                 context.Deserialize();
                 grid = context.Grids[0];
@@ -120,7 +118,7 @@ namespace Robust.Server.Maps
                     _serverEntityManager.GetComponent<MetaDataComponent>(entity).EntityLifeStage = EntityLifeStage.MapInitialized;
                 }
             }
-            else if (_pauseManager.IsMapInitialized(mapId))
+            else if (_mapManager.IsMapInitialized(mapId))
             {
                 foreach (var entity in context.Entities)
                 {
@@ -128,7 +126,7 @@ namespace Robust.Server.Maps
                 }
             }
 
-            if (_pauseManager.IsMapPaused(mapId))
+            if (_mapManager.IsMapPaused(mapId))
             {
                 foreach (var entity in context.Entities)
                 {
@@ -141,7 +139,7 @@ namespace Robust.Server.Maps
         public void SaveMap(MapId mapId, string yamlPath)
         {
             Logger.InfoS("map", $"Saving map {mapId} to {yamlPath}");
-            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _pauseManager, _prototypeManager);
+            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _prototypeManager);
             foreach (var grid in _mapManager.GetAllMapGrids(mapId))
             {
                 context.RegisterGrid(grid);
@@ -207,7 +205,7 @@ namespace Robust.Server.Maps
 
                 LoadedMapData?.Invoke(data.Stream, resPath.ToString());
 
-                var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _pauseManager,
+                var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager,
                     _prototypeManager, (YamlMappingNode) data.RootNode, mapId, options);
                 context.Deserialize();
 
@@ -226,7 +224,6 @@ namespace Robust.Server.Maps
             private readonly IMapManagerInternal _mapManager;
             private readonly ITileDefinitionManager _tileDefinitionManager;
             private readonly IServerEntityManagerInternal _serverEntityManager;
-            private readonly IPauseManager _pauseManager;
             private readonly IPrototypeManager _prototypeManager;
 
             private readonly MapLoadOptions? _loadOptions;
@@ -260,12 +257,11 @@ namespace Robust.Server.Maps
             public bool MapIsPostInit { get; private set; }
 
             public MapContext(IMapManagerInternal maps, ITileDefinitionManager tileDefs,
-                IServerEntityManagerInternal entities, IPauseManager pauseManager, IPrototypeManager prototypeManager)
+                IServerEntityManagerInternal entities, IPrototypeManager prototypeManager)
             {
                 _mapManager = maps;
                 _tileDefinitionManager = tileDefs;
                 _serverEntityManager = entities;
-                _pauseManager = pauseManager;
                 _prototypeManager = prototypeManager;
 
                 RootNode = new YamlMappingNode();
@@ -283,13 +279,12 @@ namespace Robust.Server.Maps
 
             public MapContext(IMapManagerInternal maps, ITileDefinitionManager tileDefs,
                 IServerEntityManagerInternal entities,
-                IPauseManager pauseManager, IPrototypeManager prototypeManager,
+                IPrototypeManager prototypeManager,
                 YamlMappingNode node, MapId targetMapId, MapLoadOptions options)
             {
                 _mapManager = maps;
                 _tileDefinitionManager = tileDefs;
                 _serverEntityManager = entities;
-                _pauseManager = pauseManager;
                 _loadOptions = options;
 
                 RootNode = node;
@@ -612,7 +607,7 @@ namespace Robust.Server.Maps
 
                     if (!MapIsPostInit)
                     {
-                        _pauseManager.AddUninitializedMap(TargetMap);
+                        _mapManager.AddUninitializedMap(TargetMap);
                     }
                 }
             }
@@ -719,7 +714,7 @@ namespace Robust.Server.Maps
                 var isPostInit = false;
                 foreach (var grid in Grids)
                 {
-                    if (_pauseManager.IsMapInitialized(grid.ParentMapId))
+                    if (_mapManager.IsMapInitialized(grid.ParentMapId))
                     {
                         isPostInit = true;
                         break;

Robust.Server/Maps/YamlGridSerializer.cs

@@ -36,7 +36,7 @@ namespace Robust.Server.Maps
             return gridn;
         }
 
-        private static YamlNode SerializeChunk(IMapChunk chunk)
+        private static YamlNode SerializeChunk(MapChunk chunk)
         {
             var root = new YamlMappingNode();
             var value = new YamlScalarNode($"{chunk.X},{chunk.Y}");
@@ -51,7 +51,7 @@ namespace Robust.Server.Maps
             return root;
         }
 
-        private static string SerializeTiles(IMapChunk chunk)
+        private static string SerializeTiles(MapChunk chunk)
         {
             // number of bytes written per tile, because sizeof(Tile) is useless.
             const int structSize = 4;

Robust.Server/Placement/PlacementManager.cs

@@ -209,7 +209,7 @@ namespace Robust.Server.Placement
         {
             EntityCoordinates start = msg.EntityCoordinates;
             Vector2 rectSize = msg.RectSize;
-            foreach (EntityUid entity in IoCManager.Resolve<IEntityLookup>().GetEntitiesIntersecting(start.GetMapId(_entityManager),
+            foreach (EntityUid entity in EntitySystem.Get<EntityLookupSystem>().GetEntitiesIntersecting(start.GetMapId(_entityManager),
                 new Box2(start.Position, start.Position + rectSize)))
             {
                 if (_entityManager.Deleted(entity) || _entityManager.HasComponent<IMapGridComponent>(entity) || _entityManager.HasComponent<ActorComponent>(entity))

Robust.Server/ServerIoC.cs

@@ -50,7 +50,6 @@ namespace Robust.Server
             IoCManager.Register<IMapManagerInternal, NetworkedMapManager>();
             IoCManager.Register<INetworkedMapManager, NetworkedMapManager>();
             IoCManager.Register<IEntityManager, ServerEntityManager>();
-            IoCManager.Register<IEntityLookup, EntityLookup>();
             IoCManager.Register<IEntityNetworkManager, ServerEntityManager>();
             IoCManager.Register<IServerEntityNetworkManager, ServerEntityManager>();
             IoCManager.Register<IMapLoader, MapLoader>();

Robust.Shared.Maths/Box2i.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -135,5 +135,17 @@ namespace Robust.Shared.Maths
         {
             return $"({Left}, {Bottom}, {Right}, {Top})";
         }
+
+        /// <summary>
+        /// Multiplies each side of the box by the scalar.
+        /// </summary>
+        public Box2i Scale(int scalar)
+        {
+            return new Box2i(
+                Left * scalar,
+                Bottom * scalar,
+                Right * scalar,
+                Top * scalar);
+        }
     }
 }

Robust.Shared.Maths/Vector2.cs

@@ -130,6 +130,12 @@ namespace Robust.Shared.Maths
             return new((int) MathF.Floor(X), (int) MathF.Floor(Y));
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public readonly Vector2i Ceiled()
+        {
+            return new((int) MathF.Ceiling(X), (int) MathF.Ceiling(Y));
+        }
+
         /// <summary>
         ///     Subtracts a vector from another, returning a new vector.
         /// </summary>

Robust.Shared/CVars.cs

@@ -1006,6 +1006,17 @@ namespace Robust.Shared
         public static readonly CVarDef<bool> ResTexturePreloadCache =
             CVarDef.Create("res.texture_preload_cache", true, CVar.CLIENTONLY);
 
+        /// <summary>
+        /// Override seekability of resource streams returned by ResourceManager.
+        /// See <see cref="ContentPack.StreamSeekMode"/> for int values.
+        /// </summary>
+        /// <remarks>
+        /// This is intended to be a debugging tool primarily.
+        /// Non-default seek modes WILL result in worse performance.
+        /// </remarks>
+        public static readonly CVarDef<int> ResStreamSeekMode =
+            CVarDef.Create("res.stream_seek_mode", (int)ContentPack.StreamSeekMode.None);
+
         /*
          * DEBUG
          */

Robust.Shared/Console/CommandBuffer.cs

@@ -0,0 +1,81 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Robust.Shared.Console;
+
+public sealed class CommandBuffer
+{
+    private const string DelayMarker = "-DELAY-";
+
+    private int _tickrate = 0;
+    private int _delay = 0;
+
+    private readonly LinkedList<string> _commandBuffer = new();
+
+    public void Append(string command)
+    {
+        _commandBuffer.AddLast(command);
+    }
+
+    public void Insert(string command)
+    {
+        _commandBuffer.AddFirst(command);
+    }
+
+    public void Tick(byte tickRate)
+    {
+        _tickrate = tickRate;
+
+        if (_delay > 0)
+        {
+            _delay -= 1;
+        }
+    }
+
+    public bool TryGetCommand([MaybeNullWhen(false)]out string command)
+    {
+        var next = _commandBuffer.First;
+
+        if (next is null) // nothing to do here
+        {
+            command = null;
+            return false;
+        }
+
+        if (next.Value.Equals(DelayMarker))
+        {
+            if (_delay == 0) // just finished
+            {
+                _commandBuffer.RemoveFirst();
+                return TryGetCommand(out command);
+            }
+            else // currently counting down delay
+            {
+                command = null;
+                return false;
+            }
+        }
+
+        if (next.Value.StartsWith("wait "))
+        {
+            var sTicks = next.Value.Substring(5);
+            _commandBuffer.RemoveFirst();
+            if (string.IsNullOrWhiteSpace(sTicks) || !int.TryParse(sTicks, out var ticks)) // messed up command
+            {
+                return TryGetCommand(out command);
+            }
+
+            // Setup Timing
+            _commandBuffer.AddFirst(DelayMarker);
+            _delay = ticks;
+
+            command = null;
+            return false;
+        }
+
+        // normal command
+        _commandBuffer.RemoveFirst();
+        command = next.Value;
+        return true;
+    }
+}

Robust.Shared/Console/Commands/ExecCommand.cs

@@ -48,7 +48,7 @@ namespace Robust.Shared.Console.Commands
                     continue;
                 }
 
-                shell.ExecuteCommand(line);
+                shell.ConsoleHost.AppendCommand(line);
             }
         }
     }

Robust.Shared/Console/ConsoleHost.cs

@@ -7,6 +7,7 @@ using Robust.Shared.Log;
 using Robust.Shared.Network;
 using Robust.Shared.Players;
 using Robust.Shared.Reflection;
+using Robust.Shared.Timing;
 using Robust.Shared.ViewVariables;
 
 namespace Robust.Shared.Console
@@ -17,13 +18,16 @@ namespace Robust.Shared.Console
         protected const string SawmillName = "con";
 
         [Dependency] protected readonly ILogManager LogManager = default!;
-        [Dependency] protected readonly IReflectionManager ReflectionManager = default!;
+        [Dependency] private readonly IReflectionManager ReflectionManager = default!;
         [Dependency] protected readonly INetManager NetManager = default!;
         [Dependency] private readonly IDynamicTypeFactoryInternal _typeFactory = default!;
+        [Dependency] private readonly IGameTiming _timing = default!;
 
         [ViewVariables]
         protected readonly Dictionary<string, IConsoleCommand> AvailableCommands = new();
 
+        private readonly CommandBuffer _commandBuffer = new CommandBuffer();
+
         /// <inheritdoc />
         public bool IsServer => NetManager.IsServer;
 
@@ -116,6 +120,36 @@ namespace Robust.Shared.Console
             ExecuteCommand(null, command);
         }
 
+        /// <inheritdoc />
+        public void AppendCommand(string command)
+        {
+            _commandBuffer.Append(command);
+        }
+
+        /// <inheritdoc />
+        public void InsertCommand(string command)
+        {
+            _commandBuffer.Insert(command);
+        }
+
+        /// <inheritdoc />
+        public void CommandBufferExecute()
+        {
+            _commandBuffer.Tick(_timing.TickRate);
+
+            while (_commandBuffer.TryGetCommand(out var cmd))
+            {
+                try
+                {
+                    ExecuteCommand(cmd);
+                }
+                catch (Exception e)
+                {
+                    LocalShell.WriteError(e.Message);
+                }
+            }
+        }
+
         /// <summary>
         /// A console command that was registered inline through <see cref="IConsoleHost"/>.
         /// </summary>

Robust.Shared/Console/IConsoleHost.cs

@@ -81,11 +81,35 @@ namespace Robust.Shared.Console
         IConsoleShell GetSessionShell(ICommonSession session);
 
         /// <summary>
-        /// Execute a command string on the local shell.
+        /// Execute a command string immediately on the local shell, bypassing the command buffer completely.
         /// </summary>
         /// <param name="command">Command string to execute.</param>
         void ExecuteCommand(string command);
 
+        /// <summary>
+        /// Appends a command into the end of the command buffer on the local shell.
+        /// </summary>
+        /// <remarks>
+        ///  This command will be ran *sometime* in the future, depending on how many waits are in the buffer.
+        /// </remarks>
+        /// <param name="command">Command string to execute.</param>
+        void AppendCommand(string command);
+
+        /// <summary>
+        /// Inserts a command into the front of the command buffer on the local shell.
+        /// </summary>
+        /// <remarks>
+        ///  This command will preempt the next command executed in the command buffer.
+        /// </remarks>
+        /// <param name="command">Command string to execute.</param>
+        void InsertCommand(string command);
+
+        /// <summary>
+        /// Processes any contents of the command buffer on the local shell. This needs to be called regularly (once a tick),
+        /// inside the simulation. Pausing the server should prevent the buffer from being processed.
+        /// </summary>
+        void CommandBufferExecute();
+
         /// <summary>
         /// Executes a command string on this specific session shell. If the command does not exist, the command will be forwarded
         /// to the

Robust.Shared/Containers/BaseContainer.cs

@@ -81,6 +81,7 @@ namespace Robust.Shared.Containers
             // spatially move the object to the location of the container. If you don't want this functionality, the
             // calling code can save the local position before calling this function, and apply it afterwords.
             transform.LocalPosition = Vector2.Zero;
+            transform.LocalRotation = Angle.Zero;
 
             return true;
         }

Robust.Shared/Containers/SharedContainerSystem.cs

@@ -209,6 +209,43 @@ namespace Robust.Shared.Containers
             return false;
         }
 
+        /// <summary>
+        /// Gets the top-most container in the hierarchy for this entity, if it exists.
+        /// </summary>
+        public bool TryGetOuterContainer(EntityUid uid, TransformComponent xform, [NotNullWhen(true)] out IContainer? container)
+        {
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            return TryGetOuterContainer(uid, xform, out container, xformQuery);
+        }
+
+        public bool TryGetOuterContainer(EntityUid uid, TransformComponent xform,
+            [NotNullWhen(true)] out IContainer? container, EntityQuery<TransformComponent> xformQuery)
+        {
+            container = null;
+
+            if (!uid.IsValid())
+                return false;
+
+            var conQuery = EntityManager.GetEntityQuery<ContainerManagerComponent>();
+            var child = uid;
+            var parent = xform.ParentUid;
+
+            while (parent.IsValid())
+            {
+                if (conQuery.TryGetComponent(parent, out var conManager) &&
+                    conManager.TryGetContainer(child, out var parentContainer))
+                {
+                    container = parentContainer;
+                }
+
+                var parentXform = xformQuery.GetComponent(parent);
+                child = parent;
+                parent = parentXform.ParentUid;
+            }
+
+            return container != null;
+        }
+
         #endregion
 
         // Eject entities from their parent container if the parent change is done by the transform only.

Robust.Shared/ContentPack/AssemblyTypeChecker.cs

@@ -111,7 +111,7 @@ namespace Robust.Shared.ContentPack
             var fullStopwatch = Stopwatch.StartNew();
 
             var resolver = CreateResolver();
-            using var peReader = new PEReader(assembly, PEStreamOptions.LeaveOpen);
+            using var peReader = ModLoader.MakePEReader(assembly, leaveOpen: true);
             var reader = peReader.GetMetadataReader();
 
             var asmName = reader.GetString(reader.GetAssemblyDefinition().Name);
@@ -853,13 +853,13 @@ namespace Robust.Shared.ContentPack
                         continue;
                     }
 
-                    return ReaderFromStream(File.OpenRead(path));
+                    return ModLoader.MakePEReader(File.OpenRead(path));
                 }
 
                 var extraStream = _parent.ExtraRobustLoader?.Invoke(dllName);
                 if (extraStream != null)
                 {
-                    return ReaderFromStream(extraStream);
+                    return ModLoader.MakePEReader(extraStream);
                 }
 
                 foreach (var resLoadPath in _resLoadPaths)
@@ -867,7 +867,7 @@ namespace Robust.Shared.ContentPack
                     try
                     {
                         var path = resLoadPath / dllName;
-                        return ReaderFromStream(_parent._res.ContentFileRead(path));
+                        return ModLoader.MakePEReader(_parent._res.ContentFileRead(path));
                     }
                     catch (FileNotFoundException)
                     {
@@ -877,23 +877,6 @@ namespace Robust.Shared.ContentPack
                 return null;
             }
 
-            private static PEReader ReaderFromStream(Stream stream)
-            {
-                if (OperatingSystem.IsLinux() && stream is FileStream)
-                {
-                    // PEReader is bugged on Linux and not properly thread safe when doing memory mapping.
-                    // As such, we never pass it a file stream so it uses a different, non-bugged code path.
-                    // See https://github.com/dotnet/runtime/issues/60545
-                    var ms = new MemoryStream();
-                    stream.CopyTo(ms);
-                    ms.Seek(0, SeekOrigin.Begin);
-                    stream.Dispose();
-                    stream = ms;
-                }
-
-                return new PEReader(stream);
-            }
-
             public PEReader? Resolve(string simpleName)
             {
                 return _dictionary.GetOrAdd(simpleName, ResolveCore);

Robust.Shared/ContentPack/ModLoader.cs

@@ -160,7 +160,7 @@ namespace Robust.Shared.ContentPack
 
         private static (string[] refs, string name) GetAssemblyReferenceData(Stream stream)
         {
-            using var reader = new PEReader(stream);
+            using var reader = ModLoader.MakePEReader(stream);
             var metaReader = reader.GetMetadataReader();
 
             var name = metaReader.GetString(metaReader.GetAssemblyDefinition().Name);
@@ -383,5 +383,13 @@ namespace Robust.Shared.ContentPack
                 EngineModuleDirectories = _engineModuleDirectories.ToArray()
             };
         }
+
+        internal static PEReader MakePEReader(Stream stream, bool leaveOpen=false)
+        {
+            if (!stream.CanSeek)
+                stream = leaveOpen ? stream.CopyToMemoryStream() : stream.ConsumeToMemoryStream();
+
+            return new PEReader(stream, leaveOpen ? PEStreamOptions.LeaveOpen : default);
+        }
     }
 }

