Enable nullables as errors in Robust (#1732)

* Removed SnapGridOffset, there is only center now.

* SnapGridComponent methods are now static.

* Removed SnapGridComponent.OnPositionChanged.

* Refactored static functions off SnapGridComponent to MapGrid.
Refactored away usages of SnapGridComponent.Position.

* Added Transform.Anchored for checking if an entity is a tile entity.
More refactoring for static MapGrid functions.

* Static snapgrid methods on MapGrid are no longer static.

* Removed IMapGrid.SnapSize, it is now always equal to the IMapGrid.TileSize.

* Add setter to ITransformComponent.Anchored.
Removed direct references to SnapGridComponent from content.

* Grid functions now deal with EntityUids instead of SnapGridComponents.
Began renaming public API functions from SnapGrid to Anchor.

* Add some unit tests.

* SnapGridComponent now anchors itself in startup, instead of Initialize (sending directed events in init is an error).

Avalonia.Base/Avalonia.Base.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net5.0</TargetFramework>
+    </PropertyGroup>
+
+</Project>

Avalonia.Base/README.md

@@ -0,0 +1,2 @@
+See `Robust.Client/UserInterface/XAML/RiderNotes.md` for why this project exists.
+We are not actually using Avalonia (yet).

MSBuild/Robust.Engine.props

@@ -4,5 +4,6 @@
         <TargetFramework>net5.0</TargetFramework>
         <LangVersion>9</LangVersion>
         <Nullable>enable</Nullable>
+        <WarningsAsErrors>nullable</WarningsAsErrors>
     </PropertyGroup>
 </Project>

README.md

@@ -1,25 +1,16 @@
 ![Robust Toolbox](https://raw.githubusercontent.com/space-wizards/asset-dump/3dd3078e49e3a7e06709a6e0fc6e3223d8d44ca2/robust.png)
 
-[![Build status](https://ci.appveyor.com/api/projects/status/ygb7t8hsj3wt7pnm/branch/master?svg=true)](https://ci.appveyor.com/project/Silvertorch5/space-station-14/branch/master)
-[![Coverage](https://sonarcloud.io/api/project_badges/measure?project=ss14&metric=coverage)](https://sonarcloud.io/dashboard?id=ss14)
+Robust Toolbox is an engine primarily being developed for [Space Station 14](https://github.com/space-wizards/space-station-14), although we're working on making it usable for both [singleplayer](https://github.com/space-wizards/RobustToolboxTemplateSingleplayer) and [multiplayer](https://github.com/space-wizards/RobustToolboxTemplate) projects.
 
-Robust Toolbox is a client/server backend for [Space Station 14](https://github.com/space-wizards/space-station-14).
+Use the [content repo](https://github.com/space-wizards/space-station-14) for actual development, even if you're modifying the engine itself.
 
-### *This repository is the *engine* section of SS14. This is the base engine all SS14 servers will be built on. As such, it does not start on its own: it needs the [content repo](https://github.com/space-wizards/space-station-14). Use said repo for actual development, even if you're modifying the engine itself. Think of Robust Toolbox as BYOND in the context of Spacestation 13.*
+## Project Links
 
-## Getting in Touch
+[Website](https://spacestation14.io/) | [Discord](https://discord.gg/t2jac3p) | [Forum](https://forum.spacestation14.io/) | [Steam](https://store.steampowered.com/app/1255460/Space_Station_14/) | [Standalone Download](https://spacestation14.io/about/nightlies/)
 
-* Website: [spacestation14.io](https://spacestation14.io/)
-* Discord: [Invite Link](https://discord.gg/t2jac3p)
-* IRC: `irc.rizon.net#spacebus`
-* Code Analysis: [Sonar Cloud](https://sonarcloud.io/dashboard?id=ss14)
-* Automatic Content Builds: [builds.spacestation14.io](https://builds.spacestation14.io/jenkins/)
+## Documentation/Wiki
 
-The IRC is setup to relay back and forth to the Discord server so [IRC nerds](https://xkcd.com/1782/) will not be left out.
-
-## Documentation
-
-We have various technical documentation articles on the [HackMD Wiki](https://hackmd.io/@ss14/docs/%2F%40ss14%2Ftechnical-documentation-overview).
+The [HackMD Wiki](https://hackmd.io/@ss14/docs/wiki) has documentation on SS14s content, engine, game design and more. We also have lots of resources for new contributors to the project.
 
 ## Contributing
 
@@ -27,8 +18,8 @@ We are happy to accept contributions from anybody. Get in Discord or IRC if you
 
 ## Building
 
-**In practice, you usually don't build this repository directly.**
+This repository is the **engine** part of SS14. It's the base engine all SS14 servers will be built on. As such, it does not start on its own: it needs the [content repo](https://github.com/space-wizards/space-station-14). Think of Robust Toolbox as BYOND in the context of Spacestation 13.
 
 ## Legal Info
 
-See `legal.md` for licenses and copyright.
+See [legal.md](https://github.com/space-wizards/RobustToolbox/blob/master/legal.md) for licenses and copyright.

Resources/Prototypes/dbg_rotationMarker.yml

@@ -1,40 +0,0 @@
-- type: entity
-  id: debugRotation1
-  name: dbg_rotation1
-  components:
-  - type: Clickable
-  - type: InteractionOutline
-  - type: Sprite
-    netsync: false
-    visible: true
-    sprite: debugRotation.rsi
-    state: direction1
-  placement:
-    mode: AlignTileAny
-
-- type: entity
-  id: debugRotation4
-  name: dbg_rotation4
-  components:
-  - type: Clickable
-  - type: InteractionOutline
-  - type: Sprite
-    netsync: false
-    visible: true
-    sprite: debugRotation.rsi
-    state: direction4
-  placement:
-    mode: AlignTileAny
-
-- type: entity
-  id: debugRotationTex
-  name: dbg_rotationTex
-  components:
-  - type: Clickable
-  - type: InteractionOutline
-  - type: Sprite
-    netsync: false
-    visible: true
-    texture: debugRotation.rsi/direction1.png
-  placement:
-    mode: AlignTileAny

Resources/Prototypes/dummy_entity.yml

@@ -1,4 +0,0 @@
-- type: entity
-  name: blank entity
-  id: BlankEntity
-  abstract: true

Resources/Shaders/Internal/fov-lighting.swsl

@@ -28,5 +28,10 @@ void fragment()
 
     highp float occlusion = ChebyshevUpperBound(occlDist, ourDist);
 
+    if (occlusion >= 1.0)
+    {
+        discard;
+    }
+
     COLOR = vec4(0.0, 0.0, 0.0, 1.0 - occlusion);
 }

Resources/Shaders/Internal/light-soft.swsl

@@ -1,5 +1,11 @@
 #include "/Shaders/Internal/light_shared.swsl"
 
+highp vec4 calcGaussianWeights(highp float sigma, highp vec4 offset)
+{
+    highp vec4 eExp = offset * offset / (2.0 * sigma * sigma);
+    return exp(-eExp) / (sigma * sqrt(2.0 * PI));
+}
+
 highp float createOcclusion(highp vec2 diff)
 {
     // Calculate vector perpendicular to light vector.
@@ -8,23 +14,57 @@ highp float createOcclusion(highp vec2 diff)
 
     highp float ourDist = length(diff);
 
-    highp vec2 occlDist = occludeDepth(diff, shadowMap, lightIndex);
+    // Sample 7 points on a line perpendicular to the light source.
+    // Depending on the closest point, we change the gaussian weights down below
+    // to change the "narrowness" of the samples.
+    perpendicular *= lightSoftness * 1.5;
+
+    // Get all the samples we need.
+    highp vec2 sample1 = occludeDepth(diff, shadowMap, lightIndex);
+    highp vec2 sample2 = occludeDepth(diff + perpendicular, shadowMap, lightIndex);
+    highp vec2 sample3 = occludeDepth(diff - perpendicular, shadowMap, lightIndex);
+    highp vec2 sample4 = occludeDepth(diff + perpendicular * 2.0, shadowMap, lightIndex);
+    highp vec2 sample5 = occludeDepth(diff - perpendicular * 2.0, shadowMap, lightIndex);
+    highp vec2 sample6 = occludeDepth(diff + perpendicular * 3.0, shadowMap, lightIndex);
+    highp vec2 sample7 = occludeDepth(diff - perpendicular * 3.0, shadowMap, lightIndex);
+
+    highp float mindist =
+        min(sample1.x,
+        min(sample2.x,
+        min(sample3.x,
+        min(sample4.x,
+        min(sample5.x,
+        min(sample6.x,
+            sample7.x))))));
+
+    mindist = max(0.001, mindist);
 
     // Change soft shadow size based on distance from primary occluder.
-    highp float distRatio = (ourDist - occlDist.x) / occlDist.x / 2.0;
+    highp float distRatio = (ourDist - mindist);
 
-    perpendicular *= distRatio * lightSoftness;
+    // Sigma can never be zero so make sure to clamp.
+    // TODO: Scaling the dist ratio here in a more sane way might make shadows look better buuuut I'm lazy.
+    // Shadows look pretty nice already.
+    highp float sigma = max(0.001, distRatio * 0.75);
+    highp vec4 weights = calcGaussianWeights(sigma, vec4(0.0, 1.0, 2.0, 3.0));
 
-    // Totally not hacky PCF on top of VSM.
-    highp float occlusion = smoothstep(0.1, 1.0, ChebyshevUpperBound(occlDist, ourDist));
+    // Calculation of gaussian weights here is broken because it doesn't add up to 1.
+    // Fixing this is hard and if I had to guess too expensive for GPU shaders.
+    // So instead we add up the total weights and scale the result with that,
+    // so that we still end up with 0-1.
+    highp float totalWeigths = weights.x + weights.y * 2.0 + weights.z * 2.0 + weights.w * 2.0;
 
-    occlusion += shadowContrib(diff + perpendicular);
-    occlusion += shadowContrib(diff - perpendicular);
-    occlusion += shadowContrib(diff + perpendicular * 2.0);
-    occlusion += shadowContrib(diff - perpendicular * 2.0);
-    occlusion += shadowContrib(diff + perpendicular * 3.0);
-    occlusion += shadowContrib(diff - perpendicular * 3.0);
+    highp float occlusion = 0.0;
 
-    return occlusion / 7.0;
+    // Calculate actual occlusion with new weights.
+    occlusion += ChebyshevUpperBound(sample1, ourDist) * weights.x;
+    occlusion += ChebyshevUpperBound(sample2, ourDist) * weights.y;
+    occlusion += ChebyshevUpperBound(sample3, ourDist) * weights.y;
+    occlusion += ChebyshevUpperBound(sample4, ourDist) * weights.z;
+    occlusion += ChebyshevUpperBound(sample5, ourDist) * weights.z;
+    occlusion += ChebyshevUpperBound(sample6, ourDist) * weights.w;
+    occlusion += ChebyshevUpperBound(sample7, ourDist) * weights.w;
+
+    return occlusion / totalWeigths;
 }
 

Robust.Benchmarks/Program.cs

@@ -0,0 +1,12 @@
+using BenchmarkDotNet.Running;
+
+namespace Robust.Benchmarks
+{
+    internal class Program
+    {
+        public static void Main(string[] args)
+        {
+            BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run();
+        }
+    }
+}

Robust.Benchmarks/Robust.Benchmarks.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <Import Project="..\MSBuild\Robust.Properties.targets" />
+    <Import Project="..\MSBuild\Robust.Engine.props" />
+    <PropertyGroup>
+        <IsPackable>false</IsPackable>
+        <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+        <OutputPath>../bin/Benchmarks</OutputPath>
+        <OutputType>Exe</OutputType>
+    </PropertyGroup>
+    <ItemGroup>
+      <ProjectReference Include="..\Robust.Server\Robust.Server.csproj" />
+      <ProjectReference Include="..\Robust.Shared\Robust.Shared.csproj" />
+    </ItemGroup>
+    <ItemGroup>
+      <PackageReference Include="BenchmarkDotNet" Version="0.12.1" />
+    </ItemGroup>
+    <Import Project="..\MSBuild\Robust.Engine.targets" />
+</Project>

Robust.Benchmarks/Serialization/DataDefinitionWithString.cs

@@ -0,0 +1,11 @@
+using Robust.Shared.Serialization.Manager.Attributes;
+
+namespace Robust.Benchmarks.Serialization
+{
+    [DataDefinition]
+    public class DataDefinitionWithString
+    {
+        [field: DataField("string")]
+        private string StringField { get; } = default!;
+    }
+}

Robust.Benchmarks/Serialization/Initialize/SerializationInitializeBenchmark.cs

@@ -0,0 +1,21 @@
+using BenchmarkDotNet.Attributes;
+using Robust.Shared.Serialization.Manager;
+
+namespace Robust.Benchmarks.Serialization.Initialize
+{
+    public class SerializationInitializeBenchmark : SerializationBenchmark
+    {
+        [IterationCleanup]
+        public void IterationCleanup()
+        {
+            SerializationManager.Shutdown();
+        }
+
+        [Benchmark]
+        public ISerializationManager Initialize()
+        {
+            InitializeSerialization();
+            return SerializationManager;
+        }
+    }
+}

Robust.Benchmarks/Serialization/Read/SerializationReadBenchmark.cs

@@ -0,0 +1,55 @@
+using System.IO;
+using BenchmarkDotNet.Attributes;
+using Robust.Shared.Serialization.Markdown;
+using YamlDotNet.RepresentationModel;
+
+namespace Robust.Benchmarks.Serialization.Read
+{
+    public class SerializationReadBenchmark : SerializationBenchmark
+    {
+        public SerializationReadBenchmark()
+        {
+            InitializeSerialization();
+
+            StringDataDefNode = new MappingDataNode();
+            StringDataDefNode.AddNode(new ValueDataNode("string"), new ValueDataNode("ABC"));
+
+            var yamlStream = new YamlStream();
+            yamlStream.Load(new StringReader(SeedDataDefinition.Prototype));
+
+            SeedNode = yamlStream.Documents[0].RootNode.ToDataNodeCast<SequenceDataNode>().Cast<MappingDataNode>(0);
+        }
+
+        private ValueDataNode StringNode { get; } = new("ABC");
+
+        private ValueDataNode IntNode { get; } = new("1");
+
+        private MappingDataNode StringDataDefNode { get; }
+
+        private MappingDataNode SeedNode { get; }
+
+        [Benchmark]
+        public string? ReadString()
+        {
+            return SerializationManager.ReadValue<string>(StringNode);
+        }
+
+        [Benchmark]
+        public int? ReadInteger()
+        {
+            return SerializationManager.ReadValue<int>(IntNode);
+        }
+
+        [Benchmark]
+        public DataDefinitionWithString? ReadDataDefinitionWithString()
+        {
+            return SerializationManager.ReadValue<DataDefinitionWithString>(StringDataDefNode);
+        }
+
+        [Benchmark]
+        public SeedDataDefinition? ReadSeedDataDefinition()
+        {
+            return SerializationManager.ReadValue<SeedDataDefinition>(SeedNode);
+        }
+    }
+}

Robust.Benchmarks/Serialization/SeedDataDefinition.cs

@@ -0,0 +1,184 @@
+using System.Collections.Generic;
+using Robust.Shared.Maths;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.Utility;
+using Robust.Shared.ViewVariables;
+
+namespace Robust.Benchmarks.Serialization
+{
+    [Prototype("seed")]
+    public class SeedDataDefinition : IPrototype
+    {
+        public const string Prototype = @"
+- type: seed
+  id: tobacco
+  name: tobacco
+  seedName: tobacco
+  displayName: tobacco plant
+  productPrototypes:
+    - LeavesTobacco
+  harvestRepeat: Repeat
+  lifespan: 75
+  maturation: 5
+  production: 5
+  yield: 2
+  potency: 20
+  growthStages: 3
+  idealLight: 9
+  idealHeat: 298
+  chemicals:
+    chem.Nicotine:
+      Min: 1
+      Max: 10
+      PotencyDivisor: 10";
+
+        private const string SeedPrototype = "SeedBase";
+
+        [ViewVariables]
+        [field: DataField("id", required: true)]
+        public string ID { get; private init; } = default!;
+
+        /// <summary>
+        ///     Unique identifier of this seed. Do NOT set this.
+        /// </summary>
+        public int Uid { get; internal set; } = -1;
+
+        #region Tracking
+
+        [ViewVariables] [DataField("name")] public string Name { get; set; } = string.Empty;
+        [ViewVariables] [DataField("seedName")] public string SeedName { get; set; } = string.Empty;
+
+        [ViewVariables]
+        [DataField("seedNoun")]
+        public string SeedNoun { get; set; } = "seeds";
+        [ViewVariables] [DataField("displayName")] public string DisplayName { get; set; } = string.Empty;
+
+        [ViewVariables]
+        [DataField("roundStart")]
+        public bool RoundStart { get; private set; } = true;
+        [ViewVariables] [DataField("mysterious")] public bool Mysterious { get; set; }
+        [ViewVariables] [DataField("immutable")] public bool Immutable { get; set; }
+        #endregion
+
+        #region Output
+
+        [ViewVariables]
+        [DataField("productPrototypes")]
+        public List<string> ProductPrototypes { get; set; } = new();
+
+        [ViewVariables]
+        [DataField("chemicals")]
+        public Dictionary<string, SeedChemQuantity> Chemicals { get; set; } = new();
+
+        [ViewVariables]
+        [DataField("consumeGasses")]
+        public Dictionary<Gas, float> ConsumeGasses { get; set; } = new();
+
+        [ViewVariables]
+        [DataField("exudeGasses")]
+        public Dictionary<Gas, float> ExudeGasses { get; set; } = new();
+        #endregion
+
+        #region Tolerances
+
+        [ViewVariables]
+        [DataField("nutrientConsumption")]
+        public float NutrientConsumption { get; set; } = 0.25f;
+
+        [ViewVariables] [DataField("waterConsumption")] public float WaterConsumption { get; set; } = 3f;
+        [ViewVariables] [DataField("idealHeat")] public float IdealHeat { get; set; } = 293f;
+        [ViewVariables] [DataField("heatTolerance")] public float HeatTolerance { get; set; } = 20f;
+        [ViewVariables] [DataField("idealLight")] public float IdealLight { get; set; } = 7f;
+        [ViewVariables] [DataField("lightTolerance")] public float LightTolerance { get; set; } = 5f;
+        [ViewVariables] [DataField("toxinsTolerance")] public float ToxinsTolerance { get; set; } = 4f;
+
+        [ViewVariables]
+        [DataField("lowPressureTolerance")]
+        public float LowPressureTolerance { get; set; } = 25f;
+
+        [ViewVariables]
+        [DataField("highPressureTolerance")]
+        public float HighPressureTolerance { get; set; } = 200f;
+
+        [ViewVariables]
+        [DataField("pestTolerance")]
+        public float PestTolerance { get; set; } = 5f;
+
+        [ViewVariables]
+        [DataField("weedTolerance")]
+        public float WeedTolerance { get; set; } = 5f;
+        #endregion
+
+        #region General traits
+
+        [ViewVariables]
+        [DataField("endurance")]
+        public float Endurance { get; set; } = 100f;
+        [ViewVariables] [DataField("yield")] public int Yield { get; set; }
+        [ViewVariables] [DataField("lifespan")] public float Lifespan { get; set; }
+        [ViewVariables] [DataField("maturation")] public float Maturation { get; set; }
+        [ViewVariables] [DataField("production")] public float Production { get; set; }
+        [ViewVariables] [DataField("growthStages")] public int GrowthStages { get; set; } = 6;
+        [ViewVariables] [DataField("harvestRepeat")] public HarvestType HarvestRepeat { get; set; } = HarvestType.NoRepeat;
+
+        [ViewVariables] [DataField("potency")] public float Potency { get; set; } = 1f;
+        // No, I'm not removing these.
+        //public PlantSpread Spread { get; set; }
+        //public PlantMutation Mutation { get; set; }
+        //public float AlterTemperature { get; set; }
+        //public PlantCarnivorous Carnivorous { get; set; }
+        //public bool Parasite { get; set; }
+        //public bool Hematophage { get; set; }
+        //public bool Thorny { get; set; }
+        //public bool Stinging { get; set; }
+        [DataField("ligneous")]
+        public bool Ligneous { get; set; }
+        // public bool Teleporting { get; set; }
+        // public PlantJuicy Juicy { get; set; }
+        #endregion
+
+        #region Cosmetics
+
+        [ViewVariables]
+        [DataField("plantRsi", required: true)]
+        public ResourcePath PlantRsi { get; set; } = default!;
+
+        [ViewVariables]
+        [DataField("plantIconState")]
+        public string PlantIconState { get; set; } = "produce";
+
+        [ViewVariables]
+        [DataField("bioluminescent")]
+        public bool Bioluminescent { get; set; }
+
+        [ViewVariables]
+        [DataField("bioluminescentColor")]
+        public Color BioluminescentColor { get; set; } = Color.White;
+
+        [ViewVariables]
+        [DataField("splatPrototype")]
+        public string? SplatPrototype { get; set; }
+
+        #endregion
+    }
+
+    public enum HarvestType
+    {
+        NoRepeat,
+        Repeat
+    }
+
+    public enum Gas {}
+
+    [DataDefinition]
+    public struct SeedChemQuantity
+    {
+        [DataField("Min")]
+        public int Min;
+        [DataField("Max")]
+        public int Max;
+        [DataField("PotencyDivisor")]
+        public int PotencyDivisor;
+    }
+}

Robust.Benchmarks/Serialization/SerializationBenchmark.cs

@@ -0,0 +1,43 @@
+using System;
+using Robust.Server;
+using Robust.Shared.Configuration;
+using Robust.Shared.ContentPack;
+using Robust.Shared.IoC;
+using Robust.Shared.Reflection;
+using Robust.Shared.Serialization.Manager;
+
+namespace Robust.Benchmarks.Serialization
+{
+    public abstract class SerializationBenchmark
+    {
+        public SerializationBenchmark()
+        {
+            IoCManager.InitThread();
+            ServerIoC.RegisterIoC();
+            IoCManager.BuildGraph();
+
+            var assemblies = new[]
+            {
+                AppDomain.CurrentDomain.GetAssemblyByName("Robust.Shared"),
+                AppDomain.CurrentDomain.GetAssemblyByName("Robust.Server"),
+                AppDomain.CurrentDomain.GetAssemblyByName("Robust.Benchmarks")
+            };
+
+            foreach (var assembly in assemblies)
+            {
+                IoCManager.Resolve<IConfigurationManagerInternal>().LoadCVarsFromAssembly(assembly);
+            }
+
+            IoCManager.Resolve<IReflectionManager>().LoadAssemblies(assemblies);
+
+            SerializationManager = IoCManager.Resolve<ISerializationManager>();
+        }
+
+        protected ISerializationManager SerializationManager { get; }
+
+        public void InitializeSerialization()
+        {
+            SerializationManager.Initialize();
+        }
+    }
+}

Robust.Client/Audio/Midi/MidiManager.cs

@@ -11,7 +11,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Broadphase;
 using Robust.Shared.Utility;
@@ -321,6 +320,11 @@ namespace Robust.Client.Audio.Midi
                             continue;
                         }
 
+                        if (renderer.TrackingEntity != null)
+                        {
+                            renderer.Source.SetVelocity(renderer.TrackingEntity.GlobalLinearVelocity());
+                        }
+
                         if (float.IsNaN(pos.Position.X) || float.IsNaN(pos.Position.Y))
                         {
                             // just duck out instead of move to NaN

Robust.Client/BaseClient.cs

@@ -8,6 +8,7 @@ using Robust.Client.Utility;
 using Robust.Shared;
 using Robust.Shared.Configuration;
 using Robust.Shared.Enums;
+using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
@@ -96,6 +97,25 @@ namespace Robust.Client
             _net.ClientDisconnect(reason);
         }
 
+        /// <inheritdoc />
+        public void StartSinglePlayer()
+        {
+            DebugTools.Assert(RunLevel < ClientRunLevel.Connecting);
+            DebugTools.Assert(!_net.IsConnected);
+            _playMan.Startup();
+            _playMan.LocalPlayer!.Name = PlayerNameOverride ?? _configManager.GetCVar(CVars.PlayerName);
+            OnRunLevelChanged(ClientRunLevel.SinglePlayerGame);
+            GameStartedSetup();
+        }
+
+        /// <inheritdoc />
+        public void StopSinglePlayer()
+        {
+            DebugTools.Assert(RunLevel == ClientRunLevel.SinglePlayerGame);
+            DebugTools.Assert(!_net.IsConnected);
+            GameStoppedReset();
+        }
+
         /// <inheritdoc />
         public event EventHandler<RunLevelChangedEventArgs>? RunLevelChanged;
 
@@ -132,7 +152,7 @@ namespace Robust.Client
             var userId = _net.ServerChannel.UserId;
             _discord.Update(info.ServerName, userName, info.ServerMaxPlayers.ToString());
             // start up player management
-            _playMan.Startup(_net.ServerChannel!);
+            _playMan.Startup();
 
             _playMan.LocalPlayer!.UserId = userId;
             _playMan.LocalPlayer.Name = userName;
@@ -150,12 +170,18 @@ namespace Robust.Client
             DebugTools.Assert(RunLevel < ClientRunLevel.Connected);
             OnRunLevelChanged(ClientRunLevel.Connected);
 
+            GameStartedSetup();
+
+            PlayerJoinedServer?.Invoke(this, new PlayerEventArgs(session));
+        }
+
+        private void GameStartedSetup()
+        {
             _entityManager.Startup();
             _mapManager.Startup();
 
             _timing.ResetSimTime();
             _timing.Paused = false;
-            PlayerJoinedServer?.Invoke(this, new PlayerEventArgs(session));
         }
 
         /// <summary>
@@ -189,10 +215,15 @@ namespace Robust.Client
             PlayerLeaveServer?.Invoke(this, new PlayerEventArgs(_playMan.LocalPlayer?.Session));
 
             LastDisconnectReason = args.Reason;
+            GameStoppedReset();
+        }
 
+        private void GameStoppedReset()
+        {
             IoCManager.Resolve<INetConfigurationManager>().FlushMessages();
             _gameStates.Reset();
             _playMan.Shutdown();
+            IoCManager.Resolve<IEntityLookup>().Shutdown();
             _entityManager.Shutdown();
             _mapManager.Shutdown();
             _discord.ClearPresence();
@@ -249,6 +280,11 @@ namespace Robust.Client
         ///     The client is now in the game, moving around.
         /// </summary>
         InGame,
+
+        /// <summary>
+        ///     The client is now in singleplayer mode, in-game.
+        /// </summary>
+        SinglePlayerGame,
     }
 
     /// <summary>

Robust.Client/ClientIoC.cs

@@ -14,6 +14,7 @@ using Robust.Client.Prototypes;
 using Robust.Client.Reflection;
 using Robust.Client.ResourceManagement;
 using Robust.Client.State;
+using Robust.Client.Timing;
 using Robust.Client.UserInterface;
 using Robust.Client.Utility;
 using Robust.Client.ViewVariables;
@@ -27,8 +28,7 @@ using Robust.Shared.Network;
 using Robust.Shared.Players;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Reflection;
-using Robust.Shared.Serialization;
-using Robust.Shared.Serialization.Manager;
+using Robust.Shared.Timing;
 
 namespace Robust.Client
 {
@@ -38,8 +38,14 @@ namespace Robust.Client
         {
             SharedIoC.RegisterIoC();
 
+            IoCManager.Register<IGameTiming, ClientGameTiming>();
+            IoCManager.Register<IClientGameTiming, ClientGameTiming>();
             IoCManager.Register<IPrototypeManager, ClientPrototypeManager>();
+            IoCManager.Register<IMapManager, ClientMapManager>();
+            IoCManager.Register<IMapManagerInternal, ClientMapManager>();
+            IoCManager.Register<IClientMapManager, ClientMapManager>();
             IoCManager.Register<IEntityManager, ClientEntityManager>();
+            IoCManager.Register<IEntityLookup, SharedEntityLookup>();
             IoCManager.Register<IComponentFactory, ClientComponentFactory>();
             IoCManager.Register<ITileDefinitionManager, ClydeTileDefinitionManager>();
             IoCManager.Register<IClydeTileDefinitionManager, ClydeTileDefinitionManager>();
@@ -52,7 +58,8 @@ namespace Robust.Client
             IoCManager.Register<IResourceCacheInternal, ResourceCache>();
             IoCManager.Register<IClientNetManager, NetManager>();
             IoCManager.Register<IClientEntityManager, ClientEntityManager>();
-            IoCManager.Register<IEntityNetworkManager, ClientEntityNetworkManager>();
+            IoCManager.Register<IClientEntityManagerInternal, ClientEntityManager>();
+            IoCManager.Register<IEntityNetworkManager, ClientEntityManager>();
             IoCManager.Register<IClientGameStateManager, ClientGameStateManager>();
             IoCManager.Register<IBaseClient, BaseClient>();
             IoCManager.Register<IPlayerManager, PlayerManager>();
@@ -66,8 +73,6 @@ namespace Robust.Client
             IoCManager.Register<IDiscordRichPresence, DiscordRichPresence>();
             IoCManager.Register<IClientConsoleHost, ClientConsoleHost>();
             IoCManager.Register<IConsoleHost, ClientConsoleHost>();
-            IoCManager.Register<IFontManager, FontManager>();
-            IoCManager.Register<IFontManagerInternal, FontManager>();
             IoCManager.Register<IMidiManager, MidiManager>();
             IoCManager.Register<IAuthManager, AuthManager>();
             switch (mode)
@@ -94,8 +99,9 @@ namespace Robust.Client
                     throw new ArgumentOutOfRangeException();
             }
 
+            IoCManager.Register<IFontManager, FontManager>();
+            IoCManager.Register<IFontManagerInternal, FontManager>();
             IoCManager.Register<IEyeManager, EyeManager>();
-
             IoCManager.Register<IPlacementManager, PlacementManager>();
             IoCManager.Register<IOverlayManager, OverlayManager>();
             IoCManager.Register<IOverlayManagerInternal, OverlayManager>();

Robust.Client/Console/Commands/Debug.cs

@@ -280,12 +280,12 @@ namespace Robust.Client.Console.Commands
     internal class SnapGridGetCell : IConsoleCommand
     {
         public string Command => "sggcell";
-        public string Help => "sggcell <gridID> <vector2i> [offset]\nThat vector2i param is in the form x<int>,y<int>.";
+        public string Help => "sggcell <gridID> <vector2i>\nThat vector2i param is in the form x<int>,y<int>.";
         public string Description => "Lists entities on a snap grid cell.";
 
         public void Execute(IConsoleShell shell, string argStr, string[] args)
         {
-            if (args.Length != 2 && args.Length != 3)
+            if (args.Length != 2)
             {
                 shell.WriteLine(Help);
                 return;
@@ -293,7 +293,6 @@ namespace Robust.Client.Console.Commands
 
             string gridId = args[0];
             string indices = args[1];
-            string offset = args.Length == 3 ? args[2] : "Center";
 
             if (!int.TryParse(args[0], out var id))
             {
@@ -307,29 +306,17 @@ namespace Robust.Client.Console.Commands
                 return;
             }
 
-            SnapGridOffset selectedOffset;
-            if (Enum.IsDefined(typeof(SnapGridOffset), offset))
-            {
-                    selectedOffset = (SnapGridOffset)Enum.Parse(typeof(SnapGridOffset), offset);
-            }
-            else
-            {
-                shell.WriteError("given offset type is not defined");
-                return;
-            }
-
             var mapMan = IoCManager.Resolve<IMapManager>();
 
             if (mapMan.GridExists(new GridId(int.Parse(gridId, CultureInfo.InvariantCulture))))
             {
                 foreach (var entity in
-                    mapMan.GetGrid(new GridId(int.Parse(gridId, CultureInfo.InvariantCulture))).GetSnapGridCell(
+                    mapMan.GetGrid(new GridId(int.Parse(gridId, CultureInfo.InvariantCulture))).GetAnchoredEntities(
                         new Vector2i(
                             int.Parse(indices.Split(',')[0], CultureInfo.InvariantCulture),
-                            int.Parse(indices.Split(',')[1], CultureInfo.InvariantCulture)),
-                        selectedOffset))
+                            int.Parse(indices.Split(',')[1], CultureInfo.InvariantCulture))))
                 {
-                    shell.WriteLine(entity.Owner.Uid.ToString());
+                    shell.WriteLine(entity.ToString());
                 }
             }
             else