Robust.Shared/ContentPack/NonSeekableStream.cs

@@ -0,0 +1,95 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Robust.Shared.ContentPack;
+
+internal sealed class NonSeekableStream : Stream
+{
+    private readonly Stream _baseStream;
+
+    public NonSeekableStream(Stream baseStream)
+    {
+        _baseStream = baseStream;
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (disposing)
+            _baseStream.Dispose();
+    }
+
+    public override ValueTask DisposeAsync()
+    {
+        return _baseStream.DisposeAsync();
+    }
+
+    public override void Flush()
+    {
+        _baseStream.Flush();
+    }
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        return _baseStream.Read(buffer, offset, count);
+    }
+
+    public override int Read(Span<byte> buffer)
+    {
+        return _baseStream.Read(buffer);
+    }
+
+    public override int ReadByte()
+    {
+        return _baseStream.ReadByte();
+    }
+
+    public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = new CancellationToken())
+    {
+        return _baseStream.ReadAsync(buffer, cancellationToken);
+    }
+
+    public override long Seek(long offset, SeekOrigin origin)
+    {
+        throw new NotSupportedException();
+    }
+
+    public override void SetLength(long value)
+    {
+        throw new NotSupportedException();
+    }
+
+    public override void Write(byte[] buffer, int offset, int count)
+    {
+        _baseStream.Write(buffer, offset, count);
+    }
+
+    public override void Write(ReadOnlySpan<byte> buffer)
+    {
+        _baseStream.Write(buffer);
+    }
+
+    public override void WriteByte(byte value)
+    {
+        _baseStream.WriteByte(value);
+    }
+
+    public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = new CancellationToken())
+    {
+        return _baseStream.WriteAsync(buffer, cancellationToken);
+    }
+
+    public override bool CanRead => _baseStream.CanRead;
+    public override bool CanSeek => false;
+    public override bool CanWrite => _baseStream.CanWrite;
+    // .NET mingles seekability and exposing length.
+    // This makes absolutely no sense but ok.
+    public override long Length => throw new NotSupportedException();
+
+    public override long Position
+    {
+        get => throw new NotSupportedException();
+        set => throw new NotSupportedException();
+    }
+}

Robust.Shared/ContentPack/ResourceManager.cs

@@ -23,6 +23,8 @@ namespace Robust.Shared.ContentPack
         private readonly List<(ResourcePath prefix, IContentRoot root)> _contentRoots =
             new();
 
+        private StreamSeekMode _streamSeekMode;
+
         // Special file names on Windows like serial ports.
         private static readonly Regex BadPathSegmentRegex =
             new("^(CON|PRN|AUX|NUL|COM[1-9]|LPT[1-9])$", RegexOptions.IgnoreCase);
@@ -45,6 +47,8 @@ namespace Robust.Shared.ContentPack
             {
                 UserData = new VirtualWritableDirProvider();
             }
+
+            _config.OnValueChanged(CVars.ResStreamSeekMode, i => _streamSeekMode = (StreamSeekMode)i, true);
         }
 
         /// <inheritdoc />
@@ -191,8 +195,9 @@ namespace Robust.Shared.ContentPack
                         continue;
                     }
 
-                    if (root.TryGetFile(relative, out fileStream))
+                    if (root.TryGetFile(relative, out var stream))
                     {
+                        fileStream = WrapStream(stream);
                         return true;
                     }
                 }
@@ -206,6 +211,35 @@ namespace Robust.Shared.ContentPack
             }
         }
 
+        /// <summary>
+        /// Apply <see cref="_streamSeekMode"/> to the provided stream.
+        /// </summary>
+        private Stream WrapStream(Stream stream)
+        {
+            switch (_streamSeekMode)
+            {
+                case StreamSeekMode.None:
+                    return stream;
+
+                case StreamSeekMode.ForceSeekable:
+                    if (stream.CanSeek)
+                        return stream;
+
+                    var ms = new MemoryStream(stream.CopyToArray(), writable: false);
+                    stream.Dispose();
+                    return ms;
+
+                case StreamSeekMode.ForceNonSeekable:
+                    if (!stream.CanSeek)
+                        return stream;
+
+                    return new NonSeekableStream(stream);
+
+                default:
+                    throw new InvalidOperationException();
+            }
+        }
+
         /// <inheritdoc />
         public bool ContentFileExists(string path)
         {

Robust.Shared/ContentPack/Sandbox.yml

@@ -689,6 +689,7 @@ Types:
     CancellationToken: { All: True }
     CancellationTokenSource: { All: True }
     Interlocked: { All: True }
+    Monitor: { All: True }
   System.Web:
     HttpUtility:
       Methods:

Robust.Shared/ContentPack/StreamSeekMode.cs

@@ -0,0 +1,22 @@
+namespace Robust.Shared.ContentPack;
+
+/// <summary>
+/// Seekability force mode for ResourceManager.
+/// </summary>
+public enum StreamSeekMode
+{
+    /// <summary>
+    /// Do not do anything special. Streams will be seekable if the VFS can provide it (e.g. not compressed).
+    /// </summary>
+    None = 0,
+
+    /// <summary>
+    /// All streams will be forced as seekable by buffering them in memory if necessary.
+    /// </summary>
+    ForceSeekable = 1,
+
+    /// <summary>
+    /// Force streams to be non-seekable by wrapping them in another stream instances.
+    /// </summary>
+    ForceNonSeekable = 2
+}

Robust.Shared/GameObjects/Components/Appearance/AppearanceComponent.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using Robust.Shared.GameStates;
+using Robust.Shared.Utility;
 using Robust.Shared.ViewVariables;
 
 namespace Robust.Shared.GameObjects;
@@ -27,6 +28,8 @@ public abstract class AppearanceComponent : Component
         if (AppearanceData.TryGetValue(key, out var existing) && existing.Equals(value))
             return;
 
+        DebugTools.Assert(value.GetType().IsValueType || value is ICloneable, "Appearance data values must be cloneable.");
+
         AppearanceData[key] = value;
         Dirty();
         EntitySystem.Get<SharedAppearanceSystem>().MarkDirty(this);
@@ -37,6 +40,8 @@ public abstract class AppearanceComponent : Component
         if (AppearanceData.TryGetValue(key, out var existing) && existing.Equals(value))
             return;
 
+        DebugTools.Assert(value.GetType().IsValueType || value is ICloneable, "Appearance data values must be cloneable.");
+
         AppearanceData[key] = value;
         Dirty();
         EntitySystem.Get<SharedAppearanceSystem>().MarkDirty(this);

Robust.Shared/GameObjects/Components/Collidable/ILookupWorldBox2Component.cs

@@ -1,9 +1,10 @@
 using Robust.Shared.Maths;
+using Robust.Shared.Physics;
 
 namespace Robust.Shared.GameObjects
 {
     public interface ILookupWorldBox2Component
     {
-        Box2 GetWorldAABB(Vector2? worldPos = null, Angle? worldRot = null);
+        Box2 GetAABB(Transform transform);
     }
 }

Robust.Shared/GameObjects/Components/Collidable/PhysicsComponent.Physics.cs

@@ -266,12 +266,8 @@ namespace Robust.Shared.GameObjects
             Dirty(_entMan);
         }
 
-        public Box2 GetWorldAABB(Vector2? worldPos = null, Angle? worldRot = null)
+        public Box2 GetAABB(Transform transform)
         {
-            worldPos ??= _entMan.GetComponent<TransformComponent>(Owner).WorldPosition;
-            worldRot ??= _entMan.GetComponent<TransformComponent>(Owner).WorldRotation;
-            var transform = new Transform(worldPos.Value, (float) worldRot.Value.Theta);
-
             var bounds = new Box2(transform.Position, transform.Position);
 
             foreach (var fixture in _entMan.GetComponent<FixturesComponent>(Owner).Fixtures.Values)
@@ -286,13 +282,24 @@ namespace Robust.Shared.GameObjects
             return bounds;
         }
 
-        public Box2 GetWorldAABB(Vector2 worldPos, Angle worldRot, EntityQuery<FixturesComponent> fixtures)
+        [Obsolete("Use the GetWorldAABB on EntityLookupSystem")]
+        public Box2 GetWorldAABB(Vector2? worldPos = null, Angle? worldRot = null)
         {
-            var transform = new Transform(worldPos, (float) worldRot.Theta);
+            if (worldPos == null && worldRot == null)
+            {
+                (worldPos, worldRot) = _entMan.GetComponent<TransformComponent>(Owner).GetWorldPositionRotation();
+            }
+            else
+            {
+                worldPos ??= _entMan.GetComponent<TransformComponent>(Owner).WorldPosition;
+                worldRot ??= _entMan.GetComponent<TransformComponent>(Owner).WorldRotation;
+            }
+
+            var transform = new Transform(worldPos.Value, (float) worldRot.Value.Theta);
 
             var bounds = new Box2(transform.Position, transform.Position);
 
-            foreach (var fixture in fixtures.GetComponent(Owner).Fixtures.Values)
+            foreach (var fixture in _entMan.GetComponent<FixturesComponent>(Owner).Fixtures.Values)
             {
                 for (var i = 0; i < fixture.Shape.ChildCount; i++)
                 {
@@ -651,7 +658,10 @@ namespace Robust.Shared.GameObjects
                 if (value * value > 0.0f)
                     Awake = true;
 
-                if (MathHelper.CloseToPercent(_angularVelocity, value, 0.0001f))
+                // CloseToPercent tolerance needs to be small enough such that an angular velocity just above
+                // sleep-tolerance can damp down to sleeping.
+
+                if (MathHelper.CloseToPercent(_angularVelocity, value, 0.00001f))
                     return;
 
                 _angularVelocity = value;

Robust.Shared/GameObjects/Components/IgnorePauseComponent.cs

@@ -1,25 +1,24 @@
 using Robust.Shared.IoC;
-using Robust.Shared.Timing;
+using Robust.Shared.Map;
 
 namespace Robust.Shared.GameObjects
 {
     [RegisterComponent]
     public sealed class IgnorePauseComponent : Component
     {
-        [Dependency] private readonly IEntityManager _entMan = default!;
-
         protected override void OnAdd()
         {
             base.OnAdd();
-            _entMan.GetComponent<MetaDataComponent>(Owner).EntityPaused = false;
+            IoCManager.Resolve<IEntityManager>().GetComponent<MetaDataComponent>(Owner).EntityPaused = false;
         }
 
         protected override void OnRemove()
         {
             base.OnRemove();
-            if (IoCManager.Resolve<IPauseManager>().IsMapPaused(_entMan.GetComponent<TransformComponent>(Owner).MapID))
+            var entMan = IoCManager.Resolve<IEntityManager>();
+            if (IoCManager.Resolve<IMapManager>().IsMapPaused(entMan.GetComponent<TransformComponent>(Owner).MapID))
             {
-                _entMan.GetComponent<MetaDataComponent>(Owner).EntityPaused = true;
+                entMan.GetComponent<MetaDataComponent>(Owner).EntityPaused = true;
             }
         }
     }

Robust.Shared/GameObjects/Components/Map/MapComponent.cs

@@ -15,12 +15,13 @@ namespace Robust.Shared.GameObjects
     {
         bool LightingEnabled { get; set; }
         MapId WorldMap { get; }
-        void ClearMapId();
+        bool MapPaused { get; internal set; }
+        bool MapPreInit { get; internal set; }
     }
 
     /// <inheritdoc cref="IMapComponent"/>
     [ComponentReference(typeof(IMapComponent))]
-    [NetworkedComponent()]
+    [NetworkedComponent]
     public sealed class MapComponent : Component, IMapComponent
     {
         [Dependency] private readonly IEntityManager _entMan = default!;
@@ -40,10 +41,22 @@ namespace Robust.Shared.GameObjects
             internal set => _mapIndex = value;
         }
 
+        internal bool MapPaused { get; set; } = false;
+
         /// <inheritdoc />
-        public void ClearMapId()
+        bool IMapComponent.MapPaused
         {
-            _mapIndex = MapId.Nullspace;
+            get => this.MapPaused;
+            set => this.MapPaused = value;
+        }
+
+        internal bool MapPreInit { get; set; } = false;
+
+        /// <inheritdoc />
+        bool IMapComponent.MapPreInit
+        {
+            get => this.MapPreInit;
+            set => this.MapPreInit = value;
         }
 
         /// <inheritdoc />
@@ -62,8 +75,9 @@ namespace Robust.Shared.GameObjects
 
             _mapIndex = state.MapId;
             LightingEnabled = state.LightingEnabled;
+            var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
 
-            _entMan.GetComponent<TransformComponent>(Owner).ChangeMapId(_mapIndex);
+            xformQuery.GetComponent(Owner).ChangeMapId(_mapIndex, xformQuery);
         }
     }
 

Robust.Shared/GameObjects/Components/Map/MapGridComponent.cs

@@ -78,7 +78,7 @@ namespace Robust.Shared.GameObjects
 
             if (result)
             {
-                xform.Parent = _entMan.GetComponent<TransformComponent>(Owner);
+                xform.ParentUid = Owner;
 
                 // anchor snapping
                 xform.LocalPosition = Grid.GridTileToLocal(tileIndices).Position;

Robust.Shared/GameObjects/Components/MetaDataComponent.cs

@@ -50,11 +50,9 @@ namespace Robust.Shared.GameObjects
     [NetworkedComponent]
     public sealed class MetaDataComponent : Component
     {
-        [DataField("name")]
-        private string? _entityName;
-        [DataField("desc")]
-        private string? _entityDescription;
-        private EntityPrototype? _entityPrototype;
+        [DataField("name")] internal string? _entityName;
+        [DataField("desc")] internal string? _entityDescription;
+        internal EntityPrototype? _entityPrototype;
         private bool _entityPaused;
 
         // Every entity starts at tick 1, because they are conceptually created in the time between 0->1
@@ -134,6 +132,9 @@ namespace Robust.Shared.GameObjects
         [ViewVariables]
         public EntityLifeStage EntityLifeStage { get; internal set; }
 
+        [ViewVariables]
+        public MetaDataFlags Flags { get; internal set; }
+
         /// <summary>
         ///     The sum of our visibility layer and our parent's visibility layers.
         ///     Server-only.
@@ -147,9 +148,11 @@ namespace Robust.Shared.GameObjects
             get => _entityPaused;
             set
             {
-                var entMan = IoCManager.Resolve<IEntityManager>();
+                if (_entityPaused == value)
+                    return;
 
-                if (_entityPaused == value || value && entMan.HasComponent<IgnorePauseComponent>(Owner))
+                var entMan = IoCManager.Resolve<IEntityManager>();
+                if (value && entMan.HasComponent<IgnorePauseComponent>(Owner))
                     return;
 
                 _entityPaused = value;
@@ -161,26 +164,6 @@ namespace Robust.Shared.GameObjects
         public bool EntityInitializing => EntityLifeStage == EntityLifeStage.Initializing;
         public bool EntityDeleted => EntityLifeStage >= EntityLifeStage.Deleted;
 
-
-        public override ComponentState GetComponentState()
-        {
-            return new MetaDataComponentState(_entityName, _entityDescription, EntityPrototype?.ID);
-        }
-
-        public override void HandleComponentState(ComponentState? curState, ComponentState? nextState)
-        {
-            base.HandleComponentState(curState, nextState);
-
-            if (!(curState is MetaDataComponentState state))
-                return;
-
-            _entityName = state.Name;
-            _entityDescription = state.Description;
-
-            if(state.PrototypeId != null)
-                _entityPrototype = IoCManager.Resolve<IPrototypeManager>().Index<EntityPrototype>(state.PrototypeId);
-        }
-
         internal override void ClearTicks()
         {
             // Do not clear modified ticks.
@@ -190,4 +173,14 @@ namespace Robust.Shared.GameObjects
             ClearCreationTick();
         }
     }
+
+    [Flags]
+    public enum MetaDataFlags : byte
+    {
+        None = 0,
+        /// <summary>
+        /// Whether the entity has states specific to a particular player.
+        /// </summary>
+        EntitySpecific = 1 << 0,
+    }
 }

Robust.Shared/GameObjects/Components/Renderable/SharedSpriteComponent.cs

@@ -77,7 +77,7 @@ namespace Robust.Shared.GameObjects
             [DataField("color")]
             public Color Color = Color.White;
             [DataField("map")]
-            public List<string>? MapKeys;
+            public HashSet<string>? MapKeys;
 
             public static PrototypeLayerData New()
             {

Robust.Shared/GameObjects/Components/Transform/TransformComponent.cs

@@ -8,6 +8,7 @@ using Robust.Shared.IoC;
 using Robust.Shared.Log; //Needed for release build, do not remove
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
+using Robust.Shared.Physics;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.Utility;
@@ -84,10 +85,12 @@ namespace Robust.Shared.GameObjects
                 if (_gridId.Equals(value)) return;
 
                 _gridId = value;
-                foreach (var transformComponent in Children)
+                var childEnumerator = ChildEnumerator;
+                var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
+
+                while (childEnumerator.MoveNext(out var child))
                 {
-                    var child = transformComponent;
-                    child.GridID = value;
+                    xformQuery.GetComponent(child.Value).GridID = value;
                 }
             }
         }
@@ -137,7 +140,7 @@ namespace Robust.Shared.GameObjects
                 if (!DeferUpdates)
                 {
                     RebuildMatrices();
-                    var rotateEvent = new RotateEvent(Owner, oldRotation, _localRotation);
+                    var rotateEvent = new RotateEvent(Owner, oldRotation, _localRotation, this);
                     _entMan.EventBus.RaiseLocalEvent(Owner, ref rotateEvent);
                 }
                 else
@@ -155,12 +158,18 @@ namespace Robust.Shared.GameObjects
         {
             get
             {
-                if (_parent.IsValid())
+                var parent = _parent;
+                var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
+                var rotation = _localRotation;
+
+                while (parent.IsValid())
                 {
-                    return Parent!.WorldRotation + _localRotation;
+                    var parentXform = xformQuery.GetComponent(parent);
+                    rotation += parentXform._localRotation;
+                    parent = parentXform.ParentUid;
                 }
 
-                return _localRotation;
+                return rotation;
             }
             set
             {
@@ -201,7 +210,11 @@ namespace Robust.Shared.GameObjects
         public EntityUid ParentUid
         {
             get => _parent;
-            set => Parent = _entMan.GetComponent<TransformComponent>(value);
+            set
+            {
+                if (value == _parent) return;
+                Parent = _entMan.GetComponent<TransformComponent>(value);
+            }
         }
 
         /// <summary>
@@ -211,15 +224,21 @@ namespace Robust.Shared.GameObjects
         {
             get
             {
-                if (_parent.IsValid())
+                var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
+                var parent = _parent;
+                var myMatrix = _localMatrix;
+
+                while (parent.IsValid())
                 {
-                    var parentMatrix = Parent!.WorldMatrix;
-                    var myMatrix = GetLocalMatrix();
+                    var parentXform = xformQuery.GetComponent(parent);
+                    var parentMatrix = parentXform._localMatrix;
+                    parent = parentXform.ParentUid;
+
                     Matrix3.Multiply(ref myMatrix, ref parentMatrix, out var result);
-                    return result;
+                    myMatrix = result;
                 }
 
-                return GetLocalMatrix();
+                return myMatrix;
             }
         }
 
@@ -230,15 +249,21 @@ namespace Robust.Shared.GameObjects
         {
             get
             {
-                if (_parent.IsValid())
+                var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
+                var parent = _parent;
+                var myMatrix = _invLocalMatrix;
+
+                while (parent.IsValid())
                 {
-                    var matP = Parent!.InvWorldMatrix;
-                    var myMatrix = GetLocalMatrixInv();
-                    Matrix3.Multiply(ref matP, ref myMatrix, out var result);
-                    return result;
+                    var parentXform = xformQuery.GetComponent(parent);
+                    var parentMatrix = parentXform._invLocalMatrix;
+                    parent = parentXform.ParentUid;
+
+                    Matrix3.Multiply(ref parentMatrix, ref myMatrix, out var result);
+                    myMatrix = result;
                 }
 
-                return GetLocalMatrixInv();
+                return myMatrix;
             }
         }
 
@@ -314,25 +339,26 @@ namespace Robust.Shared.GameObjects
 
                 if (!sameParent)
                 {
+                    var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
                     changedParent = true;
-                    var newParent = _entMan.GetComponent<TransformComponent>(value.EntityId);
+                    var newParent = xformQuery.GetComponent(value.EntityId);
 
                     DebugTools.Assert(newParent != this,
                         $"Can't parent a {nameof(TransformComponent)} to itself.");
 
                     // That's already our parent, don't bother attaching again.
 
-                    var oldParent = Parent;
+                    var oldParent = _parent.IsValid() ? xformQuery.GetComponent(_parent) : null;
                     var uid = Owner;
                     oldParent?._children.Remove(uid);
                     newParent._children.Add(uid);
 
                     // offset position from world to parent
                     _parent = value.EntityId;
-                    ChangeMapId(newParent.MapID);
+                    ChangeMapId(newParent.MapID, xformQuery);
 
                     // Cache new GridID before raising the event.
-                    GridID = GetGridIndex();
+                    GridID = GetGridIndex(xformQuery);
 
                     var entParentChangedMessage = new EntParentChangedMessage(Owner, oldParent?.Owner);
                     _entMan.EventBus.RaiseLocalEvent(Owner, ref entParentChangedMessage);
@@ -343,7 +369,8 @@ namespace Robust.Shared.GameObjects
                 // This may not in fact be the right thing.
                 if (changedParent || !DeferUpdates)
                     RebuildMatrices();
-                Dirty();
+
+                Dirty(_entMan);
 
                 if (!DeferUpdates)
                 {
@@ -459,10 +486,11 @@ namespace Robust.Shared.GameObjects
                 if (_children.Count == 0) yield break;
 
                 var xforms = _entMan.GetEntityQuery<TransformComponent>();
+                var children = ChildEnumerator;
 
-                foreach (var child in _children)
+                while (children.MoveNext(out var child))
                 {
-                    yield return xforms.GetComponent(child);
+                    yield return xforms.GetComponent(child.Value);
                 }
             }
         }
@@ -507,22 +535,23 @@ namespace Robust.Shared.GameObjects
             // Children MAY be initialized here before their parents are.
             // We do this whole dance to handle this recursively,
             // setting _mapIdInitialized along the way to avoid going to the IMapComponent every iteration.
-            static MapId FindMapIdAndSet(TransformComponent p, IEntityManager entMan)
+            static MapId FindMapIdAndSet(TransformComponent xform, IEntityManager entMan, EntityQuery<TransformComponent> xformQuery)
             {
-                if (p._mapIdInitialized)
+                if (xform._mapIdInitialized)
                 {
-                    return p.MapID;
+                    return xform.MapID;
                 }
 
                 MapId value;
-                if (p._parent.IsValid())
+
+                if (xform._parent.IsValid())
                 {
-                    value = FindMapIdAndSet((TransformComponent) p.Parent!, entMan);
+                    value = FindMapIdAndSet(xformQuery.GetComponent(xform._parent), entMan, xformQuery);
                 }
                 else
                 {
                     // second level node, terminates recursion up the branch of the tree
-                    if (entMan.TryGetComponent(p.Owner, out IMapComponent? mapComp))
+                    if (entMan.TryGetComponent(xform.Owner, out IMapComponent? mapComp))
                     {
                         value = mapComp.WorldMap;
                     }
@@ -532,14 +561,16 @@ namespace Robust.Shared.GameObjects
                     }
                 }
 
-                p.MapID = value;
-                p._mapIdInitialized = true;
+                xform.MapID = value;
+                xform._mapIdInitialized = true;
                 return value;
             }
 
+            var xformQuery = _entMan.GetEntityQuery<TransformComponent>();
+
             if (!_mapIdInitialized)
             {
-                FindMapIdAndSet(this, _entMan);
+                FindMapIdAndSet(this, _entMan, xformQuery);
 
                 _mapIdInitialized = true;
             }
@@ -549,14 +580,14 @@ namespace Robust.Shared.GameObjects
             {
                 // Note that _children is a SortedSet<EntityUid>,
                 // so duplicate additions (which will happen) don't matter.
-                ((TransformComponent) Parent!)._children.Add(Owner);
+                xformQuery.GetComponent(_parent)._children.Add(Owner);
             }
 
-            GridID = GetGridIndex();
+            GridID = GetGridIndex(xformQuery);
             RebuildMatrices();
         }
 
-        private GridId GetGridIndex()
+        private GridId GetGridIndex(EntityQuery<TransformComponent> xformQuery)
         {
             if (_entMan.HasComponent<IMapComponent>(Owner))
             {
@@ -570,7 +601,7 @@ namespace Robust.Shared.GameObjects
 
             if (_parent.IsValid())
             {
-                return Parent!.GridID;
+                return xformQuery.GetComponent(_parent).GridID;
             }
 
             return _mapManager.TryFindGridAt(MapID, WorldPosition, out var mapgrid) ? mapgrid.Index : GridId.Invalid;
@@ -585,13 +616,13 @@ namespace Robust.Shared.GameObjects
             base.Startup();
 
             // Keep the cached matrices in sync with the fields.
-            Dirty();
+            Dirty(_entMan);
         }
 
         /// <summary>
         ///     Run MoveEvent, RotateEvent, and UpdateEntityTree updates.
         /// </summary>
-        public void RunDeferred(Box2 worldAABB)
+        public void RunDeferred()
         {
             // if we resolved to (close enough) to the OG position then no update.
             if ((_oldCoords == null || _oldCoords.Equals(Coordinates)) &&
@@ -604,14 +635,14 @@ namespace Robust.Shared.GameObjects
 
             if (_oldCoords != null)
             {
-                var moveEvent = new MoveEvent(Owner, _oldCoords.Value, Coordinates, this, worldAABB);
+                var moveEvent = new MoveEvent(Owner, _oldCoords.Value, Coordinates, this);
                 _entMan.EventBus.RaiseLocalEvent(Owner, ref moveEvent);
                 _oldCoords = null;
             }
 
             if (_oldLocalRotation != null)
             {
-                var rotateEvent = new RotateEvent(Owner, _oldLocalRotation.Value, _localRotation, worldAABB);
+                var rotateEvent = new RotateEvent(Owner, _oldLocalRotation.Value, _localRotation, this);
                 _entMan.EventBus.RaiseLocalEvent(Owner, ref rotateEvent);
                 _oldLocalRotation = null;
             }
@@ -622,6 +653,12 @@ namespace Robust.Shared.GameObjects
         /// </summary>
         public void AttachToGridOrMap()
         {
+            bool TerminatingOrDeleted(EntityUid uid)
+            {
+                return !_entMan.TryGetComponent(uid, out MetaDataComponent? meta)
+                       || meta.EntityLifeStage >= EntityLifeStage.Terminating;
+            }
+
             // nothing to do
             var oldParent = Parent;
             if (oldParent == null)
@@ -632,11 +669,13 @@ namespace Robust.Shared.GameObjects
             var mapPos = MapPosition;
 
             EntityUid newMapEntity;
-            if (_mapManager.TryFindGridAt(mapPos, out var mapGrid))
+            if (_mapManager.TryFindGridAt(mapPos, out var mapGrid) && !TerminatingOrDeleted(mapGrid.GridEntityId))
             {
                 newMapEntity = mapGrid.GridEntityId;
             }
-            else if (_mapManager.HasMapEntity(mapPos.MapId))
+            else if (_mapManager.HasMapEntity(mapPos.MapId)
+                     && _mapManager.GetMapEntityIdOrThrow(mapPos.MapId) is var mapEnt
+                     && !TerminatingOrDeleted(mapEnt))
             {
                 newMapEntity = _mapManager.GetMapEntityIdOrThrow(mapPos.MapId);
             }
@@ -721,25 +760,36 @@ namespace Robust.Shared.GameObjects
             Coordinates = new EntityCoordinates(newParent.Owner, newParent.InvWorldMatrix.Transform(WorldPosition));
         }
 
-        internal void ChangeMapId(MapId newMapId)
+        internal void ChangeMapId(MapId newMapId, EntityQuery<TransformComponent> xformQuery)
         {
             if (newMapId == MapID)
                 return;
 
             var oldMapId = MapID;
 
+            //Set Paused state
+            var mapPaused = _mapManager.IsMapPaused(newMapId);
+            var metaData = _entMan.GetComponent<MetaDataComponent>(Owner);
+            metaData.EntityPaused = mapPaused;
+
             MapID = newMapId;
             MapIdChanged(oldMapId);
-            UpdateChildMapIdsRecursive(MapID, _entMan);
+            var xforms = _entMan.GetEntityQuery<TransformComponent>();
+            var metaEnts = _entMan.GetEntityQuery<MetaDataComponent>();
+            UpdateChildMapIdsRecursive(MapID, mapPaused, xforms, metaEnts);
         }
 
-        private void UpdateChildMapIdsRecursive(MapId newMapId, IEntityManager entMan)
+        private void UpdateChildMapIdsRecursive(MapId newMapId, bool mapPaused, EntityQuery<TransformComponent> xformQuery, EntityQuery<MetaDataComponent> metaQuery)
         {
-            var xforms = _entMan.GetEntityQuery<TransformComponent>();
+            var childEnumerator = ChildEnumerator;
 
-            foreach (var child in _children)
+            while (childEnumerator.MoveNext(out var child))
             {
-                var concrete = xforms.GetComponent(child);
+                //Set Paused state
+                var metaData = metaQuery.GetComponent(child.Value);
+                metaData.EntityPaused = mapPaused;
+
+                var concrete = xformQuery.GetComponent(child.Value);
                 var old = concrete.MapID;
 
                 concrete.MapID = newMapId;
@@ -747,7 +797,7 @@ namespace Robust.Shared.GameObjects
 
                 if (concrete.ChildCount != 0)
                 {
-                    concrete.UpdateChildMapIdsRecursive(newMapId, entMan);
+                    concrete.UpdateChildMapIdsRecursive(newMapId, mapPaused, xformQuery, metaQuery);
                 }
             }
         }
@@ -800,14 +850,14 @@ namespace Robust.Shared.GameObjects
         {
             var parent = _parent;
             var worldRot = _localRotation;
-            var worldMatrix = GetLocalMatrix();
+            var worldMatrix = _localMatrix;
 
             // By doing these all at once we can elide multiple IsValid + GetComponent calls
             while (parent.IsValid())
             {
                 var xform = xforms.GetComponent(parent);
                 worldRot += xform.LocalRotation;
-                var parentMatrix = xform.GetLocalMatrix();
+                var parentMatrix = xform._localMatrix;
                 Matrix3.Multiply(ref worldMatrix, ref parentMatrix, out var result);
                 worldMatrix = result;
                 parent = xform.ParentUid;
@@ -861,8 +911,8 @@ namespace Robust.Shared.GameObjects
         {
             var parent = _parent;
             var worldRot = _localRotation;
-            var invMatrix = GetLocalMatrixInv();
-            var worldMatrix = GetLocalMatrix();
+            var invMatrix = _invLocalMatrix;
+            var worldMatrix = _localMatrix;
 
             // By doing these all at once we can elide multiple IsValid + GetComponent calls
             while (parent.IsValid())
@@ -870,11 +920,11 @@ namespace Robust.Shared.GameObjects
                 var xform = xformQuery.GetComponent(parent);
                 worldRot += xform.LocalRotation;
 
-                var parentMatrix = xform.GetLocalMatrix();
+                var parentMatrix = xform._localMatrix;
                 Matrix3.Multiply(ref worldMatrix, ref parentMatrix, out var result);
                 worldMatrix = result;
 
-                var parentInvMatrix = xform.GetLocalMatrixInv();
+                var parentInvMatrix = xform._invLocalMatrix;
                 Matrix3.Multiply(ref parentInvMatrix, ref invMatrix, out var invResult);
                 invMatrix = invResult;
 
@@ -1005,16 +1055,6 @@ namespace Robust.Shared.GameObjects
             }
         }
 
-        public Matrix3 GetLocalMatrix()
-        {
-            return _localMatrix;
-        }
-
-        public Matrix3 GetLocalMatrixInv()
-        {
-            return _invLocalMatrix;
-        }
-
         private void RebuildMatrices()
         {
             var pos = _localPosition;
@@ -1109,24 +1149,18 @@ namespace Robust.Shared.GameObjects
     [ByRefEvent]
     public readonly struct MoveEvent
     {
-        public MoveEvent(EntityUid sender, EntityCoordinates oldPos, EntityCoordinates newPos, TransformComponent component, Box2? worldAABB = null)
+        public MoveEvent(EntityUid sender, EntityCoordinates oldPos, EntityCoordinates newPos, TransformComponent component)
         {
             Sender = sender;
             OldPosition = oldPos;
             NewPosition = newPos;
             Component = component;
-            WorldAABB = worldAABB;
         }
 
         public readonly EntityUid Sender;
         public readonly EntityCoordinates OldPosition;
         public readonly EntityCoordinates NewPosition;
         public readonly TransformComponent Component;
-
-        /// <summary>
-        ///     New AABB of the entity.
-        /// </summary>
-        public readonly Box2? WorldAABB;
     }
 
     /// <summary>
@@ -1135,22 +1169,18 @@ namespace Robust.Shared.GameObjects
     [ByRefEvent]
     public readonly struct RotateEvent
     {
-        public RotateEvent(EntityUid sender, Angle oldRotation, Angle newRotation, Box2? worldAABB = null)
+        public RotateEvent(EntityUid sender, Angle oldRotation, Angle newRotation, TransformComponent xform)
         {
             Sender = sender;
             OldRotation = oldRotation;
             NewRotation = newRotation;
-            WorldAABB = worldAABB;
+            Component = xform;
         }
 
         public readonly EntityUid Sender;
         public readonly Angle OldRotation;
         public readonly Angle NewRotation;
-
-        /// <summary>
-        ///     New AABB of the entity.
-        /// </summary>
-        public readonly Box2? WorldAABB;
+        public readonly TransformComponent Component;
     }
 
     public struct TransformChildrenEnumerator : IDisposable

Robust.Shared/GameObjects/EntityManager.cs

@@ -20,7 +20,6 @@ namespace Robust.Shared.GameObjects
         [IoC.Dependency] protected readonly IEntitySystemManager EntitySystemManager = default!;
         [IoC.Dependency] private readonly IMapManager _mapManager = default!;
         [IoC.Dependency] private readonly IGameTiming _gameTiming = default!;
-        [IoC.Dependency] private readonly IPauseManager _pauseManager = default!;
 
         #endregion Dependencies
 
@@ -83,6 +82,7 @@ namespace Robust.Shared.GameObjects
             if (Started)
                 throw new InvalidOperationException("Startup() called multiple times");
 
+            // TODO: Probably better to call this on its own given it's so infrequent.
             EntitySystemManager.Initialize();
             Started = true;
         }
@@ -277,12 +277,13 @@ namespace Robust.Shared.GameObjects
 
         private void RecursiveDeleteEntity(EntityUid uid)
         {
-            if (!TryGetComponent(uid, out MetaDataComponent metadata) || metadata.EntityDeleted) 
+            if (!TryGetComponent(uid, out MetaDataComponent metadata) || metadata.EntityDeleted)
                 return; //TODO: Why was this still a child if it was already deleted?
 
             var transform = GetComponent<TransformComponent>(uid);
             metadata.EntityLifeStage = EntityLifeStage.Terminating;
-            EventBus.RaiseLocalEvent(uid, new EntityTerminatingEvent(), false);
+            var ev = new EntityTerminatingEvent(uid);
+            EventBus.RaiseLocalEvent(uid, ref ev, false);
 
             // DeleteEntity modifies our _children collection, we must cache the collection to iterate properly
             foreach (var child in transform._children.ToArray())
@@ -438,7 +439,7 @@ namespace Robust.Shared.GameObjects
                 StartEntity(entity);
 
                 // If the map we're initializing the entity on is initialized, run map init on it.
-                if (_pauseManager.IsMapInitialized(mapId))
+                if (_mapManager.IsMapInitialized(mapId))
                     entity.RunMapInit();
             }
             catch (Exception e)

Robust.Shared/GameObjects/EntitySystem.Proxy.cs

@@ -571,4 +571,47 @@ public partial class EntitySystem
         => new($"Entity {uid} does not have a component of type {typeof(T)}");
 
     #endregion
+
+    #region Entity Query
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected EntityQuery<T> GetEntityQuery<T>() where T : Component
+    {
+        return EntityManager.GetEntityQuery<T>();
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected IEnumerable<TComp1> EntityQuery<TComp1>(bool includePaused = false) where TComp1 : Component
+    {
+        return EntityManager.EntityQuery<TComp1>(includePaused);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected IEnumerable<(TComp1, TComp2)> EntityQuery<TComp1, TComp2>(bool includePaused = false)
+        where TComp1 : Component
+        where TComp2 : Component
+    {
+        return EntityManager.EntityQuery<TComp1, TComp2>(includePaused);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected IEnumerable<(TComp1, TComp2, TComp3)> EntityQuery<TComp1, TComp2, TComp3>(bool includePaused = false)
+        where TComp1 : Component
+        where TComp2 : Component
+        where TComp3 : Component
+    {
+        return EntityManager.EntityQuery<TComp1, TComp2, TComp3>(includePaused);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected IEnumerable<(TComp1, TComp2, TComp3, TComp4)> EntityQuery<TComp1, TComp2, TComp3, TComp4>(bool includePaused = false)
+        where TComp1 : Component
+        where TComp2 : Component
+        where TComp3 : Component
+        where TComp4 : Component
+    {
+        return EntityManager.EntityQuery<TComp1, TComp2, TComp3, TComp4>(includePaused);
+    }
+
+    #endregion
 }

Robust.Shared/GameObjects/EntitySystemManager.cs

@@ -105,14 +105,29 @@ namespace Robust.Shared.GameObjects
         }
 
         /// <inheritdoc />
-        public void Initialize()
+        public void Initialize(bool discover = true)
         {
+            // Tempted to make this an assert
+            // However, EntityManager calls this directly so we'd need to remove that and manually call it.
+            if (_initialized) return;
+
             var excludedTypes = new HashSet<Type>();
 
             _systemDependencyCollection = new(IoCManager.Instance!);
             var subTypes = new Dictionary<Type, Type>();
             _systemTypes.Clear();
-            foreach (var type in _reflectionManager.GetAllChildren<IEntitySystem>().Concat(_extraLoadedTypes))
+            IEnumerable<Type> systems;
+
+            if (discover)
+            {
+                systems = _reflectionManager.GetAllChildren<IEntitySystem>().Concat(_extraLoadedTypes);
+            }
+            else
+            {
+                systems = _extraLoadedTypes;
+            }
+
+            foreach (var type in systems)
             {
                 Logger.DebugS("go.sys", "Initializing entity system {0}", type);
 
@@ -251,6 +266,7 @@ namespace Robust.Shared.GameObjects
 
         public void Clear()
         {
+            _extraLoadedTypes.Clear();
             _systemTypes.Clear();
             _updateOrder = Array.Empty<UpdateReg>();
             _frameUpdateOrder = Array.Empty<IEntitySystem>();

Robust.Shared/GameObjects/EntitySystemMessages/EntParentChangedMessage.cs

@@ -4,7 +4,7 @@
     ///     Raised when an entity parent is changed.
     /// </summary>
     [ByRefEvent]
-    public sealed class EntParentChangedMessage : EntityEventArgs
+    public readonly struct EntParentChangedMessage
     {
         /// <summary>
         ///     Entity that was adopted. The transform component has a property with the new parent.