Robust.Client/Console/Commands/MonitorCommands.cs

@@ -0,0 +1,44 @@
+using System.Linq;
+using JetBrains.Annotations;
+using Robust.Client.Graphics;
+using Robust.Shared.Console;
+using Robust.Shared.IoC;
+
+namespace Robust.Client.Console.Commands
+{
+    [UsedImplicitly]
+    public sealed class LsMonitorCommand : IConsoleCommand
+    {
+        public string Command => "lsmonitor";
+        public string Description => "";
+        public string Help => "";
+
+        public void Execute(IConsoleShell shell, string argStr, string[] args)
+        {
+            var clyde = IoCManager.Resolve<IClyde>();
+
+            foreach (var monitor in clyde.EnumerateMonitors())
+            {
+                shell.WriteLine(
+                    $"[{monitor.Id}] {monitor.Name}: {monitor.Size.X}x{monitor.Size.Y}@{monitor.RefreshRate}Hz");
+            }
+        }
+    }
+
+    [UsedImplicitly]
+    public sealed class SetMonitorCommand : IConsoleCommand
+    {
+        public string Command => "setmonitor";
+        public string Description => "";
+        public string Help => "Usage: setmonitor <id>";
+
+        public void Execute(IConsoleShell shell, string argStr, string[] args)
+        {
+            var clyde = IoCManager.Resolve<IClyde>();
+
+            var id = int.Parse(args[0]);
+            var monitor = clyde.EnumerateMonitors().Single(m => m.Id == id);
+            clyde.SetWindowMonitor(monitor);
+        }
+    }
+}

Robust.Client/ContentStart.cs

@@ -5,10 +5,15 @@ namespace Robust.Client
         public static void Start(string[] args)
         {
 #if FULL_RELEASE
-            throw new System.InvalidOperationException("ContentStart is not available on a full release.");
+            throw new System.InvalidOperationException("ContentStart.Start is not available on a full release.");
 #else
             GameController.Start(args, true);
 #endif
         }
+
+        public static void StartLibrary(string[] args, GameControllerOptions options)
+        {
+            GameController.Start(args, true, null, options);
+        }
     }
 }

Robust.Client/Debugging/DebugDrawing.cs

@@ -1,15 +1,18 @@
-using System;
+using System;
 using System.Collections.Generic;
 using Robust.Client.Graphics;
 using Robust.Client.Input;
 using Robust.Client.ResourceManagement;
+using Robust.Shared.Enums;
 using Robust.Shared;
 using Robust.Shared.Configuration;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Broadphase;
+using Robust.Shared.Physics.Dynamics.Joints;
 using Robust.Shared.Prototypes;
 
 namespace Robust.Client.Debugging
@@ -18,11 +21,10 @@ namespace Robust.Client.Debugging
     public class DebugDrawing : IDebugDrawing
     {
         [Dependency] private readonly IOverlayManager _overlayManager = default!;
-        [Dependency] private readonly IComponentManager _componentManager = default!;
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
-        [Dependency] private readonly IPhysicsManager _physicsManager = default!;
         [Dependency] private readonly IEntityManager _entityManager = default!;
+        [Dependency] private readonly IMapManager _mapManager = default!;
         [Dependency] private readonly IInputManager _inputManager = default!;
 
         private bool _debugColliders;
@@ -41,14 +43,14 @@ namespace Robust.Client.Debugging
 
                 _debugColliders = value;
 
-                if (value)
+                if (value && !_overlayManager.HasOverlay<PhysicsOverlay>())
                 {
-                    _overlayManager.AddOverlay(new PhysicsOverlay(_componentManager, _eyeManager,
-                        _prototypeManager, _inputManager, _physicsManager));
+                    _overlayManager.AddOverlay(new PhysicsOverlay(_eyeManager,
+                        _prototypeManager, _inputManager, _mapManager));
                 }
                 else
                 {
-                    _overlayManager.RemoveOverlay(nameof(PhysicsOverlay));
+                    _overlayManager.RemoveOverlay<PhysicsOverlay>();
                 }
             }
         }
@@ -66,23 +68,22 @@ namespace Robust.Client.Debugging
 
                 _debugPositions = value;
 
-                if (value)
+                if (value && !_overlayManager.HasOverlay<EntityPositionOverlay>())
                 {
                     _overlayManager.AddOverlay(new EntityPositionOverlay(_entityManager, _eyeManager));
                 }
                 else
                 {
-                    _overlayManager.RemoveOverlay(nameof(EntityPositionOverlay));
+                    _overlayManager.RemoveOverlay<EntityPositionOverlay>();
                 }
             }
         }
 
         private class PhysicsOverlay : Overlay
         {
-            private readonly IComponentManager _componentManager;
             private readonly IEyeManager _eyeManager;
+            private readonly IMapManager _mapManager;
             private readonly IInputManager _inputManager;
-            private readonly IPhysicsManager _physicsManager;
 
             public override OverlaySpace Space => OverlaySpace.WorldSpace | OverlaySpace.ScreenSpace;
             private readonly ShaderInstance _shader;
@@ -91,13 +92,12 @@ namespace Robust.Client.Debugging
             private Vector2 _hoverStartScreen = Vector2.Zero;
             private List<IPhysBody> _hoverBodies = new();
 
-            public PhysicsOverlay(IComponentManager compMan, IEyeManager eyeMan, IPrototypeManager protoMan, IInputManager inputManager, IPhysicsManager physicsManager)
-                : base(nameof(PhysicsOverlay))
+
+            public PhysicsOverlay(IEyeManager eyeMan, IPrototypeManager protoMan, IInputManager inputManager, IMapManager mapManager)
             {
-                _componentManager = compMan;
                 _eyeManager = eyeMan;
                 _inputManager = inputManager;
-                _physicsManager = physicsManager;
+                _mapManager = mapManager;
 
                 _shader = protoMan.Index<ShaderPrototype>("unshaded").Instance();
                 var cache = IoCManager.Resolve<IResourceCache>();
@@ -105,22 +105,23 @@ namespace Robust.Client.Debugging
             }
 
             /// <inheritdoc />
-            protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+            protected internal override void Draw(in OverlayDrawArgs args)
             {
-                switch (currentSpace)
+                switch (args.Space)
                 {
                     case OverlaySpace.ScreenSpace:
-                        DrawScreen((DrawingHandleScreen) handle);
+                        DrawScreen(args);
                         break;
                     case OverlaySpace.WorldSpace:
-                        DrawWorld((DrawingHandleWorld) handle);
+                        DrawWorld(args);
                         break;
                 }
 
             }
 
-            private void DrawScreen(DrawingHandleScreen screenHandle)
+            private void DrawScreen(in OverlayDrawArgs args)
             {
+                var screenHandle = args.ScreenHandle;
                 var lineHeight = _font.GetLineHeight(1f);
                 Vector2 drawPos = _hoverStartScreen + new Vector2(20, 0) + new Vector2(0, -(_hoverBodies.Count * 4 * lineHeight / 2f));
                 int row = 0;
@@ -133,7 +134,7 @@ namespace Robust.Client.Debugging
                         row++;
                     }
 
-                    DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Ent: {body.Entity}");
+                    DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Ent: {body.Owner}");
                     row++;
                     DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Layer: {Convert.ToString(body.CollisionLayer, 2)}");
                     row++;
@@ -145,8 +146,9 @@ namespace Robust.Client.Debugging
 
             }
 
-            private void DrawWorld(DrawingHandleWorld worldHandle)
+            private void DrawWorld(in OverlayDrawArgs args)
             {
+                var worldHandle = args.WorldHandle;
                 worldHandle.UseShader(_shader);
                 var drawing = new PhysDrawingAdapter(worldHandle);
 
@@ -160,23 +162,31 @@ namespace Robust.Client.Debugging
                 if (viewport.IsEmpty()) return;
 
                 var mapId = _eyeManager.CurrentMap;
+                var sleepThreshold = IoCManager.Resolve<IConfigurationManager>().GetCVar(CVars.TimeToSleep);
+                var colorEdge = Color.Red.WithAlpha(0.33f);
+                var drawnJoints = new HashSet<Joint>();
 
                 foreach (var physBody in EntitySystem.Get<SharedBroadPhaseSystem>().GetCollidingEntities(mapId, viewport))
                 {
                     // all entities have a TransformComponent
-                    var transform = physBody.Entity.Transform;
+                    var transform = physBody.Owner.Transform;
 
-                    var worldBox = physBody.GetWorldAABB();
+                    var worldBox = physBody.GetWorldAABB(_mapManager);
                     if (worldBox.IsEmpty()) continue;
 
-                    var colorEdge = Color.Red.WithAlpha(0.33f);
-                    var sleepThreshold = IoCManager.Resolve<IConfigurationManager>().GetCVar(CVars.TimeToSleep);
-
                     foreach (var fixture in physBody.Fixtures)
                     {
                         var shape = fixture.Shape;
                         var sleepPercent = physBody.Awake ? physBody.SleepTime / sleepThreshold : 1.0f;
-                        shape.DebugDraw(drawing, transform.WorldMatrix, in viewport,  sleepPercent);
+                        shape.DebugDraw(drawing, transform.WorldMatrix, in viewport, sleepPercent);
+                    }
+
+                    foreach (var joint in physBody.Joints)
+                    {
+                        if (drawnJoints.Contains(joint)) continue;
+                        drawnJoints.Add(joint);
+
+                        joint.DebugDraw(drawing, in viewport);
                     }
 
                     if (worldBox.Contains(mouseWorldPos))
@@ -193,9 +203,9 @@ namespace Robust.Client.Debugging
             {
                 var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
 
-                foreach (var chr in str)
+                foreach (var rune in str.EnumerateRunes())
                 {
-                    var advance = font.DrawChar(handle, chr, baseLine, 1, Color.White);
+                    var advance = font.DrawChar(handle, rune, baseLine, 1, Color.White);
                     baseLine += new Vector2(advance, 0);
                 }
             }
@@ -265,17 +275,17 @@ namespace Robust.Client.Debugging
 
             public override OverlaySpace Space => OverlaySpace.WorldSpace;
 
-            public EntityPositionOverlay(IEntityManager entityManager, IEyeManager eyeManager) : base(nameof(EntityPositionOverlay))
+            public EntityPositionOverlay(IEntityManager entityManager, IEyeManager eyeManager)
             {
                 _entityManager = entityManager;
                 _eyeManager = eyeManager;
             }
 
-            protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+            protected internal override void Draw(in OverlayDrawArgs args)
             {
                 const float stubLength = 0.25f;
 
-                var worldHandle = (DrawingHandleWorld) handle;
+                var worldHandle = (DrawingHandleWorld) args.DrawingHandle;
                 foreach (var entity in _entityManager.GetEntities())
                 {
                     var transform = entity.Transform;

Robust.Client/Debugging/DebugDrawingManager.cs

@@ -1,10 +1,11 @@
-using Robust.Shared.IoC;
+using Robust.Shared.IoC;
 using Robust.Shared.Network.Messages;
 using System;
 using System.Collections.Generic;
 using Robust.Client.Graphics;
 using Robust.Shared.Maths;
 using Robust.Shared.Timing;
+using Robust.Shared.Enums;
 using Robust.Shared.Network;
 
 namespace Robust.Client.Debugging
@@ -38,13 +39,13 @@ namespace Robust.Client.Debugging
 
                 _debugDrawRays = value;
 
-                if (value)
+                if (value && !_overlayManager.HasOverlay<DebugDrawRayOverlay>())
                 {
                     _overlayManager.AddOverlay(new DebugDrawRayOverlay(this));
                 }
                 else
                 {
-                    _overlayManager.RemoveOverlay(nameof(DebugDrawRayOverlay));
+                    _overlayManager.RemoveOverlay<DebugDrawRayOverlay>();
                 }
             }
         }
@@ -81,13 +82,14 @@ namespace Robust.Client.Debugging
             private readonly DebugDrawingManager _owner;
             public override OverlaySpace Space => OverlaySpace.WorldSpace;
 
-            public DebugDrawRayOverlay(DebugDrawingManager owner) : base(nameof(DebugDrawRayOverlay))
+            public DebugDrawRayOverlay(DebugDrawingManager owner)
             {
                 _owner = owner;
             }
 
-            protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+            protected internal override void Draw(in OverlayDrawArgs args)
             {
+                var handle = args.WorldHandle;
                 foreach (var ray in _owner.raysWithLifeTime)
                 {
                     handle.DrawLine(

Robust.Client/Debugging/DebugPhysicsSystem.cs

@@ -24,6 +24,7 @@
 
 using System;
 using Robust.Client.Graphics;
+using Robust.Shared.Enums;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
@@ -55,7 +56,7 @@ namespace Robust.Client.Debugging
                     IoCManager.Resolve<IOverlayManager>().AddOverlay(new PhysicsDebugOverlay(this));
 
                 if (value == PhysicsDebugFlags.None)
-                    IoCManager.Resolve<IOverlayManager>().RemoveOverlay(nameof(PhysicsDebugOverlay));
+                    IoCManager.Resolve<IOverlayManager>().RemoveOverlay(typeof(PhysicsDebugOverlay));
 
                 _flags = value;
             }
@@ -119,16 +120,16 @@ namespace Robust.Client.Debugging
 
         public override OverlaySpace Space => OverlaySpace.WorldSpace;
 
-        public PhysicsDebugOverlay(DebugPhysicsSystem system) : base(nameof(PhysicsDebugOverlay))
+        public PhysicsDebugOverlay(DebugPhysicsSystem system)
         {
             _physics = system;
         }
 
-        protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+        protected internal override void Draw(in OverlayDrawArgs args)
         {
             if (_physics.Flags == PhysicsDebugFlags.None) return;
 
-            var worldHandle = (DrawingHandleWorld) handle;
+            var worldHandle = args.WorldHandle;
 
             if ((_physics.Flags & PhysicsDebugFlags.Shapes) != 0)
             {

Robust.Client/GameController.cs

@@ -1,5 +1,6 @@
-using System;
+using System;
 using System.IO;
+using System.Management;
 using System.Net;
 using System.Threading.Tasks;
 using Robust.Client.Audio.Midi;
@@ -48,6 +49,7 @@ 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!;
@@ -59,17 +61,18 @@ namespace Robust.Client
         [Dependency] private readonly IFontManagerInternal _fontManager = default!;
         [Dependency] private readonly IModLoaderInternal _modLoader = default!;
         [Dependency] private readonly IScriptClient _scriptClient = default!;
-        [Dependency] private readonly IComponentManager _componentManager = default!;
-        [Dependency] private readonly IPlayerManager _playerManager = default!;
         [Dependency] private readonly IRobustMappedStringSerializer _stringSerializer = default!;
         [Dependency] private readonly IAuthManager _authManager = default!;
         [Dependency] private readonly IMidiManager _midiManager = default!;
+        [Dependency] private readonly IEyeManager _eyeManager = default!;
 
         private CommandLineArgs? _commandLineArgs;
-        private bool _disableAssemblyLoadContext;
+
         // Arguments for loader-load. Not used otherwise.
         private IMainArgs? _loaderArgs;
 
+        public bool ContentStart { get; set; } = false;
+        public GameControllerOptions Options { get; private set; } = new();
         public InitialLaunchState LaunchState { get; private set; } = default!;
 
         public bool LoadConfigAndUserData { get; set; } = true;
@@ -80,6 +83,77 @@ namespace Robust.Client
         }
 
         public bool Startup(Func<ILogHandler>? logHandlerFactory = null)
+        {
+            if (!StartupSystemSplash(logHandlerFactory))
+                return false;
+
+            // Disable load context usage on content start.
+            // This prevents Content.Client being loaded twice and things like csi blowing up because of it.
+            _modLoader.SetUseLoadContext(!ContentStart);
+            _modLoader.SetEnableSandboxing(Options.Sandboxing);
+
+            if (!_modLoader.TryLoadModulesFrom(new ResourcePath("/Assemblies/"), Options.ContentModulePrefix))
+            {
+                Logger.Fatal("Errors while loading content assemblies.");
+                return false;
+            }
+
+            foreach (var loadedModule in _modLoader.LoadedModules)
+            {
+                _configurationManager.LoadCVarsFromAssembly(loadedModule);
+            }
+
+            IoCManager.Resolve<ISerializationManager>().Initialize();
+
+            // Call Init in game assemblies.
+            _modLoader.BroadcastRunLevel(ModRunLevel.PreInit);
+            _modLoader.BroadcastRunLevel(ModRunLevel.Init);
+
+            _resourceCache.PreloadTextures();
+            _userInterfaceManager.Initialize();
+            _eyeManager.Initialize();
+            _networkManager.Initialize(false);
+            IoCManager.Resolve<INetConfigurationManager>().SetupNetworking();
+            _serializer.Initialize();
+            _inputManager.Initialize();
+            _console.Initialize();
+            _prototypeManager.Initialize();
+            _prototypeManager.LoadDirectory(Options.PrototypeDirectory);
+            _prototypeManager.Resync();
+            _mapManager.Initialize();
+            _entityManager.Initialize();
+            IoCManager.Resolve<IEntityLookup>().Initialize();
+            _gameStateManager.Initialize();
+            _placementManager.Initialize();
+            _viewVariablesManager.Initialize();
+            _scriptClient.Initialize();
+
+            _client.Initialize();
+            _discord.Initialize();
+            _modLoader.BroadcastRunLevel(ModRunLevel.PostInit);
+
+            if (_commandLineArgs?.Username != null)
+            {
+                _client.PlayerNameOverride = _commandLineArgs.Username;
+            }
+
+            _authManager.LoadFromEnv();
+
+            GC.Collect();
+
+            _clyde.Ready();
+
+            if (!Options.DisableCommandLineConnect &&
+                (_commandLineArgs?.Connect == true || _commandLineArgs?.Launcher == true)
+                && LaunchState.ConnectEndpoint != null)
+            {
+                _client.ConnectToServer(LaunchState.ConnectEndpoint);
+            }
+
+            return true;
+        }
+
+        private bool StartupSystemSplash(Func<ILogHandler>? logHandlerFactory)
         {
             ReadInitialLaunchState();
 
@@ -99,7 +173,7 @@ namespace Robust.Client
 
             if (LoadConfigAndUserData)
             {
-                var configFile = Path.Combine(userDataDir, "client_config.toml");
+                var configFile = Path.Combine(userDataDir, Options.ConfigFileName);
                 if (File.Exists(configFile))
                 {
                     // Load config from user data if available.
@@ -119,9 +193,16 @@ namespace Robust.Client
                 _configurationManager.OverrideConVars(_commandLineArgs.CVars);
             }
 
+            ProfileOptSetup.Setup(_configurationManager);
+
             _resourceCache.Initialize(LoadConfigAndUserData ? userDataDir : null);
 
-            ProgramShared.DoMounts(_resourceCache, _commandLineArgs?.MountOptions, "Content.Client", _loaderArgs != null);
+            var mountOptions = _commandLineArgs != null
+                ? MountOptions.Merge(_commandLineArgs.MountOptions, Options.MountOptions) : Options.MountOptions;
+
+            ProgramShared.DoMounts(_resourceCache, mountOptions, Options.ContentBuildDirectory,
+                _loaderArgs != null && !Options.ResourceMountDisabled, ContentStart);
+
             if (_loaderArgs != null)
             {
                 _stringSerializer.EnableCaching = false;
@@ -129,73 +210,22 @@ namespace Robust.Client
                 _modLoader.VerifierExtraLoadHandler = VerifierExtraLoadHandler;
             }
 
+            _clyde.TextEntered += TextEntered;
+            _clyde.MouseMove += MouseMove;
+            _clyde.KeyUp += KeyUp;
+            _clyde.KeyDown += KeyDown;
+            _clyde.MouseWheel += MouseWheel;
+            _clyde.CloseWindow += Shutdown;
+
             // Bring display up as soon as resources are mounted.
             if (!_clyde.Initialize())
             {
                 return false;
             }
 
-            _clyde.SetWindowTitle("Space Station 14");
-
-            _fontManager.Initialize();
-
-            // Disable load context usage on content start.
-            // This prevents Content.Client being loaded twice and things like csi blowing up because of it.
-            _modLoader.SetUseLoadContext(!_disableAssemblyLoadContext);
-            _modLoader.SetEnableSandboxing(true);
-
-            if (!_modLoader.TryLoadModulesFrom(new ResourcePath("/Assemblies/"), "Content."))
-            {
-                Logger.Fatal("Errors while loading content assemblies.");
-                return false;
-            }
-
-            foreach (var loadedModule in _modLoader.LoadedModules)
-            {
-                _configurationManager.LoadCVarsFromAssembly(loadedModule);
-            }
-
-            IoCManager.Resolve<ISerializationManager>().Initialize();
-
-            // Call Init in game assemblies.
-            _modLoader.BroadcastRunLevel(ModRunLevel.PreInit);
-            _modLoader.BroadcastRunLevel(ModRunLevel.Init);
-
-            _userInterfaceManager.Initialize();
-            _networkManager.Initialize(false);
-            IoCManager.Resolve<INetConfigurationManager>().SetupNetworking();
-            _serializer.Initialize();
-            _inputManager.Initialize();
-            _console.Initialize();
-            _prototypeManager.Initialize();
-            _prototypeManager.LoadDirectory(new ResourcePath(@"/Prototypes/"));
-            _prototypeManager.Resync();
-            _mapManager.Initialize();
-            _entityManager.Initialize();
-            _gameStateManager.Initialize();
-            _placementManager.Initialize();
-            _viewVariablesManager.Initialize();
-            _scriptClient.Initialize();
-
-            _client.Initialize();
-            _discord.Initialize();
-            _modLoader.BroadcastRunLevel(ModRunLevel.PostInit);
-
-            if (_commandLineArgs?.Username != null)
-            {
-                _client.PlayerNameOverride = _commandLineArgs.Username;
-            }
-
-            _authManager.LoadFromEnv();
-
-            _clyde.Ready();
-
-            if ((_commandLineArgs?.Connect == true || _commandLineArgs?.Launcher == true)
-                && LaunchState.ConnectEndpoint != null)
-            {
-                _client.ConnectToServer(LaunchState.ConnectEndpoint);
-            }
+            _clyde.SetWindowTitle(Options.DefaultWindowTitle);
 
+            _fontManager.SetFontDpi((uint) _configurationManager.GetCVar(CVars.DisplayFontDpi));
             return true;
         }
 
@@ -272,17 +302,20 @@ namespace Robust.Client
             _modLoader.BroadcastUpdate(ModUpdateLevel.PreEngine, frameEventArgs);
             _timerManager.UpdateTimers(frameEventArgs);
             _taskManager.ProcessPendingTasks();
-            _userInterfaceManager.Update(frameEventArgs);
 
-            if (_client.RunLevel >= ClientRunLevel.Connected)
+            // GameStateManager is in full control of the simulation update in multiplayer.
+            if (_client.RunLevel == ClientRunLevel.InGame || _client.RunLevel == ClientRunLevel.Connected)
             {
-                _componentManager.CullRemovedComponents();
                 _gameStateManager.ApplyGameState();
-                _entityManager.Update(frameEventArgs.DeltaSeconds);
-                _playerManager.Update(frameEventArgs.DeltaSeconds);
             }
 
-            _stateManager.Update(frameEventArgs);
+            // In singleplayer, however, we're in full control instead.
+            else if (_client.RunLevel == ClientRunLevel.SinglePlayerGame)
+            {
+                _entityManager.TickUpdate(frameEventArgs.DeltaSeconds);
+                _lookup.Update();
+            }
+
             _modLoader.BroadcastUpdate(ModUpdateLevel.PostEngine, frameEventArgs);
         }
 
@@ -303,11 +336,6 @@ namespace Robust.Client
             _modLoader.BroadcastUpdate(ModUpdateLevel.FramePostEngine, frameEventArgs);
         }
 
-        private void Render()
-        {
-
-        }
-
         internal static void SetupLogging(ILogManager logManager, Func<ILogHandler> logHandlerFactory)
         {
             logManager.RootSawmill.AddHandler(logHandlerFactory());
@@ -384,6 +412,7 @@ namespace Robust.Client
         {
             _networkManager.Shutdown("Client shutting down");
             _midiManager.Shutdown();
+            IoCManager.Resolve<IEntityLookup>().Shutdown();
             _entityManager.Shutdown();
             _clyde.Shutdown();
         }

Robust.Client/GameController/GameController.Standalone.cs

@@ -19,7 +19,7 @@ namespace Robust.Client
             Start(args);
         }
 
-        public static void Start(string[] args, bool contentStart = false, IMainArgs? loaderArgs=null)
+        public static void Start(string[] args, bool contentStart = false, IMainArgs? loaderArgs=null, GameControllerOptions? options = null)
         {
             if (_hasStarted)
             {
@@ -30,11 +30,11 @@ namespace Robust.Client
 
             if (CommandLineArgs.TryParse(args, out var parsed))
             {
-                ParsedMain(parsed, contentStart, loaderArgs);
+                ParsedMain(parsed, contentStart, loaderArgs, options);
             }
         }
 
-        private static void ParsedMain(CommandLineArgs args, bool contentStart, IMainArgs? loaderArgs)
+        private static void ParsedMain(CommandLineArgs args, bool contentStart, IMainArgs? loaderArgs, GameControllerOptions? options)
         {
             IoCManager.InitThread();
 
@@ -45,11 +45,13 @@ namespace Robust.Client
             var gc = (GameController) IoCManager.Resolve<IGameController>();
             gc.SetCommandLineArgs(args);
             gc._loaderArgs = loaderArgs;
+            if(options != null)
+                gc.Options = options;
 
             // When the game is ran with the startup executable being content,
             // we have to disable the separate load context.
             // Otherwise the content assemblies will be loaded twice which causes *many* fun bugs.
-            gc._disableAssemblyLoadContext = contentStart;
+            gc.ContentStart = contentStart;
             if (!gc.Startup())
             {
                 Logger.Fatal("Failed to start game controller!");

Robust.Client/GameControllerOptions.cs

@@ -0,0 +1,60 @@
+using Robust.Shared;
+using Robust.Shared.Utility;
+
+namespace Robust.Client
+{
+    public class GameControllerOptions
+    {
+        /// <summary>
+        ///     Whether content sandboxing will be enabled & enforced.
+        /// </summary>
+        public bool Sandboxing { get; init; } = true;
+
+        // TODO: Expose mounting methods to games using Robust as a library.
+        /// <summary>
+        ///     Lists of mount options to mount.
+        /// </summary>
+        public MountOptions MountOptions { get; init; } = new();
+
+        /// <summary>
+        ///     Name the userdata directory will have.
+        /// </summary>
+        public string UserDataDirectoryName { get; init; } = "Space Station 14";
+
+        /// <summary>
+        ///     Name of the configuration file in the user data directory.
+        /// </summary>
+        public string ConfigFileName { get; init; } = "client_config.toml";
+
+        // TODO: Define engine branding from json file in resources.
+        /// <summary>
+        ///     Default window title.
+        /// </summary>
+        public string DefaultWindowTitle { get; init; } = "Space Station 14";
+
+        /// <summary>
+        ///     Assemblies with this prefix will be loaded.
+        /// </summary>
+        public string ContentModulePrefix { get; init; } = "Content.";
+
+        /// <summary>
+        ///     Name of the content build directory, for game pack mounting purposes.
+        /// </summary>
+        public string ContentBuildDirectory { get; init; } = "Content.Client";
+
+        /// <summary>
+        ///     Directory to load all prototypes from.
+        /// </summary>
+        public ResourcePath PrototypeDirectory { get; init; } = new(@"/Prototypes/");
+
+        /// <summary>
+        ///     Whether to disable mounting the "Resources/" folder on FULL_RELEASE.
+        /// </summary>
+        public bool ResourceMountDisabled { get; init; } = false;
+
+        /// <summary>
+        ///     Whether to disable command line args server auto-connecting.
+        /// </summary>
+        public bool DisableCommandLineConnect { get; init; } = false;
+    }
+}

Robust.Client/GameObjects/ClientEntityManager.cs

@@ -1,11 +1,17 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using JetBrains.Annotations;
+using Prometheus;
+using Robust.Client.GameStates;
 using Robust.Shared.Exceptions;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
+using Robust.Shared.Network;
+using Robust.Shared.Network.Messages;
+using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 
 namespace Robust.Client.GameObjects
@@ -13,303 +19,152 @@ namespace Robust.Client.GameObjects
     /// <summary>
     /// Manager for entities -- controls things like template loading and instantiation
     /// </summary>
-    public sealed class ClientEntityManager : EntityManager, IClientEntityManager
+    public sealed class ClientEntityManager : EntityManager, IClientEntityManagerInternal
     {
-        [Dependency] private readonly IMapManager _mapManager = default!;
-        [Dependency] private readonly IComponentFactory _compFactory = default!;
-#if EXCEPTION_TOLERANCE
-        [Dependency] private readonly IRuntimeLog _runtimeLog = default!;
-#endif
+        [Dependency] private readonly IClientNetManager _networkManager = default!;
+        [Dependency] private readonly IClientGameStateManager _gameStateManager = default!;
+        [Dependency] private readonly IGameTiming _gameTiming = default!;
 
-        private int _nextClientEntityUid = EntityUid.ClientUid + 1;
+        protected override int NextEntityUid { get; set; } = EntityUid.ClientUid + 1;
 
-        public override void Startup()
+        public override void Initialize()
         {
-            base.Startup();
+            SetupNetworking();
+            ReceivedComponentMessage += (_, compMsg) => DispatchComponentMessage(compMsg);
+            ReceivedSystemMessage += (_, systemMsg) => EventBus.RaiseEvent(EventSource.Network, systemMsg);
 
-            if (Started)
-            {
-                throw new InvalidOperationException("Startup() called multiple times");
-            }
-
-            EntitySystemManager.Initialize();
-            Started = true;
+            base.Initialize();
         }
 
-        public List<EntityUid> ApplyEntityStates(EntityState[]? curEntStates, IEnumerable<EntityUid>? deletions,
-            EntityState[]? nextEntStates)
+        IEntity IClientEntityManagerInternal.CreateEntity(string? prototypeName, EntityUid? uid)
         {
-            var toApply = new Dictionary<IEntity, (EntityState?, EntityState?)>();
-            var toInitialize = new List<Entity>();
-            var created = new List<EntityUid>();
-            deletions ??= new EntityUid[0];
+            return base.CreateEntity(prototypeName, uid);
+        }
 
-            if (curEntStates != null && curEntStates.Length != 0)
+        void IClientEntityManagerInternal.InitializeEntity(IEntity entity)
+        {
+            EntityManager.InitializeEntity((Entity)entity);
+        }
+
+        void IClientEntityManagerInternal.StartEntity(IEntity entity)
+        {
+            base.StartEntity((Entity)entity);
+        }
+
+        #region IEntityNetworkManager impl
+
+        public override IEntityNetworkManager EntityNetManager => this;
+
+        /// <inheritdoc />
+        public event EventHandler<NetworkComponentMessage>? ReceivedComponentMessage;
+
+        /// <inheritdoc />
+        public event EventHandler<object>? ReceivedSystemMessage;
+
+        private readonly PriorityQueue<(uint seq, MsgEntity msg)> _queue = new(new MessageTickComparer());
+        private uint _incomingMsgSequence = 0;
+
+        /// <inheritdoc />
+        public void SetupNetworking()
+        {
+            _networkManager.RegisterNetMessage<MsgEntity>(MsgEntity.NAME, HandleEntityNetworkMessage);
+        }
+
+        public override void TickUpdate(float frameTime, Histogram? histogram)
+        {
+            using (histogram?.WithLabels("EntityNet").NewTimer())
             {
-                foreach (var es in curEntStates)
+                while (_queue.Count != 0 && _queue.Peek().msg.SourceTick <= _gameStateManager.CurServerTick)
                 {
-                    //Known entities
-                    if (Entities.TryGetValue(es.Uid, out var entity))
-                    {
-                        toApply.Add(entity, (es, null));
-                    }
-                    else //Unknown entities
-                    {
-                        var metaState = (MetaDataComponentState?) es.ComponentStates
-                            ?.FirstOrDefault(c => c.NetID == NetIDs.META_DATA);
-                        if (metaState == null)
-                        {
-                            throw new InvalidOperationException($"Server sent new entity state for {es.Uid} without metadata component!");
-                        }
-                        var newEntity = CreateEntity(metaState.PrototypeId, es.Uid);
-                        toApply.Add(newEntity, (es, null));
-                        toInitialize.Add(newEntity);
-                        created.Add(newEntity.Uid);
-                    }
+                    var (_, msg) = _queue.Take();
+                    // Logger.DebugS("net.ent", "Dispatching: {0}: {1}", seq, msg);
+                    DispatchMsgEntity(msg);
                 }
             }
 