Robust.Shared/GameObjects/EntitySystemMessages/EntityTerminatingEvent.cs

@@ -3,5 +3,14 @@ namespace Robust.Shared.GameObjects
     /// <summary>
     /// The children of this entity are about to be deleted.
     /// </summary>
-    public sealed class EntityTerminatingEvent : EntityEventArgs { }
+    [ByRefEvent]
+    public struct EntityTerminatingEvent
+    {
+        public EntityUid Owner;
+
+        public EntityTerminatingEvent(EntityUid uid)
+        {
+            Owner = uid;
+        }
+    }
 }

Robust.Shared/GameObjects/EntityUid.cs

@@ -3,7 +3,6 @@ using JetBrains.Annotations;
 using Robust.Shared.IoC;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
-using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom;
 using Robust.Shared.Timing;
 using Robust.Shared.ViewVariables;
 
@@ -172,7 +171,7 @@ namespace Robust.Shared.GameObjects
             set
             {
                 if (MetaData is {} metaData)
-                    metaData.EntityName = value;
+                    metaData.EntityDescription = value;
             }
         }
 

Robust.Shared/GameObjects/IEntitySystemManager.cs

@@ -89,8 +89,9 @@ namespace Robust.Shared.GameObjects
         /// <summary>
         /// Initialize, discover systems and initialize them through <see cref="IEntitySystem.Initialize"/>.
         /// </summary>
+        /// <param name="discover">Whether we should automatically find systems or have they been supplied already.</param>
         /// <seealso cref="IEntitySystem.Initialize"/>
-        void Initialize();
+        void Initialize(bool discover = true);
 
         /// <summary>
         /// Clean up, shut down all systems through <see cref="IEntitySystem.Shutdown"/> and remove them.

Robust.Shared/GameObjects/Systems/EntityLookup.LegacyQueries.cs

@@ -0,0 +1,476 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Physics;
+using Robust.Shared.Utility;
+
+namespace Robust.Shared.GameObjects;
+
+public sealed partial class EntityLookupSystem
+{
+    // TODO: Need to nuke most of the below and cleanup when entitylookup gets optimised some more (physics + containers).
+
+    private LookupsEnumerator GetLookupsIntersecting(MapId mapId, Box2 worldAABB)
+    {
+        _mapManager.FindGridsIntersectingEnumerator(mapId, worldAABB, out var gridEnumerator, true);
+
+        return new LookupsEnumerator(EntityManager, _mapManager, mapId, gridEnumerator);
+    }
+
+    private struct LookupsEnumerator
+    {
+        private IEntityManager EntityManager;
+        private IMapManager _mapManager;
+
+        private MapId _mapId;
+        private FindGridsEnumerator _enumerator;
+
+        private bool _final;
+
+        public LookupsEnumerator(IEntityManager entityManager, IMapManager mapManager, MapId mapId, FindGridsEnumerator enumerator)
+        {
+            EntityManager = entityManager;
+            _mapManager = mapManager;
+
+            _mapId = mapId;
+            _enumerator = enumerator;
+            _final = false;
+        }
+
+        public bool MoveNext([NotNullWhen(true)] out EntityLookupComponent? component)
+        {
+            if (!_enumerator.MoveNext(out var grid))
+            {
+                if (_final || _mapId == MapId.Nullspace)
+                {
+                    component = null;
+                    return false;
+                }
+
+                _final = true;
+                EntityUid mapUid = _mapManager.GetMapEntityIdOrThrow(_mapId);
+                component = EntityManager.GetComponent<EntityLookupComponent>(mapUid);
+                return true;
+            }
+
+            // TODO: Recursive and all that.
+            component = EntityManager.GetComponent<EntityLookupComponent>(grid.GridEntityId);
+            return true;
+        }
+    }
+
+    private IEnumerable<EntityUid> GetAnchored(MapId mapId, Box2 worldAABB, LookupFlags flags)
+    {
+        if ((flags & LookupFlags.IncludeAnchored) == 0x0) yield break;
+        foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldAABB))
+        {
+            foreach (var uid in grid.GetAnchoredEntities(worldAABB))
+            {
+                if (!EntityManager.EntityExists(uid)) continue;
+                yield return uid;
+            }
+        }
+    }
+
+    private IEnumerable<EntityUid> GetAnchored(MapId mapId, Box2Rotated worldBounds, LookupFlags flags)
+    {
+        if ((flags & LookupFlags.IncludeAnchored) == 0x0) yield break;
+        foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldBounds))
+        {
+            foreach (var uid in grid.GetAnchoredEntities(worldBounds))
+            {
+                if (!EntityManager.EntityExists(uid)) continue;
+                yield return uid;
+            }
+        }
+    }
+
+    /// <inheritdoc />
+    public bool AnyEntitiesIntersecting(MapId mapId, Box2 box, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var found = false;
+        var enumerator = GetLookupsIntersecting(mapId, box);
+
+        while (enumerator.MoveNext(out var lookup))
+        {
+            var offsetBox = EntityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(box);
+
+            lookup.Tree.QueryAabb(ref found, (ref bool found, in EntityUid ent) =>
+            {
+                if (EntityManager.Deleted(ent))
+                    return true;
+
+                found = true;
+                return false;
+
+            }, offsetBox, (flags & LookupFlags.Approximate) != 0x0);
+        }
+
+        if (!found)
+        {
+            foreach (var _ in GetAnchored(mapId, box, flags))
+            {
+                return true;
+            }
+        }
+
+        return found;
+    }
+
+    /// <inheritdoc />
+    [MethodImpl(MethodImplOptions.AggressiveOptimization)]
+    public void FastEntitiesIntersecting(in MapId mapId, ref Box2 worldAABB, EntityUidQueryCallback callback, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var enumerator = GetLookupsIntersecting(mapId, worldAABB);
+        while (enumerator.MoveNext(out var lookup))
+        {
+            var offsetBox = EntityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldAABB);
+
+            lookup.Tree._b2Tree.FastQuery(ref offsetBox, (ref EntityUid data) => callback(data));
+        }
+
+        if ((flags & LookupFlags.IncludeAnchored) != 0x0)
+        {
+            foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldAABB))
+            {
+                foreach (var uid in grid.GetAnchoredEntities(worldAABB))
+                {
+                    if (!EntityManager.EntityExists(uid)) continue;
+                    callback(uid);
+                }
+            }
+        }
+    }
+
+    /// <inheritdoc />
+    public void FastEntitiesIntersecting(EntityLookupComponent lookup, ref Box2 localAABB, EntityUidQueryCallback callback)
+    {
+        lookup.Tree._b2Tree.FastQuery(ref localAABB, (ref EntityUid data) => callback(data));
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2 worldAABB, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
+
+        var list = new List<EntityUid>();
+        var enumerator = GetLookupsIntersecting(mapId, worldAABB);
+
+        while (enumerator.MoveNext(out var lookup))
+        {
+            var offsetBox = EntityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldAABB);
+
+            lookup.Tree.QueryAabb(ref list, (ref List<EntityUid> list, in EntityUid ent) =>
+            {
+                if (!EntityManager.Deleted(ent))
+                {
+                    list.Add(ent);
+                }
+                return true;
+            }, offsetBox, (flags & LookupFlags.Approximate) != 0x0);
+        }
+
+        foreach (var ent in GetAnchored(mapId, worldAABB, flags))
+        {
+            list.Add(ent);
+        }
+
+        return list;
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2Rotated worldBounds, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
+
+        var list = new List<EntityUid>();
+        var worldAABB = worldBounds.CalcBoundingBox();
+        var enumerator = GetLookupsIntersecting(mapId, worldAABB);
+
+        while (enumerator.MoveNext(out var lookup))
+        {
+            var offsetBox = EntityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldBounds);
+
+            lookup.Tree.QueryAabb(ref list, (ref List<EntityUid> list, in EntityUid ent) =>
+            {
+                if (!EntityManager.Deleted(ent))
+                {
+                    list.Add(ent);
+                }
+                return true;
+            }, offsetBox, (flags & LookupFlags.Approximate) != 0x0);
+        }
+
+        foreach (var ent in GetAnchored(mapId, worldBounds, flags))
+        {
+            list.Add(ent);
+        }
+
+        return list;
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Vector2 position, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
+
+        var aabb = new Box2(position, position).Enlarged(PointEnlargeRange);
+        var list = new List<EntityUid>();
+        var state = (list, position);
+
+        var enumerator = GetLookupsIntersecting(mapId, aabb);
+
+        while (enumerator.MoveNext(out var lookup))
+        {
+            var localPoint = EntityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.Transform(position);
+
+            lookup.Tree.QueryPoint(ref state, (ref (List<EntityUid> list, Vector2 position) state, in EntityUid ent) =>
+            {
+                if (Intersecting(ent, state.position))
+                {
+                    state.list.Add(ent);
+                }
+                return true;
+            }, localPoint, (flags & LookupFlags.Approximate) != 0x0);
+        }
+
+        if ((flags & LookupFlags.IncludeAnchored) != 0x0 &&
+            _mapManager.TryFindGridAt(mapId, position, out var grid) &&
+            grid.TryGetTileRef(position, out var tile))
+        {
+            foreach (var uid in grid.GetAnchoredEntities(tile.GridIndices))
+            {
+                if (!EntityManager.EntityExists(uid)) continue;
+                state.list.Add(uid);
+            }
+        }
+
+        return list;
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesIntersecting(MapCoordinates position, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        return GetEntitiesIntersecting(position.MapId, position.Position, flags);
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesIntersecting(EntityCoordinates position, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var mapPos = position.ToMap(EntityManager);
+        return GetEntitiesIntersecting(mapPos.MapId, mapPos.Position, flags);
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesIntersecting(EntityUid entity, float enlarged = 0f, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var worldAABB = GetWorldAABB(entity);
+        var xform = EntityManager.GetComponent<TransformComponent>(entity);
+
+        var (worldPos, worldRot) = xform.GetWorldPositionRotation();
+
+        var enumerator = GetLookupsIntersecting(xform.MapID, worldAABB);
+        var list = new List<EntityUid>();
+
+        while (enumerator.MoveNext(out var lookup))
+        {
+            // To get the tightest bounds possible we'll re-calculate it for each lookup.
+            var localBounds = GetLookupBounds(entity, lookup, worldPos, worldRot, enlarged);
+
+            lookup.Tree.QueryAabb(ref list, (ref List<EntityUid> list, in EntityUid ent) =>
+            {
+                if (!EntityManager.Deleted(ent))
+                {
+                    list.Add(ent);
+                }
+                return true;
+            }, localBounds, (flags & LookupFlags.Approximate) != 0x0);
+        }
+
+        foreach (var ent in GetAnchored(xform.MapID, worldAABB, flags))
+        {
+            list.Add(ent);
+        }
+
+        return list;
+    }
+
+    private Box2 GetLookupBounds(EntityUid uid, EntityLookupComponent lookup, Vector2 worldPos, Angle worldRot, float enlarged)
+    {
+        var (_, lookupRot, lookupInvWorldMatrix) = EntityManager.GetComponent<TransformComponent>(lookup.Owner).GetWorldPositionRotationInvMatrix();
+
+        var localPos = lookupInvWorldMatrix.Transform(worldPos);
+        var localRot = worldRot - lookupRot;
+
+        if (EntityManager.TryGetComponent(uid, out FixturesComponent? manager))
+        {
+            var transform = new Transform(localPos, localRot);
+            Box2? aabb = null;
+
+            foreach (var (_, fixture) in manager.Fixtures)
+            {
+                if (!fixture.Hard) continue;
+                for (var i = 0; i < fixture.Shape.ChildCount; i++)
+                {
+                    aabb = aabb?.Union(fixture.Shape.ComputeAABB(transform, i)) ?? fixture.Shape.ComputeAABB(transform, i);
+                }
+            }
+
+            if (aabb != null)
+            {
+                return aabb.Value.Enlarged(enlarged);
+            }
+        }
+
+        // So IsEmpty checks don't get triggered
+        return new Box2(localPos - float.Epsilon, localPos + float.Epsilon);
+    }
+
+    /// <inheritdoc />
+    public bool IsIntersecting(EntityUid entityOne, EntityUid entityTwo)
+    {
+        var position = EntityManager.GetComponent<TransformComponent>(entityOne).MapPosition.Position;
+        return Intersecting(entityTwo, position);
+    }
+
+    private bool Intersecting(EntityUid entity, Vector2 mapPosition)
+    {
+        if (EntityManager.TryGetComponent(entity, out IPhysBody? component))
+        {
+            if (component.GetWorldAABB().Contains(mapPosition))
+                return true;
+        }
+        else
+        {
+            var transform = EntityManager.GetComponent<TransformComponent>(entity);
+            var entPos = transform.WorldPosition;
+            if (MathHelper.CloseToPercent(entPos.X, mapPosition.X)
+                && MathHelper.CloseToPercent(entPos.Y, mapPosition.Y))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesInRange(EntityCoordinates position, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var mapCoordinates = position.ToMap(EntityManager);
+        var mapPosition = mapCoordinates.Position;
+        var aabb = new Box2(mapPosition - new Vector2(range, range),
+            mapPosition + new Vector2(range, range));
+        return GetEntitiesIntersecting(mapCoordinates.MapId, aabb, flags);
+        // TODO: Use a circle shape here mate
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesInRange(MapId mapId, Box2 box, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var aabb = box.Enlarged(range);
+        return GetEntitiesIntersecting(mapId, aabb, flags);
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesInRange(MapId mapId, Vector2 point, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var aabb = new Box2(point, point).Enlarged(range);
+        return GetEntitiesIntersecting(mapId, aabb, flags);
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesInRange(EntityUid entity, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var worldAABB = GetWorldAABB(entity);
+        return GetEntitiesInRange(EntityManager.GetComponent<TransformComponent>(entity).MapID, worldAABB, range, flags);
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesInArc(EntityCoordinates coordinates, float range, Angle direction,
+        float arcWidth, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        var position = coordinates.ToMap(EntityManager).Position;
+
+        foreach (var entity in GetEntitiesInRange(coordinates, range * 2, flags))
+        {
+            var angle = new Angle(EntityManager.GetComponent<TransformComponent>(entity).WorldPosition - position);
+            if (angle.Degrees < direction.Degrees + arcWidth / 2 &&
+                angle.Degrees > direction.Degrees - arcWidth / 2)
+                yield return entity;
+        }
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesInMap(MapId mapId, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        DebugTools.Assert((flags & LookupFlags.Approximate) == 0x0);
+
+        foreach (EntityLookupComponent comp in EntityManager.EntityQuery<EntityLookupComponent>(true))
+        {
+            if (EntityManager.GetComponent<TransformComponent>(comp.Owner).MapID != mapId) continue;
+
+            foreach (var entity in comp.Tree)
+            {
+                if (EntityManager.Deleted(entity)) continue;
+
+                yield return entity;
+            }
+        }
+
+        if ((flags & LookupFlags.IncludeAnchored) == 0x0) yield break;
+
+        foreach (var grid in _mapManager.GetAllMapGrids(mapId))
+        {
+            foreach (var tile in grid.GetAllTiles())
+            {
+                foreach (var uid in grid.GetAnchoredEntities(tile.GridIndices))
+                {
+                    if (!EntityManager.EntityExists(uid)) continue;
+                    yield return uid;
+                }
+            }
+        }
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<EntityUid> GetEntitiesAt(MapId mapId, Vector2 position, LookupFlags flags = LookupFlags.IncludeAnchored)
+    {
+        if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
+
+        var list = new List<EntityUid>();
+
+        var state = (list, position);
+
+        var aabb = new Box2(position, position).Enlarged(PointEnlargeRange);
+        var enumerator = GetLookupsIntersecting(mapId, aabb);
+
+        while (enumerator.MoveNext(out var lookup))
+        {
+            var offsetPos = EntityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.Transform(position);
+
+            lookup.Tree.QueryPoint(ref state, (ref (List<EntityUid> list, Vector2 position) state, in EntityUid ent) =>
+            {
+                state.list.Add(ent);
+                return true;
+            }, offsetPos, (flags & LookupFlags.Approximate) != 0x0);
+        }
+
+        if ((flags & LookupFlags.IncludeAnchored) != 0x0)
+        {
+            foreach (var grid in _mapManager.FindGridsIntersecting(mapId, aabb))
+            {
+                foreach (var uid in grid.GetAnchoredEntities(aabb))
+                {
+                    if (!EntityManager.EntityExists(uid)) continue;
+                    list.Add(uid);
+                }
+            }
+        }
+
+        return list;
+    }
+}

Robust.Shared/GameObjects/Systems/EntityLookup.Queries.cs

@@ -6,7 +6,7 @@ using Robust.Shared.Maths;
 
 namespace Robust.Shared.GameObjects;
 
-public sealed partial class EntityLookup
+public sealed partial class EntityLookupSystem
 {
     #region Grid Methods
 
@@ -21,7 +21,7 @@ public sealed partial class EntityLookup
         // Technically this doesn't consider anything overlapping from outside the grid but is this an issue?
         if (!_mapManager.TryGetGrid(gridId, out var grid)) return Enumerable.Empty<EntityUid>();
 
-        var lookup = _entityManager.GetComponent<EntityLookupComponent>(grid.GridEntityId);
+        var lookup = EntityManager.GetComponent<EntityLookupComponent>(grid.GridEntityId);
         var results = new HashSet<EntityUid>();
         var tileSize = grid.TileSize;
 
@@ -32,13 +32,13 @@ public sealed partial class EntityLookup
 
             lookup.Tree._b2Tree.FastQuery(ref aabb, (ref EntityUid data) =>
             {
-                if (_entityManager.Deleted(data)) return;
+                if (EntityManager.Deleted(data)) return;
                 results.Add(data);
             });
 
             foreach (var ent in grid.GetAnchoredEntities(index))
             {
-                if (_entityManager.Deleted(ent)) continue;
+                if (EntityManager.Deleted(ent)) continue;
                 results.Add(ent);
             }
         }
@@ -51,7 +51,7 @@ public sealed partial class EntityLookup
         // Technically this doesn't consider anything overlapping from outside the grid but is this an issue?
         if (!_mapManager.TryGetGrid(gridId, out var grid)) return Enumerable.Empty<EntityUid>();
 