-            if (nextEntStates != null && nextEntStates.Length != 0)
-            {
-                foreach (var es in nextEntStates)
-                {
-                    if (Entities.TryGetValue(es.Uid, out var entity))
-                    {
-                        if (toApply.TryGetValue(entity, out var state))
-                        {
-                            toApply[entity] = (state.Item1, es);
-                        }
-                        else
-                        {
-                            toApply[entity] = (null, es);
-                        }
-                    }
-                }
-            }
-
-            // Make sure this is done after all entities have been instantiated.
-            foreach (var kvStates in toApply)
-            {
-                var ent = kvStates.Key;
-                var entity = (Entity) ent;
-                HandleEntityState(entity.EntityManager.ComponentManager, entity, kvStates.Value.Item1,
-                    kvStates.Value.Item2);
-            }
-
-            foreach (var kvp in toApply)
-            {
-                UpdateEntityTree(kvp.Key);
-            }
-
-            foreach (var id in deletions)
-            {
-                DeleteEntity(id);
-            }
-
-#if EXCEPTION_TOLERANCE
-            HashSet<Entity> brokenEnts = new HashSet<Entity>();
-#endif
-
-            foreach (var entity in toInitialize)
-            {
-#if EXCEPTION_TOLERANCE
-                try
-                {
-#endif
-                    InitializeEntity(entity);
-#if EXCEPTION_TOLERANCE
-                }
-                catch (Exception e)
-                {
-                    Logger.ErrorS("state", $"Server entity threw in Init: uid={entity.Uid}, proto={entity.Prototype}\n{e}");
-                    brokenEnts.Add(entity);
-                }
-#endif
-            }
-
-            foreach (var entity in toInitialize)
-            {
-#if EXCEPTION_TOLERANCE
-                if(brokenEnts.Contains(entity))
-                    continue;
-
-                try
-                {
-#endif
-                    StartEntity(entity);
-#if EXCEPTION_TOLERANCE
-                }
-                catch (Exception e)
-                {
-                    Logger.ErrorS("state", $"Server entity threw in Start: uid={entity.Uid}, proto={entity.Prototype}\n{e}");
-                    brokenEnts.Add(entity);
-                }
-#endif
-            }
-
-            foreach (var entity in toInitialize)
-            {
-#if EXCEPTION_TOLERANCE
-                if(brokenEnts.Contains(entity))
-                    continue;
-#endif
-                UpdateEntityTree(entity);
-            }
-#if EXCEPTION_TOLERANCE
-            foreach (var entity in brokenEnts)
-            {
-                entity.Delete();
-            }
-#endif
-
-            return created;
+            base.TickUpdate(frameTime, histogram);
         }
 
         /// <inheritdoc />
-        public override IEntity CreateEntityUninitialized(string? prototypeName)
+        public void SendSystemNetworkMessage(EntityEventArgs message)
         {
-            return CreateEntity(prototypeName);
+            SendSystemNetworkMessage(message, default(uint));
+        }
+
+        public void SendSystemNetworkMessage(EntityEventArgs message, uint sequence)
+        {
+            var msg = _networkManager.CreateNetMessage<MsgEntity>();
+            msg.Type = EntityMessageType.SystemMessage;
+            msg.SystemMessage = message;
+            msg.SourceTick = _gameTiming.CurTick;
+            msg.Sequence = sequence;
+
+            _networkManager.ClientSendMessage(msg);
         }
 
         /// <inheritdoc />
-        public override IEntity CreateEntityUninitialized(string? prototypeName, EntityCoordinates coordinates)
+        public void SendSystemNetworkMessage(EntityEventArgs message, INetChannel channel)
         {
-            var newEntity = CreateEntity(prototypeName, GenerateEntityUid());
-
-            if (TryGetEntity(coordinates.EntityId, out var entity))
-            {
-                newEntity.Transform.AttachParent(entity);
-                newEntity.Transform.Coordinates = coordinates;
-            }
-
-            return newEntity;
+            throw new NotSupportedException();
         }
 
         /// <inheritdoc />
-        public override IEntity CreateEntityUninitialized(string? prototypeName, MapCoordinates coordinates)
+        public void SendComponentNetworkMessage(INetChannel? channel, IEntity entity, IComponent component, ComponentMessage message)
         {
-            var newEntity = CreateEntity(prototypeName, GenerateEntityUid());
-            newEntity.Transform.AttachParent(_mapManager.GetMapEntity(coordinates.MapId));
-            newEntity.Transform.WorldPosition = coordinates.Position;
-            return newEntity;
+            if (!component.NetID.HasValue)
+                throw new ArgumentException($"Component {component.Name} does not have a NetID.", nameof(component));
+
+            var msg = _networkManager.CreateNetMessage<MsgEntity>();
+            msg.Type = EntityMessageType.ComponentMessage;
+            msg.EntityUid = entity.Uid;
+            msg.NetId = component.NetID.Value;
+            msg.ComponentMessage = message;
+            msg.SourceTick = _gameTiming.CurTick;
+
+            _networkManager.ClientSendMessage(msg);
         }
 
-        /// <inheritdoc />
-        public override IEntity SpawnEntity(string? protoName, EntityCoordinates coordinates)
+        private void HandleEntityNetworkMessage(MsgEntity message)
         {
-            var newEnt = CreateEntityUninitialized(protoName, coordinates);
-            InitializeAndStartEntity((Entity) newEnt);
-            UpdateEntityTree(newEnt);
-            return newEnt;
-        }
-
-        /// <inheritdoc />
-        public override IEntity SpawnEntity(string? protoName, MapCoordinates coordinates)
-        {
-            var entity = CreateEntityUninitialized(protoName, coordinates);
-            InitializeAndStartEntity((Entity) entity);
-            UpdateEntityTree(entity);
-            return entity;
-        }
-
-        /// <inheritdoc />
-        public override IEntity SpawnEntityNoMapInit(string? protoName, EntityCoordinates coordinates)
-        {
-            return SpawnEntity(protoName, coordinates);
-        }
-
-        protected override EntityUid GenerateEntityUid()
-        {
-            return new(_nextClientEntityUid++);
-        }
-
-        private void HandleEntityState(IComponentManager compMan, IEntity entity, EntityState? curState,
-            EntityState? nextState)
-        {
-            var compStateWork = new Dictionary<uint, (ComponentState? curState, ComponentState? nextState)>();
-            var entityUid = entity.Uid;
-
-            if (curState?.ComponentChanges != null)
+            if (message.SourceTick <= _gameStateManager.CurServerTick)
             {
-                foreach (var compChange in curState.ComponentChanges)
-                {
-                    if (compChange.Deleted)
-                    {
-                        if (compMan.TryGetComponent(entityUid, compChange.NetID, out var comp))
-                        {
-                            compMan.RemoveComponent(entityUid, comp);
-                        }
-                    }
-                    else
-                    {
-                        if (compMan.HasComponent(entityUid, compChange.NetID))
-                            continue;
-
-                        var newComp = (Component) _compFactory.GetComponent(compChange.ComponentName!);
-                        newComp.Owner = entity;
-                        compMan.AddComponent(entity, newComp, true);
-                    }
-                }
+                DispatchMsgEntity(message);
+                return;
             }
 
-            if (curState?.ComponentStates != null)
-            {
-                foreach (var compState in curState.ComponentStates)
-                {
-                    compStateWork[compState.NetID] = (compState, null);
-                }
-            }
+            // MsgEntity is sent with ReliableOrdered so Lidgren guarantees ordering of incoming messages.
+            // We still need to store a sequence input number to ensure ordering remains consistent in
+            // the priority queue.
+            _queue.Add((++_incomingMsgSequence, message));
+        }
 
-            if (nextState?.ComponentStates != null)
+        private void DispatchMsgEntity(MsgEntity message)
+        {
+            switch (message.Type)
             {
-                foreach (var compState in nextState.ComponentStates)
-                {
-                    if (compStateWork.TryGetValue(compState.NetID, out var state))
-                    {
-                        compStateWork[compState.NetID] = (state.curState, compState);
-                    }
-                    else
-                    {
-                        compStateWork[compState.NetID] = (null, compState);
-                    }
-                }
-            }
+                case EntityMessageType.ComponentMessage:
+                    ReceivedComponentMessage?.Invoke(this, new NetworkComponentMessage(message));
+                    return;
 
-            foreach (var (netId, (cur, next)) in compStateWork)
-            {
-                if (compMan.TryGetComponent(entityUid, netId, out var component))
-                {
-                    try
-                    {
-                        component.HandleComponentState(cur, next);
-                    }
-                    catch (Exception e)
-                    {
-                        var wrapper = new ComponentStateApplyException(
-                            $"Failed to apply comp state: entity={component.Owner}, comp={component.Name}", e);
-#if EXCEPTION_TOLERANCE
-                    _runtimeLog.LogException(wrapper, "Component state apply");
-#else
-                        throw wrapper;
-#endif
-                    }
-                }
-                else
-                {
-                    // The component can be null here due to interp.
-                    // Because the NEXT state will have a new component, but this one doesn't yet.
-                    // That's fine though.
-                    if (cur == null)
-                    {
-                        continue;
-                    }
-
-                    var eUid = entityUid;
-                    var eRegisteredNetUidName = _compFactory.GetRegistration(netId).Name;
-                    DebugTools.Assert(
-                        $"Component does not exist for state: entUid={eUid}, expectedNetId={netId}, expectedName={eRegisteredNetUidName}");
-                }
+                case EntityMessageType.SystemMessage:
+                    ReceivedSystemMessage?.Invoke(this, message.SystemMessage);
+                    return;
             }
         }
+
+        private sealed class MessageTickComparer : IComparer<(uint seq, MsgEntity msg)>
+        {
+            public int Compare((uint seq, MsgEntity msg) x, (uint seq, MsgEntity msg) y)
+            {
+                var cmp = y.msg.SourceTick.CompareTo(x.msg.SourceTick);
+                if (cmp != 0)
+                {
+                    return cmp;
+                }
+
+                return y.seq.CompareTo(x.seq);
+            }
+        }
+        #endregion
     }
 }

Robust.Client/GameObjects/ClientEntityNetworkManager.cs

@@ -1,128 +0,0 @@
-using System;
-using System.Collections.Generic;
-using Robust.Client.GameStates;
-using Robust.Shared.GameObjects;
-using Robust.Shared.IoC;
-using Robust.Shared.Network;
-using Robust.Shared.Network.Messages;
-using Robust.Shared.Timing;
-using Robust.Shared.Utility;
-
-namespace Robust.Client.GameObjects
-{
-    /// <summary>
-    /// The client implementation of the Entity Network Manager.
-    /// </summary>
-    public class ClientEntityNetworkManager : IEntityNetworkManager
-    {
-        [Dependency] private readonly IClientNetManager _networkManager = default!;
-        [Dependency] private readonly IClientGameStateManager _gameStateManager = default!;
-        [Dependency] private readonly IGameTiming _gameTiming = default!;
-
-        /// <inheritdoc />
-        public event EventHandler<NetworkComponentMessage>? ReceivedComponentMessage;
-
-        /// <inheritdoc />
-        public event EventHandler<object>? ReceivedSystemMessage;
-
-        private readonly PriorityQueue<(uint seq, MsgEntity msg)> _queue = new(new MessageTickComparer());
-        private uint _incomingMsgSequence = 0;
-
-        /// <inheritdoc />
-        public void SetupNetworking()
-        {
-            _networkManager.RegisterNetMessage<MsgEntity>(MsgEntity.NAME, HandleEntityNetworkMessage);
-        }
-
-        public void Update()
-        {
-            while (_queue.Count != 0 && _queue.Peek().msg.SourceTick <= _gameStateManager.CurServerTick)
-            {
-                var (_, msg) = _queue.Take();
-                // Logger.DebugS("net.ent", "Dispatching: {0}: {1}", seq, msg);
-                DispatchMsgEntity(msg);
-            }
-        }
-
-        /// <inheritdoc />
-        public void SendSystemNetworkMessage(EntitySystemMessage message)
-        {
-            SendSystemNetworkMessage(message, default(uint));
-        }
-
-        public void SendSystemNetworkMessage(EntitySystemMessage message, uint sequence)
-        {
-            var msg = _networkManager.CreateNetMessage<MsgEntity>();
-            msg.Type = EntityMessageType.SystemMessage;
-            msg.SystemMessage = message;
-            msg.SourceTick = _gameTiming.CurTick;
-            msg.Sequence = sequence;
-
-            _networkManager.ClientSendMessage(msg);
-        }
-
-        /// <inheritdoc />
-        public void SendSystemNetworkMessage(EntitySystemMessage message, INetChannel channel)
-        {
-            throw new NotSupportedException();
-        }
-
-        /// <inheritdoc />
-        public void SendComponentNetworkMessage(INetChannel? channel, IEntity entity, IComponent component, ComponentMessage message)
-        {
-            if (!component.NetID.HasValue)
-                throw new ArgumentException($"Component {component.Name} does not have a NetID.", nameof(component));
-
-            var msg = _networkManager.CreateNetMessage<MsgEntity>();
-            msg.Type = EntityMessageType.ComponentMessage;
-            msg.EntityUid = entity.Uid;
-            msg.NetId = component.NetID.Value;
-            msg.ComponentMessage = message;
-            msg.SourceTick = _gameTiming.CurTick;
-
-            _networkManager.ClientSendMessage(msg);
-        }
-
-        private void HandleEntityNetworkMessage(MsgEntity message)
-        {
-            if (message.SourceTick <= _gameStateManager.CurServerTick)
-            {
-                DispatchMsgEntity(message);
-                return;
-            }
-
-            // MsgEntity is sent with ReliableOrdered so Lidgren guarantees ordering of incoming messages.
-            // We still need to store a sequence input number to ensure ordering remains consistent in
-            // the priority queue.
-            _queue.Add((++_incomingMsgSequence, message));
-        }
-
-        private void DispatchMsgEntity(MsgEntity message)
-        {
-            switch (message.Type)
-            {
-                case EntityMessageType.ComponentMessage:
-                    ReceivedComponentMessage?.Invoke(this, new NetworkComponentMessage(message));
-                    return;
-
-                case EntityMessageType.SystemMessage:
-                    ReceivedSystemMessage?.Invoke(this, message.SystemMessage);
-                    return;
-            }
-        }
-
-        private sealed class MessageTickComparer : IComparer<(uint seq, MsgEntity msg)>
-        {
-            public int Compare((uint seq, MsgEntity msg) x, (uint seq, MsgEntity msg) y)
-            {
-                var cmp = y.msg.SourceTick.CompareTo(x.msg.SourceTick);
-                if (cmp != 0)
-                {
-                    return cmp;
-                }
-
-                return y.seq.CompareTo(x.seq);
-            }
-        }
-    }
-}

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

@@ -94,8 +94,7 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            EntitySystem.Get<AppearanceSystem>()
-                .EnqueueAppearanceUpdate(this);
+            EntitySystem.Get<AppearanceSystem>().EnqueueUpdate(this);
             _appearanceDirty = true;
         }
 
@@ -115,21 +114,6 @@ namespace Robust.Client.GameObjects
 
             MarkDirty();
         }
-
-
-        internal class SpriteLayerToggle : AppearanceVisualizer
-        {
-            public const string NAME = "sprite_layer_toggle";
-
-            public readonly object Key;
-            public readonly int SpriteLayer;
-
-            public SpriteLayerToggle(object key, int spriteLayer)
-            {
-                Key = key;
-                SpriteLayer = spriteLayer;
-            }
-        }
     }
 
     /// <summary>

Robust.Client/GameObjects/Components/Eye/EyeComponent.cs

@@ -1,4 +1,4 @@
-using Robust.Client.Graphics;
+using Robust.Client.Graphics;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
@@ -25,7 +25,7 @@ namespace Robust.Client.GameObjects
         [DataField("drawFov")]
         private bool _setDrawFovOnInitialize = true;
         [DataField("zoom")]
-        private Vector2 _setZoomOnInitialize = Vector2.One/2f;
+        private Vector2 _setZoomOnInitialize = Vector2.One;
         private Vector2 _offset = Vector2.Zero;
 
         public IEye? Eye => _eye;
@@ -152,6 +152,7 @@ namespace Robust.Client.GameObjects
             Zoom = state.Zoom;
             Offset = state.Offset;
             Rotation = state.Rotation;
+            VisibilityMask = state.VisibilityMask;
         }
 
         public override void OnRemove()

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

@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.ViewVariables;
@@ -8,8 +10,8 @@ namespace Robust.Client.GameObjects
 {
     internal sealed class ClientOccluderComponent : OccluderComponent
     {
-        internal SnapGridComponent? SnapGrid { get; private set; }
-
+        [Dependency] private readonly IMapManager _mapManager = default!;
+        
         [ViewVariables] private (GridId, Vector2i) _lastPosition;
         [ViewVariables] internal OccluderDir Occluding { get; private set; }
         [ViewVariables] internal uint UpdateGeneration { get; set; }
@@ -29,39 +31,36 @@ namespace Robust.Client.GameObjects
         {
             base.Startup();
 
-            if (Owner.TryGetComponent(out SnapGridComponent? snap))
+            if (Owner.Transform.Anchored)
             {
-                SnapGrid = snap;
-                SnapGrid.OnPositionChanged += SnapGridOnPositionChanged;
-
                 SnapGridOnPositionChanged();
             }
         }
 
-        private void SnapGridOnPositionChanged()
+        public void SnapGridOnPositionChanged()
         {
             SendDirty();
-            _lastPosition = (Owner.Transform.GridID, SnapGrid!.Position);
+
+            if(!Owner.Transform.Anchored)
+                return;
+
+            var grid = _mapManager.GetGrid(Owner.Transform.GridID);
+            _lastPosition = (Owner.Transform.GridID, grid.TileIndicesFor(Owner.Transform.Coordinates));
         }
 
         protected override void Shutdown()
         {
             base.Shutdown();
 
-            if (SnapGrid != null)
-            {
-                SnapGrid.OnPositionChanged -= SnapGridOnPositionChanged;
-            }
-
             SendDirty();
         }
 
         private void SendDirty()
         {
-            if (SnapGrid != null)
+            if (Owner.Transform.Anchored)
             {
                 Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local,
-                    new OccluderDirtyEvent(Owner, _lastPosition, SnapGrid.Offset));
+                    new OccluderDirtyEvent(Owner, _lastPosition));
             }
         }
 
@@ -69,16 +68,18 @@ namespace Robust.Client.GameObjects
         {
             Occluding = OccluderDir.None;
 
-            if (Deleted || SnapGrid == null)
+            if (Deleted || !Owner.Transform.Anchored)
             {
                 return;
             }
 
             void CheckDir(Direction dir, OccluderDir oclDir)
             {
-                foreach (var neighbor in SnapGrid.GetInDir(dir))
+                var grid = _mapManager.GetGrid(Owner.Transform.GridID);
+                var position = Owner.Transform.Coordinates;
+                foreach (var neighbor in grid.GetInDir(position, dir))
                 {
-                    if (neighbor.TryGetComponent(out ClientOccluderComponent? comp) && comp.Enabled)
+                    if (Owner.EntityManager.ComponentManager.TryGetComponent(neighbor, out ClientOccluderComponent? comp) && comp.Enabled)
                     {
                         Occluding |= oclDir;
                         break;

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

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
@@ -19,6 +19,7 @@ using Robust.Shared.Reflection;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager;
 using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 using Robust.Shared.ViewVariables;
@@ -36,13 +37,13 @@ namespace Robust.Client.GameObjects
         private bool _visible = true;
 
         [ViewVariables(VVAccess.ReadWrite)]
-        public bool Visible
+        public override bool Visible
         {
             get => _visible;
             set => _visible = value;
         }
 
-        [DataFieldWithConstant("drawdepth", typeof(DrawDepthTag))]
+        [DataField("drawdepth", customTypeSerializer: typeof(ConstantSerializer<DrawDepthTag>))]
         private int drawDepth = DrawDepthTag.Default;
 
         /// <summary>
@@ -847,8 +848,8 @@ namespace Robust.Client.GameObjects
                 }
                 else
                 {
-                    Logger.ErrorS(LogCategory, "State '{0}' does not exist in RSI. Trace:\n{1}", stateId,
-                        Environment.StackTrace);
+                    Logger.ErrorS(LogCategory, "State '{0}' does not exist in RSI {1}. Trace:\n{2}", stateId,
+                        actualRsi.Path, Environment.StackTrace);
                     theLayer.Texture = null;
                 }
             }
@@ -2084,6 +2085,7 @@ namespace Robust.Client.GameObjects
             public IEntityManager EntityManager { get; } = null!;
             public string Name { get; set; } = string.Empty;
             public EntityUid Uid { get; } = EntityUid.Invalid;
+            EntityLifeStage IEntity.LifeStage { get => _lifeStage; set => _lifeStage = value; }
             public bool Initialized { get; } = false;
             public bool Initializing { get; } = false;
             public bool Deleted { get; } = true;
@@ -2100,6 +2102,7 @@ namespace Robust.Client.GameObjects
             public IMetaDataComponent MetaData { get; } = null!;
 
             private Dictionary<Type, IComponent> _components = new();
+            private EntityLifeStage _lifeStage;
 
             public T AddComponent<T>() where T : Component, new()
             {
@@ -2147,11 +2150,6 @@ namespace Robust.Client.GameObjects
                 return null!;
             }
 
-            public IComponent GetComponent(uint netID)
-            {
-                return null!;
-            }
-
             public bool TryGetComponent<T>([NotNullWhen(true)] out T? component) where T : class
             {
                 component = null;
@@ -2178,21 +2176,6 @@ namespace Robust.Client.GameObjects
                 return null;
             }
 
-            public bool TryGetComponent(uint netId, [NotNullWhen(true)]  out IComponent? component)
-            {
-                component = null;
-                return false;
-            }
-
-            public IComponent? GetComponentOrNull(uint netId)
-            {
-                return null;
-            }
-
-            public void Shutdown()
-            {
-            }
-
             public void Delete()
             {
             }

Robust.Client/GameObjects/EntityManagerExt.cs

@@ -9,13 +9,13 @@ namespace Robust.Client.GameObjects
     public static class EntityManagerExt
     {
         public static void RaisePredictiveEvent<T>(this IEntityManager entityManager, T msg)
-            where T : EntitySystemMessage
+            where T : EntityEventArgs
         {
             var localPlayer = IoCManager.Resolve<IPlayerManager>().LocalPlayer;
             DebugTools.AssertNotNull(localPlayer);
 
             var sequence = IoCManager.Resolve<IClientGameStateManager>().SystemMessageDispatched(msg);
-            entityManager.EntityNetManager.SendSystemNetworkMessage(msg, sequence);
+            entityManager.EntityNetManager?.SendSystemNetworkMessage(msg, sequence);
 
             var eventArgs = new EntitySessionEventArgs(localPlayer!.Session);
 

Robust.Client/GameObjects/EntitySystems/AppearanceSystem.cs

@@ -1,51 +1,33 @@
 using System.Collections.Generic;
+using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
 
 namespace Robust.Client.GameObjects
 {
+    [UsedImplicitly]
     internal sealed class AppearanceSystem : EntitySystem
     {
-        private readonly Queue<AppearanceComponent> _updatesQueued = new();
+        private readonly Queue<AppearanceComponent> _queuedUpdates = new();
+
+        public void EnqueueUpdate(AppearanceComponent component)
+        {
+            _queuedUpdates.Enqueue(component);
+        }
 
         public override void FrameUpdate(float frameTime)
         {
-            while (_updatesQueued.TryDequeue(out var appearance))
+            while (_queuedUpdates.TryDequeue(out var appearance))
             {
-                UpdateComponent(appearance);
+                if (appearance.Deleted)
+                    return;
+
+                foreach (var visualizer in appearance.Visualizers)
+                {
+                    visualizer.OnChangeData(appearance);
+                }
+
                 appearance.UnmarkDirty();
             }
         }
-
-        private static void UpdateComponent(AppearanceComponent component)
-        {
-            if (component.Deleted)
-                return;
-
-            foreach (var visualizer in component.Visualizers)
-            {
-                switch (visualizer)
-                {
-                    case AppearanceComponent.SpriteLayerToggle spriteLayerToggle:
-                        UpdateSpriteLayerToggle(component, spriteLayerToggle);
-                        break;
-
-                    default:
-                        visualizer.OnChangeData(component);
-                        break;
-                }
-            }
-        }
-
-        private static void UpdateSpriteLayerToggle(AppearanceComponent component, AppearanceComponent.SpriteLayerToggle toggle)
-        {
-            component.TryGetData(toggle.Key, out bool visible);
-            var sprite = component.Owner.GetComponent<SpriteComponent>();
-            sprite.LayerSetVisible(toggle.SpriteLayer, visible);
-        }
-
-        public void EnqueueAppearanceUpdate(AppearanceComponent component)
-        {
-            _updatesQueued.Enqueue(component);
-        }
     }
 }

Robust.Client/GameObjects/EntitySystems/AudioSystem.cs

@@ -8,7 +8,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Broadphase;
 using Robust.Shared.Player;
@@ -42,6 +41,17 @@ namespace Robust.Client.GameObjects
             _broadPhaseSystem = Get<SharedBroadPhaseSystem>();
         }
 
+        public override void Shutdown()
+        {
+            base.Shutdown();
+            UnsubscribeNetworkEvent<PlayAudioEntityMessage>();
+            UnsubscribeNetworkEvent<PlayAudioGlobalMessage>();
+            UnsubscribeNetworkEvent<PlayAudioPositionalMessage>();
+            UnsubscribeNetworkEvent<StopAudioMessageClient>();
+
+            UnsubscribeLocalEvent<SoundSystem.QueryAudioSystem>();
+        }
+
         private void StopAudioMessageHandler(StopAudioMessageClient ev)
         {
             var stream = _playingClydeStreams.Find(p => p.NetIdentifier == ev.Identifier);
@@ -165,6 +175,12 @@ namespace Robust.Client.GameObjects
                             Logger.Warning("Interrupting positional audio, can't set position.");
                             stream.Source.StopPlaying();
                         }
+
+                        if (stream.TrackingEntity != null)
+                        {
+                            stream.Source.SetVelocity(stream.TrackingEntity.GlobalLinearVelocity());
+                        }
+
                     }
                 }
             }
@@ -188,7 +204,7 @@ namespace Robust.Client.GameObjects
         /// </summary>
         /// <param name="filename">The resource path to the OGG Vorbis file to play.</param>
         /// <param name="audioParams"></param>
-        public IPlayingAudioStream? Play(string filename, AudioParams? audioParams = null)
+        private IPlayingAudioStream? Play(string filename, AudioParams? audioParams = null)
         {
             if (_resourceCache.TryGetResource<AudioResource>(new ResourcePath(filename), out var audio))
             {
@@ -204,7 +220,7 @@ namespace Robust.Client.GameObjects
         /// </summary>
         /// <param name="stream">The audio stream to play.</param>
         /// <param name="audioParams"></param>
-        public IPlayingAudioStream Play(AudioStream stream, AudioParams? audioParams = null)
+        private IPlayingAudioStream Play(AudioStream stream, AudioParams? audioParams = null)
         {
             var source = _clyde.CreateAudioSource(stream);
             ApplyAudioParams(audioParams, source);
@@ -226,7 +242,7 @@ namespace Robust.Client.GameObjects
         /// <param name="filename">The resource path to the OGG Vorbis file to play.</param>
         /// <param name="entity">The entity "emitting" the audio.</param>
         /// <param name="audioParams"></param>
-        public IPlayingAudioStream? Play(string filename, IEntity entity, AudioParams? audioParams = null)
+        private IPlayingAudioStream? Play(string filename, IEntity entity, AudioParams? audioParams = null)
         {
             if (_resourceCache.TryGetResource<AudioResource>(new ResourcePath(filename), out var audio))
             {
@@ -243,7 +259,7 @@ namespace Robust.Client.GameObjects
         /// <param name="stream">The audio stream to play.</param>
         /// <param name="entity">The entity "emitting" the audio.</param>
         /// <param name="audioParams"></param>
-        public IPlayingAudioStream? Play(AudioStream stream, IEntity entity, AudioParams? audioParams = null)
+        private IPlayingAudioStream? Play(AudioStream stream, IEntity entity, AudioParams? audioParams = null)
         {
             var source = _clyde.CreateAudioSource(stream);
             if (!source.SetPosition(entity.Transform.WorldPosition))
@@ -272,7 +288,7 @@ namespace Robust.Client.GameObjects
         /// <param name="filename">The resource path to the OGG Vorbis file to play.</param>
         /// <param name="coordinates">The coordinates at which to play the audio.</param>
         /// <param name="audioParams"></param>
-        public IPlayingAudioStream? Play(string filename, EntityCoordinates coordinates, AudioParams? audioParams = null)
+        private IPlayingAudioStream? Play(string filename, EntityCoordinates coordinates, AudioParams? audioParams = null)
         {
             if (_resourceCache.TryGetResource<AudioResource>(new ResourcePath(filename), out var audio))
             {
@@ -289,7 +305,7 @@ namespace Robust.Client.GameObjects
         /// <param name="stream">The audio stream to play.</param>
         /// <param name="coordinates">The coordinates at which to play the audio.</param>
         /// <param name="audioParams"></param>
-        public IPlayingAudioStream? Play(AudioStream stream, EntityCoordinates coordinates,
+        private IPlayingAudioStream? Play(AudioStream stream, EntityCoordinates coordinates,
             AudioParams? audioParams = null)
         {
             var source = _clyde.CreateAudioSource(stream);

Robust.Client/GameObjects/EntitySystems/ClientOccluderSystem.cs

@@ -6,6 +6,7 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
+using Robust.Shared.Utility;
 
 namespace Robust.Client.GameObjects
 {
@@ -20,10 +21,11 @@ namespace Robust.Client.GameObjects
     {
         [Dependency] private readonly IMapManager _mapManager = default!;
 
-        private readonly Queue<IEntity> _dirtyEntities = new();
+        private readonly Queue<EntityUid> _dirtyEntities = new();
 
         private uint _updateGeneration;
 
+        /// <inheritdoc />
         public override void Initialize()
         {
             base.Initialize();
@@ -32,6 +34,18 @@ namespace Robust.Client.GameObjects
             UpdatesAfter.Add(typeof(PhysicsSystem));
 
             SubscribeLocalEvent<OccluderDirtyEvent>(HandleDirtyEvent);
+
+            SubscribeLocalEvent<ClientOccluderComponent, SnapGridPositionChangedEvent>(HandleSnapGridMove);
+        }
+
+        /// <inheritdoc />
+        public override void Shutdown()
+        {
+            UnsubscribeLocalEvent<OccluderDirtyEvent>();
+
+            UnsubscribeLocalEvent<ClientOccluderComponent, SnapGridPositionChangedEvent>(HandleSnapGridMove);
+
+            base.Shutdown();
         }
 
         public override void FrameUpdate(float frameTime)
@@ -47,8 +61,8 @@ namespace Robust.Client.GameObjects
 
             while (_dirtyEntities.TryDequeue(out var entity))
             {
-                if (!entity.Deleted
-                    && entity.TryGetComponent(out ClientOccluderComponent? occluder)
+                if (EntityManager.EntityExists(entity)
+                    && ComponentManager.TryGetComponent(entity, out ClientOccluderComponent? occluder)
                     && occluder.UpdateGeneration != _updateGeneration)
                 {
                     occluder.Update();
@@ -58,6 +72,11 @@ namespace Robust.Client.GameObjects
             }
         }
 
+        private static void HandleSnapGridMove(EntityUid uid, ClientOccluderComponent component, SnapGridPositionChangedEvent args)
+        {
+            component.SnapGridOnPositionChanged();
+        }
+
         private void HandleDirtyEvent(OccluderDirtyEvent ev)
         {
             var sender = ev.Sender;
@@ -65,13 +84,14 @@ namespace Robust.Client.GameObjects
                 sender.TryGetComponent(out ClientOccluderComponent? iconSmooth)
                 && iconSmooth.Running)
             {
-                var snapGrid = sender.GetComponent<SnapGridComponent>();
+                var grid1 = _mapManager.GetGrid(sender.Transform.GridID);
+                var coords = sender.Transform.Coordinates;
 
-                _dirtyEntities.Enqueue(sender);
-                AddValidEntities(snapGrid.GetInDir(Direction.North));
-                AddValidEntities(snapGrid.GetInDir(Direction.South));
-                AddValidEntities(snapGrid.GetInDir(Direction.East));
-                AddValidEntities(snapGrid.GetInDir(Direction.West));
+                _dirtyEntities.Enqueue(sender.Uid);
+                AddValidEntities(grid1.GetInDir(coords, Direction.North));
+                AddValidEntities(grid1.GetInDir(coords, Direction.South));
+                AddValidEntities(grid1.GetInDir(coords, Direction.East));
+                AddValidEntities(grid1.GetInDir(coords, Direction.West));
             }
 