-        var lookup = _entityManager.GetComponent<EntityLookupComponent>(grid.GridEntityId);
+        var lookup = EntityManager.GetComponent<EntityLookupComponent>(grid.GridEntityId);
         var tileSize = grid.TileSize;
 
         var aabb = GetLocalBounds(gridIndices, tileSize);
@@ -59,13 +59,13 @@ public sealed partial class EntityLookup
 
         lookup.Tree._b2Tree.FastQuery(ref aabb, (ref EntityUid data) =>
         {
-            if (_entityManager.Deleted(data)) return;
+            if (EntityManager.Deleted(data)) return;
             results.Add(data);
         });
 
         foreach (var ent in grid.GetAnchoredEntities(gridIndices))
         {
-            if (_entityManager.Deleted(ent)) continue;
+            if (EntityManager.Deleted(ent)) continue;
             results.Add(ent);
         }
 
@@ -98,7 +98,7 @@ public sealed partial class EntityLookup
 
         if (worldMatrix == null || angle == null)
         {
-            var gridXform = _entityManager.GetComponent<TransformComponent>(grid.GridEntityId);
+            var gridXform = EntityManager.GetComponent<TransformComponent>(grid.GridEntityId);
             var (_, wAng, wMat) = gridXform.GetWorldPositionRotationMatrix();
             worldMatrix = wMat;
             angle = wAng;

Robust.Shared/GameObjects/Systems/EntityLookup.cs

@@ -1,890 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
-using System.Linq;
-using System.Runtime.CompilerServices;
-using JetBrains.Annotations;
-using Robust.Shared.Configuration;
-using Robust.Shared.Containers;
-using Robust.Shared.IoC;
-using Robust.Shared.Map;
-using Robust.Shared.Maths;
-using Robust.Shared.Physics;
-using Robust.Shared.Utility;
-
-namespace Robust.Shared.GameObjects
-{
-    [Flags]
-    public enum LookupFlags : byte
-    {
-        None = 0,
-        Approximate = 1 << 0,
-        IncludeAnchored = 1 << 1,
-        // IncludeGrids = 1 << 2,
-    }
-
-    // TODO: Nuke IEntityLookup and just make a system
-    public interface IEntityLookup
-    {
-        // Not an EntitySystem given _entityManager has a dependency on it which means it's just easier to IoC it for tests.
-
-        void Startup();
-
-        void Shutdown();
-
-        void Update();
-        bool AnyEntitiesIntersecting(MapId mapId, Box2 box, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesInMap(MapId mapId, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesAt(MapId mapId, Vector2 position, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesInArc(EntityCoordinates coordinates, float range, Angle direction,
-            float arcWidth, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(GridId gridId, IEnumerable<Vector2i> gridIndices);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(GridId gridId, Vector2i gridIndices);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(TileRef tileRef);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2 worldAABB, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2Rotated worldAABB, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(EntityUid entity, float enlarged = 0f, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(MapCoordinates position, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(EntityCoordinates position, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Vector2 position, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        void FastEntitiesIntersecting(in MapId mapId, ref Box2 worldAABB, EntityUidQueryCallback callback, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        void FastEntitiesIntersecting(EntityLookupComponent lookup, ref Box2 localAABB, EntityUidQueryCallback callback);
-
-        IEnumerable<EntityUid> GetEntitiesInRange(EntityCoordinates position, float range, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesInRange(EntityUid entity, float range, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesInRange(MapId mapId, Vector2 point, float range, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        IEnumerable<EntityUid> GetEntitiesInRange(MapId mapId, Box2 box, float range, LookupFlags flags = LookupFlags.IncludeAnchored);
-
-        bool IsIntersecting(EntityUid entityOne, EntityUid entityTwo);
-        
-        bool UpdateEntityTree(EntityUid entity, TransformComponent xform, Box2? worldAABB = null);
-        
-        void RemoveFromEntityTrees(EntityUid entity);
-
-        Box2 GetWorldAabbFromEntity(in EntityUid ent, TransformComponent? xform = null);
-
-        Box2 GetLocalBounds(TileRef tileRef, ushort tileSize);
-
-        Box2 GetLocalBounds(Vector2i gridIndices, ushort tileSize);
-
-        Box2Rotated GetWorldBounds(TileRef tileRef, Matrix3? worldMatrix = null, Angle? angle = null);
-    }
-
-    [UsedImplicitly]
-    public sealed partial class EntityLookup : IEntityLookup, IEntityEventSubscriber
-    {
-        private readonly IEntityManager _entityManager;
-        private readonly IMapManager _mapManager;
-
-        private const int GrowthRate = 256;
-
-        private const float PointEnlargeRange = .00001f / 2;
-
-        // Using stacks so we always use latest data (given we only run it once per entity).
-        private readonly Stack<MoveEvent> _moveQueue = new();
-        private readonly Stack<RotateEvent> _rotateQueue = new();
-        private readonly Queue<EntParentChangedMessage> _parentChangeQueue = new();
-
-        /// <summary>
-        /// Like RenderTree we need to enlarge our lookup range for EntityLookupComponent as an entity is only ever on
-        /// 1 EntityLookupComponent at a time (hence it may overlap without another lookup).
-        /// </summary>
-        private float _lookupEnlargementRange;
-
-        /// <summary>
-        /// Move and rotate events generate the same update so no point duplicating work in the same tick.
-        /// </summary>
-        private readonly HashSet<EntityUid> _handledThisTick = new();
-
-        // TODO: Should combine all of the methods that check for IPhysBody and just use the one GetWorldAabbFromEntity method
-
-        // TODO: Combine GridTileLookupSystem and entity anchoring together someday.
-        // Queries are a bit of spaghet rn but ideally you'd just have:
-        // A) The fast tile-based one
-        // B) The physics-only one (given physics needs it to be fast af)
-        // C) A generic use one that covers anything not caught in the above.
-
-        public bool Started { get; private set; } = false;
-
-        public EntityLookup(IEntityManager entityManager, IMapManager mapManager)
-        {
-            _entityManager = entityManager;
-            _mapManager = mapManager;
-        }
-
-        public void Startup()
-        {
-            if (Started)
-            {
-                throw new InvalidOperationException("Startup() called multiple times.");
-            }
-
-            var configManager = IoCManager.Resolve<IConfigurationManager>();
-            configManager.OnValueChanged(CVars.LookupEnlargementRange, value => _lookupEnlargementRange = value, true);
-
-            var eventBus = _entityManager.EventBus;
-            eventBus.SubscribeEvent(EventSource.Local, this, (ref MoveEvent ev) => _moveQueue.Push(ev));
-            eventBus.SubscribeEvent(EventSource.Local, this, (ref RotateEvent ev) => _rotateQueue.Push(ev));
-            eventBus.SubscribeEvent(EventSource.Local, this, (ref EntParentChangedMessage ev) => _parentChangeQueue.Enqueue(ev));
-            eventBus.SubscribeEvent<AnchorStateChangedEvent>(EventSource.Local, this, HandleAnchored);
-
-            eventBus.SubscribeLocalEvent<EntityLookupComponent, ComponentAdd>(OnLookupAdd);
-            eventBus.SubscribeLocalEvent<EntityLookupComponent, ComponentShutdown>(OnLookupShutdown);
-            eventBus.SubscribeEvent<GridInitializeEvent>(EventSource.Local, this, OnGridInit);
-
-            _entityManager.EntityDeleted += OnEntityDeleted;
-            _entityManager.EntityInitialized += OnEntityInit;
-            _mapManager.MapCreated += OnMapCreated;
-            Started = true;
-        }
-
-        public void Shutdown()
-        {
-            // If we haven't even started up, there's nothing to clean up then.
-            if (!Started)
-                return;
-
-            _moveQueue.Clear();
-            _rotateQueue.Clear();
-            _handledThisTick.Clear();
-            _parentChangeQueue.Clear();
-
-            _entityManager.EntityDeleted -= OnEntityDeleted;
-            _entityManager.EntityInitialized -= OnEntityInit;
-            _mapManager.MapCreated -= OnMapCreated;
-            Started = false;
-        }
-
-        private void HandleAnchored(ref AnchorStateChangedEvent @event)
-        {
-            // This event needs to be handled immediately as anchoring is handled immediately
-            // and any callers may potentially get duplicate entities that just changed state.
-            if (@event.Anchored)
-            {
-                RemoveFromEntityTrees(@event.Entity);
-            }
-            else if (_entityManager.TryGetComponent(@event.Entity, out MetaDataComponent? meta) && meta.EntityLifeStage < EntityLifeStage.Terminating)
-            {
-                var xform = _entityManager.GetComponent<TransformComponent>(@event.Entity);
-                UpdateEntityTree(@event.Entity, xform);
-            }
-            // else -> the entity is terminating. We can ignore this un-anchor event, as this entity will be removed by the tree via OnEntityDeleted.
-        }
-
-        private void OnLookupShutdown(EntityUid uid, EntityLookupComponent component, ComponentShutdown args)
-        {
-            component.Tree.Clear();
-        }
-
-        private void OnGridInit(GridInitializeEvent ev)
-        {
-            _entityManager.EnsureComponent<EntityLookupComponent>(ev.EntityUid);
-        }
-
-        private void OnLookupAdd(EntityUid uid, EntityLookupComponent component, ComponentAdd args)
-        {
-            int capacity;
-
-            if (_entityManager.TryGetComponent(uid, out TransformComponent? xform))
-            {
-                capacity = (int) Math.Min(256, Math.Ceiling(xform.ChildCount / (float) GrowthRate) * GrowthRate);
-            }
-            else
-            {
-                capacity = 256;
-            }
-
-            component.Tree = new DynamicTree<EntityUid>(
-                GetRelativeAABBFromEntity,
-                capacity: capacity,
-                growthFunc: x => x == GrowthRate ? GrowthRate * 8 : x * 2
-            );
-        }
-
-        private Box2 GetRelativeAABBFromEntity(in EntityUid entity)
-        {
-            // TODO: Should feed in AABB to lookup so it's not enlarged unnecessarily
-
-            var aabb = GetWorldAABB(entity);
-            var tree = GetLookup(entity);
-
-            if (tree == null)
-                return aabb;
-
-            return _entityManager.GetComponent<TransformComponent>(tree.Owner).InvWorldMatrix.TransformBox(aabb);
-        }
-
-        private void OnEntityDeleted(object? sender, EntityUid uid)
-        {
-            RemoveFromEntityTrees(uid);
-        }
-
-        private void OnEntityInit(object? sender, EntityUid uid)
-        {
-            var xform = _entityManager.GetComponent<TransformComponent>(uid);
-            if (xform.Anchored) return;
-            UpdateEntityTree(uid, xform);
-        }
-
-        private void OnMapCreated(object? sender, MapEventArgs eventArgs)
-        {
-            if (eventArgs.Map == MapId.Nullspace) return;
-
-            _mapManager.GetMapEntityId(eventArgs.Map).EnsureComponent<EntityLookupComponent>();
-        }
-
-        public void Update()
-        {
-            // Acruid said he'd deal with Update being called around I_entityManager later.
-
-            // Could be more efficient but essentially nuke their old lookup and add to new lookup if applicable.
-            while (_parentChangeQueue.TryDequeue(out var mapChangeEvent))
-            {
-                _handledThisTick.Add(mapChangeEvent.Entity);
-                RemoveFromEntityTrees(mapChangeEvent.Entity);
-
-                if (_entityManager.Deleted(mapChangeEvent.Entity)) continue;
-
-                var xform = _entityManager.GetComponent<TransformComponent>(mapChangeEvent.Entity);
-
-                if (xform.Anchored) continue;
-
-                UpdateEntityTree(mapChangeEvent.Entity, xform, GetWorldAabbFromEntity(mapChangeEvent.Entity));
-            }
-
-            while (_moveQueue.TryPop(out var moveEvent))
-            {
-                if (!_handledThisTick.Add(moveEvent.Sender) ||
-                    _entityManager.Deleted(moveEvent.Sender)) continue;
-
-                var xform = _entityManager.GetComponent<TransformComponent>(moveEvent.Sender);
-
-                if (xform.Anchored) continue;
-
-                DebugTools.Assert(!xform.Anchored);
-                UpdateEntityTree(moveEvent.Sender, xform, moveEvent.WorldAABB);
-            }
-
-            while (_rotateQueue.TryPop(out var rotateEvent))
-            {
-                if (!_handledThisTick.Add(rotateEvent.Sender) ||
-                    _entityManager.Deleted(rotateEvent.Sender)) continue;
-
-                var xform = _entityManager.GetComponent<TransformComponent>(rotateEvent.Sender);
-
-                if (xform.Anchored) continue;
-
-                DebugTools.Assert(!xform.Anchored);
-                UpdateEntityTree(rotateEvent.Sender, xform, rotateEvent.WorldAABB);
-            }
-
-            _handledThisTick.Clear();
-        }
-
-        #region Spatial Queries
-
-        private LookupsEnumerator GetLookupsIntersecting(MapId mapId, Box2 worldAABB)
-        {
-            _mapManager.FindGridsIntersectingEnumerator(mapId, worldAABB, out var gridEnumerator, true);
-
-            return new LookupsEnumerator(_entityManager, _mapManager, mapId, gridEnumerator);
-        }
-
-        private struct LookupsEnumerator
-        {
-            private IEntityManager _entityManager;
-            private IMapManager _mapManager;
-
-            private MapId _mapId;
-            private FindGridsEnumerator _enumerator;
-
-            private bool _final;
-
-            public LookupsEnumerator(IEntityManager entityManager, IMapManager mapManager, MapId mapId, FindGridsEnumerator enumerator)
-            {
-                _entityManager = entityManager;
-                _mapManager = mapManager;
-
-                _mapId = mapId;
-                _enumerator = enumerator;
-                _final = false;
-            }
-
-            public bool MoveNext([NotNullWhen(true)] out EntityLookupComponent? component)
-            {
-                if (!_enumerator.MoveNext(out var grid))
-                {
-                    if (_final || _mapId == MapId.Nullspace)
-                    {
-                        component = null;
-                        return false;
-                    }
-
-                    _final = true;
-                    EntityUid mapUid = _mapManager.GetMapEntityIdOrThrow(_mapId);
-                    component = _entityManager.GetComponent<EntityLookupComponent>(mapUid);
-                    return true;
-                }
-
-                // TODO: Recursive and all that.
-                component = _entityManager.GetComponent<EntityLookupComponent>(grid.GridEntityId);
-                return true;
-            }
-        }
-
-        private IEnumerable<EntityUid> GetAnchored(MapId mapId, Box2 worldAABB, LookupFlags flags)
-        {
-            if ((flags & LookupFlags.IncludeAnchored) == 0x0) yield break;
-            foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldAABB))
-            {
-                foreach (var uid in grid.GetAnchoredEntities(worldAABB))
-                {
-                    if (!_entityManager.EntityExists(uid)) continue;
-                    yield return uid;
-                }
-            }
-        }
-
-        private IEnumerable<EntityUid> GetAnchored(MapId mapId, Box2Rotated worldBounds, LookupFlags flags)
-        {
-            if ((flags & LookupFlags.IncludeAnchored) == 0x0) yield break;
-            foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldBounds))
-            {
-                foreach (var uid in grid.GetAnchoredEntities(worldBounds))
-                {
-                    if (!_entityManager.EntityExists(uid)) continue;
-                    yield return uid;
-                }
-            }
-        }
-
-        /// <inheritdoc />
-        public bool AnyEntitiesIntersecting(MapId mapId, Box2 box, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var found = false;
-            var enumerator = GetLookupsIntersecting(mapId, box);
-
-            while (enumerator.MoveNext(out var lookup))
-            {
-                var offsetBox = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(box);
-
-                lookup.Tree.QueryAabb(ref found, (ref bool found, in EntityUid ent) =>
-                {
-                    if (_entityManager.Deleted(ent))
-                        return true;
-
-                    found = true;
-                    return false;
-
-                }, offsetBox, (flags & LookupFlags.Approximate) != 0x0);
-            }
-
-            if (!found)
-            {
-                foreach (var _ in GetAnchored(mapId, box, flags))
-                {
-                    return true;
-                }
-            }
-
-            return found;
-        }
-
-        /// <inheritdoc />
-        [MethodImpl(MethodImplOptions.AggressiveOptimization)]
-        public void FastEntitiesIntersecting(in MapId mapId, ref Box2 worldAABB, EntityUidQueryCallback callback, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var enumerator = GetLookupsIntersecting(mapId, worldAABB);
-            while (enumerator.MoveNext(out var lookup))
-            {
-                var offsetBox = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldAABB);
-
-                lookup.Tree._b2Tree.FastQuery(ref offsetBox, (ref EntityUid data) => callback(data));
-            }
-
-            if ((flags & LookupFlags.IncludeAnchored) != 0x0)
-            {
-                foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldAABB))
-                {
-                    foreach (var uid in grid.GetAnchoredEntities(worldAABB))
-                    {
-                        if (!_entityManager.EntityExists(uid)) continue;
-                        callback(uid);
-                    }
-                }
-            }
-        }
-
-        /// <inheritdoc />
-        public void FastEntitiesIntersecting(EntityLookupComponent lookup, ref Box2 localAABB, EntityUidQueryCallback callback)
-        {
-            lookup.Tree._b2Tree.FastQuery(ref localAABB, (ref EntityUid data) => callback(data));
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2 worldAABB, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
-
-            var list = new List<EntityUid>();
-            var enumerator = GetLookupsIntersecting(mapId, worldAABB);
-
-            while (enumerator.MoveNext(out var lookup))
-            {
-                var offsetBox = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldAABB);
-
-                lookup.Tree.QueryAabb(ref list, (ref List<EntityUid> list, in EntityUid ent) =>
-                {
-                    if (!_entityManager.Deleted(ent))
-                    {
-                        list.Add(ent);
-                    }
-                    return true;
-                }, offsetBox, (flags & LookupFlags.Approximate) != 0x0);
-            }
-
-            foreach (var ent in GetAnchored(mapId, worldAABB, flags))
-            {
-                list.Add(ent);
-            }
-
-            return list;
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2Rotated worldBounds, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
-
-            var list = new List<EntityUid>();
-            var worldAABB = worldBounds.CalcBoundingBox();
-            var enumerator = GetLookupsIntersecting(mapId, worldAABB);
-
-            while (enumerator.MoveNext(out var lookup))
-            {
-                var offsetBox = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldBounds);
-
-                lookup.Tree.QueryAabb(ref list, (ref List<EntityUid> list, in EntityUid ent) =>
-                {
-                    if (!_entityManager.Deleted(ent))
-                    {
-                        list.Add(ent);
-                    }
-                    return true;
-                }, offsetBox, (flags & LookupFlags.Approximate) != 0x0);
-            }
-
-            foreach (var ent in GetAnchored(mapId, worldBounds, flags))
-            {
-                list.Add(ent);
-            }
-
-            return list;
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesIntersecting(MapId mapId, Vector2 position, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
-
-            var aabb = new Box2(position, position).Enlarged(PointEnlargeRange);
-            var list = new List<EntityUid>();
-            var state = (list, position);
-
-            var enumerator = GetLookupsIntersecting(mapId, aabb);
-
-            while (enumerator.MoveNext(out var lookup))
-            {
-                var localPoint = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.Transform(position);
-
-                lookup.Tree.QueryPoint(ref state, (ref (List<EntityUid> list, Vector2 position) state, in EntityUid ent) =>
-                {
-                    if (Intersecting(ent, state.position))
-                    {
-                        state.list.Add(ent);
-                    }
-                    return true;
-                }, localPoint, (flags & LookupFlags.Approximate) != 0x0);
-            }
-
-            if ((flags & LookupFlags.IncludeAnchored) != 0x0 &&
-                _mapManager.TryFindGridAt(mapId, position, out var grid) &&
-                grid.TryGetTileRef(position, out var tile))
-            {
-                foreach (var uid in grid.GetAnchoredEntities(tile.GridIndices))
-                {
-                    if (!_entityManager.EntityExists(uid)) continue;
-                    state.list.Add(uid);
-                }
-            }
-
-            return list;
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesIntersecting(MapCoordinates position, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            return GetEntitiesIntersecting(position.MapId, position.Position, flags);
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesIntersecting(EntityCoordinates position, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var mapPos = position.ToMap(_entityManager);
-            return GetEntitiesIntersecting(mapPos.MapId, mapPos.Position, flags);
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesIntersecting(EntityUid entity, float enlarged = 0f, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var worldAABB = GetWorldAabbFromEntity(entity);
-            var xform = _entityManager.GetComponent<TransformComponent>(entity);
-
-            var (worldPos, worldRot) = xform.GetWorldPositionRotation();
-
-            var enumerator = GetLookupsIntersecting(xform.MapID, worldAABB);
-            var list = new List<EntityUid>();
-
-            while (enumerator.MoveNext(out var lookup))
-            {
-                // To get the tightest bounds possible we'll re-calculate it for each lookup.
-                var localBounds = GetLookupBounds(entity, lookup, worldPos, worldRot, enlarged);
-
-                lookup.Tree.QueryAabb(ref list, (ref List<EntityUid> list, in EntityUid ent) =>
-                {
-                    if (!_entityManager.Deleted(ent))
-                    {
-                        list.Add(ent);
-                    }
-                    return true;
-                }, localBounds, (flags & LookupFlags.Approximate) != 0x0);
-            }
-
-            foreach (var ent in GetAnchored(xform.MapID, worldAABB, flags))
-            {
-                list.Add(ent);
-            }
-
-            return list;
-        }
-
-        private Box2 GetLookupBounds(EntityUid uid, EntityLookupComponent lookup, Vector2 worldPos, Angle worldRot, float enlarged)
-        {
-            var (_, lookupRot, lookupInvWorldMatrix) = _entityManager.GetComponent<TransformComponent>(lookup.Owner).GetWorldPositionRotationInvMatrix();
-
-            var localPos = lookupInvWorldMatrix.Transform(worldPos);
-            var localRot = worldRot - lookupRot;
-
-            if (_entityManager.TryGetComponent(uid, out FixturesComponent? manager))
-            {
-                var transform = new Transform(localPos, localRot);
-                Box2? aabb = null;
-
-                foreach (var (_, fixture) in manager.Fixtures)
-                {
-                    if (!fixture.Hard) continue;
-                    for (var i = 0; i < fixture.Shape.ChildCount; i++)
-                    {
-                        aabb = aabb?.Union(fixture.Shape.ComputeAABB(transform, i)) ?? fixture.Shape.ComputeAABB(transform, i);
-                    }
-                }
-
-                if (aabb != null)
-                {
-                    return aabb.Value.Enlarged(enlarged);
-                }
-            }
-
-            // So IsEmpty checks don't get triggered
-            return new Box2(localPos - float.Epsilon, localPos + float.Epsilon);
-        }
-
-        /// <inheritdoc />
-        public bool IsIntersecting(EntityUid entityOne, EntityUid entityTwo)
-        {
-            var position = _entityManager.GetComponent<TransformComponent>(entityOne).MapPosition.Position;
-            return Intersecting(entityTwo, position);
-        }
-
-        private bool Intersecting(EntityUid entity, Vector2 mapPosition)
-        {
-            if (_entityManager.TryGetComponent(entity, out IPhysBody? component))
-            {
-                if (component.GetWorldAABB().Contains(mapPosition))
-                    return true;
-            }
-            else
-            {
-                var transform = _entityManager.GetComponent<TransformComponent>(entity);
-                var entPos = transform.WorldPosition;
-                if (MathHelper.CloseToPercent(entPos.X, mapPosition.X)
-                    && MathHelper.CloseToPercent(entPos.Y, mapPosition.Y))
-                {
-                    return true;
-                }
-            }
-
-            return false;
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesInRange(EntityCoordinates position, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var mapCoordinates = position.ToMap(_entityManager);
-            var mapPosition = mapCoordinates.Position;
-            var aabb = new Box2(mapPosition - new Vector2(range, range),
-                mapPosition + new Vector2(range, range));
-            return GetEntitiesIntersecting(mapCoordinates.MapId, aabb, flags);
-            // TODO: Use a circle shape here mate
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesInRange(MapId mapId, Box2 box, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var aabb = box.Enlarged(range);
-            return GetEntitiesIntersecting(mapId, aabb, flags);
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesInRange(MapId mapId, Vector2 point, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var aabb = new Box2(point, point).Enlarged(range);
-            return GetEntitiesIntersecting(mapId, aabb, flags);
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesInRange(EntityUid entity, float range, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var worldAABB = GetWorldAabbFromEntity(entity);
-            return GetEntitiesInRange(_entityManager.GetComponent<TransformComponent>(entity).MapID, worldAABB, range, flags);
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesInArc(EntityCoordinates coordinates, float range, Angle direction,
-            float arcWidth, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            var position = coordinates.ToMap(_entityManager).Position;
-
-            foreach (var entity in GetEntitiesInRange(coordinates, range * 2, flags))
-            {
-                var angle = new Angle(_entityManager.GetComponent<TransformComponent>(entity).WorldPosition - position);
-                if (angle.Degrees < direction.Degrees + arcWidth / 2 &&
-                    angle.Degrees > direction.Degrees - arcWidth / 2)
-                    yield return entity;
-            }
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesInMap(MapId mapId, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            DebugTools.Assert((flags & LookupFlags.Approximate) == 0x0);
-
-            foreach (EntityLookupComponent comp in _entityManager.EntityQuery<EntityLookupComponent>(true))
-            {
-                if (_entityManager.GetComponent<TransformComponent>(comp.Owner).MapID != mapId) continue;
-
-                foreach (var entity in comp.Tree)
-                {
-                    if (_entityManager.Deleted(entity)) continue;
-
-                    yield return entity;
-                }
-            }
-
-            if ((flags & LookupFlags.IncludeAnchored) == 0x0) yield break;
-
-            foreach (var grid in _mapManager.GetAllMapGrids(mapId))
-            {
-                foreach (var tile in grid.GetAllTiles())
-                {
-                    foreach (var uid in grid.GetAnchoredEntities(tile.GridIndices))
-                    {
-                        if (!_entityManager.EntityExists(uid)) continue;
-                        yield return uid;
-                    }
-                }
-            }
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<EntityUid> GetEntitiesAt(MapId mapId, Vector2 position, LookupFlags flags = LookupFlags.IncludeAnchored)
-        {
-            if (mapId == MapId.Nullspace) return Enumerable.Empty<EntityUid>();
-
-            var list = new List<EntityUid>();
-
-            var state = (list, position);
-
-            var aabb = new Box2(position, position).Enlarged(PointEnlargeRange);
-            var enumerator = GetLookupsIntersecting(mapId, aabb);
-
-            while (enumerator.MoveNext(out var lookup))
-            {
-                var offsetPos = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.Transform(position);
-
-                lookup.Tree.QueryPoint(ref state, (ref (List<EntityUid> list, Vector2 position) state, in EntityUid ent) =>
-                {
-                    state.list.Add(ent);
-                    return true;
-                }, offsetPos, (flags & LookupFlags.Approximate) != 0x0);
-            }
-
-            if ((flags & LookupFlags.IncludeAnchored) != 0x0)
-            {
-                foreach (var grid in _mapManager.FindGridsIntersecting(mapId, aabb))
-                {
-                    foreach (var uid in grid.GetAnchoredEntities(aabb))
-                    {
-                        if (!_entityManager.EntityExists(uid)) continue;
-                        list.Add(uid);
-                    }
-                }
-            }
-
-            return list;
-        }
-
-        #endregion
-
-        #region Entity DynamicTree
-
-        private EntityLookupComponent? GetLookup(EntityUid entity)
-        {
-            // TODO: This should just be passed in when we cleanup EntityLookup a bit.
-            var xforms = _entityManager.GetEntityQuery<TransformComponent>();
-            var xform = xforms.GetComponent(entity);
-
-            if (xform.MapID == MapId.Nullspace)
-                return null;
-
-            var lookups = _entityManager.GetEntityQuery<EntityLookupComponent>();
-            var parent = xform.ParentUid;
-
-            // if it's map return null. Grids should return the map's broadphase.
-            if (lookups.HasComponent(entity) &&
-                !parent.IsValid())
-            {
-                return null;
-            }
-
-            while (parent.IsValid())
-            {
-                if (lookups.TryGetComponent(parent, out var comp)) return comp;
-                parent = xforms.GetComponent(parent).ParentUid;
-            }
-
-            return null;
-        }
-
-        /// <inheritdoc />
-        public bool UpdateEntityTree(EntityUid entity, TransformComponent xform, Box2? worldAABB = null)
-        {
-            DebugTools.Assert(!_entityManager.Deleted(entity));
-
-            var lookup = GetLookup(entity);
-
-            if (lookup == null)
-            {
-                RemoveFromEntityTrees(entity);
-                return true;
-            }
-
-            // Temp PVS guard for when we clear dynamictree for now.
-            worldAABB ??= GetWorldAabbFromEntity(entity, xform);
-            var center = worldAABB.Value.Center;
-
-            DebugTools.Assert(!float.IsNaN(center.X) && !float.IsNaN(center.Y));
-
-            var aabb = _entityManager.GetComponent<TransformComponent>(lookup.Owner).InvWorldMatrix.TransformBox(worldAABB.Value);
-
-            // for debugging
-            var necessary = 0;
-
-            if (lookup.Tree.AddOrUpdate(entity, aabb))
-            {
-                ++necessary;
-            }
-
-            if (!_entityManager.HasComponent<EntityLookupComponent>(entity))
-            {
-                DebugTools.Assert(!_entityManager.HasComponent<IMapGridComponent>(entity));
-
-                var children = xform.ChildEnumerator;
-
-                while (children.MoveNext(out var child))
-                {
-                    if (!_handledThisTick.Add(child.Value)) continue;
-
-                    var childXform = _entityManager.GetComponent<TransformComponent>(child.Value);
-
-                    if (UpdateEntityTree(child.Value, childXform))
-                    {
-                        ++necessary;
-                    }
-                }
-            }
-
-            return necessary > 0;
-        }
-
-        /// <inheritdoc />
-        public void RemoveFromEntityTrees(EntityUid entity)
-        {
-            // TODO: Need to fix ordering issues and then we can just directly remove it from the tree
-            // rather than this O(n) legacy garbage.
-            // Also we can't early returns because somehow it gets added to multiple trees!!!
-            foreach (var lookup in _entityManager.EntityQuery<EntityLookupComponent>(true))
-            {
-                lookup.Tree.Remove(entity);
-            }
-        }
-
-        public Box2 GetWorldAabbFromEntity(in EntityUid ent, TransformComponent? xform = null)
-        {
-            return GetWorldAABB(ent, xform);
-        }
-
-        private Box2 GetWorldAABB(in EntityUid ent, TransformComponent? xform = null)
-        {
-            Vector2 pos;
-            xform ??= _entityManager.GetComponent<TransformComponent>(ent);
-
-            if ((!_entityManager.EntityExists(ent) ? EntityLifeStage.Deleted : _entityManager.GetComponent<MetaDataComponent>(ent).EntityLifeStage) >= EntityLifeStage.Deleted)
-            {
-                pos = xform.WorldPosition;
-                return new Box2(pos, pos);
-            }
-
-            // MOCKS WHY
-            if (ent.TryGetContainer(out var container, _entityManager))
-            {
-                return GetWorldAABB(container.Owner);
-            }
-
-            pos = xform.WorldPosition;
-
-            return _entityManager.TryGetComponent(ent, out ILookupWorldBox2Component? lookup) ?
-                lookup.GetWorldAABB(pos) :
-                new Box2(pos, pos);
-        }
-
-        #endregion
-    }
-}