             // Entity is no longer valid, update around the last position it was at.
@@ -79,44 +99,37 @@ namespace Robust.Client.GameObjects
             {
                 var pos = ev.LastPosition.Value.pos;
 
-                AddValidEntities(grid.GetSnapGridCell(pos + new Vector2i(1, 0), ev.Offset));
-                AddValidEntities(grid.GetSnapGridCell(pos + new Vector2i(-1, 0), ev.Offset));
-                AddValidEntities(grid.GetSnapGridCell(pos + new Vector2i(0, 1), ev.Offset));
-                AddValidEntities(grid.GetSnapGridCell(pos + new Vector2i(0, -1), ev.Offset));
+                AddValidEntities(grid.GetAnchoredEntities(pos + new Vector2i(1, 0)));
+                AddValidEntities(grid.GetAnchoredEntities(pos + new Vector2i(-1, 0)));
+                AddValidEntities(grid.GetAnchoredEntities(pos + new Vector2i(0, 1)));
+                AddValidEntities(grid.GetAnchoredEntities(pos + new Vector2i(0, -1)));
             }
         }
 
-        private void AddValidEntities(IEnumerable<IEntity> candidates)
+        private void AddValidEntities(IEnumerable<EntityUid> candidates)
         {
             foreach (var entity in candidates)
             {
-                if (entity.HasComponent<ClientOccluderComponent>())
+                if (ComponentManager.HasComponent<ClientOccluderComponent>(entity))
                 {
                     _dirtyEntities.Enqueue(entity);
                 }
             }
         }
-
-        private void AddValidEntities(IEnumerable<IComponent> candidates)
-        {
-            AddValidEntities(candidates.Select(c => c.Owner));
-        }
     }
 
     /// <summary>
     ///     Event raised by a <see cref="ClientOccluderComponent"/> when it needs to be recalculated.
     /// </summary>
-    internal sealed class OccluderDirtyEvent : EntitySystemMessage
+    internal sealed class OccluderDirtyEvent : EntityEventArgs
     {
-        public OccluderDirtyEvent(IEntity sender, (GridId grid, Vector2i pos)? lastPosition, SnapGridOffset offset)
+        public OccluderDirtyEvent(IEntity sender, (GridId grid, Vector2i pos)? lastPosition)
         {
             LastPosition = lastPosition;
-            Offset = offset;
             Sender = sender;
         }
 
         public (GridId grid, Vector2i pos)? LastPosition { get; }
-        public SnapGridOffset Offset { get; }
         public IEntity Sender { get; }
     }
 }

Robust.Client/GameObjects/EntitySystems/EffectSystem.cs

@@ -11,6 +11,7 @@ using Robust.Shared.Log;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
+using Robust.Shared.Enums;
 
 namespace Robust.Client.GameObjects
 {
@@ -42,7 +43,7 @@ namespace Robust.Client.GameObjects
         {
             base.Shutdown();
 
-            overlayManager.RemoveOverlay("EffectSystem");
+            overlayManager.RemoveOverlay(typeof(EffectOverlay));
         }
 
         public void CreateEffect(EffectSystemMessage message)
@@ -329,7 +330,6 @@ namespace Robust.Client.GameObjects
         {
             private readonly IPlayerManager _playerManager;
 
-            public override bool AlwaysDirty => true;
             public override OverlaySpace Space => OverlaySpace.WorldSpace;
 
             private readonly ShaderInstance _unshadedShader;
@@ -337,8 +337,7 @@ namespace Robust.Client.GameObjects
             private readonly IMapManager _mapManager;
             private readonly IEntityManager _entityManager;
 
-            public EffectOverlay(EffectSystem owner, IPrototypeManager protoMan, IMapManager mapMan, IPlayerManager playerMan, IEntityManager entityManager) : base(
-                "EffectSystem")
+            public EffectOverlay(EffectSystem owner, IPrototypeManager protoMan, IMapManager mapMan, IPlayerManager playerMan, IEntityManager entityManager)
             {
                 _owner = owner;
                 _unshadedShader = protoMan.Index<ShaderPrototype>("unshaded").Instance();
@@ -347,11 +346,11 @@ namespace Robust.Client.GameObjects
                 _entityManager = entityManager;
             }
 
-            protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+            protected internal override void Draw(in OverlayDrawArgs args)
             {
                 var map = _owner.eyeManager.CurrentMap;
 
-                var worldHandle = (DrawingHandleWorld) handle;
+                var worldHandle = args.WorldHandle;
                 ShaderInstance? currentShader = null;
                 var player = _playerManager.LocalPlayer?.ControlledEntity;
 

Robust.Client/GameObjects/EntitySystems/InputSystem.cs

@@ -97,7 +97,7 @@ namespace Robust.Client.GameObjects
         private void DispatchInputCommand(FullInputCmdMessage message)
         {
             _stateManager.InputCommandDispatched(message);
-            EntityNetworkManager.SendSystemNetworkMessage(message, message.InputSequence);
+            EntityManager.EntityNetManager?.SendSystemNetworkMessage(message, message.InputSequence);
         }
 
         public override void Initialize()
@@ -157,7 +157,7 @@ namespace Robust.Client.GameObjects
     /// <summary>
     ///     Entity system message that is raised when the player changes attached entities.
     /// </summary>
-    public class PlayerAttachSysMessage : EntitySystemMessage
+    public class PlayerAttachSysMessage : EntityEventArgs
     {
         /// <summary>
         ///     New entity the player is attached to.

Robust.Client/GameObjects/EntitySystems/RenderingTreeSystem.cs

@@ -19,19 +19,19 @@ namespace Robust.Client.GameObjects
 
         [Dependency] private readonly IMapManagerInternal _mapManager = default!;
 
-        private readonly Dictionary<MapId, MapTrees> _mapTrees = new();
+        private readonly Dictionary<MapId, Dictionary<GridId, MapTrees>> _gridTrees = new();
 
         private readonly List<SpriteComponent> _spriteQueue = new();
         private readonly List<PointLightComponent> _lightQueue = new();
 
-        internal DynamicTree<SpriteComponent> GetSpriteTreeForMap(MapId map)
+        internal DynamicTree<SpriteComponent> GetSpriteTreeForMap(MapId map, GridId grid)
         {
-            return _mapTrees[map].SpriteTree;
+            return _gridTrees[map][grid].SpriteTree;
         }
 
-        internal DynamicTree<PointLightComponent> GetLightTreeForMap(MapId map)
+        internal DynamicTree<PointLightComponent> GetLightTreeForMap(MapId map, GridId grid)
         {
-            return _mapTrees[map].LightTree;
+            return _gridTrees[map][grid].LightTree;
         }
 
         public override void Initialize()
@@ -44,6 +44,8 @@ namespace Robust.Client.GameObjects
 
             _mapManager.MapCreated += MapManagerOnMapCreated;
             _mapManager.MapDestroyed += MapManagerOnMapDestroyed;
+            _mapManager.OnGridCreated += MapManagerOnGridCreated;
+            _mapManager.OnGridRemoved += MapManagerOnGridRemoved;
 
             SubscribeLocalEvent<EntMapIdChangedMessage>(EntMapIdChanged);
             SubscribeLocalEvent<MoveEvent>(EntMoved);
@@ -53,18 +55,40 @@ namespace Robust.Client.GameObjects
             SubscribeLocalEvent<RenderTreeRemoveLightMessage>(RemoveLight);
         }
 
+        public override void Shutdown()
+        {
+            base.Shutdown();
+            _mapManager.MapCreated -= MapManagerOnMapCreated;
+            _mapManager.MapDestroyed -= MapManagerOnMapDestroyed;
+            _mapManager.OnGridCreated -= MapManagerOnGridCreated;
+            _mapManager.OnGridRemoved -= MapManagerOnGridRemoved;
+
+            UnsubscribeLocalEvent<EntMapIdChangedMessage>();
+            UnsubscribeLocalEvent<MoveEvent>();
+            UnsubscribeLocalEvent<EntParentChangedMessage>();
+            UnsubscribeLocalEvent<PointLightRadiusChangedMessage>();
+            UnsubscribeLocalEvent<RenderTreeRemoveSpriteMessage>();
+            UnsubscribeLocalEvent<RenderTreeRemoveLightMessage>();
+        }
+
         // For these next 2 methods (the Remove* ones):
         // If the Transform is removed BEFORE the Sprite/Light,
         // then the MapIdChanged code will handle and remove it (because MapId gets set to nullspace).
         // Otherwise these will still have their past MapId and that's all we need..
         private void RemoveLight(RenderTreeRemoveLightMessage ev)
         {
-            _mapTrees[ev.Map].LightTree.Remove(ev.Light);
+            foreach (var gridId in _mapManager.FindGridIdsIntersecting(ev.Map, MapTrees.LightAabbFunc(ev.Light), true))
+            {
+                _gridTrees[ev.Map][gridId].LightTree.Remove(ev.Light);
+            }
         }
 
         private void RemoveSprite(RenderTreeRemoveSpriteMessage ev)
         {
-            _mapTrees[ev.Map].SpriteTree.Remove(ev.Sprite);
+            foreach (var gridId in _mapManager.FindGridIdsIntersecting(ev.Map, MapTrees.SpriteAabbFunc(ev.Sprite), true))
+            {
+                _gridTrees[ev.Map][gridId].SpriteTree.Remove(ev.Sprite);
+            }
         }
 
         private void PointLightRadiusChanged(PointLightRadiusChangedMessage ev)
@@ -119,27 +143,69 @@ namespace Robust.Client.GameObjects
         {
             // Nullspace is a valid map ID for stuff to have but we also aren't gonna bother indexing it.
             // So that's why there's a GetValueOrDefault.
-            var oldMapTrees = _mapTrees.GetValueOrDefault(ev.OldMapId);
-            var newMapTrees = _mapTrees.GetValueOrDefault(ev.Entity.Transform.MapID);
+            var oldMapTrees = _gridTrees.GetValueOrDefault(ev.OldMapId);
 
+            // TODO: MMMM probably a better way to do this.
             if (ev.Entity.TryGetComponent(out SpriteComponent? sprite))
             {
-                oldMapTrees?.SpriteTree.Remove(sprite);
+                if (oldMapTrees != null)
+                {
+                    foreach (var (_, gridTree) in oldMapTrees)
+                    {
+                        gridTree.SpriteTree.Remove(sprite);
+                    }
+                }
 
-                newMapTrees?.SpriteTree.AddOrUpdate(sprite);
+                var bounds = MapTrees.SpriteAabbFunc(sprite);
+
+                foreach (var gridId in _mapManager.FindGridIdsIntersecting(ev.Entity.Transform.MapID, bounds, true))
+                {
+                    Box2 gridBounds;
+
+                    if (gridId == GridId.Invalid)
+                    {
+                        gridBounds = bounds;
+                    }
+                    else
+                    {
+                        gridBounds = bounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
+                    }
+                    _gridTrees[ev.Entity.Transform.MapID][gridId].SpriteTree.AddOrUpdate(sprite, gridBounds);
+                }
             }
 
             if (ev.Entity.TryGetComponent(out PointLightComponent? light))
             {
-                oldMapTrees?.LightTree.Remove(light);
+                if (oldMapTrees != null)
+                {
+                    foreach (var (_, gridTree) in oldMapTrees)
+                    {
+                        gridTree.LightTree.Remove(light);
+                    }
+                }
 
-                newMapTrees?.LightTree.AddOrUpdate(light);
+                var bounds = MapTrees.LightAabbFunc(light);
+
+                foreach (var gridId in _mapManager.FindGridIdsIntersecting(ev.Entity.Transform.MapID, bounds, true))
+                {
+                    Box2 gridBounds;
+
+                    if (gridId == GridId.Invalid)
+                    {
+                        gridBounds = bounds;
+                    }
+                    else
+                    {
+                        gridBounds = bounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
+                    }
+                    _gridTrees[ev.Entity.Transform.MapID][gridId].LightTree.AddOrUpdate(light, gridBounds);
+                }
             }
         }
 
         private void MapManagerOnMapDestroyed(object? sender, MapEventArgs e)
         {
-            _mapTrees.Remove(e.Map);
+            _gridTrees.Remove(e.Map);
         }
 
         private void MapManagerOnMapCreated(object? sender, MapEventArgs e)
@@ -149,36 +215,59 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            _mapTrees.Add(e.Map, new MapTrees());
+            _gridTrees.Add(e.Map, new Dictionary<GridId, MapTrees>
+            {
+                {GridId.Invalid, new MapTrees()}
+            });
+        }
+
+        private void MapManagerOnGridCreated(MapId mapId, GridId gridId)
+        {
+            _gridTrees[mapId].Add(gridId, new MapTrees());
+        }
+
+        private void MapManagerOnGridRemoved(MapId mapId, GridId gridId)
+        {
+            _gridTrees[mapId].Remove(gridId);
         }
 
         public override void FrameUpdate(float frameTime)
         {
             foreach (var queuedUpdateSprite in _spriteQueue)
             {
-                var transform = queuedUpdateSprite.Owner.Transform;
-                var map = transform.MapID;
+                var map = queuedUpdateSprite.Owner.Transform.MapID;
                 if (map == MapId.Nullspace)
                 {
                     continue;
                 }
-                var updateMapTree = _mapTrees[map].SpriteTree;
 
-                updateMapTree.AddOrUpdate(queuedUpdateSprite);
+                var mapTree = _gridTrees[map];
+
+                foreach (var gridId in _mapManager.FindGridIdsIntersecting(map,
+                    MapTrees.SpriteAabbFunc(queuedUpdateSprite), true))
+                {
+                    mapTree[gridId].SpriteTree.AddOrUpdate(queuedUpdateSprite);
+                }
+
                 queuedUpdateSprite.TreeUpdateQueued = false;
             }
 
             foreach (var queuedUpdateLight in _lightQueue)
             {
-                var transform = queuedUpdateLight.Owner.Transform;
-                var map = transform.MapID;
+                var map = queuedUpdateLight.Owner.Transform.MapID;
                 if (map == MapId.Nullspace)
                 {
                     continue;
                 }
-                var updateMapTree = _mapTrees[map].LightTree;
 
-                updateMapTree.AddOrUpdate(queuedUpdateLight);
+                var mapTree = _gridTrees[map];
+
+                foreach (var gridId in _mapManager.FindGridIdsIntersecting(map,
+                    MapTrees.LightAabbFunc(queuedUpdateLight), true))
+                {
+                    mapTree[gridId].LightTree.AddOrUpdate(queuedUpdateLight);
+                }
+
                 queuedUpdateLight.TreeUpdateQueued = false;
             }
 
@@ -197,14 +286,14 @@ namespace Robust.Client.GameObjects
                 LightTree = new DynamicTree<PointLightComponent>(LightAabbFunc);
             }
 
-            private static Box2 SpriteAabbFunc(in SpriteComponent value)
+            internal static Box2 SpriteAabbFunc(in SpriteComponent value)
             {
                 var worldPos = value.Owner.Transform.WorldPosition;
 
                 return new Box2(worldPos, worldPos);
             }
 
-            private static Box2 LightAabbFunc(in PointLightComponent value)
+            internal static Box2 LightAabbFunc(in PointLightComponent value)
             {
                 var worldPos = value.Owner.Transform.WorldPosition;
 

Robust.Client/GameObjects/EntitySystems/SpriteSystem.cs

@@ -3,6 +3,7 @@ using Robust.Client.Graphics;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
+using Robust.Shared.Maths;
 
 namespace Robust.Client.GameObjects
 {
@@ -13,6 +14,7 @@ namespace Robust.Client.GameObjects
     public class SpriteSystem : EntitySystem
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
+        [Dependency] private readonly IMapManager _mapManager = default!;
 
         /// <inheritdoc />
         public override void FrameUpdate(float frameTime)
@@ -29,18 +31,32 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            var mapTree = renderTreeSystem.GetSpriteTreeForMap(currentMap);
-
-            mapTree.QueryAabb(ref frameTime, (ref float state, in SpriteComponent value) =>
+            foreach (var gridId in _mapManager.FindGridIdsIntersecting(currentMap, pvsBounds, true))
             {
-                if (value.IsInert)
+                Box2 gridBounds;
+
+                if (gridId == GridId.Invalid)
                 {
-                    return true;
+                    gridBounds = pvsBounds;
+                }
+                else
+                {
+                    gridBounds = pvsBounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
                 }
 
-                value.FrameUpdate(state);
-                return true;
-            }, pvsBounds, approx: true);
+                var mapTree = renderTreeSystem.GetSpriteTreeForMap(currentMap, gridId);
+
+                mapTree.QueryAabb(ref frameTime, (ref float state, in SpriteComponent value) =>
+                {
+                    if (value.IsInert)
+                    {
+                        return true;
+                    }
+
+                    value.FrameUpdate(state);
+                    return true;
+                }, gridBounds, approx: true);
+            }
         }
     }
 }

Robust.Client/GameObjects/IClientEntityManager.cs

@@ -3,10 +3,8 @@ using Robust.Shared.GameObjects;
 
 namespace Robust.Client.GameObjects
 {
-    public interface IClientEntityManager : IEntityManager
+    public interface IClientEntityManager : IEntityManager, IEntityNetworkManager
     {
-        /// <returns>The list of new entities created.</returns>
-        List<EntityUid> ApplyEntityStates(EntityState[]? curEntStates, IEnumerable<EntityUid>? deletions,
-            EntityState[]? nextEntStates);
+
     }
 }

Robust.Client/GameObjects/IClientEntityManagerInternal.cs

@@ -0,0 +1,15 @@
+using Robust.Shared.GameObjects;
+
+namespace Robust.Client.GameObjects
+{
+    internal interface IClientEntityManagerInternal : IClientEntityManager
+    {
+        // These methods are used by the Game State Manager.
+
+        IEntity CreateEntity(string? prototypeName, EntityUid? uid = null);
+
+        void InitializeEntity(IEntity entity);
+
+        void StartEntity(IEntity entity);
+    }
+}

Robust.Client/GameStates/ClientGameStateManager.cs

@@ -1,14 +1,18 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using Robust.Client.GameObjects;
 using Robust.Client.Input;
+using Robust.Client.Map;
 using Robust.Shared.GameStates;
 using Robust.Shared.IoC;
 using Robust.Shared.Network.Messages;
 using Robust.Client.Player;
+using Robust.Client.Timing;
 using Robust.Shared;
 using Robust.Shared.Configuration;
+using Robust.Shared.Exceptions;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Input;
 using Robust.Shared.Log;
@@ -27,20 +31,25 @@ namespace Robust.Client.GameStates
         private uint _nextInputCmdSeq = 1;
         private readonly Queue<FullInputCmdMessage> _pendingInputs = new();
 
-        private readonly Queue<(uint sequence, GameTick sourceTick, EntitySystemMessage msg, object sessionMsg)>
+        private readonly Queue<(uint sequence, GameTick sourceTick, EntityEventArgs msg, object sessionMsg)>
             _pendingSystemMessages
                 = new();
 
-        [Dependency] private readonly IClientEntityManager _entities = default!;
+        [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!;
-        [Dependency] private readonly IMapManager _mapManager = default!;
-        [Dependency] private readonly IGameTiming _timing = default!;
+        [Dependency] private readonly IClientMapManager _mapManager = default!;
+        [Dependency] private readonly IClientGameTiming _timing = default!;
         [Dependency] private readonly INetConfigurationManager _config = default!;
         [Dependency] private readonly IEntitySystemManager _entitySystemManager = default!;
         [Dependency] private readonly IComponentManager _componentManager = default!;
         [Dependency] private readonly IInputManager _inputManager = default!;
+#if EXCEPTION_TOLERANCE
+        [Dependency] private readonly IRuntimeLog _runtimeLog = default!;
+#endif
 
         /// <inheritdoc />
         public int MinBufferSize => _processor.MinBufferSize;
@@ -126,7 +135,7 @@ namespace Robust.Client.GameStates
             _nextInputCmdSeq++;
         }
 
-        public uint SystemMessageDispatched<T>(T message) where T : EntitySystemMessage
+        public uint SystemMessageDispatched<T>(T message) where T : EntityEventArgs
         {
             if (!Predicting)
             {
@@ -242,65 +251,69 @@ namespace Robust.Client.GameStates
 
             if (!Predicting) return;
 
-            using var _ = _timing.StartPastPredictionArea();
-
-
-            if (_pendingInputs.Count > 0)
+            using(var _ = _timing.StartPastPredictionArea())
             {
-                Logger.DebugS(CVars.NetPredict.Name,  "CL> Predicted:");
+                if (_pendingInputs.Count > 0)
+                {
+                    Logger.DebugS(CVars.NetPredict.Name,  "CL> Predicted:");
+                }
+
+                var pendingInputEnumerator = _pendingInputs.GetEnumerator();
+                var pendingMessagesEnumerator = _pendingSystemMessages.GetEnumerator();
+                var hasPendingInput = pendingInputEnumerator.MoveNext();
+                var hasPendingMessage = pendingMessagesEnumerator.MoveNext();
+
+                var ping = _network.ServerChannel!.Ping / 1000f + PredictLagBias; // seconds.
+                var targetTick = _timing.CurTick.Value + _processor.TargetBufferSize +
+                                 (int) Math.Ceiling(_timing.TickRate * ping) + PredictTickBias;
+
+                // Logger.DebugS("net.predict", $"Predicting from {_lastProcessedTick} to {targetTick}");
+
+                for (var t = _lastProcessedTick.Value + 1; t <= targetTick; t++)
+                {
+                    var tick = new GameTick(t);
+                    _timing.CurTick = tick;
+
+                    while (hasPendingInput && pendingInputEnumerator.Current.Tick <= tick)
+                    {
+                        var inputCmd = pendingInputEnumerator.Current;
+
+                        _inputManager.NetworkBindMap.TryGetKeyFunction(inputCmd.InputFunctionId, out var boundFunc);
+
+                        Logger.DebugS(CVars.NetPredict.Name,
+                            $"    seq={inputCmd.InputSequence}, sub={inputCmd.SubTick}, dTick={tick}, func={boundFunc.FunctionName}, " +
+                            $"state={inputCmd.State}");
+
+
+                        input.PredictInputCommand(inputCmd);
+
+                        hasPendingInput = pendingInputEnumerator.MoveNext();
+                    }
+
+                    while (hasPendingMessage && pendingMessagesEnumerator.Current.sourceTick <= tick)
+                    {
+                        var msg = pendingMessagesEnumerator.Current.msg;
+
+                        _entities.EventBus.RaiseEvent(EventSource.Local, msg);
+                        _entities.EventBus.RaiseEvent(EventSource.Local, pendingMessagesEnumerator.Current.sessionMsg);
+
+                        hasPendingMessage = pendingMessagesEnumerator.MoveNext();
+                    }
+
+                    if (t != targetTick)
+                    {
+                        // Don't run EntitySystemManager.TickUpdate if this is the target tick,
+                        // because the rest of the main loop will call into it with the target tick later,
+                        // and it won't be a past prediction.
+                        _entitySystemManager.TickUpdate((float) _timing.TickPeriod.TotalSeconds);
+                        ((IBroadcastEventBusInternal) _entities.EventBus).ProcessEventQueue();
+                    }
+                }
             }
 
-            var pendingInputEnumerator = _pendingInputs.GetEnumerator();
-            var pendingMessagesEnumerator = _pendingSystemMessages.GetEnumerator();
-            var hasPendingInput = pendingInputEnumerator.MoveNext();
-            var hasPendingMessage = pendingMessagesEnumerator.MoveNext();
+            _entities.TickUpdate((float) _timing.TickPeriod.TotalSeconds);
 
-            var ping = _network.ServerChannel!.Ping / 1000f + PredictLagBias; // seconds.
-            var targetTick = _timing.CurTick.Value + _processor.TargetBufferSize +
-                             (int) Math.Ceiling(_timing.TickRate * ping) + PredictTickBias;
-
-            // Logger.DebugS("net.predict", $"Predicting from {_lastProcessedTick} to {targetTick}");
-
-            for (var t = _lastProcessedTick.Value + 1; t <= targetTick; t++)
-            {
-                var tick = new GameTick(t);
-                _timing.CurTick = tick;
-
-                while (hasPendingInput && pendingInputEnumerator.Current.Tick <= tick)
-                {
-                    var inputCmd = pendingInputEnumerator.Current;
-
-                    _inputManager.NetworkBindMap.TryGetKeyFunction(inputCmd.InputFunctionId, out var boundFunc);
-
-                    Logger.DebugS(CVars.NetPredict.Name,
-                        $"    seq={inputCmd.InputSequence}, sub={inputCmd.SubTick}, dTick={tick}, func={boundFunc.FunctionName}, " +
-                        $"state={inputCmd.State}");
-
-
-                    input.PredictInputCommand(inputCmd);
-
-                    hasPendingInput = pendingInputEnumerator.MoveNext();
-                }
-
-                while (hasPendingMessage && pendingMessagesEnumerator.Current.sourceTick <= tick)
-                {
-                    var msg = pendingMessagesEnumerator.Current.msg;
-
-                    _entities.EventBus.RaiseEvent(EventSource.Local, msg);
-                    _entities.EventBus.RaiseEvent(EventSource.Local, pendingMessagesEnumerator.Current.sessionMsg);
-
-                    hasPendingMessage = pendingMessagesEnumerator.MoveNext();
-                }
-
-                if (t != targetTick)
-                {
-                    // Don't run EntitySystemManager.Update if this is the target tick,
-                    // because the rest of the main loop will call into it with the target tick later,
-                    // and it won't be a past prediction.
-                    _entitySystemManager.Update((float) _timing.TickPeriod.TotalSeconds);
-                    ((IEntityEventBus) _entities.EventBus).ProcessEventQueue();
-                }
-            }
+            _lookup.Update();
         }
 
         private void ResetPredictedEntities(GameTick curTick)
@@ -381,7 +394,7 @@ namespace Robust.Client.GameStates
         {
             _config.TickProcessMessages();
             _mapManager.ApplyGameStatePre(curState.MapData);
-            var createdEntities = _entities.ApplyEntityStates(curState.EntityStates, curState.EntityDeletions,
+            var createdEntities = ApplyEntityStates(curState.EntityStates, curState.EntityDeletions,
                 nextState?.EntityStates);
             _players.ApplyPlayerStates(curState.PlayerStates);
             _mapManager.ApplyGameStatePost(curState.MapData);
@@ -389,6 +402,218 @@ namespace Robust.Client.GameStates
             GameStateApplied?.Invoke(new GameStateAppliedArgs(curState));
             return createdEntities;
         }
+
+        private List<EntityUid> ApplyEntityStates(EntityState[]? curEntStates, IEnumerable<EntityUid>? deletions,
+            EntityState[]? nextEntStates)
+        {
+            var toApply = new Dictionary<IEntity, (EntityState?, EntityState?)>();
+            var toInitialize = new List<Entity>();
+            var created = new List<EntityUid>();
+            deletions ??= new EntityUid[0];
+
+            if (curEntStates != null && curEntStates.Length != 0)
+            {
+                foreach (var es in curEntStates)
+                {
+                    //Known entities
+                    if (_entities.TryGetEntity(es.Uid, out var entity))
+                    {
+                        toApply.Add(entity, (es, null));
+                    }
+                    else //Unknown entities
+                    {
+                        var metaState = (MetaDataComponentState?) es.ComponentStates
+                            ?.FirstOrDefault(c => c.NetID == NetIDs.META_DATA);
+                        if (metaState == null)
+                        {
+                            throw new InvalidOperationException($"Server sent new entity state for {es.Uid} without metadata component!");
+                        }
+                        var newEntity = (Entity)_entities.CreateEntity(metaState.PrototypeId, es.Uid);
+                        toApply.Add(newEntity, (es, null));
+                        toInitialize.Add(newEntity);
+                        created.Add(newEntity.Uid);
+                    }
+                }
+            }
+
+            if (nextEntStates != null && nextEntStates.Length != 0)
+            {
+                foreach (var es in nextEntStates)
+                {
+                    if (_entities.TryGetEntity(es.Uid, out var entity))
+                    {
+                        if (toApply.TryGetValue(entity, out var state))
+                        {
+                            toApply[entity] = (state.Item1, es);
+                        }
+                        else
+                        {
+                            toApply[entity] = (null, es);
+                        }
+                    }
+                }
+            }
+
+            // Make sure this is done after all entities have been instantiated.
+            foreach (var kvStates in toApply)
+            {
+                var ent = kvStates.Key;
+                var entity = (Entity) ent;
+                HandleEntityState(entity.EntityManager.ComponentManager, entity, kvStates.Value.Item1,
+                    kvStates.Value.Item2);
+            }
+
+            foreach (var id in deletions)
+            {
+                _entities.DeleteEntity(id);
+            }
+
+#if EXCEPTION_TOLERANCE
+            HashSet<Entity> brokenEnts = new HashSet<Entity>();
+#endif
+
+            foreach (var entity in toInitialize)
+            {
+#if EXCEPTION_TOLERANCE
+                try
+                {
+#endif
+                    _entities.InitializeEntity(entity);
+#if EXCEPTION_TOLERANCE
+                }
+                catch (Exception e)
+                {
+                    Logger.ErrorS("state", $"Server entity threw in Init: uid={entity.Uid}, proto={entity.Prototype}\n{e}");
+                    brokenEnts.Add(entity);
+                }
+#endif
+            }
+
+            foreach (var entity in toInitialize)
+            {
+#if EXCEPTION_TOLERANCE
+                if (brokenEnts.Contains(entity))
+                    continue;
+
+                try
+                {
+#endif
+                    _entities.StartEntity(entity);
+#if EXCEPTION_TOLERANCE
+                }
+                catch (Exception e)
+                {
+                    Logger.ErrorS("state", $"Server entity threw in Start: uid={entity.Uid}, proto={entity.Prototype}\n{e}");
+                    brokenEnts.Add(entity);
+                }
+#endif
+            }
+
+            foreach (var entity in toInitialize)
+            {
+#if EXCEPTION_TOLERANCE
+                if (brokenEnts.Contains(entity))
+                    continue;
+#endif
+            }
+#if EXCEPTION_TOLERANCE
+            foreach (var entity in brokenEnts)
+            {
+                entity.Delete();
+            }
+#endif
+
+            return created;
+        }
+
+        private void HandleEntityState(IComponentManager compMan, IEntity entity, EntityState? curState,
+            EntityState? nextState)
+        {
+            var compStateWork = new Dictionary<uint, (ComponentState? curState, ComponentState? nextState)>();
+            var entityUid = entity.Uid;
+
+            if (curState?.ComponentChanges != null)
+            {
+                foreach (var compChange in curState.ComponentChanges)
+                {
+                    if (compChange.Deleted)
+                    {
+                        if (compMan.TryGetComponent(entityUid, compChange.NetID, out var comp))
+                        {
+                            compMan.RemoveComponent(entityUid, comp);
+                        }
+                    }
+                    else
+                    {
+                        if (compMan.HasComponent(entityUid, compChange.NetID))
+                            continue;
+
+                        var newComp = (Component) _compFactory.GetComponent(compChange.ComponentName!);
+                        newComp.Owner = entity;
+                        compMan.AddComponent(entity, newComp, true);
+                    }
+                }
+            }
+
+            if (curState?.ComponentStates != null)
+            {
+                foreach (var compState in curState.ComponentStates)
+                {
+                    compStateWork[compState.NetID] = (compState, null);
+                }
+            }
+
+            if (nextState?.ComponentStates != null)
+            {
+                foreach (var compState in nextState.ComponentStates)
+                {
+                    if (compStateWork.TryGetValue(compState.NetID, out var state))
+                    {
+                        compStateWork[compState.NetID] = (state.curState, compState);
+                    }
+                    else
+                    {
+                        compStateWork[compState.NetID] = (null, compState);
+                    }
+                }
+            }
+
+            foreach (var (netId, (cur, next)) in compStateWork)
+            {
+                if (compMan.TryGetComponent(entityUid, netId, out var component))
+                {
+                    try
+                    {
+                        component.HandleComponentState(cur, next);
+                    }
+                    catch (Exception e)
+                    {
+                        var wrapper = new ComponentStateApplyException(
+                            $"Failed to apply comp state: entity={component.Owner}, comp={component.Name}", e);
+#if EXCEPTION_TOLERANCE
+                    _runtimeLog.LogException(wrapper, "Component state apply");
+#else
+                        throw wrapper;
+#endif
+                    }
+                }
+                else
+                {
+                    // The component can be null here due to interp.
+                    // Because the NEXT state will have a new component, but this one doesn't yet.
+                    // That's fine though.
+                    if (cur == null)
+                    {
+                        continue;
+                    }
+
+                    var eUid = entityUid;
+                    var eRegisteredNetUidName = _compFactory.GetRegistration(netId).Name;
+                    DebugTools.Assert(
+                        $"Component does not exist for state: entUid={eUid}, expectedNetId={netId}, expectedName={eRegisteredNetUidName}");
+                }
+            }
+        }
     }
 
     public class GameStateAppliedArgs : EventArgs

Robust.Client/GameStates/IClientGameStateManager.cs

@@ -70,6 +70,6 @@ namespace Robust.Client.GameStates
         /// <param name="message">Message being dispatched.</param>
         void InputCommandDispatched(FullInputCmdMessage message);
 
-        uint SystemMessageDispatched<T>(T message) where T : EntitySystemMessage;
+        uint SystemMessageDispatched<T>(T message) where T : EntityEventArgs;
     }
 }

Robust.Client/GameStates/NetEntityOverlay.cs

@@ -1,13 +1,16 @@
 using System.Collections.Generic;
 using Robust.Client.Graphics;
+using Robust.Client.Player;
 using Robust.Client.ResourceManagement;
 using Robust.Shared.Configuration;
 using Robust.Shared.Console;
+using Robust.Shared.Enums;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
 using Robust.Shared.Network;
 using Robust.Shared.Timing;
+using Robust.Shared.Utility;
 
 namespace Robust.Client.GameStates
 {
@@ -27,13 +30,13 @@ namespace Robust.Client.GameStates
         private const int TrafficHistorySize = 64; // Size of the traffic history bar in game ticks.
 
         /// <inheritdoc />
-        public override OverlaySpace Space => OverlaySpace.ScreenSpace;
-        
+        public override OverlaySpace Space => OverlaySpace.ScreenSpace | OverlaySpace.WorldSpace;
+
         private readonly Font _font;
         private readonly int _lineHeight;
         private readonly List<NetEntity> _netEnts = new();
 
-        public NetEntityOverlay() : base(nameof(NetEntityOverlay))
+        public NetEntityOverlay()
         {
             IoCManager.InjectDependencies(this);
             var cache = IoCManager.Resolve<IResourceCache>();
@@ -42,12 +45,12 @@ namespace Robust.Client.GameStates
 
             _gameStateManager.GameStateApplied += HandleGameStateApplied;
         }
-        
+
         private void HandleGameStateApplied(GameStateAppliedArgs args)
         {
             if(_gameTiming.InPrediction) // we only care about real server states.
                 return;
-            
+
             // Shift traffic history down one
             for (var i = 0; i < _netEnts.Count; i++)
             {
@@ -74,7 +77,7 @@ namespace Robust.Client.GameStates
 
                         if (netEnt.Id != entityState.Uid)
                             continue;
-                    
+
                         //TODO: calculate size of state and record it here.
                         netEnt.Traffic[^1] = 1;
                         netEnt.LastUpdate = gameState.ToSequence;
@@ -94,15 +97,15 @@ namespace Robust.Client.GameStates
             }
 
             bool pvsEnabled = _configurationManager.GetCVar<bool>("net.pvs");
-            float pvsSize = _configurationManager.GetCVar<float>("net.maxupdaterange");
+            float pvsRange = _configurationManager.GetCVar<float>("net.maxupdaterange");
             var pvsCenter = _eyeManager.CurrentEye.Position;
-            Box2 pvsBox = Box2.CenteredAround(pvsCenter.Position, new Vector2(pvsSize*2, pvsSize*2));
+            Box2 pvsBox = Box2.CenteredAround(pvsCenter.Position, new Vector2(pvsRange*2, pvsRange*2));
 
             int timeout = _gameTiming.TickRate * 3;
             for (int i = 0; i < _netEnts.Count; i++)
             {
                 var netEnt = _netEnts[i];
-                
+
                 if(_entityManager.EntityExists(netEnt.Id))
                 {
                     //TODO: Whoever is working on PVS remake, change the InPVS detection.
@@ -123,22 +126,58 @@ namespace Robust.Client.GameStates
                 _netEnts[i] = netEnt; // copy struct back
             }
         }
-        
-        protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+
+        protected internal override void Draw(in OverlayDrawArgs args)
         {
             if (!_netManager.IsConnected)
                 return;
 
+            switch (args.Space)
+            {
+                case OverlaySpace.ScreenSpace:
+                    DrawScreen(args);
+                    break;
+                case OverlaySpace.WorldSpace:
+                    DrawWorld(args);
+                    break;
+            }
+        }
+
+        private void DrawWorld(in OverlayDrawArgs args)
+        {
+            bool pvsEnabled = _configurationManager.GetCVar<bool>("net.pvs");
+
+            if(!pvsEnabled)
+                return;
+
+            float pvsSize = _configurationManager.GetCVar<float>("net.maxupdaterange");
+            var pvsCenter = _eyeManager.CurrentEye.Position;
+            Box2 pvsBox = Box2.CenteredAround(pvsCenter.Position, new Vector2(pvsSize, pvsSize));
+
+            var worldHandle = args.WorldHandle;
+
+            worldHandle.DrawRect(pvsBox, Color.Red, false);
+        }
+
+        private void DrawScreen(in OverlayDrawArgs args)
+        {
             // remember, 0,0 is top left of ui with +X right and +Y down
-            var screenHandle = (DrawingHandleScreen)handle;
-            
+            var screenHandle = args.ScreenHandle;
+
             for (int i = 0; i < _netEnts.Count; i++)
             {
                 var netEnt = _netEnts[i];
 
+                if (!_entityManager.TryGetEntity(netEnt.Id, out var ent))
+                {
+                    _netEnts.RemoveSwap(i);
+                    i--;
+                    continue;
+                }
+
                 var xPos = 100;
                 var yPos = 10 + _lineHeight * i;
-                var name = $"({netEnt.Id}) {_entityManager.GetEntity(netEnt.Id).Prototype?.ID}";
+                var name = $"({netEnt.Id}) {ent.Prototype?.ID}";
                 var color = CalcTextColor(ref netEnt);
                 DrawString(screenHandle, _font, new Vector2(xPos + (TrafficHistorySize + 4), yPos), name, color);
                 DrawTrafficBox(screenHandle, ref netEnt, xPos, yPos);
@@ -179,20 +218,19 @@ namespace Robust.Client.GameStates
             return Color.Green; // Entity in PVS, but not updated recently.
         }
 
-        protected override void Dispose(bool disposing)
+        protected override void DisposeBehavior()
         {
             _gameStateManager.GameStateApplied -= HandleGameStateApplied;
-
-            base.Dispose(disposing);
+            base.DisposeBehavior();
         }
 
         private static void DrawString(DrawingHandleScreen handle, Font font, Vector2 pos, string str, Color textColor)
         {
             var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
 
-            foreach (var chr in str)
+            foreach (var rune in str.EnumerateRunes())
             {
-                var advance = font.DrawChar(handle, chr, baseLine, 1, textColor);
+                var advance = font.DrawChar(handle, rune, baseLine, 1, textColor);
                 baseLine += new Vector2(advance, 0);
             }
         }
@@ -225,7 +263,7 @@ namespace Robust.Client.GameStates
             {
                 if (args.Length != 1)
                 {
-                    shell.WriteError("Invalid argument amount. Expected 2 arguments.");
+                    shell.WriteError("Invalid argument amount. Expected 1 arguments.");
                     return;
                 }
 
@@ -238,14 +276,14 @@ namespace Robust.Client.GameStates
                 var bValue = iValue > 0;
                 var overlayMan = IoCManager.Resolve<IOverlayManager>();
 
-                if(bValue && !overlayMan.HasOverlay(nameof(NetEntityOverlay)))
+                if(bValue && !overlayMan.HasOverlay(typeof(NetEntityOverlay)))
                 {
                     overlayMan.AddOverlay(new NetEntityOverlay());
                     shell.WriteLine("Enabled network entity report overlay.");
                 }
-                else if(!bValue && overlayMan.HasOverlay(nameof(NetEntityOverlay)))
+                else if(!bValue && overlayMan.HasOverlay(typeof(NetEntityOverlay)))
                 {
-                    overlayMan.RemoveOverlay(nameof(NetEntityOverlay));
+                    overlayMan.RemoveOverlay(typeof(NetEntityOverlay));
                     shell.WriteLine("Disabled network entity report overlay.");
                 }
             }

Robust.Client/GameStates/NetGraphOverlay.cs

@@ -1,7 +1,11 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
+using System.Text;
 using Robust.Client.Graphics;
 using Robust.Client.ResourceManagement;
+using Robust.Shared.Enums;
 using Robust.Shared.Console;
+using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
 using Robust.Shared.Network;
@@ -34,7 +38,11 @@ namespace Robust.Client.GameStates
 
         private readonly List<(GameTick Tick, int Payload, int lag, int interp)> _history = new(HistorySize+10);
 
-        public NetGraphOverlay() : base(nameof(NetGraphOverlay))
+        private int _totalHistoryPayload; // sum of all data point sizes in bytes
+
+        public EntityUid WatchEntId { get; set; }
+
+        public NetGraphOverlay()
         {
             IoCManager.InjectDependencies(this);
             var cache = IoCManager.Resolve<IResourceCache>();
@@ -58,7 +66,73 @@ namespace Robust.Client.GameStates
             // calc interp info
             var interpBuff = _gameStateManager.CurrentBufferSize - _gameStateManager.MinBufferSize;
 
+            _totalHistoryPayload += sz;
             _history.Add((toSeq, sz, lag, interpBuff));
+
+            // not watching an ent
+            if(!WatchEntId.IsValid() || WatchEntId.IsClientSide())
+                return;
+
+            string? entStateString = null;
+            string? entDelString = null;
+            var conShell = IoCManager.Resolve<IConsoleHost>().LocalShell;
+
+            var entStates = args.AppliedState.EntityStates;
+            if (entStates is not null)
+            {
+                var sb = new StringBuilder();
+                foreach (var entState in entStates)
+                {
+                    if (entState.Uid == WatchEntId)
+                    {
+                        if(entState.ComponentChanges is not null)
+                        {
+                            sb.Append($"\n  Changes:");
+                            foreach (var compChange in entState.ComponentChanges)
+                            {
+                                var del = compChange.Deleted ? 'D' : 'C';
+                                sb.Append($"\n    [{del}]{compChange.NetID}:{compChange.ComponentName}");
+                            }
+                        }
+
+                        if (entState.ComponentStates is not null)
+                        {
+                            sb.Append($"\n  States:");
+                            foreach (var compState in entState.ComponentStates)
+                            {
+                                sb.Append($"\n    {compState.NetID}:{compState.GetType().Name}");
+                            }
+                        }
+                    }
+                }
+                entStateString = sb.ToString();
+            }
+
+            var entDeletes = args.AppliedState.EntityDeletions;
+            if (entDeletes is not null)
+            {
+                var sb = new StringBuilder();
+                foreach (var entDelete in entDeletes)
+                {
+                    if (entDelete == WatchEntId)
+                    {
+                        entDelString = "\n  Deleted";
+                    }
+                }
+            }
+
+            if (!string.IsNullOrWhiteSpace(entStateString) || !string.IsNullOrWhiteSpace(entDelString))
+            {
+                var fullString = $"watchEnt: from={args.AppliedState.FromSequence}, to={args.AppliedState.ToSequence}, eid={WatchEntId}";
+                if (!string.IsNullOrWhiteSpace(entStateString))
+                    fullString += entStateString;
+
+                if (!string.IsNullOrWhiteSpace(entDelString))
+                    fullString += entDelString;
+
+                conShell.WriteLine(fullString + "\n");
+            }
+
         }
 
         /// <inheritdoc />
@@ -67,19 +141,27 @@ namespace Robust.Client.GameStates
             base.FrameUpdate(args);
 
             var over = _history.Count - HistorySize;
-            if (over > 0)
+            if (over <= 0)
+                return;
+
+            for (int i = 0; i < over; i++)
             {
-                _history.RemoveRange(0, over);
+                var point = _history[i];
+                _totalHistoryPayload -= point.Payload;
             }
+
+            _history.RemoveRange(0, over);
         }
 
-        protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+        protected internal override void Draw(in OverlayDrawArgs args)
         {
             // remember, 0,0 is top left of ui with +X right and +Y down
 
             var leftMargin = 300;
             var width = HistorySize;
             var height = 500;
+            var drawSizeThreshold = Math.Min(_totalHistoryPayload / HistorySize, 300);
+            var handle = args.ScreenHandle;
 
             // bottom payload line
             handle.DrawLine(new Vector2(leftMargin, height), new Vector2(leftMargin + width, height), Color.DarkGray.WithAlpha(0.8f));
@@ -99,6 +181,12 @@ namespace Robust.Client.GameStates
                 var yoff = height - state.Payload / BytesPerPixel;
                 handle.DrawLine(new Vector2(xOff, height), new Vector2(xOff, yoff), Color.LightGreen.WithAlpha(0.8f));
 
+                // Draw size if above average
+                if (drawSizeThreshold * 1.5 < state.Payload)
+                {
+                    DrawString(handle, _font, new Vector2(xOff, yoff - _font.GetLineHeight(1)), state.Payload.ToString());
+                }
+
                 // second tick marks
                 if (state.Tick.Value % _gameTiming.TickRate == 0)
                 {
@@ -123,6 +211,10 @@ namespace Robust.Client.GameStates
                 handle.DrawLine(new Vector2(xOff, height + LowerGraphOffset), new Vector2(xOff, height + LowerGraphOffset + state.interp * 6), interpColor.WithAlpha(0.8f));
             }
 
+            // average payload line
+            var avgyoff = height - drawSizeThreshold / BytesPerPixel;
+            handle.DrawLine(new Vector2(leftMargin, avgyoff), new Vector2(leftMargin + width, avgyoff), Color.DarkGray.WithAlpha(0.8f));
+
             // top payload warning line
             var warnYoff = height - _warningPayloadSize / BytesPerPixel;
             handle.DrawLine(new Vector2(leftMargin, warnYoff), new Vector2(leftMargin + width, warnYoff), Color.DarkGray.WithAlpha(0.8f));
@@ -132,30 +224,30 @@ namespace Robust.Client.GameStates
             handle.DrawLine(new Vector2(leftMargin, midYoff), new Vector2(leftMargin + width, midYoff), Color.DarkGray.WithAlpha(0.8f));
 
             // payload text
-            DrawString((DrawingHandleScreen)handle, _font, new Vector2(leftMargin + width, warnYoff), "56K");
-            DrawString((DrawingHandleScreen)handle, _font, new Vector2(leftMargin + width, midYoff), "33.6K");
+            DrawString(handle, _font, new Vector2(leftMargin + width, warnYoff), "56K");
+            DrawString(handle, _font, new Vector2(leftMargin + width, midYoff), "33.6K");
 
             // interp text info
             if(lastLagY != -1)
-                DrawString((DrawingHandleScreen)handle, _font, new Vector2(leftMargin + width, lastLagY), $"{lastLagMs.ToString()}ms");
+                DrawString(handle, _font, new Vector2(leftMargin + width, lastLagY), $"{lastLagMs.ToString()}ms");
 
-            DrawString((DrawingHandleScreen)handle, _font, new Vector2(leftMargin, height + LowerGraphOffset), $"{_gameStateManager.CurrentBufferSize.ToString()} states");
+            DrawString(handle, _font, new Vector2(leftMargin, height + LowerGraphOffset), $"{_gameStateManager.CurrentBufferSize.ToString()} states");
         }
 
-        protected override void Dispose(bool disposing)
+        protected override void DisposeBehavior()
         {
             _gameStateManager.GameStateApplied -= HandleGameStateApplied;
 
-            base.Dispose(disposing);
+            base.DisposeBehavior();
         }
 
         private void DrawString(DrawingHandleScreen handle, Font font, Vector2 pos, string str)
         {
             var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
 
-            foreach (var chr in str)
+            foreach (var rune in str.EnumerateRunes())
             {
-                var advance = font.DrawChar(handle, chr, baseLine, 1, Color.White);
+                var advance = font.DrawChar(handle, rune, baseLine, 1, Color.White);
                 baseLine += new Vector2(advance, 0);
             }
         }
@@ -183,17 +275,48 @@ namespace Robust.Client.GameStates
                 var bValue = iValue > 0;
                 var overlayMan = IoCManager.Resolve<IOverlayManager>();
 
-                if(bValue && !overlayMan.HasOverlay(nameof(NetGraphOverlay)))
+                if(bValue && !overlayMan.HasOverlay(typeof(NetGraphOverlay)))
                 {
                     overlayMan.AddOverlay(new NetGraphOverlay());
                     shell.WriteLine("Enabled network overlay.");
                 }
-                else if(overlayMan.HasOverlay(nameof(NetGraphOverlay)))
+                else if(overlayMan.HasOverlay(typeof(NetGraphOverlay)))
                 {
-                    overlayMan.RemoveOverlay(nameof(NetGraphOverlay));
+                    overlayMan.RemoveOverlay(typeof(NetGraphOverlay));
                     shell.WriteLine("Disabled network overlay.");
                 }
             }
         }
+
+        private class NetWatchEntCommand : IConsoleCommand
+        {
+            public string Command => "net_watchent";
+            public string Help => "net_watchent <0|EntityUid>";
+            public string Description => "Dumps all network updates for an EntityId to the console.";
+
+            public void Execute(IConsoleShell shell, string argStr, string[] args)
+            {
+                if (args.Length != 1)
+                {
+                    shell.WriteError("Invalid argument amount. Expected 1 argument.");
+                    return;
+                }
+
+                if (!EntityUid.TryParse(args[0], out var eValue))
+                {
+                    shell.WriteError("Invalid argument: Needs to be 0 or an entityId.");
+                    return;
+                }
+
+                var overlayMan = IoCManager.Resolve<IOverlayManager>();
+
+                if (overlayMan.HasOverlay(typeof(NetGraphOverlay)))
+                {
+                    var netOverlay = overlayMan.GetOverlay<NetGraphOverlay>();
+
+                    netOverlay.WatchEntId = eValue;
+                }
+            }
+        }
     }
 }

Robust.Client/GameStates/NetInterpOverlay.cs

@@ -1,3 +1,4 @@
+using Robust.Shared.Enums;
 using Robust.Client.Graphics;
 using Robust.Shared.Console;
 using Robust.Shared.GameObjects;
@@ -5,6 +6,7 @@ using Robust.Shared.IoC;
 using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Prototypes;
+using System;
 using Robust.Shared.Timing;
 
 namespace Robust.Client.GameStates
@@ -18,14 +20,15 @@ namespace Robust.Client.GameStates
         public override OverlaySpace Space => OverlaySpace.WorldSpace;
         private readonly ShaderInstance _shader;
 
-        public NetInterpOverlay() : base(nameof(NetInterpOverlay))
+        public NetInterpOverlay()
         {
             IoCManager.InjectDependencies(this);
             _shader = _prototypeManager.Index<ShaderPrototype>("unshaded").Instance();
         }
 
-        protected override void Draw(DrawingHandleBase handle, OverlaySpace currentSpace)
+        protected internal override void Draw(in OverlayDrawArgs args)
         {
+            var handle = args.DrawingHandle;
             handle.UseShader(_shader);
             var worldHandle = (DrawingHandleWorld) handle;
             var viewport = _eyeManager.GetWorldViewport();
@@ -85,14 +88,14 @@ namespace Robust.Client.GameStates
                 var bValue = iValue > 0;
                 var overlayMan = IoCManager.Resolve<IOverlayManager>();
 
-                if (bValue && !overlayMan.HasOverlay(nameof(NetInterpOverlay)))
+                if (bValue && !overlayMan.HasOverlay<NetInterpOverlay>())
                 {
                     overlayMan.AddOverlay(new NetInterpOverlay());
                     shell.WriteLine("Enabled network interp overlay.");
                 }
-                else if (overlayMan.HasOverlay(nameof(NetInterpOverlay)))
+                else if (overlayMan.HasOverlay<NetInterpOverlay>())
                 {
-                    overlayMan.RemoveOverlay(nameof(NetInterpOverlay));
+                    overlayMan.RemoveOverlay<NetInterpOverlay>();
                     shell.WriteLine("Disabled network interp overlay.");
                 }
             }

Robust.Client/Graphics/AtlasTexture.cs

@@ -1,4 +1,4 @@
-using JetBrains.Annotations;
+using JetBrains.Annotations;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
 

Robust.Client/Graphics/ClientEye/Eye.cs

@@ -50,9 +50,9 @@ namespace Robust.Client.Graphics
         }
 
         /// <inheritdoc />
-        public void GetViewMatrix(out Matrix3 viewMatrix)
+        public void GetViewMatrix(out Matrix3 viewMatrix, Vector2 renderScale)
         {
-            var scaleMat = Matrix3.CreateScale(_scale.X, _scale.Y);
+            var scaleMat = Matrix3.CreateScale(_scale.X * renderScale.X, _scale.Y * renderScale.Y);
             var rotMat = Matrix3.CreateRotation(_rotation);
             var transMat = Matrix3.CreateTranslation(-_coords.Position);
 
@@ -60,9 +60,9 @@ namespace Robust.Client.Graphics
         }
 
         /// <inheritdoc />
-        public void GetViewMatrixInv(out Matrix3 viewMatrixInv)
+        public void GetViewMatrixInv(out Matrix3 viewMatrixInv, Vector2 renderScale)
         {
-            GetViewMatrix(out var viewMatrix);
+            GetViewMatrix(out var viewMatrix, renderScale);
             viewMatrixInv = Matrix3.Invert(viewMatrix);
         }
     }

Robust.Client/Graphics/ClientEye/EyeManager.cs

@@ -1,4 +1,6 @@
-using Robust.Shared.GameObjects;
+using Robust.Client.UserInterface;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
@@ -19,6 +21,7 @@ namespace Robust.Client.Graphics
 
         [Dependency] private readonly IClyde _displayManager = default!;
         [Dependency] private readonly IEntityManager _entityManager = default!;
+        [Dependency] private readonly IUserInterfaceManager _uiManager = default!;
 
         // We default to this when we get set to a null eye.
         private readonly FixedEye _defaultEye = new();
@@ -32,11 +35,18 @@ namespace Robust.Client.Graphics
             set => _currentEye = value;
         }
 
+        public IViewportControl MainViewport { get; set; } = default!;
+
         public void ClearCurrentEye()
         {
             _currentEye = _defaultEye;
         }
 
+        void IEyeManager.Initialize()
+        {
+            MainViewport = _uiManager.MainViewport;
+        }
+
         /// <inheritdoc />
         public MapId CurrentMap => CurrentEye.Position.MapId;
 
@@ -49,7 +59,7 @@ namespace Robust.Client.Graphics
             var topRight = ScreenToMap(new Vector2(vpSize.X, 0));
             var bottomRight = ScreenToMap(vpSize);
             var bottomLeft = ScreenToMap(new Vector2(0, vpSize.Y));
-            
+
             var left = MathHelper.Min(topLeft.X, topRight.X, bottomRight.X, bottomLeft.X);
             var bottom = MathHelper.Min(topLeft.Y, topRight.Y, bottomRight.Y, bottomLeft.Y);
             var right = MathHelper.Max(topLeft.X, topRight.X, bottomRight.X, bottomLeft.X);
@@ -61,16 +71,7 @@ namespace Robust.Client.Graphics
         /// <inheritdoc />
         public Vector2 WorldToScreen(Vector2 point)
         {
-            var newPoint = point;
-
-            CurrentEye.GetViewMatrix(out var viewMatrix);
-            newPoint = viewMatrix * newPoint;
-
-            // (inlined version of UiProjMatrix)
-            newPoint *= new Vector2(1, -1) * PixelsPerMeter;
-            newPoint += _displayManager.ScreenSize / 2f;
-
-            return newPoint;
+            return MainViewport.WorldToScreen(point);
         }
 
         /// <inheritdoc />
@@ -115,17 +116,7 @@ namespace Robust.Client.Graphics
         /// <inheritdoc />
         public MapCoordinates ScreenToMap(Vector2 point)
         {
-            var newPoint = point;
-
-            // (inlined version of UiProjMatrix^-1)
-            newPoint -= _displayManager.ScreenSize / 2f;
-            newPoint *= new Vector2(1, -1) / PixelsPerMeter;
-
-            // view matrix
-            CurrentEye.GetViewMatrixInv(out var viewMatrixInv);
-            newPoint = viewMatrixInv * newPoint;
-
-            return new MapCoordinates(newPoint, CurrentMap);
+            return MainViewport.ScreenToMap(point);
         }
     }
 }

Robust.Client/Graphics/ClientEye/IEye.cs

@@ -41,13 +41,15 @@ namespace Robust.Client.Graphics
         /// world space to camera space.
         /// </summary>
         /// <param name="viewMatrix">View matrix for this camera.</param>
-        void GetViewMatrix(out Matrix3 viewMatrix);
+        /// <param name="renderScale"></param>
+        void GetViewMatrix(out Matrix3 viewMatrix, Vector2 renderScale);
 
         /// <summary>
         /// Returns the inverted view matrix for this eye, used to convert a point from
         /// camera space to world space.
         /// </summary>
         /// <param name="viewMatrixInv">Inverted view matrix for this camera.</param>
-        void GetViewMatrixInv(out Matrix3 viewMatrixInv);
+        /// <param name="renderScale"></param>
+        void GetViewMatrixInv(out Matrix3 viewMatrixInv, Vector2 renderScale);
     }
 }

Robust.Client/Graphics/ClientEye/IEyeManager.cs

@@ -1,4 +1,5 @@
-using Robust.Shared.Map;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
@@ -17,6 +18,8 @@ namespace Robust.Client.Graphics
         /// </remarks>
         IEye CurrentEye { get; set; }
 
+        IViewportControl MainViewport { get; set; }
+
         /// <summary>
         /// The ID of the map on which the current eye is "placed".
         /// </summary>
@@ -72,5 +75,6 @@ namespace Robust.Client.Graphics
         MapCoordinates ScreenToMap(Vector2 point);
 
         void ClearCurrentEye();
+        void Initialize();
     }
 }

Robust.Client/Graphics/Clyde/Audio/Clyde.Audio.cs

@@ -53,7 +53,7 @@ namespace Robust.Client.Graphics.Clyde
 
             IsEfxSupported = HasAlDeviceExtension("ALC_EXT_EFX");
 
-            _configurationManager.OnValueChanged(CVars.AudioMasterVolume, SetMasterVolume, true);
+            ConfigurationManager.OnValueChanged(CVars.AudioMasterVolume, SetMasterVolume, true);
         }
 
         private void _audioCreateContext()
@@ -81,7 +81,7 @@ namespace Robust.Client.Graphics.Clyde
 
         private void _audioOpenDevice()
         {
-            var preferredDevice = _configurationManager.GetCVar(CVars.AudioDevice);
+            var preferredDevice = ConfigurationManager.GetCVar(CVars.AudioDevice);
 
             // Open device.
             if (!string.IsNullOrEmpty(preferredDevice))
@@ -482,7 +482,7 @@ namespace Robust.Client.Graphics.Clyde
 
                 var (x, y) = position;
 
-                if (!ValidatePosition(x, y))
+                if (!AreFinite(x, y))
                 {
                     return false;
                 }
@@ -503,7 +503,7 @@ namespace Robust.Client.Graphics.Clyde
                 return true;
             }
 
-            private static bool ValidatePosition(float x, float y)
+            private static bool AreFinite(float x, float y)
             {
                 if (float.IsFinite(x) && float.IsFinite(y))
                 {
@@ -513,6 +513,22 @@ namespace Robust.Client.Graphics.Clyde
                 return false;
             }
 
+            public void SetVelocity(Vector2 velocity)
+            {
+                _checkDisposed();
+
+                var (x, y) = velocity;
+
+                if (!AreFinite(x, y))
+                {
+                    return;
+                }
+
+                AL.Source(SourceHandle, ALSource3f.Velocity, x, y, 0);
+
+                _checkAlError();
+            }
+
             public void SetPitch(float pitch)
             {
                 _checkDisposed();
@@ -667,7 +683,6 @@ namespace Robust.Client.Graphics.Clyde
                 _checkAlError();
             }
 
-
             private void SetOcclusionEfx(float gain, float cutoff)
             {
                 if (FilterHandle == 0)
@@ -694,7 +709,7 @@ namespace Robust.Client.Graphics.Clyde
 
                 var (x, y) = position;
 
-                if (!ValidatePosition(x, y))
+                if (!AreFinite(x, y))
                 {
                     return false;
                 }
@@ -706,7 +721,7 @@ namespace Robust.Client.Graphics.Clyde
                 return true;
             }
 
-            private static bool ValidatePosition(float x, float y)
+            private static bool AreFinite(float x, float y)
             {
                 if (float.IsFinite(x) && float.IsFinite(y))
                 {
@@ -716,6 +731,22 @@ namespace Robust.Client.Graphics.Clyde
                 return false;
             }
 
+            public void SetVelocity(Vector2 velocity)
+            {
+                _checkDisposed();
+
+                var (x, y) = velocity;
+
+                if (!AreFinite(x, y))
+                {
+                    return;
+                }
+
+                AL.Source(SourceHandle!.Value, ALSource3f.Velocity, x, y, 0);
+
+                _checkAlError();
+            }
+
             public void SetPitch(float pitch)
             {
                 _checkDisposed();

Robust.Client/Graphics/Clyde/Clyde.DllMap.cs

@@ -12,7 +12,8 @@ namespace Robust.Client.Graphics.Clyde
         static Clyde()
         {
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&
-                RuntimeInformation.ProcessArchitecture == Architecture.X64)
+                RuntimeInformation.ProcessArchitecture == Architecture.X64 &&
+                Environment.GetEnvironmentVariable("ROBUST_INTEGRATED_GPU") != "1")
             {
                 try
                 {

Robust.Client/Graphics/Clyde/Clyde.GLFeatures.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using OpenToolkit.Graphics.OpenGL4;
 using Robust.Shared.Log;
@@ -115,7 +115,7 @@ namespace Robust.Client.Graphics.Clyde
 
                 var prev = cap;
                 var cVarName = $"display.ogl_block_{capName}";
-                var block = _configurationManager.GetCVar<bool>(cVarName);
+                var block = ConfigurationManager.GetCVar<bool>(cVarName);
 
                 if (block)
                 {
@@ -146,7 +146,7 @@ namespace Robust.Client.Graphics.Clyde
 
             foreach (var cvar in cvars)
             {
-                _configurationManager.RegisterCVar($"display.ogl_block_{cvar}", false);
+                ConfigurationManager.RegisterCVar($"display.ogl_block_{cvar}", false);
             }
         }
 

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

@@ -208,12 +208,12 @@ namespace Robust.Client.Graphics.Clyde
             _setChunkDirty(grid, chunk);
         }
 
-        private void _updateOnGridCreated(GridId gridId)
+        private void _updateOnGridCreated(MapId mapId, GridId gridId)
         {
             _mapChunkData.Add(gridId, new Dictionary<Vector2i, MapChunkData>());
         }
 
-        private void _updateOnGridRemoved(GridId gridId)
+        private void _updateOnGridRemoved(MapId mapId, GridId gridId)
         {
             var data = _mapChunkData[gridId];
             foreach (var chunkDatum in data.Values)

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

@@ -7,6 +7,9 @@ using Robust.Client.ResourceManagement;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
+using OpenToolkit.Graphics.OpenGL4;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Enums;
 
 namespace Robust.Client.Graphics.Clyde
 {
@@ -65,67 +68,136 @@ namespace Robust.Client.Graphics.Clyde
                 return;
             }
 
-            RenderOverlays(OverlaySpace.ScreenSpaceBelowWorld);
-
-            _mainViewport.Eye = _eyeManager.CurrentEye;
-            RenderViewport(_mainViewport);
-
+            foreach (var weak in _viewports.Values)
             {
-                var handle = _renderHandle.DrawingHandleScreen;
-                var tex = _mainViewport.RenderTarget.Texture;
-
-                handle.DrawTexture(tex, (0, 0));
-                FlushRenderQueue();
+                if (weak.TryGetTarget(out var viewport) && viewport.AutomaticRender)
+                    RenderViewport(viewport);
             }
 
-            TakeScreenshot(ScreenshotType.BeforeUI);
-
-            RenderOverlays(OverlaySpace.ScreenSpace);
-
             using (DebugGroup("UI"))
             {
                 _userInterfaceManager.Render(_renderHandle);
                 FlushRenderQueue();
             }
 
-            TakeScreenshot(ScreenshotType.AfterUI);
+            TakeScreenshot(ScreenshotType.Final);
 