Robust.Shared/GameObjects/Systems/EntityLookupSystem.cs

@@ -0,0 +1,465 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using JetBrains.Annotations;
+using Robust.Shared.Configuration;
+using Robust.Shared.Containers;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Physics;
+using Robust.Shared.Utility;
+
+namespace Robust.Shared.GameObjects
+{
+    [Flags]
+    public enum LookupFlags : byte
+    {
+        None = 0,
+        Approximate = 1 << 0,
+        IncludeAnchored = 1 << 1,
+        // IncludeGrids = 1 << 2,
+    }
+
+    public sealed partial class EntityLookupSystem : EntitySystem
+    {
+        [IoC.Dependency] private readonly IMapManager _mapManager = default!;
+        [IoC.Dependency] private readonly SharedContainerSystem _container = default!;
+        [IoC.Dependency] private readonly SharedTransformSystem _transform = default!;
+
+        private const int GrowthRate = 256;
+
+        private const float PointEnlargeRange = .00001f / 2;
+
+        /// <summary>
+        /// Like RenderTree we need to enlarge our lookup range for EntityLookupComponent as an entity is only ever on
+        /// 1 EntityLookupComponent at a time (hence it may overlap without another lookup).
+        /// </summary>
+        private float _lookupEnlargementRange;
+
+        public override void Initialize()
+        {
+            base.Initialize();
+            var configManager = IoCManager.Resolve<IConfigurationManager>();
+            configManager.OnValueChanged(CVars.LookupEnlargementRange, value => _lookupEnlargementRange = value, true);
+
+            SubscribeLocalEvent<MoveEvent>(OnMove);
+            SubscribeLocalEvent<RotateEvent>(OnRotate);
+            SubscribeLocalEvent<EntParentChangedMessage>(OnParentChange);
+            SubscribeLocalEvent<AnchorStateChangedEvent>(OnAnchored);
+            SubscribeLocalEvent<UpdateLookupBoundsEvent>(OnBoundsUpdate);
+
+            SubscribeLocalEvent<EntityLookupComponent, ComponentAdd>(OnLookupAdd);
+            SubscribeLocalEvent<EntityLookupComponent, ComponentShutdown>(OnLookupShutdown);
+            SubscribeLocalEvent<GridInitializeEvent>(OnGridInit);
+
+            SubscribeLocalEvent<EntityTerminatingEvent>(OnTerminate);
+
+            EntityManager.EntityInitialized += OnEntityInit;
+            SubscribeLocalEvent<MapChangedEvent>(OnMapCreated);
+        }
+
+        public override void Shutdown()
+        {
+            base.Shutdown();
+            EntityManager.EntityInitialized -= OnEntityInit;
+        }
+
+        private void OnAnchored(ref AnchorStateChangedEvent args)
+        {
+            // This event needs to be handled immediately as anchoring is handled immediately
+            // and any callers may potentially get duplicate entities that just changed state.
+            if (args.Anchored)
+            {
+                RemoveFromEntityTree(args.Entity);
+            }
+            else if (EntityManager.TryGetComponent(args.Entity, out MetaDataComponent? meta) && meta.EntityLifeStage < EntityLifeStage.Terminating)
+            {
+                var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+                var xform = xformQuery.GetComponent(args.Entity);
+                var lookup = GetLookup(args.Entity, xform, xformQuery);
+
+                if (lookup == null)
+                    throw new InvalidOperationException();
+
+                var lookupXform = xformQuery.GetComponent(lookup.Owner);
+                var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+                DebugTools.Assert(coordinates.EntityId == lookup.Owner);
+
+                // If we're contained then LocalRotation should be 0 anyway.
+                var aabb = GetAABB(args.Entity, coordinates.Position, _transform.GetWorldRotation(xform) - _transform.GetWorldRotation(lookupXform), xform, xformQuery);
+                AddToEntityTree(lookup, xform, aabb, xformQuery);
+            }
+            // else -> the entity is terminating. We can ignore this un-anchor event, as this entity will be removed by the tree via OnEntityDeleted.
+        }
+
+        #region DynamicTree
+
+        private void OnLookupShutdown(EntityUid uid, EntityLookupComponent component, ComponentShutdown args)
+        {
+            component.Tree.Clear();
+        }
+
+        private void OnGridInit(GridInitializeEvent ev)
+        {
+            EntityManager.EnsureComponent<EntityLookupComponent>(ev.EntityUid);
+        }
+
+        private void OnLookupAdd(EntityUid uid, EntityLookupComponent component, ComponentAdd args)
+        {
+            int capacity;
+
+            if (EntityManager.TryGetComponent(uid, out TransformComponent? xform))
+            {
+                capacity = (int) Math.Min(256, Math.Ceiling(xform.ChildCount / (float) GrowthRate) * GrowthRate);
+            }
+            else
+            {
+                capacity = 256;
+            }
+
+            component.Tree = new DynamicTree<EntityUid>(
+                GetTreeAABB,
+                capacity: capacity,
+                growthFunc: x => x == GrowthRate ? GrowthRate * 8 : x * 2
+            );
+        }
+
+        private void OnMapCreated(MapChangedEvent eventArgs)
+        {
+            if(eventArgs.Destroyed)
+                return;
+
+            if (eventArgs.Map == MapId.Nullspace) return;
+
+            EntityManager.EnsureComponent<EntityLookupComponent>(_mapManager.GetMapEntityId(eventArgs.Map));
+        }
+
+        private Box2 GetTreeAABB(in EntityUid entity)
+        {
+            // TODO: Should feed in AABB to lookup so it's not enlarged unnecessarily
+            var aabb = GetWorldAABB(entity);
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            var tree = GetLookup(entity, xformQuery);
+
+            if (tree == null)
+                return aabb;
+
+            return xformQuery.GetComponent(tree.Owner).InvWorldMatrix.TransformBox(aabb);
+        }
+
+        #endregion
+
+        #region Entity events
+
+        private void OnTerminate(ref EntityTerminatingEvent args)
+        {
+            RemoveFromEntityTree(args.Owner, false);
+        }
+
+        private void OnEntityInit(object? sender, EntityUid uid)
+        {
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+
+            if (!xformQuery.TryGetComponent(uid, out var xform) ||
+                xform.Anchored ||
+                _mapManager.IsMap(uid) ||
+                _mapManager.IsGrid(uid)) return;
+
+            var lookup = GetLookup(uid, xform, xformQuery);
+
+            // If nullspace or the likes.
+            if (lookup == null) return;
+
+            var lookupXform = xformQuery.GetComponent(lookup.Owner);
+            var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+            DebugTools.Assert(coordinates.EntityId == lookup.Owner);
+
+            // If we're contained then LocalRotation should be 0 anyway.
+            var aabb = GetAABB(uid, coordinates.Position, _transform.GetWorldRotation(xform) - _transform.GetWorldRotation(lookupXform), xform, xformQuery);
+
+            // Any child entities should be handled by their own OnEntityInit
+            AddToEntityTree(lookup, xform, aabb, xformQuery, false);
+        }
+
+        private void OnMove(ref MoveEvent args)
+        {
+            UpdatePosition(args.Sender, args.Component);
+        }
+
+        private void OnRotate(ref RotateEvent args)
+        {
+            UpdatePosition(args.Sender, args.Component);
+        }
+
+        private void UpdatePosition(EntityUid uid, TransformComponent xform)
+        {
+            // Even if the entity is contained it may have children that aren't so we still need to update.
+            if (!CanMoveUpdate(uid, xform)) return;
+
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            var lookup = GetLookup(uid, xform, xformQuery);
+
+            if (lookup == null) return;
+
+            var lookupXform = xformQuery.GetComponent(lookup.Owner);
+            var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+            var aabb = GetAABB(uid, coordinates.Position, _transform.GetWorldRotation(xform) - _transform.GetWorldRotation(lookupXform), xformQuery.GetComponent(uid), xformQuery);
+            AddToEntityTree(lookup, xform, aabb, xformQuery);
+        }
+
+        private bool CanMoveUpdate(EntityUid uid, TransformComponent xform)
+        {
+            return !_mapManager.IsMap(uid) &&
+                     !_mapManager.IsGrid(uid) &&
+                     !_container.IsEntityInContainer(uid, xform);
+        }
+
+        private void OnParentChange(ref EntParentChangedMessage args)
+        {
+            if (_mapManager.IsMap(args.Entity) ||
+                _mapManager.IsGrid(args.Entity) ||
+                EntityManager.GetComponent<MetaDataComponent>(args.Entity).EntityLifeStage < EntityLifeStage.Initialized) return;
+
+            EntityLookupComponent? oldLookup = null;
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            var xform = xformQuery.GetComponent(args.Entity);
+
+            if (args.OldParent != null)
+            {
+                oldLookup = GetLookup(args.OldParent.Value, xformQuery);
+            }
+
+            var newLookup = GetLookup(args.Entity, xform, xformQuery);
+
+            // If parent is the same then no need to do anything as position should stay the same.
+            if (oldLookup == newLookup) return;
+
+            RemoveFromEntityTree(oldLookup, xform, xformQuery);
+
+            if (newLookup != null)
+                AddToEntityTree(newLookup, xform, xformQuery);
+        }
+
+        private void OnBoundsUpdate(ref UpdateLookupBoundsEvent ev)
+        {
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            var xform = xformQuery.GetComponent(ev.Uid);
+
+            if (xform.Anchored || _container.IsEntityInContainer(ev.Uid, xform)) return;
+
+            var lookup = GetLookup(ev.Uid, xform, xformQuery);
+
+            if (lookup == null) return;
+
+            var lookupXform = xformQuery.GetComponent(lookup.Owner);
+            var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+            // If we're contained then LocalRotation should be 0 anyway.
+            var aabb = GetAABB(xform.Owner, coordinates.Position, _transform.GetWorldRotation(xform) - _transform.GetWorldRotation(lookupXform), xform, xformQuery);
+
+            // TODO: Only container children need updating so could manually do this slightly better.
+            AddToEntityTree(lookup, xform, aabb, xformQuery);
+        }
+
+        private void AddToEntityTree(
+            EntityLookupComponent lookup,
+            TransformComponent xform,
+            EntityQuery<TransformComponent> xformQuery,
+            bool recursive = true,
+            bool contained = false)
+        {
+            var lookupXform = xformQuery.GetComponent(lookup.Owner);
+            var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+            // If we're contained then LocalRotation should be 0 anyway.
+            var aabb = GetAABB(xform.Owner, coordinates.Position, _transform.GetWorldRotation(xform) - _transform.GetWorldRotation(lookupXform), xform, xformQuery);
+            AddToEntityTree(lookup, xform, aabb, xformQuery, recursive, contained);
+        }
+
+        private void AddToEntityTree(
+            EntityLookupComponent? lookup,
+            TransformComponent xform,
+            Box2 aabb,
+            EntityQuery<TransformComponent> xformQuery,
+            bool recursive = true,
+            bool contained = false)
+        {
+            // If entity is in nullspace then no point keeping track of data structure.
+            if (lookup == null) return;
+
+            if (!xform.Anchored)
+                lookup.Tree.AddOrUpdate(xform.Owner, aabb);
+
+            var childEnumerator = xform.ChildEnumerator;
+
+            if (xform.ChildCount == 0 || !recursive) return;
+
+            // TODO: Pass this down instead son.
+            var lookupXform = xformQuery.GetComponent(lookup.Owner);
+            // TODO: Just don't store contained stuff, it's way too expensive for updates and makes the tree much bigger.
+
+            // Recursively update children.
+            if (contained)
+            {
+                // Just re-use the topmost AABB.
+                while (childEnumerator.MoveNext(out var child))
+                {
+                    AddToEntityTree(lookup, xformQuery.GetComponent(child.Value), aabb, xformQuery, contained: true);
+                }
+            }
+            // If they're in a container then it just uses the parent's AABB.
+            else if (EntityManager.TryGetComponent<ContainerManagerComponent>(xform.Owner, out var conManager))
+            {
+                while (childEnumerator.MoveNext(out var child))
+                {
+                    if (conManager.ContainsEntity(child.Value))
+                    {
+                        AddToEntityTree(lookup, xformQuery.GetComponent(child.Value), aabb, xformQuery, contained: true);
+                    }
+                    else
+                    {
+                        var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+                        var childXform = xformQuery.GetComponent(child.Value);
+                        // TODO: If we have 0 position and not contained can optimise these further, but future problem.
+                        var childAABB = GetAABBNoContainer(child.Value, coordinates.Position, childXform.WorldRotation - lookupXform.WorldRotation);
+                        AddToEntityTree(lookup, childXform, childAABB, xformQuery);
+                    }
+                }
+            }
+            else
+            {
+                while (childEnumerator.MoveNext(out var child))
+                {
+                    var coordinates = _transform.GetMoverCoordinates(xform.Coordinates, xformQuery);
+                    var childXform = xformQuery.GetComponent(child.Value);
+                    // TODO: If we have 0 position and not contained can optimise these further, but future problem.
+                    var childAABB = GetAABBNoContainer(child.Value, coordinates.Position, childXform.WorldRotation - lookupXform.WorldRotation);
+                    AddToEntityTree(lookup, childXform, childAABB, xformQuery);
+                }
+            }
+        }
+
+        private void RemoveFromEntityTree(EntityUid uid, bool recursive = true)
+        {
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            var xform = xformQuery.GetComponent(uid);
+            var lookup = GetLookup(uid, xform, xformQuery);
+            RemoveFromEntityTree(lookup, xform, xformQuery, recursive);
+        }
+
+        /// <summary>
+        /// Recursively iterates through this entity's children and removes them from the entitylookupcomponent.
+        /// </summary>
+        private void RemoveFromEntityTree(EntityLookupComponent? lookup, TransformComponent xform, EntityQuery<TransformComponent> xformQuery, bool recursive = true)
+        {
+            // TODO: Move this out of the loop
+            if (lookup == null) return;
+
+            lookup.Tree.Remove(xform.Owner);
+
+            if (!recursive) return;
+
+            var childEnumerator = xform.ChildEnumerator;
+
+            while (childEnumerator.MoveNext(out var child))
+            {
+                RemoveFromEntityTree(lookup, xformQuery.GetComponent(child.Value), xformQuery);
+            }
+        }
+
+        #endregion
+
+        private EntityLookupComponent? GetLookup(EntityUid entity, EntityQuery<TransformComponent> xformQuery)
+        {
+            var xform = xformQuery.GetComponent(entity);
+            return GetLookup(entity, xform, xformQuery);
+        }
+
+        private EntityLookupComponent? GetLookup(EntityUid uid, TransformComponent xform, EntityQuery<TransformComponent> xformQuery)
+        {
+            if (xform.MapID == MapId.Nullspace)
+                return null;
+
+            var parent = xform.ParentUid;
+            var lookupQuery = EntityManager.GetEntityQuery<EntityLookupComponent>();
+
+            // If we're querying a map / grid just return it directly.
+            if (lookupQuery.TryGetComponent(uid, out var lookup))
+            {
+                return lookup;
+            }
+
+            while (parent.IsValid())
+            {
+                if (lookupQuery.TryGetComponent(parent, out var comp)) return comp;
+                parent = xformQuery.GetComponent(parent).ParentUid;
+            }
+
+            return null;
+        }
+
+        #region Bounds
+
+        /// <summary>
+        /// Get the AABB of an entity with the supplied position and angle. Tries to consider if the entity is in a container.
+        /// </summary>
+        private Box2 GetAABB(EntityUid uid, Vector2 position, Angle angle, TransformComponent xform, EntityQuery<TransformComponent> xformQuery)
+        {
+            // If we're in a container then we just use the container's bounds.
+            if (_container.TryGetOuterContainer(uid, xform, out var container, xformQuery))
+            {
+                return GetAABBNoContainer(container.Owner, position, angle);
+            }
+
+            return GetAABBNoContainer(uid, position, angle);
+        }
+
+        /// <summary>
+        /// Get the AABB of an entity with the supplied position and angle without considering containers.
+        /// </summary>
+        private Box2 GetAABBNoContainer(EntityUid uid, Vector2 position, Angle angle)
+        {
+            // DebugTools.Assert(!_container.IsEntityInContainer(uid, xform));
+            Box2 localAABB;
+            var transform = new Transform(position, angle);
+
+            if (EntityManager.TryGetComponent<ILookupWorldBox2Component>(uid, out var worldLookup))
+            {
+                localAABB = worldLookup.GetAABB(transform);
+            }
+            else
+            {
+                localAABB = new Box2Rotated(new Box2(transform.Position, transform.Position), transform.Quaternion2D.Angle, transform.Position).CalcBoundingBox();
+            }
+
+            return localAABB;
+        }
+
+        public Box2 GetWorldAABB(EntityUid uid, TransformComponent? xform = null)
+        {
+            var xformQuery = EntityManager.GetEntityQuery<TransformComponent>();
+            xform ??= xformQuery.GetComponent(uid);
+            var (worldPos, worldRot) = xform.GetWorldPositionRotation();
+
+            return GetAABB(uid, worldPos, worldRot, xform, xformQuery);
+        }
+
+        #endregion
+    }
+}
+
+/// <summary>
+/// Flags this entity for an update to their lookup bounds.
+/// </summary>
+[ByRefEvent]
+public readonly struct UpdateLookupBoundsEvent
+{
+    public readonly EntityUid Uid;
+
+    public UpdateLookupBoundsEvent(EntityUid uid)
+    {
+        Uid = uid;
+    }
+}

Robust.Shared/GameObjects/Systems/MetaDataSystem.cs

@@ -0,0 +1,70 @@
+using Robust.Shared.GameStates;
+using Robust.Shared.IoC;
+using Robust.Shared.Prototypes;
+
+namespace Robust.Shared.GameObjects;
+
+public sealed class MetaDataSystem : EntitySystem
+{
+    [Dependency] private readonly IPrototypeManager _proto = default!;
+
+    public override void Initialize()
+    {
+        SubscribeLocalEvent<MetaDataComponent, ComponentHandleState>(OnMetaDataHandle);
+        SubscribeLocalEvent<MetaDataComponent, ComponentGetState>(OnMetaDataGetState);
+    }
+
+    private void OnMetaDataGetState(EntityUid uid, MetaDataComponent component, ref ComponentGetState args)
+    {
+        args.State = new MetaDataComponentState(component._entityName, component._entityDescription, component._entityPrototype?.ID);
+    }
+
+    private void OnMetaDataHandle(EntityUid uid, MetaDataComponent component, ref ComponentHandleState args)
+    {
+        if (args.Current is not MetaDataComponentState state)
+            return;
+
+        component._entityName = state.Name;
+        component._entityDescription = state.Description;
+
+        if(state.PrototypeId != null)
+            component._entityPrototype = _proto.Index<EntityPrototype>(state.PrototypeId);
+    }
+
+    public void AddFlag(EntityUid uid, MetaDataFlags flags, MetaDataComponent? component = null)
+    {
+        if (!Resolve(uid, ref component)) return;
+
+        component.Flags |= flags;
+    }
+
+    /// <summary>
+    /// Attempts to remove the specific flag from metadata.
+    /// Other systems can choose not to allow the removal if it's still relevant.
+    /// </summary>
+    public void RemoveFlag(EntityUid uid, MetaDataFlags flags, MetaDataComponent? component = null)
+    {
+        if (!Resolve(uid, ref component) ||
+            (component.Flags & flags) == 0x0) return;
+
+        var ev = new MetaFlagRemoveAttemptEvent();
+        EntityManager.EventBus.RaiseLocalEvent(component.Owner, ref ev);
+
+        if (ev.Cancelled) return;
+
+        component.Flags &= ~flags;
+    }
+}
+
+/// <summary>
+/// Raised if <see cref="MetaDataSystem"/> is trying to remove a particular flag.
+/// </summary>
+[ByRefEvent]
+public struct MetaFlagRemoveAttemptEvent
+{
+    public bool Cancelled = false;
+
+    public MetaFlagRemoveAttemptEvent()
+    {
+    }
+}

Robust.Shared/GameObjects/Systems/OccluderSystem.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Robust.Shared.IoC;
@@ -21,8 +21,12 @@ namespace Robust.Shared.GameObjects
             base.Initialize();
 
             UpdatesOutsidePrediction = true;
-
-            _mapManager.MapCreated += OnMapCreated;
+            
+            SubscribeLocalEvent<MapChangedEvent>(ev =>
+            {
+                if (ev.Created)
+                    OnMapCreated(ev);
+            });
 
             SubscribeLocalEvent<GridInitializeEvent>(HandleGridInit);
             SubscribeLocalEvent<OccluderTreeComponent, ComponentInit>(HandleOccluderTreeInit);
@@ -92,7 +96,6 @@ namespace Robust.Shared.GameObjects
         public override void Shutdown()
         {
             base.Shutdown();
-            _mapManager.MapCreated -= OnMapCreated;
             _updates.Clear();
         }
 
@@ -156,7 +159,7 @@ namespace Robust.Shared.GameObjects
             _updates.Enqueue(new OccluderUpdateEvent(component));
         }
 
-        private void OnMapCreated(object? sender, MapEventArgs e)
+        private void OnMapCreated(MapChangedEvent e)
         {
             if (e.Map == MapId.Nullspace) return;
 

Robust.Shared/GameObjects/Systems/SharedAppearanceSystem.cs

@@ -4,7 +4,7 @@ using Robust.Shared.Serialization;
 
 namespace Robust.Shared.GameObjects;
 
-internal abstract class SharedAppearanceSystem : EntitySystem
+public abstract class SharedAppearanceSystem : EntitySystem
 {
     public virtual void MarkDirty(AppearanceComponent component) {}
 }

Robust.Shared/GameObjects/Systems/SharedGridFixtureSystem.cs

@@ -15,7 +15,6 @@ namespace Robust.Shared.GameObjects
 {
     public abstract class SharedGridFixtureSystem : EntitySystem
     {
-        [Dependency] private readonly IMapManager _mapManager = default!;
         [Dependency] private readonly FixtureSystem _fixtures = default!;
 
         private bool _enabled;
@@ -52,30 +51,25 @@ namespace Robust.Shared.GameObjects
             // Just in case there's any deleted we'll ToArray
             foreach (var (_, chunk) in gridInternal.GetMapChunks().ToArray())
             {
-                chunk.RegenerateCollision();
+                gridInternal.RegenerateCollision(chunk);
             }
         }
 
-        internal void RegenerateCollision(MapChunk chunk, List<Box2i> rectangles)
+        internal void RegenerateCollision(EntityUid gridEuid, MapChunk chunk, List<Box2i> rectangles)
         {
             if (!_enabled) return;
 
-            if (!_mapManager.TryGetGrid(chunk.GridId, out var grid) ||
-                !EntityManager.EntityExists(grid.GridEntityId)) return;
+            DebugTools.Assert(chunk.FilledTiles > 0);
 
-            var gridEnt = grid.GridEntityId;
-
-            DebugTools.Assert(chunk.ValidTiles > 0);
-
-            if (!EntityManager.TryGetComponent(gridEnt, out PhysicsComponent? physicsComponent))
+            if (!EntityManager.TryGetComponent(gridEuid, out PhysicsComponent? physicsComponent))
             {
-                Logger.ErrorS("physics", $"Trying to regenerate collision for {gridEnt} that doesn't have {nameof(physicsComponent)}");
+                Logger.ErrorS("physics", $"Trying to regenerate collision for {gridEuid} that doesn't have {nameof(physicsComponent)}");
                 return;
             }
 
-            if (!EntityManager.TryGetComponent(gridEnt, out FixturesComponent? fixturesComponent))
+            if (!EntityManager.TryGetComponent(gridEuid, out FixturesComponent? fixturesComponent))
             {
-                Logger.ErrorS("physics", $"Trying to regenerate collision for {gridEnt} that doesn't have {nameof(fixturesComponent)}");
+                Logger.ErrorS("physics", $"Trying to regenerate collision for {gridEuid} that doesn't have {nameof(fixturesComponent)}");
                 return;
             }
 
@@ -170,7 +164,7 @@ namespace Robust.Shared.GameObjects
             if (updated)
             {
                 _fixtures.FixtureUpdate(fixturesComponent, physicsComponent);
-                EntityManager.EventBus.RaiseLocalEvent(gridEnt,new GridFixtureChangeEvent {NewFixtures = chunk.Fixtures});
+                EntityManager.EventBus.RaiseLocalEvent(gridEuid,new GridFixtureChangeEvent {NewFixtures = chunk.Fixtures});
             }
         }
     }

Robust.Shared/GameObjects/Systems/SharedMapSystem.cs

@@ -1,6 +1,8 @@
+using System.Collections.Generic;
 using JetBrains.Annotations;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
+using Robust.Shared.Maths;
 
 namespace Robust.Shared.GameObjects
 {
@@ -13,12 +15,27 @@ namespace Robust.Shared.GameObjects
         {
             base.Initialize();
 
+            SubscribeLocalEvent<MapComponent, ComponentInit>(OnMapAdded);
+            SubscribeLocalEvent<MapComponent, ComponentShutdown>(OnMapRemoved);
+
             SubscribeLocalEvent<MapGridComponent, ComponentAdd>(OnGridAdd);
             SubscribeLocalEvent<MapGridComponent, ComponentInit>(OnGridInit);
             SubscribeLocalEvent<MapGridComponent, ComponentStartup>(OnGridStartup);
             SubscribeLocalEvent<MapGridComponent, ComponentShutdown>(OnGridRemove);
         }
 