             // And finally, swap those buffers!
             SwapBuffers();
         }
 
-        private void RenderOverlays(OverlaySpace space)
+        private void RenderOverlays(Viewport vp, OverlaySpace space, in Box2 worldBox)
         {
             using (DebugGroup($"Overlays: {space}"))
             {
-                var list = new List<Overlay>();
-
-                foreach (var overlay in _overlayManager.AllOverlays)
-                {
-                    if ((overlay.Space & space) != 0)
-                    {
-                        list.Add(overlay);
-                    }
-                }
-
-                list.Sort(OverlayComparer.Instance);
-
+                var list = GetOverlaysForSpace(space);
                 foreach (var overlay in list)
                 {
-                    overlay.ClydeRender(_renderHandle, space);
-                }
+                    if (overlay.RequestScreenTexture)
+                    {
+                        FlushRenderQueue();
+                        UpdateOverlayScreenTexture(space, vp.RenderTarget);
+                    }
 
-                FlushRenderQueue();
+                    if (overlay.OverwriteTargetFrameBuffer())
+                    {
+                        ClearFramebuffer(default);
+                    }
+
+                    overlay.ClydeRender(_renderHandle, space, null, vp, new UIBox2i((0, 0), vp.Size), worldBox);
+                }
             }
         }
 
-        private void DrawEntitiesAndWorldOverlay(Viewport viewport, Box2 worldBounds)
+        private void RenderOverlaysDirect(
+            Viewport vp,
+            IViewportControl vpControl,
+            DrawingHandleBase handle,
+            OverlaySpace space,
+            in UIBox2i bounds)
+        {
+            var list = GetOverlaysForSpace(space);
+
+            var worldBounds = CalcWorldBounds(vp);
+            var args = new OverlayDrawArgs(space, vpControl, vp, handle, bounds, worldBounds);
+
+            foreach (var overlay in list)
+            {
+                overlay.Draw(args);
+            }
+        }
+
+        private List<Overlay> GetOverlaysForSpace(OverlaySpace space)
+        {
+            var list = new List<Overlay>();
+
+            foreach (var overlay in _overlayManager.AllOverlays)
+            {
+                if ((overlay.Space & space) != 0)
+                {
+                    list.Add(overlay);
+                }
+            }
+
+            list.Sort(OverlayComparer.Instance);
+
+            return list;
+        }
+
+        private ClydeTexture? ScreenBufferTexture;
+        private GLHandle screenBufferHandle;
+        private Vector2 lastFrameSize;
+
+        /// <summary>
+        ///    Sends SCREEN_TEXTURE to all overlays in the given OverlaySpace that request it.
+        /// </summary>
+        private bool UpdateOverlayScreenTexture(OverlaySpace space, RenderTexture texture)
+        {
+            //This currently does NOT consider viewports and just grabs the current screen framebuffer. This will need to be improved upon in the future.
+            List<Overlay> oTargets = new List<Overlay>();
+            foreach (var overlay in _overlayManager.AllOverlays)
+            {
+                if (overlay.RequestScreenTexture && overlay.Space == space)
+                {
+                    oTargets.Add(overlay);
+                }
+            }
+
+            if (oTargets.Count > 0 && ScreenBufferTexture != null)
+            {
+                if (lastFrameSize != _framebufferSize)
+                {
+                    GL.BindTexture(TextureTarget.Texture2D, screenBufferHandle.Handle);
+                    GL.TexImage2D(TextureTarget.Texture2D, 0,
+                        _hasGLSrgb ? PixelInternalFormat.Srgb8Alpha8 : PixelInternalFormat.Rgba8, _framebufferSize.X,
+                        _framebufferSize.Y, 0,
+                        PixelFormat.Rgba, PixelType.UnsignedByte, IntPtr.Zero);
+                }
+
+                lastFrameSize = _framebufferSize;
+                CopyRenderTextureToTexture(texture, ScreenBufferTexture);
+                foreach (Overlay overlay in oTargets)
+                {
+                    overlay.ScreenTexture = ScreenBufferTexture;
+                }
+
+                oTargets.Clear();
+                return true;
+            }
+
+            return false;
+        }
+
+
+        private void DrawEntities(Viewport viewport, Box2 worldBounds)
         {
             if (_eyeManager.CurrentMap == MapId.Nullspace || !_mapManager.HasMapEntity(_eyeManager.CurrentMap))
             {
                 return;
             }
 
+            RenderOverlays(viewport, OverlaySpace.WorldSpaceBelowEntities, worldBounds);
+
             var screenSize = viewport.Size;
 
             // So we could calculate the correct size of the entities based on the contents of their sprite...
@@ -175,7 +247,13 @@ namespace Robust.Client.Graphics.Clyde
                             flushed = true;
                         }
 
-                        overlay.ClydeRender(_renderHandle, OverlaySpace.WorldSpace);
+                        overlay.ClydeRender(
+                            _renderHandle,
+                            OverlaySpace.WorldSpace,
+                            null,
+                            viewport,
+                            new UIBox2i((0, 0), viewport.Size),
+                            worldBounds);
                         overlayIndex = j;
                         continue;
                     }
@@ -194,13 +272,13 @@ namespace Robust.Client.Graphics.Clyde
                     var spriteRT = spriteBB.TopRight;
 
                     // finally we can calculate screen bounding in pixels
-                    var screenLB = _eyeManager.WorldToScreen(spriteLB);
-                    var screenRT = _eyeManager.WorldToScreen(spriteRT);
+                    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();
+                    var screenSpriteSize = (Vector2i) ((screenRT - screenLB) * postShadeScale).Rounded();
                     screenSpriteSize.Y = -screenSpriteSize.Y;
 
                     // I'm not 100% sure why it works, but without it post-shader
@@ -225,8 +303,8 @@ namespace Robust.Client.Graphics.Clyde
                         // which is necessary for light application,
                         // but it's ACTUALLY drawing into the center of the render target.
                         var spritePos = spriteBB.Center;
-                        var screenPos = _eyeManager.WorldToScreen(spritePos);
-                        var (roundedX, roundedY) = roundedPos = (Vector2i)screenPos;
+                        var screenPos = viewport.WorldToLocal(spritePos);
+                        var (roundedX, roundedY) = roundedPos = (Vector2i) screenPos;
                         var flippedPos = new Vector2i(roundedX, screenSize.Y - roundedY);
                         flippedPos -= entityPostRenderTarget.Size / 2;
                         _renderHandle.Viewport(Box2i.FromDimensions(-flippedPos, screenSize));
@@ -267,14 +345,6 @@ namespace Robust.Client.Graphics.Clyde
 
             _drawingSpriteList.Clear();
             FlushRenderQueue();
-
-            // Cleanup remainders
-            foreach (var overlay in worldOverlays)
-            {
-                overlay.ClydeRender(_renderHandle, OverlaySpace.WorldSpace);
-            }
-
-            FlushRenderQueue();
         }
 
         [MethodImpl(MethodImplOptions.NoInlining)]
@@ -283,29 +353,44 @@ namespace Robust.Client.Graphics.Clyde
         {
             var spriteSystem = _entitySystemManager.GetEntitySystem<RenderingTreeSystem>();
 
-            var tree = spriteSystem.GetSpriteTreeForMap(map);
-
-            tree.QueryAabb(ref list, ((
-                ref RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> state,
-                in SpriteComponent value) =>
+            foreach (var gridId in _mapManager.FindGridIdsIntersecting(map, worldBounds, true))
             {
-                if (value.ContainerOccluded || !value.Visible)
+                Box2 gridBounds;
+
+                if (gridId == GridId.Invalid)
                 {
-                    return true;
+                    gridBounds = worldBounds;
+                }
+                else
+                {
+                    gridBounds = worldBounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
                 }
 
-                var entity = value.Owner;
-                var transform = entity.Transform;
+                var tree = spriteSystem.GetSpriteTreeForMap(map, gridId);
 
-                ref var entry = ref state.AllocAdd();
-                entry.sprite = value;
-                entry.worldRot = transform.WorldRotation;
-                entry.matrix = transform.WorldMatrix;
-                var worldPos = entry.matrix.Transform(transform.LocalPosition);
-                entry.yWorldPos = worldPos.Y;
-                return true;
+                tree.QueryAabb(ref list, ((
+                    ref RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> state,
+                    in SpriteComponent value) =>
+                {
+                    // TODO: Probably value in storing this as its own DynamicTree
+                    if (value.ContainerOccluded || !value.Visible)
+                    {
+                        return true;
+                    }
 
-            }), worldBounds, approx: true);
+                    var entity = value.Owner;
+                    var transform = entity.Transform;
+
+                    ref var entry = ref state.AllocAdd();
+                    entry.sprite = value;
+                    entry.worldRot = transform.WorldRotation;
+                    entry.matrix = transform.WorldMatrix;
+                    var worldPos = entry.matrix.Transform(transform.LocalPosition);
+                    entry.yWorldPos = worldPos.Y;
+                    return true;
+
+                }), gridBounds, approx: true);
+            }
         }
 
         private void DrawSplash(IRenderHandle handle)
@@ -317,11 +402,13 @@ namespace Robust.Client.Graphics.Clyde
 
         private void RenderViewport(Viewport viewport)
         {
-            if (viewport.Eye == null)
+            if (viewport.Eye == null || viewport.Eye.Position.MapId == MapId.Nullspace)
             {
                 return;
             }
 
+            using var _ = DebugGroup($"Viewport: {viewport.Name}");
+
             // TODO: for the love of god all this state pushing/popping needs to be cleaned up.
 
             var oldTransform = _currentMatrixModel;
@@ -346,12 +433,11 @@ namespace Robust.Client.Graphics.Clyde
                 SetViewportImmediate(Box2i.FromDimensions(Vector2i.Zero, rt.Size));
                 _updateUniformConstants(viewport.Size);
 
-                CalcWorldMatrices(rt.Size, eye, out var proj, out var view);
+                CalcWorldMatrices(rt.Size, viewport.RenderScale, eye, out var proj, out var view);
                 SetProjViewFull(proj, view);
 
                 // Calculate world-space AABB for camera, to cull off-screen things.
-                var worldBounds = Box2.CenteredAround(eye.Position.Position,
-                    _framebufferSize / (float) EyeManager.PixelsPerMeter * eye.Zoom);
+                var worldBounds = CalcWorldBounds(viewport);
 
                 if (_eyeManager.CurrentMap != MapId.Nullspace)
                 {
@@ -360,6 +446,9 @@ namespace Robust.Client.Graphics.Clyde
                         DrawLightsAndFov(viewport, worldBounds, eye);
                     }
 
+                    RenderOverlays(viewport, OverlaySpace.WorldSpaceBelowWorld, worldBounds);
+                    FlushRenderQueue();
+
                     using (DebugGroup("Grids"))
                     {
                         _drawGrids(worldBounds);
@@ -368,9 +457,11 @@ namespace Robust.Client.Graphics.Clyde
                     // We will also render worldspace overlays here so we can do them under / above entities as necessary
                     using (DebugGroup("Entities"))
                     {
-                        DrawEntitiesAndWorldOverlay(viewport, worldBounds);
+                        DrawEntities(viewport, worldBounds);
                     }
 
+                    RenderOverlays(viewport, OverlaySpace.WorldSpaceBelowFOV, worldBounds);
+
                     if (_lightManager.Enabled && _lightManager.DrawHardFov && eye.DrawFov)
                     {
                         ApplyFovToBuffer(viewport, eye);
@@ -401,6 +492,9 @@ namespace Robust.Client.Graphics.Clyde
                         viewport.WallBleedIntermediateRenderTarget2.Texture,
                         UIBox2.FromDimensions(Vector2.Zero, ScreenSize), new Color(1, 1, 1, 0.5f));
                 }
+
+                RenderOverlays(viewport, OverlaySpace.WorldSpace, worldBounds);
+                FlushRenderQueue();
             }
 
             PopRenderStateFull(state);
@@ -411,6 +505,17 @@ namespace Robust.Client.Graphics.Clyde
             _currentViewport = oldVp;
         }
 
+        private static Box2 CalcWorldBounds(Viewport viewport)
+        {
+            var eye = viewport.Eye;
+            if (eye == null)
+                return default;
+
+            // TODO: This seems completely unfit by lacking things like rotation handling.
+            return Box2.CenteredAround(eye.Position.Position,
+                viewport.Size / viewport.RenderScale / EyeManager.PixelsPerMeter * eye.Zoom);
+        }
+
         private sealed class OverlayComparer : IComparer<Overlay>
         {
             public static readonly OverlayComparer Instance = new();

Robust.Client/Graphics/Clyde/Clyde.Helpers.cs

@@ -5,6 +5,7 @@ using OpenToolkit.Graphics.OpenGL4;
 using Robust.Shared.Log;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
+using SixLabors.ImageSharp.PixelFormats;
 using ES20 = OpenToolkit.Graphics.ES20;
 
 namespace Robust.Client.Graphics.Clyde
@@ -31,6 +32,27 @@ namespace Robust.Client.Graphics.Clyde
             CheckGlError();
             GL.BindTexture(TextureTarget.Texture2D, glHandle.Handle);
             CheckGlError();
+            GL.ActiveTexture(TextureUnit.Texture0);
+        }
+
+        private void CopyRenderTextureToTexture(RenderTexture source, ClydeTexture target) {
+            LoadedRenderTarget sourceLoaded = RtToLoaded(source);
+            bool pause = sourceLoaded != _currentBoundRenderTarget;
+            FullStoredRendererState? store = null;
+            if (pause) {
+                store = PushRenderStateFull();
+                BindRenderTargetFull(source);
+                CheckGlError();
+            }
+
+            GL.BindTexture(TextureTarget.Texture2D, _loadedTextures[target.TextureId].OpenGLObject.Handle);
+            CheckGlError();
+            GL.CopyTexSubImage2D(TextureTarget.Texture2D, 0, 0, 0, 0, 0, _framebufferSize.X, _framebufferSize.Y);
+            CheckGlError();
+
+            if (pause && store != null) {
+                PopRenderStateFull((FullStoredRendererState)store);
+            }
         }
 
         private static long EstPixelSize(PixelInternalFormat format)

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

@@ -10,6 +10,7 @@ using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using static Robust.Client.GameObjects.ClientOccluderComponent;
 using OGLTextureWrapMode = OpenToolkit.Graphics.OpenGL.TextureWrapMode;
+using TKStencilOp = OpenToolkit.Graphics.OpenGL4.StencilOp;
 
 namespace Robust.Client.Graphics.Clyde
 {
@@ -195,7 +196,6 @@ namespace Robust.Client.Graphics.Clyde
                 }
             }
 
-
             _lightSoftShaderHandle = LoadShaderHandle("/Shaders/Internal/light-soft.swsl");
             _lightHardShaderHandle = LoadShaderHandle("/Shaders/Internal/light-hard.swsl");
             _fovShaderHandle = LoadShaderHandle("/Shaders/Internal/fov.swsl");
@@ -361,16 +361,23 @@ namespace Robust.Client.Graphics.Clyde
                 FinalizeDepthDraw();
             }
 
-            BindRenderTargetImmediate(RtToLoaded(viewport.LightRenderTarget));
-            CheckGlError();
-            GLClearColor(_lightManager.AmbientLightColor);
-            GL.Clear(ClearBufferMask.ColorBufferBit);
-            CheckGlError();
+            GL.Enable(EnableCap.StencilTest);
+            _isStencilling = true;
 
             var (lightW, lightH) = GetLightMapSize(viewport.Size);
             GL.Viewport(0, 0, lightW, lightH);
             CheckGlError();
 
+            BindRenderTargetImmediate(RtToLoaded(viewport.LightRenderTarget));
+            CheckGlError();
+            GLClearColor(_lightManager.AmbientLightColor);
+            GL.ClearStencil(0xFF);
+            GL.StencilMask(0xFF);
+            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.StencilBufferBit);
+            CheckGlError();
+
+            ApplyLightingFovToBuffer(viewport, eye);
+
             var lightShader = _loadedShaders[_enableSoftShadows ? _lightSoftShaderHandle : _lightHardShaderHandle].Program;
             lightShader.Use();
 
@@ -382,6 +389,11 @@ namespace Robust.Client.Graphics.Clyde
             GL.BlendFunc(BlendingFactor.SrcAlpha, BlendingFactor.One);
             CheckGlError();
 
+            GL.StencilFunc(StencilFunction.Equal, 0xFF, 0xFF);
+            CheckGlError();
+            GL.StencilOp(TKStencilOp.Keep, TKStencilOp.Keep, TKStencilOp.Keep);
+            CheckGlError();
+
             var lastRange = float.NaN;
             var lastPower = float.NaN;
             var lastColor = new Color(float.NaN, float.NaN, float.NaN, float.NaN);
@@ -463,11 +475,11 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             ResetBlendFunc();
+            GL.Disable(EnableCap.StencilTest);
+            _isStencilling = false;
 
             CheckGlError();
 
-            ApplyLightingFovToBuffer(viewport, eye);
-
             BlurOntoWalls(viewport, eye);
 
             MergeWallLayer(viewport);
@@ -485,40 +497,55 @@ namespace Robust.Client.Graphics.Clyde
             GetLightsToRender(MapId map, in Box2 worldBounds)
         {
             var renderingTreeSystem = _entitySystemManager.GetEntitySystem<RenderingTreeSystem>();
-            var lightTree = renderingTreeSystem.GetLightTreeForMap(map);
-
             var state = (this, worldBounds, count: 0);
 
-            lightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldBounds, int count) state, in PointLightComponent light) =>
+            foreach (var gridId in _mapManager.FindGridIdsIntersecting(map, worldBounds, true))
             {
-                var transform = light.Owner.Transform;
+                Box2 gridBounds;
 
-                if (state.count >= LightsToRenderListSize)
+                if (gridId == GridId.Invalid)
                 {
-                    // There are too many lights to fit in the static memory.
-                    return false;
+                    gridBounds = worldBounds;
+                }
+                else
+                {
+                    gridBounds = worldBounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
                 }
 
-                if (!light.Enabled || light.ContainerOccluded)
+                var lightTree = renderingTreeSystem.GetLightTreeForMap(map, gridId);
+
+                lightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldBounds, int count) state, in PointLightComponent light) =>
                 {
+                    var transform = light.Owner.Transform;
+
+                    if (state.count >= LightsToRenderListSize)
+                    {
+                        // There are too many lights to fit in the static memory.
+                        return false;
+                    }
+
+                    // TODO: Don't insert into trees for these, same as sprites.
+                    if (!light.Enabled || light.ContainerOccluded)
+                    {
+                        return true;
+                    }
+
+                    var lightPos = transform.WorldMatrix.Transform(light.Offset);
+
+                    var circle = new Circle(lightPos, light.Radius);
+
+                    // If the light doesn't touch anywhere the camera can see, it doesn't matter.
+                    if (!circle.Intersects(state.worldBounds))
+                    {
+                        return true;
+                    }
+
+                    float distanceSquared = (state.worldBounds.Center - lightPos).LengthSquared;
+                    state.clyde._lightsToRenderList[state.count++] = (light, lightPos, distanceSquared);
+
                     return true;
-                }
-
-                var lightPos = transform.WorldMatrix.Transform(light.Offset);
-
-                var circle = new Circle(lightPos, light.Radius);
-
-                // If the light doesn't touch anywhere the camera can see, it doesn't matter.
-                if (!circle.Intersects(state.worldBounds))
-                {
-                    return true;
-                }
-
-                float distanceSquared = (state.worldBounds.Center - lightPos).LengthSquared;
-                state.clyde._lightsToRenderList[state.count++] = (light, lightPos, distanceSquared);
-
-                return true;
-            }, worldBounds);
+                }, gridBounds);
+            }
 
             if (state.count > _maxLightsPerScene)
             {
@@ -577,7 +604,7 @@ namespace Robust.Client.Graphics.Clyde
 
             // Have to scale the blurring radius based on viewport size and camera zoom.
             const float refCameraHeight = 14;
-            var cameraSize = eye.Zoom.Y * viewport.Size.Y / EyeManager.PixelsPerMeter;
+            var cameraSize = eye.Zoom.Y * viewport.Size.Y * (1 / viewport.RenderScale.Y) / EyeManager.PixelsPerMeter;
             // 7e-3f is just a magic factor that makes it look ok.
             var factor = 7e-3f * (refCameraHeight / cameraSize);
 
@@ -645,6 +672,12 @@ namespace Robust.Client.Graphics.Clyde
 
         private void ApplyFovToBuffer(Viewport viewport, IEye eye)
         {
+            GL.Clear(ClearBufferMask.StencilBufferBit);
+            GL.Enable(EnableCap.StencilTest);
+            GL.StencilOp(OpenToolkit.Graphics.OpenGL4.StencilOp.Keep, OpenToolkit.Graphics.OpenGL4.StencilOp.Keep, OpenToolkit.Graphics.OpenGL4.StencilOp.Replace);
+            GL.StencilFunc(StencilFunction.Always, 1, 0xFF);
+            GL.StencilMask(0xFF);
+
             // Applies FOV to the final framebuffer.
 
             var fovShader = _loadedShaders[_fovShaderHandle].Program;
@@ -658,6 +691,10 @@ namespace Robust.Client.Graphics.Clyde
             fovShader.SetUniformMaybe("center", eye.Position.Position);
 
             DrawBlit(viewport, fovShader);
+
+            GL.StencilMask(0x00);
+            GL.Disable(EnableCap.StencilTest);
+            _isStencilling = false;
         }
 
         private void ApplyLightingFovToBuffer(Viewport viewport, IEye eye)
@@ -690,6 +727,13 @@ namespace Robust.Client.Graphics.Clyde
             fovShader.SetUniformTextureMaybe(UniIMainTexture, TextureUnit.Texture0);
             fovShader.SetUniformMaybe("center", eye.Position.Position);
 
+            GL.StencilMask(0xFF);
+            CheckGlError();
+            GL.StencilFunc(StencilFunction.Always, 0, 0);
+            CheckGlError();
+            GL.StencilOp(TKStencilOp.Keep, TKStencilOp.Keep, TKStencilOp.Replace);
+            CheckGlError();
+
             DrawBlit(viewport, fovShader);
 
             if (_hasGLSamplerObjects)
@@ -939,7 +983,8 @@ namespace Robust.Client.Graphics.Clyde
             viewport.WallMaskRenderTarget = CreateRenderTarget(viewport.Size, RenderTargetColorFormat.R8,
                 name: $"{viewport.Name}-{nameof(viewport.WallMaskRenderTarget)}");
 
-            viewport.LightRenderTarget = CreateRenderTarget(lightMapSize, lightMapColorFormat,
+            viewport.LightRenderTarget = CreateRenderTarget(lightMapSize,
+                new RenderTargetFormatParameters(lightMapColorFormat, hasDepthStencil: true),
                 lightMapSampleParameters,
                 $"{viewport.Name}-{nameof(viewport.LightRenderTarget)}");
 

Robust.Client/Graphics/Clyde/Clyde.RenderTargets.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
@@ -6,6 +6,7 @@ using OpenToolkit.Graphics.OpenGL4;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
 using Robust.Shared.Log;
+using SixLabors.ImageSharp.PixelFormats;
 
 // ReSharper disable once IdentifierTypo
 using RTCF = Robust.Client.Graphics.RenderTargetColorFormat;
@@ -191,7 +192,8 @@ namespace Robust.Client.Graphics.Clyde
                 FramebufferHandle = fbo,
                 Size = size,
                 TextureHandle = textureObject.TextureId,
-                MemoryPressure = pressure
+                MemoryPressure = pressure,
+                ColorFormat = format.ColorFormat
             };
 
             //GC.AddMemoryPressure(pressure);
@@ -278,6 +280,8 @@ namespace Robust.Client.Graphics.Clyde
             public Vector2i Size;
             public bool IsSrgb;
 
+            public RTCF ColorFormat;
+
             // Remaining properties only apply if the render target is NOT a window.
             // Handle to the framebuffer object.
             public GLHandle FramebufferHandle;
@@ -302,6 +306,12 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public abstract Vector2i Size { get; }
+
+            public void CopyPixelsToMemory<T>(CopyPixelsDelegate<T> callback, UIBox2i? subRegion = null) where T : unmanaged, IPixel<T>
+            {
+                Clyde.CopyRenderTargetPixels(Handle, subRegion, callback);
+            }
+
             public ClydeHandle Handle { get; }
 
             protected virtual void Dispose(bool disposing)

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

@@ -1,17 +1,13 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using OpenToolkit.Graphics.OpenGL4;
 using Robust.Client.GameObjects;
 using Robust.Client.Utility;
-using Robust.Shared.Log;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
-using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.PixelFormats;
 using Color = Robust.Shared.Maths.Color;
 using TKStencilOp = OpenToolkit.Graphics.OpenGL4.StencilOp;
 
@@ -120,9 +116,9 @@ namespace Robust.Client.Graphics.Clyde
             view = Matrix3.Identity;
         }
 
-        private static void CalcWorldMatrices(in Vector2i screenSize, IEye eye, out Matrix3 proj, out Matrix3 view)
+        private static void CalcWorldMatrices(in Vector2i screenSize, in Vector2 renderScale, IEye eye, out Matrix3 proj, out Matrix3 view)
         {
-            eye.GetViewMatrix(out view);
+            eye.GetViewMatrix(out view, renderScale);
 
             CalcWorldProjMatrix(screenSize, out proj);
         }
@@ -280,9 +276,19 @@ namespace Robust.Client.Graphics.Clyde
         }
 
         /// <summary>
-        ///     Flush the render handle, processing and re-pooling all the command lists.
+        ///     Flushes the render handle, processing and re-pooling all the command lists.
         /// </summary>
         private void FlushRenderQueue()
+        {
+            FlushBatchQueue();
+
+            // Reset renderer state.
+            _currentMatrixModel = Matrix3.Identity;
+            _queuedShader = _defaultShader.Handle;
+            SetScissorFull(null);
+        }
+
+        private void FlushBatchQueue()
         {
             // Finish any batches that may have been WiP.
             BreakBatch();
@@ -308,11 +314,6 @@ namespace Robust.Client.Graphics.Clyde
 
             ProcessRenderCommands();
             _queuedRenderCommands.Clear();
-
-            // Reset renderer state.
-            _currentMatrixModel = Matrix3.Identity;
-            _queuedShader = _defaultShader.Handle;
-            SetScissorFull(null);
         }
 
         private void SetScissorFull(UIBox2i? state)
@@ -371,6 +372,7 @@ namespace Robust.Client.Graphics.Clyde
 
             program.Use();
 
+            int textureUnitVal = 0;
             // Assign shader parameters to uniform since they may be dirty.
             foreach (var (name, value) in instance.Parameters)
             {
@@ -413,6 +415,15 @@ namespace Robust.Client.Graphics.Clyde
                     case Matrix4 matrix4:
                         program.SetUniform(name, matrix4);
                         break;
+                    case ClydeTexture clydeTexture:
+                        //It's important to start at Texture6 here since DrawCommandBatch uses Texture0 and Texture1 immediately after calling this
+                        //function! If passing in textures as uniforms ever stops working it might be since someone made it use all the way up to Texture6 too.
+                        //Might change this in the future?
+                        TextureUnit cTarget = TextureUnit.Texture6+textureUnitVal;
+                        SetTexture(cTarget, ((ClydeTexture)clydeTexture).TextureId);
+                        program.SetUniformTexture(name, cTarget);
+                        textureUnitVal++;
+                        break;
                     default:
                         throw new InvalidOperationException($"Unable to handle shader parameter {name}: {value}");
                 }
@@ -490,6 +501,7 @@ namespace Robust.Client.Graphics.Clyde
         private void DrawTexture(ClydeHandle texture, Vector2 bl, Vector2 br, Vector2 tl, Vector2 tr, in Color modulate,
             in Box2 texCoords)
         {
+            EnsureBatchSpaceAvailable(4, GetQuadBatchIndexCount());
             EnsureBatchState(texture, in modulate, true, GetQuadBatchPrimitiveType(), _queuedShader);
 
             bl = _currentMatrixModel.Transform(bl);
@@ -515,6 +527,8 @@ namespace Robust.Client.Graphics.Clyde
             FinishBatch();
             _batchMetaData = null;
 
+            EnsureBatchSpaceAvailable(vertices.Length, indices.Length);
+
             vertices.CopyTo(BatchVertexData.AsSpan(BatchVertexIndex));
 
             // We are weaving this into the batch buffers for performance (and simplicity).
@@ -556,6 +570,8 @@ namespace Robust.Client.Graphics.Clyde
             FinishBatch();
             _batchMetaData = null;
 
+            EnsureBatchSpaceAvailable(vertices.Length, 0);
+
             vertices.CopyTo(BatchVertexData.AsSpan(BatchVertexIndex));
 
             ref var command = ref AllocRenderCommand(RenderCommandType.DrawBatch);
@@ -591,6 +607,7 @@ namespace Robust.Client.Graphics.Clyde
 
         private void DrawLine(Vector2 a, Vector2 b, Color color)
         {
+            EnsureBatchSpaceAvailable(2, 0);
             EnsureBatchState(_stockTextureWhite.TextureId, color, false, BatchPrimitiveType.LineList, _queuedShader);
 
             a = _currentMatrixModel.Transform(a);
@@ -605,6 +622,14 @@ namespace Robust.Client.Graphics.Clyde
             _debugStats.LastClydeDrawCalls += 1;
         }
 
+        private void EnsureBatchSpaceAvailable(int vtx, int idx)
+        {
+            if (BatchVertexIndex + vtx >= BatchVertexData.Length || BatchIndexIndex + idx > BatchIndexData.Length)
+            {
+                FlushBatchQueue();
+            }
+        }
+
         private void DrawSetScissor(UIBox2i? scissorBox)
         {
             BreakBatch();
@@ -763,116 +788,6 @@ namespace Robust.Client.Graphics.Clyde
             _batchMetaData = null;
         }
 
-        private unsafe void TakeScreenshot(ScreenshotType type)
-        {
-            if (_queuedScreenshots.Count == 0 || _queuedScreenshots.All(p => p.type != type))
-            {
-                return;
-            }
-
-            var delegates = _queuedScreenshots.Where(p => p.type == type).ToList();
-
-            _queuedScreenshots.RemoveAll(p => p.type == type);
-
-            GL.PixelStore(PixelStoreParameter.PackAlignment, 1);
-            CheckGlError();
-
-            var bufferLength = ScreenSize.X * ScreenSize.Y;
-            if (!(_hasGLFenceSync && HasGLAnyMapBuffer && _hasGLPixelBufferObjects))
-            {
-                Logger.DebugS("clyde.ogl", "Necessary features for async screenshots not available, falling back to blocking path.");
-
-                // We need these 3 features to be able to do asynchronous screenshots, if we don't have them,
-                // we'll have to fall back to a crappy synchronous stalling method of glReadPixels().
-
-                var buffer = new Rgba32[bufferLength];
-                fixed (Rgba32* ptr = buffer)
-                {
-                    var bufSize = sizeof(Rgba32) * bufferLength;
-                    GL.ReadnPixels(0, 0, ScreenSize.X, ScreenSize.Y, PixelFormat.Rgba, PixelType.UnsignedByte, bufSize,
-                        (IntPtr) ptr);
-                    CheckGlError();
-                }
-
-                var (w, h) = ScreenSize;
-
-                var image = new Image<Rgb24>(w, h);
-                var imageSpan = image.GetPixelSpan();
-
-                FlipCopyScreenshot(buffer, imageSpan, w, h);
-
-                RunCallback(image);
-                return;
-            }
-
-            GL.GenBuffers(1, out uint pbo);
-            CheckGlError();
-            GL.BindBuffer(BufferTarget.PixelPackBuffer, pbo);
-            CheckGlError();
-            GL.BufferData(BufferTarget.PixelPackBuffer, bufferLength * sizeof(Rgba32), IntPtr.Zero,
-                BufferUsageHint.StreamRead);
-            CheckGlError();
-            GL.ReadPixels(0, 0, ScreenSize.X, ScreenSize.Y, PixelFormat.Rgba, PixelType.UnsignedByte, IntPtr.Zero);
-            CheckGlError();
-            var fence = GL.FenceSync(SyncCondition.SyncGpuCommandsComplete, WaitSyncFlags.None);
-            CheckGlError();
-
-            GL.BindBuffer(BufferTarget.PixelPackBuffer, 0);
-            CheckGlError();
-
-            _transferringScreenshots.Add((pbo, fence, ScreenSize, RunCallback));
-
-            void RunCallback(Image<Rgb24> image) => delegates.ForEach(p => p.callback(image));
-        }
-
-        private unsafe void CheckTransferringScreenshots()
-        {
-            if (_transferringScreenshots.Count == 0)
-            {
-                return;
-            }
-
-            foreach (var screenshot in _transferringScreenshots.ToList())
-            {
-                var (pbo, fence, (width, height), callback) = screenshot;
-
-                int status;
-                GL.GetSync(fence, SyncParameterName.SyncStatus, sizeof(int), null, &status);
-                CheckGlError();
-
-                if (status == (int) All.Signaled)
-                {
-                    var bufLen = width * height;
-                    var bufSize = sizeof(Rgba32) * bufLen;
-
-                    GL.BindBuffer(BufferTarget.PixelPackBuffer, pbo);
-                    CheckGlError();
-                    var ptr = MapFullBuffer(BufferTarget.PixelPackBuffer, bufSize, BufferAccess.ReadOnly,
-                        BufferAccessMask.MapReadBit);
-
-                    var packSpan = new ReadOnlySpan<Rgba32>((void*) ptr, width * height);
-
-                    var image = new Image<Rgb24>(width, height);
-                    var imageSpan = image.GetPixelSpan();
-
-                    FlipCopyScreenshot(packSpan, imageSpan, width, height);
-
-                    UnmapBuffer(BufferTarget.PixelPackBuffer);
-                    GL.BindBuffer(BufferTarget.PixelPackBuffer, 0);
-                    CheckGlError();
-                    GL.DeleteBuffer(pbo);
-                    CheckGlError();
-                    GL.DeleteSync(fence);
-                    CheckGlError();
-
-                    _transferringScreenshots.Remove(screenshot);
-
-                    // TODO: Don't do unnecessary copy here.
-                    callback(image);
-                }
-            }
-        }
-
         private FullStoredRendererState PushRenderStateFull()
         {
             return new FullStoredRendererState(_currentMatrixProj, _currentMatrixView, _currentRenderTarget);

Robust.Client/Graphics/Clyde/Clyde.Screenshots.cs

@@ -0,0 +1,223 @@
+using System;
+using System.Collections.Generic;
+using OpenToolkit.Graphics.OpenGL4;
+using Robust.Client.Utility;
+using Robust.Shared.Log;
+using Robust.Shared.Maths;
+using Robust.Shared.Utility;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.PixelFormats;
+using PF = OpenToolkit.Graphics.OpenGL4.PixelFormat;
+using PT = OpenToolkit.Graphics.OpenGL4.PixelType;
+
+namespace Robust.Client.Graphics.Clyde
+{
+    // Contains primary screenshot and pixel-copying logic.
+
+    internal sealed partial class Clyde
+    {
+        // Full-framebuffer screenshots undergo the following sequence of events:
+        // 1. Screenshots are queued by content or whatever.
+        // 2. When the rendering code reaches the screenshot type,
+        //    we instruct the GPU driver to copy the framebuffer and asynchronously transfer it to host memory.
+        // 3. Transfer finished asynchronously, we invoke the callback.
+        //
+        // On RAW GLES2, we cannot do this asynchronously due to lacking GL features,
+        // and the game will stutter as a result. This is sadly unavoidable.
+        //
+        // For CopyPixels on render targets, the copy and transfer is started immediately when the function is called.
+
+        private readonly List<QueuedScreenshot> _queuedScreenshots = new();
+        private readonly List<TransferringPixelCopy> _transferringPixelCopies = new();
+
+        public void Screenshot(ScreenshotType type, CopyPixelsDelegate<Rgb24> callback, UIBox2i? subRegion = null)
+        {
+            _queuedScreenshots.Add(new QueuedScreenshot(type, callback, subRegion));
+        }
+
+        private void TakeScreenshot(ScreenshotType type)
+        {
+            if (_queuedScreenshots.Count == 0)
+            {
+                return;
+            }
+
+            GL.PixelStore(PixelStoreParameter.PackAlignment, 1);
+            CheckGlError();
+
+            for (var i = 0; i < _queuedScreenshots.Count; i++)
+            {
+                var (qType, callback, subRegion) = _queuedScreenshots[i];
+                if (qType != type)
+                    continue;
+
+                DoCopyPixels(ScreenSize, subRegion, callback);
+                _queuedScreenshots.RemoveSwap(i--);
+            }
+        }
+
+        private void CopyRenderTargetPixels<T>(
+            ClydeHandle renderTarget,
+            UIBox2i? subRegion,
+            CopyPixelsDelegate<T> callback)
+            where T : unmanaged, IPixel<T>
+        {
+            var loaded = _renderTargets[renderTarget];
+
+            var original = GL.GetInteger(GetPName.ReadFramebufferBinding);
+
+            GL.BindFramebuffer(FramebufferTarget.ReadFramebuffer, loaded.FramebufferHandle.Handle);
+
+            DoCopyPixels(loaded.Size, subRegion, callback);
+
+            GL.BindFramebuffer(FramebufferTarget.ReadFramebuffer, original);
+        }
+
+        private unsafe void DoCopyPixels<T>(
+            Vector2i fbSize,
+            UIBox2i? subRegion,
+            CopyPixelsDelegate<T> callback)
+            where T : unmanaged, IPixel<T>
+        {
+            var (pf, pt) = default(T) switch
+            {
+                Rgba32 => (PF.Rgba, PT.UnsignedByte),
+                Rgb24 => (PF.Rgb, PT.UnsignedByte),
+                _ => throw new ArgumentException("Unsupported pixel type.")
+            };
+
+            var size = ClampSubRegion(fbSize, subRegion);
+
+            var bufferLength = size.X * size.Y;
+            if (!(_hasGLFenceSync && HasGLAnyMapBuffer && _hasGLPixelBufferObjects))
+            {
+                Logger.DebugS("clyde.ogl",
+                    "Necessary features for async screenshots not available, falling back to blocking path.");
+
+                // We need these 3 features to be able to do asynchronous screenshots, if we don't have them,
+                // we'll have to fall back to a crappy synchronous stalling method of glReadnPixels().
+
+                var buffer = new T[bufferLength];
+                fixed (T* ptr = buffer)
+                {
+                    var bufSize = sizeof(T) * bufferLength;
+                    GL.ReadnPixels(
+                        0, 0,
+                        size.X, size.Y,
+                        pf, pt,
+                        bufSize,
+                        (nint) ptr);
+
+                    CheckGlError();
+                }
+
+                var image = new Image<T>(size.X, size.Y);
+                var imageSpan = image.GetPixelSpan();
+
+                FlipCopy(buffer, imageSpan, size.X, size.Y);
+
+                callback(image);
+                return;
+            }
+
+            GL.GenBuffers(1, out uint pbo);
+            CheckGlError();
+
+            GL.BindBuffer(BufferTarget.PixelPackBuffer, pbo);
+            CheckGlError();
+
+            GL.BufferData(
+                BufferTarget.PixelPackBuffer,
+                bufferLength * sizeof(Rgba32), IntPtr.Zero,
+                BufferUsageHint.StreamRead);
+            CheckGlError();
+
+            GL.ReadPixels(0, 0, size.X, size.Y, pf, pt, IntPtr.Zero);
+            CheckGlError();
+
+            var fence = GL.FenceSync(SyncCondition.SyncGpuCommandsComplete, WaitSyncFlags.None);
+            CheckGlError();
+
+            GL.BindBuffer(BufferTarget.PixelPackBuffer, 0);
+            CheckGlError();
+
+            var transferring = new TransferringPixelCopy(pbo, fence, size, FinishPixelTransfer<T>, callback);
+            _transferringPixelCopies.Add(transferring);
+        }
+
+        private unsafe void CheckTransferringScreenshots()
+        {
+            if (_transferringPixelCopies.Count == 0)
+            {
+                return;
+            }
+
+            for (var i = 0; i < _transferringPixelCopies.Count; i++)
+            {
+                var transferring = _transferringPixelCopies[i];
+
+                // Check if transfer done (sync signalled)
+                int status;
+                GL.GetSync(transferring.Sync, SyncParameterName.SyncStatus, sizeof(int), null, &status);
+                CheckGlError();
+
+                if (status != (int) All.Signaled)
+                    continue;
+
+                transferring.TransferContinue(transferring);
+                _transferringPixelCopies.RemoveSwap(i--);
+            }
+        }
+
+        private unsafe void FinishPixelTransfer<T>(TransferringPixelCopy transferring) where T : unmanaged, IPixel<T>
+        {
+            var (pbo, fence, (width, height), _, callback) = transferring;
+
+            var bufLen = width * height;
+            var bufSize = sizeof(T) * bufLen;
+
+            GL.BindBuffer(BufferTarget.PixelPackBuffer, pbo);
+            CheckGlError();
+
+            var ptr = MapFullBuffer(
+                BufferTarget.PixelPackBuffer,
+                bufSize,
+                BufferAccess.ReadOnly,
+                BufferAccessMask.MapReadBit);
+
+            var packSpan = new ReadOnlySpan<T>(ptr, width * height);
+
+            var image = new Image<T>(width, height);
+            var imageSpan = image.GetPixelSpan();
+
+            FlipCopy(packSpan, imageSpan, width, height);
+
+            UnmapBuffer(BufferTarget.PixelPackBuffer);
+
+            GL.BindBuffer(BufferTarget.PixelPackBuffer, 0);
+            CheckGlError();
+
+            GL.DeleteBuffer(pbo);
+            CheckGlError();
+
+            GL.DeleteSync(fence);
+            CheckGlError();
+
+            var castCallback = (CopyPixelsDelegate<T>) callback;
+            castCallback(image);
+        }
+
+        private sealed record QueuedScreenshot(
+            ScreenshotType Type,
+            CopyPixelsDelegate<Rgb24> Callback,
+            UIBox2i? SubRegion);
+
+        private sealed record TransferringPixelCopy(
+            uint Pbo,
+            nint Sync,
+            Vector2i Size,
+            // Funny callback dance to handle the generics.
+            Action<TransferringPixelCopy> TransferContinue,
+            Delegate Callback);
+    }
+}

Robust.Client/Graphics/Clyde/Clyde.Shaders.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
@@ -428,7 +428,8 @@ namespace Robust.Client.Graphics.Clyde
 
             private protected override void SetParameterImpl(string name, Texture value)
             {
-                throw new NotImplementedException();
+                var data = Parent._shaderInstances[Handle];
+                data.Parameters[name] = value;
             }
 
             private protected override void SetStencilOpImpl(StencilOp op)

Robust.Client/Graphics/Clyde/Clyde.Textures.cs

@@ -26,7 +26,7 @@ namespace Robust.Client.Graphics.Clyde
 
         private readonly ConcurrentQueue<ClydeHandle> _textureDisposeQueue = new();
 
-        public Texture LoadTextureFromPNGStream(Stream stream, string? name = null,
+        public OwnedTexture LoadTextureFromPNGStream(Stream stream, string? name = null,
             TextureLoadParameters? loadParams = null)
         {
             DebugTools.Assert(_mainThread == Thread.CurrentThread);
@@ -37,7 +37,7 @@ namespace Robust.Client.Graphics.Clyde
             return LoadTextureFromImage(image, name, loadParams);
         }
 
-        public Texture LoadTextureFromImage<T>(Image<T> image, string? name = null,
+        public OwnedTexture LoadTextureFromImage<T>(Image<T> image, string? name = null,
             TextureLoadParameters? loadParams = null) where T : unmanaged, IPixel<T>
         {
             DebugTools.Assert(_mainThread == Thread.CurrentThread);
@@ -56,19 +56,19 @@ namespace Robust.Client.Graphics.Clyde
                 {
                     // Disable sRGB so stuff doesn't get interpreter wrong.
                     actualParams.Srgb = false;
-                    var img = ApplyA8Swizzle((Image<A8>) (object) image);
+                    using var img = ApplyA8Swizzle((Image<A8>) (object) image);
                     return LoadTextureFromImage(img, name, loadParams);
                 }
 
                 if (pixelType == typeof(L8) && !actualParams.Srgb)
                 {
-                    var img = ApplyL8Swizzle((Image<L8>) (object) image);
+                    using var img = ApplyL8Swizzle((Image<L8>) (object) image);
                     return LoadTextureFromImage(img, name, loadParams);
                 }
             }
 
             // Flip image because OpenGL reads images upside down.
-            var copy = FlipClone(image);
+            using var copy = FlipClone(image);
 
             var texture = CreateBaseTextureInternal<T>(image.Width, image.Height, actualParams, name);
 
@@ -324,11 +324,13 @@ namespace Robust.Client.Graphics.Clyde
                 if (typeof(T) == typeof(A8))
                 {
                     SetSubImage(texture, dstTl, ApplyA8Swizzle((Image<A8>) (object) srcImage), srcBox);
+                    return;
                 }
 
                 if (typeof(T) == typeof(L8))
                 {
                     SetSubImage(texture, dstTl, ApplyL8Swizzle((Image<L8>) (object) srcImage), srcBox);
+                    return;
                 }
             }
 
@@ -450,24 +452,6 @@ namespace Robust.Client.Graphics.Clyde
             }
         }
 
-        private static void FlipCopyScreenshot(ReadOnlySpan<Rgba32> srcSpan, Span<Rgb24> dstSpan, int w, int h)
-        {
-            var dr = h - 1;
-            for (var r = 0; r < h; r++, dr--)
-            {
-                var si = r * w;
-                var di = dr * w;
-                var srcRow = srcSpan[si..(si + w)];
-                var dstRow = dstSpan[di..(di + w)];
-
-                for (var x = 0; x < w; x++)
-                {
-                    var src = srcRow[x];
-                    dstRow[x] = new Rgb24(src.R, src.G, src.B);
-                }
-            }
-        }
-
         private static Image<Rgba32> ApplyA8Swizzle(Image<A8> source)
         {
             var newImage = new Image<Rgba32>(source.Width, source.Height);

Robust.Client/Graphics/Clyde/Clyde.Viewport.cs

@@ -1,5 +1,8 @@
 using System;
 using System.Collections.Generic;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Enums;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics.Clyde
@@ -10,7 +13,7 @@ namespace Robust.Client.Graphics.Clyde
         private readonly Dictionary<ClydeHandle, WeakReference<Viewport>> _viewports =
             new();
 
-        private Viewport CreateViewport(Vector2i size, string? name = null)
+        private Viewport CreateViewport(Vector2i size, TextureSampleParameters? sampleParameters = default, string? name = null)
         {
             var handle = AllocRid();
             var viewport = new Viewport(handle, name, this)
@@ -18,6 +21,7 @@ namespace Robust.Client.Graphics.Clyde
                 Size = size,
                 RenderTarget = CreateRenderTarget(size,
                     new RenderTargetFormatParameters(RenderTargetColorFormat.Rgba8Srgb, true),
+                    sampleParameters: sampleParameters,
                     name: $"{name}-MainRenderTarget")
             };
 
@@ -28,9 +32,9 @@ namespace Robust.Client.Graphics.Clyde
             return viewport;
         }
 
-        IClydeViewport IClyde.CreateViewport(Vector2i size, string? name)
+        IClydeViewport IClyde.CreateViewport(Vector2i size, TextureSampleParameters? sampleParameters, string? name)
         {
-            return CreateViewport(size, name);
+            return CreateViewport(size, sampleParameters, name);
         }
 
         private static Vector2 ScreenToMap(Vector2 point, Viewport vp)
@@ -45,7 +49,7 @@ namespace Robust.Client.Graphics.Clyde
             point *= new Vector2(1, -1) / EyeManager.PixelsPerMeter;
 
             // view matrix
-            vp.Eye.GetViewMatrixInv(out var viewMatrixInv);
+            vp.Eye.GetViewMatrixInv(out var viewMatrixInv, vp.RenderScale);
             point = viewMatrixInv * point;
 
             return point;
@@ -106,12 +110,66 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public Vector2i Size { get; set; }
+            public Vector2 RenderScale { get; set; } = Vector2.One;
+            public bool AutomaticRender { get; set; }
 
             void IClydeViewport.Render()
             {
                 _clyde.RenderViewport(this);
             }
 
+            public MapCoordinates LocalToWorld(Vector2 point)
+            {
+                if (Eye == null)
+                    return default;
+
+                var newPoint = point;
+
+                // (inlined version of UiProjMatrix^-1)
+                newPoint -= Size / 2f;
+                newPoint *= new Vector2(1, -1) / EyeManager.PixelsPerMeter;
+
+                // view matrix
+                Eye.GetViewMatrixInv(out var viewMatrixInv, RenderScale);
+                newPoint = viewMatrixInv * newPoint;
+
+                return new MapCoordinates(newPoint, Eye.Position.MapId);
+            }
+
+            public Vector2 WorldToLocal(Vector2 point)
+            {
+                if (Eye == null)
+                    return default;
+
+                var eye = (IEye) Eye;
+                var newPoint = point;
+
+                eye.GetViewMatrix(out var viewMatrix, RenderScale);
+                newPoint = viewMatrix * newPoint;
+
+                // (inlined version of UiProjMatrix)
+                newPoint *= new Vector2(1, -1) * EyeManager.PixelsPerMeter;
+                newPoint += Size / 2f;
+
+                return newPoint;
+            }
+
+            public void RenderScreenOverlaysBelow(
+                DrawingHandleScreen handle,
+                IViewportControl control,
+                in UIBox2i viewportBounds)
+            {
+                _clyde.RenderOverlaysDirect(this, control, handle, OverlaySpace.ScreenSpaceBelowWorld, viewportBounds);
+            }
+
+            public void RenderScreenOverlaysAbove(
+                DrawingHandleScreen handle,
+                IViewportControl control,
+                in UIBox2i viewportBounds)
+            {
+                _clyde.RenderOverlaysDirect(this, control, handle, OverlaySpace.ScreenSpace, viewportBounds);
+            }
+
             public void Dispose()
             {
                 RenderTarget.Dispose();

Robust.Client/Graphics/Clyde/Clyde.Windowing.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.CompilerServices;
@@ -7,6 +7,7 @@ using System.Runtime.InteropServices;
 using System.Threading;
 using OpenToolkit;
 using OpenToolkit.Graphics.OpenGL4;
+using OpenToolkit.GraphicsLibraryFramework;
 using Robust.Client.Input;
 using Robust.Client.UserInterface;
 using Robust.Client.Utility;
@@ -14,6 +15,7 @@ using Robust.Shared;
 using Robust.Shared.Localization;
 using Robust.Shared.Log;
 using Robust.Shared.Maths;
+using Robust.Shared.Utility;
 using SixLabors.ImageSharp;
 using SixLabors.ImageSharp.PixelFormats;
 using static Robust.Client.Utility.LiterallyJustMessageBox;
@@ -46,6 +48,7 @@ namespace Robust.Client.Graphics.Clyde
     {
         // Keep delegates around to prevent GC issues.
         private GLFWCallbacks.ErrorCallback _errorCallback = default!;
+        private GLFWCallbacks.MonitorCallback _monitorCallback = default!;
         private GLFWCallbacks.CharCallback _charCallback = default!;
         private GLFWCallbacks.CursorPosCallback _cursorPosCallback = default!;
         private GLFWCallbacks.KeyCallback _keyCallback = default!;
@@ -73,6 +76,18 @@ namespace Robust.Client.Graphics.Clyde
 
         private Vector2 _lastMousePos;
 
+        // Can't use ClydeHandle because it's 64 bit.
+        private int _nextWindowId = 1;
+        private readonly Dictionary<int, MonitorReg> _monitors = new();
+
+        public event Action<TextEventArgs>? TextEntered;
+        public event Action<MouseMoveEventArgs>? MouseMove;
+        public event Action<KeyEventArgs>? KeyUp;
+        public event Action<KeyEventArgs>? KeyDown;
+        public event Action<MouseWheelEventArgs>? MouseWheel;
+        public event Action<string>? CloseWindow;
+        public event Action? OnWindowScaleChanged;
+
         // NOTE: in engine we pretend the framebuffer size is the screen size..
         // For practical reasons like UI rendering.
         public override Vector2i ScreenSize => _framebufferSize;
@@ -148,15 +163,60 @@ namespace Robust.Client.Graphics.Clyde
                 return false;
             }
 
+            InitMonitors();
             InitCursors();
 
             return InitWindow();
         }
 
+        private void InitMonitors()
+        {
+            var monitors = GLFW.GetMonitorsRaw(out var count);
+
+            for (var i = 0; i < count; i++)
+            {
+                SetupMonitor(monitors[i]);
+            }
+        }
+
+        private void SetupMonitor(Monitor* monitor)
+        {
+            var handle = _nextWindowId++;
+
+            DebugTools.Assert(GLFW.GetMonitorUserPointer(monitor) == null, "GLFW window already has user pointer??");
+
+            var name = GLFW.GetMonitorName(monitor);
+            var videoMode = GLFW.GetVideoMode(monitor);
+            var impl = new ClydeMonitorImpl(handle, name, (videoMode->Width, videoMode->Height), videoMode->RefreshRate);
+
+            GLFW.SetMonitorUserPointer(monitor, (void*) handle);
+            _monitors[handle] = new MonitorReg
+            {
+                Id = handle,
+                Impl = impl,
+                Monitor = monitor
+            };
+        }
+
+        private void DestroyMonitor(Monitor* monitor)
+        {
+            var ptr = GLFW.GetMonitorUserPointer(monitor);
+
+            if (ptr == null)
+            {
+                var name = GLFW.GetMonitorName(monitor);
+                Logger.WarningS("clyde.win", $"Monitor '{name}' had no user pointer set??");
+                return;
+            }
+
+            _monitors.Remove((int) ptr);
+            GLFW.SetMonitorUserPointer(monitor, null);
+        }
+
         private bool InitWindow()
         {
-            var width = _configurationManager.GetCVar(CVars.DisplayWidth);
-            var height = _configurationManager.GetCVar(CVars.DisplayHeight);
+            var width = ConfigurationManager.GetCVar(CVars.DisplayWidth);
+            var height = ConfigurationManager.GetCVar(CVars.DisplayHeight);
 
             Monitor* monitor = null;
 
@@ -166,6 +226,8 @@ namespace Robust.Client.Graphics.Clyde
                 var mode = GLFW.GetVideoMode(monitor);
                 width = mode->Width;
                 height = mode->Height;
+
+                GLFW.WindowHint(WindowHintInt.RefreshRate, mode->RefreshRate);
             }
 
 #if DEBUG
@@ -174,13 +236,19 @@ namespace Robust.Client.Graphics.Clyde
             GLFW.WindowHint(WindowHintString.X11ClassName, "SS14");
             GLFW.WindowHint(WindowHintString.X11InstanceName, "SS14");
 
-            var renderer = (Renderer) _configurationManager.GetCVar<int>(CVars.DisplayRenderer);
+            var renderer = (Renderer) ConfigurationManager.GetCVar<int>(CVars.DisplayRenderer);
 
-            Span<Renderer> renderers = (renderer == Renderer.Default) ? stackalloc Renderer[] {
-                Renderer.OpenGL33,
-                Renderer.OpenGL31,
-                Renderer.OpenGLES2
-            } : stackalloc Renderer[] {renderer};
+            Span<Renderer> renderers = (renderer == Renderer.Default)
+                ? stackalloc Renderer[]
+                {
+                    Renderer.OpenGL33,
+                    Renderer.OpenGL31,
+                    Renderer.OpenGLES2
+                }
+                : stackalloc Renderer[] {renderer};
+
+            ErrorCode lastGlfwError = default;
+            string? lastGlfwErrorDesc = default;
 
             foreach (Renderer r in renderers)
             {
@@ -193,22 +261,22 @@ namespace Robust.Client.Graphics.Clyde
                     _isCore = renderer == Renderer.OpenGL33;
                     break;
                 }
+
                 // Window failed to init due to error.
                 // Try not to treat the error code seriously.
-                var code = GLFW.GetError(out string desc);
-                Logger.DebugS("clyde.win", $"{r} unsupported: [${code}] ${desc}");
+                lastGlfwError = GLFW.GetError(out lastGlfwErrorDesc);
+                Logger.DebugS("clyde.win", $"{r} unsupported: [{lastGlfwError}] ${lastGlfwErrorDesc}");
             }
 
             if (_glfwWindow == null)
             {
                 if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
                 {
-                    var code = GLFW.GetError(out string desc);
-
                     var errorContent = "Failed to create the game window. " +
-                        "This probably means your GPU is too old to play the game. " +
-                        "That or update your graphic drivers\n" +
-                        $"The exact error is: [{code}]\n {desc}";
+                                       "This probably means your GPU is too old to play the game. " +
+                                       "Try to update your graphics drivers, " +
+                                       "or enable compatibility mode in the launcher if that fails.\n" +
+                                       $"The exact error is: {lastGlfwError}\n{lastGlfwErrorDesc}";
 
                     MessageBoxW(null,
                         errorContent,
@@ -301,6 +369,7 @@ namespace Robust.Client.Graphics.Clyde
                     GLFW.WindowHint(WindowHintOpenGlProfile.OpenGlProfile, OpenGlProfile.Any);
                     GLFW.WindowHint(WindowHintBool.SrgbCapable, false);
                 }
+
                 _glfwWindow = GLFW.CreateWindow(width, height, string.Empty, monitor, null);
             }
         }
@@ -393,11 +462,30 @@ namespace Robust.Client.Graphics.Clyde
             Logger.ErrorS("clyde.win.glfw", "GLFW Error: [{0}] {1}", code, description);
         }
 
+        private void OnGlfwMonitor(Monitor* monitor, ConnectedState state)
+        {
+            try
+            {
+                if (state == ConnectedState.Connected)
+                {
+                    SetupMonitor(monitor);
+                }
+                else
+                {
+                    DestroyMonitor(monitor);
+                }
+            }
+            catch (Exception e)
+            {
+                CatchCallbackException(e);
+            }
+        }
+
         private void OnGlfwChar(Window* window, uint codepoint)
         {
             try
             {
-                _gameController.TextEntered(new TextEventArgs(codepoint));
+                TextEntered?.Invoke(new TextEventArgs(codepoint));
             }
             catch (Exception e)
             {
@@ -413,8 +501,7 @@ namespace Robust.Client.Graphics.Clyde
                 var delta = newPos - _lastMousePos;
                 _lastMousePos = newPos;
 
-                var ev = new MouseMoveEventArgs(delta, newPos);
-                _gameController.MouseMove(ev);
+                MouseMove?.Invoke(new MouseMoveEventArgs(delta, newPos));
             }
             catch (Exception e)
             {
@@ -461,11 +548,11 @@ namespace Robust.Client.Graphics.Clyde
             switch (action)
             {
                 case InputAction.Release:
-                    _gameController.KeyUp(ev);
+                    KeyUp?.Invoke(ev);
                     break;
                 case InputAction.Press:
                 case InputAction.Repeat:
-                    _gameController.KeyDown(ev);
+                    KeyDown?.Invoke(ev);
                     break;
                 default:
                     throw new ArgumentOutOfRangeException(nameof(action), action, null);
@@ -477,7 +564,7 @@ namespace Robust.Client.Graphics.Clyde
             try
             {
                 var ev = new MouseWheelEventArgs(((float) offsetX, (float) offsetY), _lastMousePos);
-                _gameController.MouseWheel(ev);
+                MouseWheel?.Invoke(ev);
             }
             catch (Exception e)
             {
@@ -489,7 +576,7 @@ namespace Robust.Client.Graphics.Clyde
         {
             try
             {
-                _gameController.Shutdown("Window closed");
+                CloseWindow?.Invoke("Window closed");
             }
             catch (Exception e)
             {
@@ -514,11 +601,6 @@ namespace Robust.Client.Graphics.Clyde
 
                 GL.Viewport(0, 0, fbW, fbH);
                 CheckGlError();
-                if (fbW != 0 && fbH != 0)
-                {
-                    _mainViewport.Dispose();
-                    CreateMainViewport();
-                }
 
                 OnWindowResized?.Invoke(new WindowResizedEventArgs(oldSize, _framebufferSize));
             }
@@ -533,6 +615,7 @@ namespace Robust.Client.Graphics.Clyde
             try
             {
                 _windowScale = (xScale, yScale);
+                OnWindowScaleChanged?.Invoke();
             }
             catch (Exception e)
             {
@@ -568,6 +651,7 @@ namespace Robust.Client.Graphics.Clyde
         private void StoreCallbacks()
         {
             _errorCallback = OnGlfwError;
+            _monitorCallback = OnGlfwMonitor;
             _charCallback = OnGlfwChar;
             _cursorPosCallback = OnGlfwCursorPos;
             _keyCallback = OnGlfwKey;
@@ -590,6 +674,19 @@ namespace Robust.Client.Graphics.Clyde
             GLFW.SetWindowTitle(_glfwWindow, title);
         }
 
+        public void SetWindowMonitor(IClydeMonitor monitor)
+        {
+            var monitorImpl = (ClydeMonitorImpl) monitor;
+            var reg = _monitors[monitorImpl.Id];
+
+            GLFW.SetWindowMonitor(
+                _glfwWindow,
+                reg.Monitor,
+                0, 0,
+                monitorImpl.Size.X, monitorImpl.Size.Y,
+                monitorImpl.RefreshRate);
+        }
+
         public void RequestWindowAttention()
         {
             GLFW.RequestWindowAttention(_glfwWindow);
@@ -654,18 +751,40 @@ namespace Robust.Client.Graphics.Clyde
 
                 GLFW.GetWindowPos(_glfwWindow, out var x, out var y);
                 _prevWindowPos = (x, y);
-                var monitor = GLFW.GetPrimaryMonitor();
+                var monitor = MonitorForWindow(_glfwWindow);
                 var mode = GLFW.GetVideoMode(monitor);
 
-                GLFW.SetWindowMonitor(_glfwWindow, GLFW.GetPrimaryMonitor(), 0, 0, mode->Width, mode->Height,
+                GLFW.SetWindowMonitor(_glfwWindow, monitor, 0, 0, mode->Width, mode->Height,
                     mode->RefreshRate);
             }
             else
             {
-                GLFW.SetWindowMonitor(_glfwWindow, null, _prevWindowPos.X, _prevWindowPos.Y, _prevWindowSize.X, _prevWindowSize.Y, 0);
+                GLFW.SetWindowMonitor(_glfwWindow, null, _prevWindowPos.X, _prevWindowPos.Y, _prevWindowSize.X,
+                    _prevWindowSize.Y, 0);
             }
         }
 
+        // glfwGetWindowMonitor only works for fullscreen windows.
+        // Picks the monitor with the top-left corner of the window.
+        private Monitor* MonitorForWindow(Window* window)
+        {
+            GLFW.GetWindowPos(window, out var winPosX, out var winPosY);
+            var monitors = GLFW.GetMonitorsRaw(out var count);
+            for (var i = 0; i < count; i++)
+            {
+                var monitor = monitors[i];
+                GLFW.GetMonitorPos(monitor, out var monPosX, out var monPosY);
+                var videoMode = GLFW.GetVideoMode(monitor);
+
+                var box = Box2i.FromDimensions(monPosX, monPosY, videoMode->Width, videoMode->Height);
+                if (box.Contains(winPosX, winPosY))
+                    return monitor;
+            }
+
+            // Fallback
+            return GLFW.GetPrimaryMonitor();
+        }
+
         string IClipboardManager.GetText()
         {
             return GLFW.GetClipboardString(_glfwWindow);
@@ -676,6 +795,11 @@ namespace Robust.Client.Graphics.Clyde
             GLFW.SetClipboardString(_glfwWindow, text);
         }
 
+        public IEnumerable<IClydeMonitor> EnumerateMonitors()
+        {
+            return _monitors.Values.Select(c => c.Impl);
+        }
+
         // We can't let exceptions unwind into GLFW, as that can cause the CLR to crash.
         // And it probably messes up GLFW too.
         // So all the callbacks are passed to this method.
@@ -689,5 +813,28 @@ namespace Robust.Client.Graphics.Clyde
 
             _glfwExceptionList.Add(e);
         }
+
+        private sealed class MonitorReg
+        {
+            public int Id;
+            public Monitor* Monitor;
+            public ClydeMonitorImpl Impl = default!;
+        }
+
+        private sealed class ClydeMonitorImpl : IClydeMonitor
+        {
+            public ClydeMonitorImpl(int id, string name, Vector2i size, int refreshRate)
+            {
+                Id = id;
+                Name = name;
+                Size = size;
+                RefreshRate = refreshRate;
+            }
+
+            public int Id { get; }
+            public string Name { get; }
+            public Vector2i Size { get; }
+            public int RefreshRate { get; }
+        }
     }
 }

Robust.Client/Graphics/Clyde/Clyde.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
 using System.Runtime.InteropServices;
@@ -12,10 +11,7 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 using Robust.Shared.Timing;
-using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.PixelFormats;
 using DependencyAttribute = Robust.Shared.IoC.DependencyAttribute;
 
 namespace Robust.Client.Graphics.Clyde
@@ -47,8 +43,6 @@ namespace Robust.Client.Graphics.Clyde
         private GLBuffer QuadVBO = default!;
         private GLHandle QuadVAO;
 