+        private void OnMapAdded(EntityUid uid, MapComponent component, ComponentInit args)
+        {
+            var msg = new MapChangedEvent(component.WorldMap, true);
+            EntityManager.EventBus.RaiseLocalEvent(uid, msg);
+        }
+
+        private void OnMapRemoved(EntityUid uid, MapComponent component, ComponentShutdown args)
+        {
+            var msg = new MapChangedEvent(component.WorldMap, false);
+            EntityManager.EventBus.RaiseLocalEvent(uid, msg);
+        }
+
         private void OnGridAdd(EntityUid uid, MapGridComponent component, ComponentAdd args)
         {
             // GridID is not set yet so we don't include it.
@@ -45,6 +62,36 @@ namespace Robust.Shared.GameObjects
         }
     }
 
+    /// <summary>
+    ///     Arguments for when a map is created or deleted.
+    /// </summary>
+    public sealed class MapChangedEvent : EntityEventArgs
+    {
+        /// <summary>
+        ///     Creates a new instance of this class.
+        /// </summary>
+        public MapChangedEvent(MapId map, bool created)
+        {
+            Map = map;
+            Created = created;
+        }
+
+        /// <summary>
+        ///     Map that is being modified.
+        /// </summary>
+        public MapId Map { get; }
+
+        /// <summary>
+        ///     The map is being created.
+        /// </summary>
+        public bool Created { get; }
+
+        /// <summary>
+        ///     The map is being destroyed (not <see cref="Created"/>).
+        /// </summary>
+        public bool Destroyed => !Created;
+    }
+
     public sealed class GridStartupEvent : EntityEventArgs
     {
         public EntityUid EntityUid { get; }
@@ -96,4 +143,54 @@ namespace Robust.Shared.GameObjects
             EntityUid = uid;
         }
     }
+
+    /// <summary>
+    ///     Arguments for when a single tile on a grid is changed locally or remotely.
+    /// </summary>
+    public sealed class TileChangedEvent : EntityEventArgs
+    {
+        /// <summary>
+        ///     Creates a new instance of this class.
+        /// </summary>
+        public TileChangedEvent(TileRef newTile, Tile oldTile)
+        {
+            NewTile = newTile;
+            OldTile = oldTile;
+        }
+
+        /// <summary>
+        ///     New tile that replaced the old one.
+        /// </summary>
+        public TileRef NewTile { get; }
+
+        /// <summary>
+        ///     Old tile that was replaced.
+        /// </summary>
+        public Tile OldTile { get; }
+    }
+
+    /// <summary>
+    ///     Arguments for when a one or more tiles on a grid are modified at once.
+    /// </summary>
+    public sealed class GridModifiedEvent : EntityEventArgs
+    {
+        /// <summary>
+        ///     Grid being changed.
+        /// </summary>
+        public IMapGrid Grid { get; }
+
+        /// <summary>
+        /// Set of tiles that were modified.
+        /// </summary>
+        public IReadOnlyCollection<(Vector2i position, Tile tile)> Modified { get; }
+
+        /// <summary>
+        ///     Creates a new instance of this class.
+        /// </summary>
+        public GridModifiedEvent(IMapGrid grid, IReadOnlyCollection<(Vector2i position, Tile tile)> modified)
+        {
+            Grid = grid;
+            Modified = modified;
+        }
+    }
 }

Robust.Shared/GameObjects/Systems/SharedPhysicsSystem.Fixtures.cs

@@ -0,0 +1,105 @@
+using Robust.Shared.IoC;
+using Robust.Shared.Physics;
+using Robust.Shared.Physics.Dynamics;
+using Robust.Shared.Utility;
+
+namespace Robust.Shared.GameObjects;
+
+public abstract partial class SharedPhysicsSystem
+{
+    [Dependency] private readonly FixtureSystem _fixtures = default!;
+
+    #region Collision Masks & Layers
+
+    public void AddCollisionMask(FixturesComponent component, Fixture fixture, int mask)
+    {
+        if ((fixture.CollisionMask & mask) == mask) return;
+
+        DebugTools.Assert(component.Fixtures.ContainsKey(fixture.ID));
+        fixture._collisionMask |= mask;
+
+        if (TryComp<PhysicsComponent>(component.Owner, out var body))
+        {
+            _fixtures.FixtureUpdate(component, body);
+        }
+
+        _broadphaseSystem.Refilter(fixture);
+    }
+
+    public void SetCollisionMask(FixturesComponent component, Fixture fixture, int mask)
+    {
+        if (fixture.CollisionMask == mask) return;
+
+        DebugTools.Assert(component.Fixtures.ContainsKey(fixture.ID));
+        fixture._collisionMask = mask;
+
+        if (TryComp<PhysicsComponent>(component.Owner, out var body))
+        {
+            _fixtures.FixtureUpdate(component, body);
+        }
+
+        _broadphaseSystem.Refilter(fixture);
+    }
+
+    public void RemoveCollisionMask(FixturesComponent component, Fixture fixture, int mask)
+    {
+        if ((fixture.CollisionMask & mask) == 0x0) return;
+
+        DebugTools.Assert(component.Fixtures.ContainsKey(fixture.ID));
+        fixture._collisionMask &= ~mask;
+
+        if (TryComp<PhysicsComponent>(component.Owner, out var body))
+        {
+            _fixtures.FixtureUpdate(component, body);
+        }
+
+        _broadphaseSystem.Refilter(fixture);
+    }
+
+    public void AddCollisionLayer(FixturesComponent component, Fixture fixture, int layer)
+    {
+        if ((fixture.CollisionLayer & layer) == layer) return;
+
+        DebugTools.Assert(component.Fixtures.ContainsKey(fixture.ID));
+        fixture._collisionLayer |= layer;
+
+        if (TryComp<PhysicsComponent>(component.Owner, out var body))
+        {
+            _fixtures.FixtureUpdate(component, body);
+        }
+
+        _broadphaseSystem.Refilter(fixture);
+    }
+
+    public void SetCollisionLayer(FixturesComponent component, Fixture fixture, int layer)
+    {
+        if (fixture.CollisionLayer == layer) return;
+
+        DebugTools.Assert(component.Fixtures.ContainsKey(fixture.ID));
+        fixture._collisionLayer = layer;
+
+        if (TryComp<PhysicsComponent>(component.Owner, out var body))
+        {
+            _fixtures.FixtureUpdate(component, body);
+        }
+
+        _broadphaseSystem.Refilter(fixture);
+    }
+
+    public void RemoveCollisionLayer(FixturesComponent component, Fixture fixture, int layer)
+    {
+        if ((fixture.CollisionLayer & layer) == 0x0) return;
+
+        DebugTools.Assert(component.Fixtures.ContainsKey(fixture.ID));
+        fixture._collisionLayer &= ~layer;
+
+        if (TryComp<PhysicsComponent>(component.Owner, out var body))
+        {
+            _fixtures.FixtureUpdate(component, body);
+        }
+
+        _broadphaseSystem.Refilter(fixture);
+    }
+
+    #endregion
+}

Robust.Shared/GameObjects/Systems/SharedPhysicsSystem.cs

@@ -53,7 +53,11 @@ namespace Robust.Shared.GameObjects
         public override void Initialize()
         {
             base.Initialize();
-            MapManager.MapCreated += HandleMapCreated;
+            SubscribeLocalEvent<MapChangedEvent>(ev =>
+            {
+                if (ev.Created)
+                    HandleMapCreated(ev);
+            });
 
             SubscribeLocalEvent<GridInitializeEvent>(HandleGridInit);
             SubscribeLocalEvent<CollisionChangeMessage>(HandlePhysicsUpdateMessage);
@@ -70,7 +74,7 @@ namespace Robust.Shared.GameObjects
             IoCManager.Resolve<IIslandManager>().Initialize();
 
             var configManager = IoCManager.Resolve<IConfigurationManager>();
-            configManager.OnValueChanged(CVars.AutoClearForces, OnAutoClearChange, true);
+            configManager.OnValueChanged(CVars.AutoClearForces, OnAutoClearChange);
         }
 
         private void HandlePhysicsMapInit(EntityUid uid, SharedPhysicsMapComponent component, ComponentInit args)
@@ -81,6 +85,7 @@ namespace Robust.Shared.GameObjects
             component.ContactManager = new();
             component.ContactManager.Initialize();
             component.ContactManager.MapId = component.MapId;
+            component.AutoClearForces = IoCManager.Resolve<IConfigurationManager>().GetCVar(CVars.AutoClearForces);
 
             component.ContactManager.KinematicControllerCollision += KinematicControllerCollision;
         }
@@ -195,13 +200,11 @@ namespace Robust.Shared.GameObjects
         {
             base.Shutdown();
 
-            MapManager.MapCreated -= HandleMapCreated;
-
             var configManager = IoCManager.Resolve<IConfigurationManager>();
             configManager.UnsubValueChanged(CVars.AutoClearForces, OnAutoClearChange);
         }
 
-        protected abstract void HandleMapCreated(object? sender, MapEventArgs eventArgs);
+        protected abstract void HandleMapCreated(MapChangedEvent eventArgs);
 
         private void HandleMapChange(EntMapIdChangedMessage message)
         {

Robust.Shared/GameObjects/Systems/SharedTransformSystem.Component.cs

@@ -0,0 +1,83 @@
+using System.Runtime.CompilerServices;
+using JetBrains.Annotations;
+using Robust.Shared.Maths;
+
+namespace Robust.Shared.GameObjects;
+
+public abstract partial class SharedTransformSystem
+{
+    #region World Matrix
+
+    [Pure]
+    public Matrix3 GetWorldMatrix(EntityUid uid)
+    {
+        return Transform(uid).WorldMatrix;
+    }
+
+    // Temporary until it's moved here
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public Matrix3 GetWorldMatrix(TransformComponent component)
+    {
+        return component.WorldMatrix;
+    }
+
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public Matrix3 GetWorldMatrix(EntityUid uid, EntityQuery<TransformComponent> xformQuery)
+    {
+        return GetWorldMatrix(xformQuery.GetComponent(uid));
+    }
+
+    #endregion
+
+    #region World Rotation
+
+    [Pure]
+    public Angle GetWorldRotation(EntityUid uid)
+    {
+        return Transform(uid).WorldRotation;
+    }
+
+    // Temporary until it's moved here
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public Angle GetWorldRotation(TransformComponent component)
+    {
+        return component.WorldRotation;
+    }
+
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public Angle GetWorldRotation(EntityUid uid, EntityQuery<TransformComponent> xformQuery)
+    {
+        return GetWorldRotation(xformQuery.GetComponent(uid));
+    }
+
+    #endregion
+
+    #region Inverse World Matrix
+
+    [Pure]
+    public Matrix3 GetInvWorldMatrix(EntityUid uid)
+    {
+        return Comp<TransformComponent>(uid).InvWorldMatrix;
+    }
+
+    // Temporary until it's moved here
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public Matrix3 GetInvWorldMatrix(TransformComponent component)
+    {
+        return component.InvWorldMatrix;
+    }
+
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public Matrix3 GetInvWorldMatrix(EntityUid uid, EntityQuery<TransformComponent> xformQuery)
+    {
+        return GetInvWorldMatrix(xformQuery.GetComponent(uid));
+    }
+
+    #endregion
+}

Robust.Shared/GameObjects/Systems/SharedTransformSystem.cs

@@ -7,10 +7,10 @@ using Robust.Shared.Utility;
 
 namespace Robust.Shared.GameObjects
 {
-    public abstract class SharedTransformSystem : EntitySystem
+    public abstract partial class SharedTransformSystem : EntitySystem
     {
         [Dependency] private readonly IMapManager _mapManager = default!;
-        [Dependency] private readonly IEntityLookup _entityLookup = default!;
+        [Dependency] private readonly EntityLookupSystem _entityLookup = default!;
 
         private readonly Queue<MoveEvent> _gridMoves = new();
         private readonly Queue<MoveEvent> _otherMoves = new();
@@ -21,16 +21,10 @@ namespace Robust.Shared.GameObjects
 
             UpdatesOutsidePrediction = true;
 
-            _mapManager.TileChanged += MapManagerOnTileChanged;
+            SubscribeLocalEvent<TileChangedEvent>(MapManagerOnTileChanged);
         }
 
-        public override void Shutdown()
-        {
-            _mapManager.TileChanged -= MapManagerOnTileChanged;
-            base.Shutdown();
-        }
-
-        private void MapManagerOnTileChanged(object? sender, TileChangedEventArgs e)
+        private void MapManagerOnTileChanged(TileChangedEvent e)
         {
             if(e.NewTile.Tile != Tile.Empty)
                 return;
@@ -100,5 +94,65 @@ namespace Robust.Shared.GameObjects
                 }
             }
         }
+
+        public EntityCoordinates GetMoverCoordinates(TransformComponent xform)
+        {
+            // If they're parented directly to the map or grid then just return the coordinates.
+            if (!_mapManager.TryGetGrid(xform.GridID, out var grid))
+            {
+                var mapUid = _mapManager.GetMapEntityId(xform.MapID);
+                var coordinates = xform.Coordinates;
+
+                // Parented directly to the map.
+                if (xform.ParentUid == mapUid)
+                    return coordinates;
+
+                return new EntityCoordinates(mapUid, coordinates.ToMapPos(EntityManager));
+            }
+
+            // Parented directly to the grid
+            if (grid.GridEntityId == xform.ParentUid)
+                return xform.Coordinates;
+
+            // Parented to grid so convert their pos back to the grid.
+            var gridPos = Transform(grid.GridEntityId).InvWorldMatrix.Transform(xform.WorldPosition);
+            return new EntityCoordinates(grid.GridEntityId, gridPos);
+        }
+
+        public EntityCoordinates GetMoverCoordinates(EntityCoordinates coordinates, EntityQuery<TransformComponent> xformQuery)
+        {
+            // GridID isn't ready during EntityInit so YAY
+            IMapGrid? grid = null;
+            var ent = coordinates.EntityId;
+
+            while (ent.IsValid())
+            {
+                if (_mapManager.TryGetGrid(ent, out grid))
+                    break;
+
+                ent = xformQuery.GetComponent(ent).ParentUid;
+            }
+
+            // If they're parented directly to the map or grid then just return the coordinates.
+            if (grid == null)
+            {
+                var mapPos = coordinates.ToMap(EntityManager);
+                var mapUid = _mapManager.GetMapEntityId(mapPos.MapId);
+
+                // Parented directly to the map.
+                if (coordinates.EntityId == mapUid)
+                    return coordinates;
+
+                return new EntityCoordinates(mapUid, mapPos.Position);
+            }
+
+            // Parented directly to the grid
+            if (grid.GridEntityId == coordinates.EntityId)
+                return coordinates;
+
+            // Parented to grid so convert their pos back to the grid.
+            var gridPos = Transform(grid.GridEntityId).InvWorldMatrix.Transform(coordinates.ToMapPos(EntityManager));
+            return new EntityCoordinates(grid.GridEntityId, gridPos);
+        }
     }
 }

Robust.Shared/Localization/LocHelper.cs

@@ -1,30 +1,69 @@
 using System;
+using System.Collections.Generic;
 using System.Text;
 using Linguini.Bundle.Errors;
 using Linguini.Syntax.Parser.Error;
 
-namespace Robust.Shared.Localization
+namespace Robust.Shared.Localization;
+
+internal static class LocHelper
 {
-    internal static class LocHelper
+    public static string FormatCompileErrors(this ParseError self, ReadOnlyMemory<char> resource,
+        string? newLine = null)
     {
-        public static string FormatCompileErrors(this ParseError self, ReadOnlyMemory<char> resource)
+        ErrorSpan span = new(self.Row, self.Slice!.Value.Start.Value, self.Slice.Value.End.Value,
+            self.Position.Start.Value, self.Position.End.Value);
+        return FormatErrors(self.Message, span, resource, newLine);
+    }
+
+    private static string FormatErrors(string message, ErrorSpan span, ReadOnlyMemory<char> resource, string? newLine)
+    {
+        var sb = new StringBuilder();
+        var errContext = resource.Slice(span.StartSpan, span.EndSpan - span.StartSpan).ToString();
+        var lines = new List<ReadOnlyMemory<char>>(5);
+        var currLineOffset = 0;
+        var lastStart = 0;
+        for (var i = 0; i < span.StartMark - span.StartSpan; i++)
         {
-            ErrorSpan span = new(self.Row, self.Slice!.Value.Start.Value, self.Slice.Value.End.Value,
-                self.Position.Start.Value, self.Position.End.Value);
-            return FormatErrors(self.Message, span, resource);
+            switch (errContext[i])
+            {
+                // Reset current line so that mark aligns with the reported error
+                // We cheat here a bit, since we both `\r\n` and `\n` end with '\n'
+                case '\n':
+                    if (i > 0 && errContext[i - 1] == '\r')
+                    {
+                        lines.Add(resource.Slice(lastStart, currLineOffset - 1));
+                    }
+                    else
+                    {
+                        lines.Add(resource.Slice(lastStart, currLineOffset));
+                    }
+
+                    lastStart = currLineOffset + 1;
+                    currLineOffset = 0;
+                    break;
+                default:
+                    currLineOffset++;
+                    break;
+            }
         }
 
-        private static string FormatErrors(string message, ErrorSpan span, ReadOnlyMemory<char> resource)
+        lines.Add(resource.Slice(lastStart, resource.Length - lastStart));
+
+
+        var lastLine = $"{span.Row + lines.Count - 1}".Length;
+        for (var index = 0; index < lines.Count; index++)
         {
-            var sb = new StringBuilder();
-            var row = $"  {span.Row}  ";
-            var errContext = resource.Slice(span.StartSpan, span.EndSpan - span.StartSpan).ToString();
-            sb.Append(row).Append('|')
-                .AppendLine(errContext);
-            sb.Append(' ', row.Length).Append('|')
-                .Append(' ', span.StartMark - span.StartSpan - 1).Append('^', span.EndMark - span.StartMark)
-                .AppendLine($" {message}");
-            return sb.ToString();
+            var line = lines[index];
+
+            sb.Append(newLine ?? Environment.NewLine).Append(' ').Append($"{span.Row + index}".PadLeft(lastLine))
+                .Append(" |").Append(line);
         }
+
+        sb.Append(newLine ?? Environment.NewLine)
+            .Append(' ', currLineOffset + lastLine + 3)
+            .Append('^', span.EndMark - span.StartMark)
+            .Append($" {message}");
+        return sb.ToString();
     }
 }

Robust.Shared/Localization/LocalizationManager.cs

@@ -47,7 +47,7 @@ namespace Robust.Shared.Localization
 
             if (!TryGetString(messageId, out var msg))
             {
-                _logSawmill.Warning("Unknown messageId ({culture}): {messageId}", _defaultCulture.Name, messageId);
+                _logSawmill.Debug("Unknown messageId ({culture}): {messageId}", _defaultCulture.Name, messageId);
                 msg = messageId;
             }
 
@@ -62,7 +62,7 @@ namespace Robust.Shared.Localization
 
             if (!TryGetString(messageId, out var msg, args0))
             {
-                _logSawmill.Warning("Unknown messageId ({culture}): {messageId}", _defaultCulture.Name, messageId);
+                _logSawmill.Debug("Unknown messageId ({culture}): {messageId}", _defaultCulture.Name, messageId);
                 msg = messageId;
             }