-        private Viewport _mainViewport = default!;
-
         private bool _drawingSplash = true;
 
         private GLShaderProgram? _currentProgram;
@@ -59,13 +53,6 @@ namespace Robust.Client.Graphics.Clyde
 
         private bool _checkGLErrors;
 
-        private readonly List<(ScreenshotType type, Action<Image<Rgb24>> callback)> _queuedScreenshots
-            = new();
-
-        private readonly List<(uint pbo, IntPtr sync, Vector2i size, Action<Image<Rgb24>> callback)>
-            _transferringScreenshots
-                = new();
-
         public Clyde()
         {
             // Init main window render target.
@@ -87,7 +74,7 @@ namespace Robust.Client.Graphics.Clyde
         {
             base.Initialize();
 
-            _configurationManager.OnValueChanged(CVars.DisplayOGLCheckErrors, b => _checkGLErrors = b, true);
+            ConfigurationManager.OnValueChanged(CVars.DisplayOGLCheckErrors, b => _checkGLErrors = b, true);
 
             if (!InitWindowing())
             {
@@ -124,9 +111,9 @@ namespace Robust.Client.Graphics.Clyde
         protected override void ReadConfig()
         {
             base.ReadConfig();
-            _lightmapDivider = _configurationManager.GetCVar(CVars.DisplayLightMapDivider);
-            _maxLightsPerScene = _configurationManager.GetCVar(CVars.DisplayMaxLightsPerScene);
-            _enableSoftShadows = _configurationManager.GetCVar(CVars.DisplaySoftShadows);
+            _lightmapDivider = ConfigurationManager.GetCVar(CVars.DisplayLightMapDivider);
+            _maxLightsPerScene = ConfigurationManager.GetCVar(CVars.DisplayMaxLightsPerScene);
+            _enableSoftShadows = ConfigurationManager.GetCVar(CVars.DisplaySoftShadows);
         }
 
         protected override void ReloadConfig()
@@ -152,11 +139,6 @@ namespace Robust.Client.Graphics.Clyde
 
         public override event Action<WindowFocusedEventArgs>? OnWindowFocused;
 
-        public void Screenshot(ScreenshotType type, Action<Image<Rgb24>> callback)
-        {
-            _queuedScreenshots.Add((type, callback));
-        }
-
         private void InitOpenGL()
         {
             var vendor = GL.GetString(StringName.Vendor);
@@ -238,7 +220,7 @@ namespace Robust.Client.Graphics.Clyde
 
         private (int major, int minor)? ParseGLOverrideVersion()
         {
-            var overrideGLVersion = _configurationManager.GetCVar(CVars.DisplayOGLOverrideVersion);
+            var overrideGLVersion = ConfigurationManager.GetCVar(CVars.DisplayOGLOverrideVersion);
             if (string.IsNullOrEmpty(overrideGLVersion))
             {
                 return null;
@@ -314,18 +296,10 @@ namespace Robust.Client.Graphics.Clyde
             ProjViewUBO = new GLUniformBuffer<ProjViewMatrices>(this, BindingIndexProjView, nameof(ProjViewUBO));
             UniformConstantsUBO = new GLUniformBuffer<UniformConstants>(this, BindingIndexUniformConstants, nameof(UniformConstantsUBO));
 
-            CreateMainViewport();
-        }
-
-        private void CreateMainViewport()
-        {
-            var (w, h) = _framebufferSize;
-
-            // Ensure viewport size is always even to avoid artifacts.
-            if (w % 2 == 1) w += 1;
-            if (h % 2 == 1) h += 1;
-
-            _mainViewport = CreateViewport((w, h), nameof(_mainViewport));
+            screenBufferHandle = new GLHandle(GL.GenTexture());
+            GL.BindTexture(TextureTarget.Texture2D, screenBufferHandle.Handle);
+            ApplySampleParameters(TextureSampleParameters.Default);
+            ScreenBufferTexture = GenTexture(screenBufferHandle, _framebufferSize, true, null, TexturePixelType.Rgba32);
         }
 
         [Conditional("DEBUG")]

Robust.Client/Graphics/Clyde/ClydeHeadless.cs

@@ -1,8 +1,11 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using JetBrains.Annotations;
 using Robust.Client.Audio;
 using Robust.Client.Input;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Timing;
 using SixLabors.ImageSharp;
@@ -37,6 +40,13 @@ namespace Robust.Client.Graphics.Clyde
         public IClydeDebugInfo DebugInfo { get; } = new DummyDebugInfo();
         public IClydeDebugStats DebugStats { get; } = new DummyDebugStats();
 
+        public event Action<TextEventArgs>? TextEntered;
+        public event Action<MouseMoveEventArgs>? MouseMove;
+        public event Action<KeyEventArgs>? KeyUp;
+        public event Action<KeyEventArgs>? KeyDown;
+        public event Action<MouseWheelEventArgs>? MouseWheel;
+        public event Action<string>? CloseWindow;
+
         public Texture GetStockTexture(ClydeStockTexture stockTexture)
         {
             return new DummyTexture((1, 1));
@@ -63,6 +73,11 @@ namespace Robust.Client.Graphics.Clyde
             // Nada.
         }
 
+        public void SetWindowMonitor(IClydeMonitor monitor)
+        {
+            // Nada.
+        }
+
         public void RequestWindowAttention()
         {
             // Nada.
@@ -86,6 +101,12 @@ namespace Robust.Client.Graphics.Clyde
             remove { }
         }
 
+        public event Action OnWindowScaleChanged
+        {
+            add { }
+            remove { }
+        }
+
         public void Render()
         {
             // Nada.
@@ -101,7 +122,7 @@ namespace Robust.Client.Graphics.Clyde
             // Nada.
         }
 
-        public Texture LoadTextureFromPNGStream(Stream stream, string? name = null,
+        public OwnedTexture LoadTextureFromPNGStream(Stream stream, string? name = null,
             TextureLoadParameters? loadParams = null)
         {
             using (var image = Image.Load<Rgba32>(stream))
@@ -110,7 +131,7 @@ namespace Robust.Client.Graphics.Clyde
             }
         }
 
-        public Texture LoadTextureFromImage<T>(Image<T> image, string? name = null,
+        public OwnedTexture LoadTextureFromImage<T>(Image<T> image, string? name = null,
             TextureLoadParameters? loadParams = null) where T : unmanaged, IPixel<T>
         {
             return new DummyTexture((image.Width, image.Height));
@@ -146,14 +167,23 @@ namespace Robust.Client.Graphics.Clyde
             // Nada.
         }
 
-        public void Screenshot(ScreenshotType type, Action<Image<Rgb24>> callback)
+        public void Screenshot(ScreenshotType type, CopyPixelsDelegate<Rgb24> callback, UIBox2i? subRegion = null)
         {
-            callback(new Image<Rgb24>(ScreenSize.X, ScreenSize.Y));
+            // Immediately call callback with an empty buffer.
+            var (x, y) = ClampSubRegion(ScreenSize, subRegion);
+            callback(new Image<Rgb24>(x, y));
         }
 
-        public IClydeViewport CreateViewport(Vector2i size, string? name = null)
+        public IClydeViewport CreateViewport(Vector2i size, TextureSampleParameters? sampleParameters,
+            string? name = null)
         {
-            return new Viewport();
+            return new Viewport(size);
+        }
+
+        public IEnumerable<IClydeMonitor> EnumerateMonitors()
+        {
+            // TODO: Actually return something.
+            yield break;
         }
 
         public ClydeHandle LoadShader(ParsedShader shader, string? name = null)
@@ -267,6 +297,11 @@ namespace Robust.Client.Graphics.Clyde
             {
                 // Nada.
             }
+
+            public void SetVelocity(Vector2 velocity)
+            {
+                // Nada.
+            }
         }
 
         private sealed class DummyBufferedAudioSource : DummyAudioSource, IClydeBufferedAudioSource
@@ -402,12 +437,15 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public Vector2i Size { get; }
-            public Texture Texture { get; }
 
-            public void Delete()
+            public void CopyPixelsToMemory<T>(CopyPixelsDelegate<T> callback, UIBox2i? subRegion) where T : unmanaged, IPixel<T>
             {
+                var (x, y) = ClampSubRegion(Size, subRegion);
+                callback(new Image<T>(x, y));
             }
 
+            public Texture Texture { get; }
+
             public void Dispose()
             {
             }
@@ -424,6 +462,12 @@ namespace Robust.Client.Graphics.Clyde
 
             public Vector2i Size => _clyde.ScreenSize;
 
+            public void CopyPixelsToMemory<T>(CopyPixelsDelegate<T> callback, UIBox2i? subRegion) where T : unmanaged, IPixel<T>
+            {
+                var (x, y) = ClampSubRegion(Size, subRegion);
+                callback(new Image<T>(x, y));
+            }
+
             public void Dispose()
             {
             }
@@ -449,6 +493,11 @@ namespace Robust.Client.Graphics.Clyde
 
         private sealed class Viewport : IClydeViewport
         {
+            public Viewport(Vector2i size)
+            {
+                Size = size;
+            }
+
             public void Dispose()
             {
             }
@@ -458,9 +507,38 @@ namespace Robust.Client.Graphics.Clyde
 
             public IEye? Eye { get; set; }
             public Vector2i Size { get; }
+            public Vector2 RenderScale { get; set; }
+            public bool AutomaticRender { get; set; }
 
             public void Render()
             {
+                // Nada
+            }
+
+            public MapCoordinates LocalToWorld(Vector2 point)
+            {
+                return default;
+            }
+
+            public Vector2 WorldToLocal(Vector2 point)
+            {
+                return default;
+            }
+
+            public void RenderScreenOverlaysBelow(
+                DrawingHandleScreen handle,
+                IViewportControl control,
+                in UIBox2i viewportBounds)
+            {
+                // Nada
+            }
+
+            public void RenderScreenOverlaysAbove(
+                DrawingHandleScreen handle,
+                IViewportControl control,
+                in UIBox2i viewportBounds)
+            {
+                // Nada
             }
         }
     }

Robust.Client/Graphics/Clyde/GLObjects/Clyde.ShaderProgram.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 using OpenToolkit.Graphics.OpenGL4;

Robust.Client/Graphics/Clyde/Shaders/base-default.frag

@@ -4,7 +4,6 @@ varying highp vec2 Pos;
 uniform sampler2D lightMap;
 uniform highp vec4 modulate;
 
-#line 1000
 // [SHADER_HEADER_CODE]
 
 void main()
@@ -13,7 +12,6 @@ void main()
 
     lowp vec4 COLOR;
 
-    #line 10000
     // [SHADER_CODE]
 
     lowp vec3 lightSample = texture2D(lightMap, Pos).rgb;

Robust.Client/Graphics/Clyde/Shaders/z-library.glsl

@@ -89,9 +89,10 @@ uniform highp vec2 TEXTURE_PIXEL_SIZE;
 // -- srgb emulation --
 
 #ifdef HAS_SRGB
-highp vec4 zTexture(highp vec2 uv)
+
+highp vec4 zTextureSpec(sampler2D tex, highp vec2 uv)
 {
-    return texture2D(TEXTURE, uv);
+    return texture2D(tex, uv);
 }
 
 highp vec4 zAdjustResult(highp vec4 col)
@@ -101,9 +102,9 @@ highp vec4 zAdjustResult(highp vec4 col)
 #else
 uniform lowp vec2 SRGB_EMU_CONFIG;
 
-highp vec4 zTexture(highp vec2 uv)
+highp vec4 zTextureSpec(sampler2D tex, highp vec2 uv)
 {
-    highp vec4 col = texture2D(TEXTURE, uv);
+    highp vec4 col = texture2D(tex, uv);
     if (SRGB_EMU_CONFIG.x > 0.5)
     {
         return zFromSrgb(col);
@@ -121,5 +122,10 @@ highp vec4 zAdjustResult(highp vec4 col)
 }
 #endif
 
+highp vec4 zTexture(highp vec2 uv)
+{
+    return zTextureSpec(TEXTURE, uv);
+}
+
 // -- Utilities End --
 

Robust.Client/Graphics/ClydeBase.cs

@@ -18,8 +18,7 @@ namespace Robust.Client.Graphics
     /// </summary>
     internal abstract class ClydeBase
     {
-        [Dependency] protected readonly IConfigurationManager _configurationManager = default!;
-        [Dependency] protected readonly IGameControllerInternal _gameController = default!;
+        [Dependency] protected readonly IConfigurationManager ConfigurationManager = default!;
 
         protected WindowMode WindowMode { get; private set; } = WindowMode.Windowed;
         protected bool VSync { get; private set; } = true;
@@ -31,11 +30,11 @@ namespace Robust.Client.Graphics
 
         public virtual bool Initialize()
         {
-            _configurationManager.OnValueChanged(CVars.DisplayVSync, _vSyncChanged, true);
-            _configurationManager.OnValueChanged(CVars.DisplayWindowMode, _windowModeChanged, true);
-            _configurationManager.OnValueChanged(CVars.DisplayLightMapDivider, LightmapDividerChanged, true);
-            _configurationManager.OnValueChanged(CVars.DisplayMaxLightsPerScene, MaxLightsPerSceneChanged, true);
-            _configurationManager.OnValueChanged(CVars.DisplaySoftShadows, SoftShadowsChanged, true);
+            ConfigurationManager.OnValueChanged(CVars.DisplayVSync, _vSyncChanged, true);
+            ConfigurationManager.OnValueChanged(CVars.DisplayWindowMode, _windowModeChanged, true);
+            ConfigurationManager.OnValueChanged(CVars.DisplayLightMapDivider, LightmapDividerChanged, true);
+            ConfigurationManager.OnValueChanged(CVars.DisplayMaxLightsPerScene, MaxLightsPerSceneChanged, true);
+            ConfigurationManager.OnValueChanged(CVars.DisplaySoftShadows, SoftShadowsChanged, true);
 
             return true;
         }
@@ -51,8 +50,8 @@ namespace Robust.Client.Graphics
 
         protected virtual void ReadConfig()
         {
-            WindowMode = (WindowMode) _configurationManager.GetCVar(CVars.DisplayWindowMode);
-            VSync = _configurationManager.GetCVar(CVars.DisplayVSync);
+            WindowMode = (WindowMode) ConfigurationManager.GetCVar(CVars.DisplayWindowMode);
+            VSync = ConfigurationManager.GetCVar(CVars.DisplayVSync);
         }
 
         private void _vSyncChanged(bool newValue)
@@ -86,5 +85,12 @@ namespace Robust.Client.Graphics
         protected virtual void SoftShadowsChanged(bool newValue)
         {
         }
+
+        protected static Vector2i ClampSubRegion(Vector2i size, UIBox2i? subRegionSpecified)
+        {
+            return subRegionSpecified == null
+                ? size
+                : UIBox2i.FromDimensions(Vector2i.Zero, size).Intersection(subRegionSpecified.Value)?.Size ?? default;
+        }
     }
 }

Robust.Client/Graphics/Font.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Text;
 using Robust.Client.ResourceManagement;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
@@ -40,63 +41,48 @@ namespace Robust.Client.Graphics
             return GetLineHeight(scale) - GetHeight(scale);
         }
 
-        [Obsolete("Use GetAscent")] public int Ascent => GetAscent(1);
-        [Obsolete("Use GetHeight")] public int Height => GetHeight(1);
-        [Obsolete("Use GetDescent")] public int Descent => GetDescent(1);
-        [Obsolete("Use GetLineHeight")] public int LineHeight => GetLineHeight(1);
-        [Obsolete("Use GetLineSeparation")] public int LineSeparation => GetLineSeparation(1);
-
-        // Yes, I am aware that using char is bad.
-        // At the same time the font system is nowhere close to rendering Unicode so...
         /// <summary>
         ///     Draw a character at a certain baseline position on screen.
         /// </summary>
         /// <param name="handle">The drawing handle to draw to.</param>
-        /// <param name="chr">
-        ///     The Unicode code point to draw. Yes I'm aware about UTF-16 being crap,
-        ///     do you think this system can draw anything except ASCII?
-        /// </param>
+        /// <param name="rune">The Unicode code point to draw.</param>
         /// <param name="baseline">The baseline from which to draw the character.</param>
+        /// <param name="scale">DPI scale factor to render the font at.</param>
         /// <param name="color">The color of the character to draw.</param>
+        /// <param name="fallback">If the character is not available, render "<22>" instead.</param>
         /// <returns>How much to advance the cursor to draw the next character.</returns>
-        [Obsolete("Use DrawChar with scale support.")]
-        public float DrawChar(DrawingHandleScreen handle, char chr, Vector2 baseline, Color color)
-        {
-            return DrawChar(handle, chr, baseline, 1, color);
-        }
+        public abstract float DrawChar(
+            DrawingHandleScreen handle, Rune rune, Vector2 baseline, float scale,
+            Color color, bool fallback=true);
 
-        public abstract float DrawChar(DrawingHandleScreen handle, char chr, Vector2 baseline, float scale,
-            Color color);
+        [Obsolete("Use Rune variant instead")]
+        public float DrawChar(DrawingHandleScreen handle, char chr, Vector2 baseline, float scale, Color color)
+        {
+            return DrawChar(handle, (Rune) chr, baseline, scale, color);
+        }
 
         /// <summary>
         ///     Gets metrics describing the dimensions and positioning of a single glyph in the font.
         /// </summary>
-        /// <param name="chr">The character to fetch the glyph metrics for.</param>
+        /// <param name="rune">The unicode codepoint to fetch the glyph metrics for.</param>
+        /// <param name="scale">DPI scale factor to render the font at.</param>
+        /// <param name="fallback">
+        ///     If the character is not available, return data for "<22>" instead.
+        ///     This can still fail if the font does not define <20> itself.
+        /// </param>
         /// <returns>
         ///     <c>null</c> if this font does not have a glyph for the specified character,
         ///     otherwise the metrics you asked for.
         /// </returns>
         /// <seealso cref="TryGetCharMetrics"/>
-        [Obsolete("Use GetCharMetrics with scale support.")]
-        public CharMetrics? GetCharMetrics(char chr)
-        {
-            return GetCharMetrics(chr, 1);
-        }
-
-        public abstract CharMetrics? GetCharMetrics(char chr, float scale);
+        public abstract CharMetrics? GetCharMetrics(Rune rune, float scale, bool fallback=true);
 
         /// <summary>
         ///     Try-pattern version of <see cref="GetCharMetrics"/>.
         /// </summary>
-        [Obsolete("Use TryGetCharMetrics with scale support.")]
-        public bool TryGetCharMetrics(char chr, out CharMetrics metrics)
+        public bool TryGetCharMetrics(Rune rune, float scale, out CharMetrics metrics, bool fallback=true)
         {
-            return TryGetCharMetrics(chr, 1, out metrics);
-        }
-
-        public bool TryGetCharMetrics(char chr, float scale, out CharMetrics metrics)
-        {
-            var maybe = GetCharMetrics(chr, scale);
+            var maybe = GetCharMetrics(rune, scale);
             if (maybe.HasValue)
             {
                 metrics = maybe.Value;
@@ -128,15 +114,23 @@ namespace Robust.Client.Graphics
         public override int GetDescent(float scale) => Handle.GetDescent(scale);
         public override int GetLineHeight(float scale) => Handle.GetLineHeight(scale);
 
-        public override float DrawChar(DrawingHandleScreen handle, char chr, Vector2 baseline, float scale, Color color)
+        public override float DrawChar(DrawingHandleScreen handle, Rune rune, Vector2 baseline, float scale, Color color, bool fallback=true)
         {
-            var metrics = Handle.GetCharMetrics(chr, scale);
+            var metrics = Handle.GetCharMetrics(rune, scale);
             if (!metrics.HasValue)
             {
-                return 0;
+                if (fallback && !Rune.IsWhiteSpace(rune))
+                {
+                    rune = new Rune('<27>');
+                    metrics = Handle.GetCharMetrics(rune, scale);
+                    if (!metrics.HasValue)
+                        return 0;
+                }
+                else
+                    return 0;
             }
 
-            var texture = Handle.GetCharTexture(chr, scale);
+            var texture = Handle.GetCharTexture(rune, scale);
             if (texture == null)
             {
                 return metrics.Value.Advance;
@@ -147,9 +141,12 @@ namespace Robust.Client.Graphics
             return metrics.Value.Advance;
         }
 
-        public override CharMetrics? GetCharMetrics(char chr, float scale)
+        public override CharMetrics? GetCharMetrics(Rune rune, float scale, bool fallback=true)
         {
-            return Handle.GetCharMetrics(chr, scale);
+            var metrics = Handle.GetCharMetrics(rune, scale);
+            if (metrics == null && !Rune.IsWhiteSpace(rune) && fallback)
+                return Handle.GetCharMetrics(new Rune('<27>'), scale);
+            return metrics;
         }
     }
 
@@ -160,13 +157,13 @@ namespace Robust.Client.Graphics
         public override int GetDescent(float scale) => default;
         public override int GetLineHeight(float scale) => default;
 
-        public override float DrawChar(DrawingHandleScreen handle, char chr, Vector2 baseline, float scale, Color color)
+        public override float DrawChar(DrawingHandleScreen handle, Rune rune, Vector2 baseline, float scale, Color color, bool fallback=true)
         {
             // Nada, it's a dummy after all.
             return 0;
         }
 
-        public override CharMetrics? GetCharMetrics(char chr, float scale)
+        public override CharMetrics? GetCharMetrics(Rune rune, float scale, bool fallback=true)
         {
             // Nada, it's a dummy after all.
             return null;

Robust.Client/Graphics/FontManager.cs

@@ -4,9 +4,6 @@ using System.IO;
 using System.Text;
 using JetBrains.Annotations;
 using Robust.Client.Utility;
-using Robust.Shared;
-using Robust.Shared.Configuration;
-using Robust.Shared.IoC;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
 using SharpFont;
@@ -20,18 +17,18 @@ namespace Robust.Client.Graphics
         private const int SheetWidth = 256;
         private const int SheetHeight = 256;
 
-        [Dependency] private readonly IConfigurationManager _configuration = default!;
-        [Dependency] private readonly IClyde _clyde = default!;
+        private readonly IClyde _clyde;
 
-        private uint BaseFontDPI;
+        private uint _baseFontDpi = 96;
 
         private readonly Library _library;
 
         private readonly Dictionary<(FontFaceHandle, int fontSize), FontInstanceHandle> _loadedInstances =
             new();
 
-        public FontManager()
+        public FontManager(IClyde clyde)
         {
+            _clyde = clyde;
             _library = new Library();
         }
 
@@ -42,9 +39,9 @@ namespace Robust.Client.Graphics
             return handle;
         }
 
-        void IFontManagerInternal.Initialize()
+        void IFontManagerInternal.SetFontDpi(uint fontDpi)
         {
-            BaseFontDPI = (uint) _configuration.GetCVar(CVars.DisplayFontDpi);
+            _baseFontDpi = fontDpi;
         }
 
         public IFontInstanceHandle MakeInstance(IFontFaceHandle handle, int size)
@@ -64,7 +61,7 @@ namespace Robust.Client.Graphics
         private ScaledFontData _generateScaledDatum(FontInstanceHandle instance, float scale)
         {
             var ftFace = instance.FaceHandle.Face;
-            ftFace.SetCharSize(0, instance.Size, 0, (uint) (BaseFontDPI * scale));
+            ftFace.SetCharSize(0, instance.Size, 0, (uint) (_baseFontDpi * scale));
 
             var ascent = ftFace.Size.Metrics.Ascender.ToInt32();
             var descent = -ftFace.Size.Metrics.Descender.ToInt32();
@@ -83,7 +80,7 @@ namespace Robust.Client.Graphics
                 return;
 
             var face = instance.FaceHandle.Face;
-            face.SetCharSize(0, instance.Size, 0, (uint) (BaseFontDPI * scale));
+            face.SetCharSize(0, instance.Size, 0, (uint) (_baseFontDpi * scale));
             face.LoadGlyph(glyph, LoadFlags.Default, LoadTarget.Normal);
             face.Glyph.RenderGlyph(RenderMode.Normal);
 
@@ -189,7 +186,7 @@ namespace Robust.Client.Graphics
             OwnedTexture GenSheet()
             {
                 var sheet = _clyde.CreateBlankTexture<A8>((SheetWidth, SheetHeight),
-                    $"font-{face.FamilyName}-{instance.Size}-{(uint) (BaseFontDPI * scale)}-sheet{scaled.AtlasTextures.Count}");
+                    $"font-{face.FamilyName}-{instance.Size}-{(uint) (_baseFontDpi * scale)}-sheet{scaled.AtlasTextures.Count}");
                 scaled.AtlasTextures.Add(sheet);
                 return sheet;
             }

Robust.Client/Graphics/IClyde.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Threading.Tasks;
 using Robust.Shared.Maths;
@@ -7,6 +8,8 @@ using SixLabors.ImageSharp.PixelFormats;
 
 namespace Robust.Client.Graphics
 {
+    public delegate void CopyPixelsDelegate<T>(Image<T> pixels) where T : unmanaged, IPixel<T>;
+
     public interface IClyde
     {
         IRenderWindow MainWindowRenderTarget { get; }
@@ -21,6 +24,7 @@ namespace Robust.Client.Graphics
         Vector2 DefaultWindowScale { get; }
 
         void SetWindowTitle(string title);
+        void SetWindowMonitor(IClydeMonitor monitor);
 
         /// <summary>
         ///     This is the magic method to make the game window ping you in the task bar.
@@ -31,10 +35,12 @@ namespace Robust.Client.Graphics
 
         event Action<WindowFocusedEventArgs> OnWindowFocused;
 
-        Texture LoadTextureFromPNGStream(Stream stream, string? name = null,
+        event Action OnWindowScaleChanged;
+
+        OwnedTexture LoadTextureFromPNGStream(Stream stream, string? name = null,
             TextureLoadParameters? loadParams = null);
 
-        Texture LoadTextureFromImage<T>(Image<T> image, string? name = null,
+        OwnedTexture LoadTextureFromImage<T>(Image<T> image, string? name = null,
             TextureLoadParameters? loadParams = null) where T : unmanaged, IPixel<T>;
 
         /// <summary>
@@ -92,9 +98,18 @@ namespace Robust.Client.Graphics
         /// </summary>
         /// <param name="type">What kind of screenshot to take</param>
         /// <param name="callback">The callback to run when the screenshot has been made.</param>
-        void Screenshot(ScreenshotType type, Action<Image<Rgb24>> callback);
+        /// <param name="subRegion">
+        ///     The subregion of the framebuffer to copy.
+        ///     If null, the whole framebuffer is copied.
+        /// </param>
+        /// <seealso cref="ScreenshotAsync"/>
+        /// <seealso cref="IRenderTarget.CopyPixelsToMemory{T}"/>
+        void Screenshot(ScreenshotType type, CopyPixelsDelegate<Rgb24> callback, UIBox2i? subRegion = null);
 
-        Task<Image<Rgb24>> ScreenshotAsync(ScreenshotType type)
+        /// <summary>
+        ///     Async version of <see cref="Screenshot"/>.
+        /// </summary>
+        Task<Image<Rgb24>> ScreenshotAsync(ScreenshotType type, UIBox2i? subRegion = null)
         {
             var tcs = new TaskCompletionSource<Image<Rgb24>>();
 
@@ -103,7 +118,14 @@ namespace Robust.Client.Graphics
             return tcs.Task;
         }
 
-        IClydeViewport CreateViewport(Vector2i size, string? name = null);
+        IClydeViewport CreateViewport(Vector2i size, string? name = null)
+        {
+            return CreateViewport(size, default, name);
+        }
+
+        IClydeViewport CreateViewport(Vector2i size, TextureSampleParameters? sampleParameters, string? name = null);
+
+        IEnumerable<IClydeMonitor> EnumerateMonitors();
     }
 
     // TODO: Maybe implement IDisposable for render targets. I got lazy and didn't.

Robust.Client/Graphics/IClydeAudioSource.cs

@@ -20,5 +20,6 @@ namespace Robust.Client.Graphics
         void SetVolume(float decibels);
         void SetOcclusion(float blocks);
         void SetPlaybackPosition(float seconds);
+        void SetVelocity(Vector2 velocity);
     }
 }

Robust.Client/Graphics/IClydeInternal.cs

@@ -1,3 +1,4 @@
+using System;
 using Robust.Client.Input;
 using Robust.Client.UserInterface;
 using Robust.Shared.Maths;
@@ -16,6 +17,13 @@ namespace Robust.Client.Graphics
         bool Initialize();
         void Ready();
 
+        event Action<TextEventArgs> TextEntered;
+        event Action<MouseMoveEventArgs> MouseMove;
+        event Action<KeyEventArgs> KeyUp;
+        event Action<KeyEventArgs> KeyDown;
+        event Action<MouseWheelEventArgs> MouseWheel;
+        event Action<string> CloseWindow;
+
         ClydeHandle LoadShader(ParsedShader shader, string? name = null);
 
         void ReloadShader(ClydeHandle handle, ParsedShader newShader);

Robust.Client/Graphics/IClydeMonitor.cs

@@ -0,0 +1,18 @@
+using Robust.Shared.Maths;
+
+namespace Robust.Client.Graphics
+{
+    /// <summary>
+    ///     Represents a connected monitor on the user's system.
+    /// </summary>
+    public interface IClydeMonitor
+    {
+        /// <summary>
+        ///     This ID is not consistent between startups of the game.
+        /// </summary>
+        int Id { get; }
+        string Name { get; }
+        Vector2i Size { get; }
+        int RefreshRate { get; }
+    }
+}

Robust.Client/Graphics/IClydeViewport.cs

@@ -1,4 +1,6 @@
 using System;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
@@ -16,9 +18,57 @@ namespace Robust.Client.Graphics
         IEye? Eye { get; set; }
         Vector2i Size { get; }
 
+        /// <summary>
+        ///     This is, effectively, a multiplier to the eye's zoom.
+        /// </summary>
+        Vector2 RenderScale { get; set; }
+
+        /// <summary>
+        ///     If true, <see cref="Render"/> will be automatically called at the start of the frame.
+        /// </summary>
+        bool AutomaticRender { get; set; }
+
         /// <summary>
         ///     Render the state of the world in this viewport, updating the texture inside the render target.
         /// </summary>
         void Render();
+
+        /// <summary>
+        ///     Converts a point in the viewport's screen to world coordinates.
+        /// </summary>
+        MapCoordinates LocalToWorld(Vector2 point);
+
+        /// <summary>
+        ///     Converts a point in world-space to the viewport's screen coordinates.
+        /// </summary>
+        Vector2 WorldToLocal(Vector2 point);
+
+        /// <summary>
+        ///     Draw below screen-space overlays for this viewport in UI space.
+        /// </summary>
+        /// <param name="handle">The drawing handle to draw with.</param>
+        /// <param name="control">The control rendering.</param>
+        /// <param name="viewportBounds">
+        ///     Absolute screen-space bounds to draw the control at.
+        ///     Not relative to the current transform of <see cref="handle"/>.
+        /// </param>
+        public void RenderScreenOverlaysBelow(
+            DrawingHandleScreen handle,
+            IViewportControl control,
+            in UIBox2i viewportBounds);
+
+        /// <summary>
+        ///     Draw above screen-space overlays for this viewport in UI space.
+        /// </summary>
+        /// <param name="handle">The drawing handle to draw with.</param>
+        /// <param name="control">The control rendering.</param>
+        /// <param name="viewportBounds">
+        ///     Absolute screen-space bounds to draw the control at.
+        ///     Not relative to the current transform of <see cref="handle"/>.
+        /// </param>
+        public void RenderScreenOverlaysAbove(
+            DrawingHandleScreen handle,
+            IViewportControl control,
+            in UIBox2i viewportBounds);
     }
 }

Robust.Client/Graphics/IFontManager.cs

@@ -12,7 +12,7 @@ namespace Robust.Client.Graphics
     {
         IFontFaceHandle Load(Stream stream);
         IFontInstanceHandle MakeInstance(IFontFaceHandle handle, int size);
-        void Initialize();
+        void SetFontDpi(uint fontDpi);
     }
 
     internal interface IFontFaceHandle

Robust.Client/Graphics/IRenderTarget.cs

@@ -1,5 +1,6 @@
 using System;
 using Robust.Shared.Maths;
+using SixLabors.ImageSharp.PixelFormats;
 
 namespace Robust.Client.Graphics
 {
@@ -12,5 +13,7 @@ namespace Robust.Client.Graphics
         ///     The size of the render target, in physical pixels.
         /// </summary>
         Vector2i Size { get; }
+
+        void CopyPixelsToMemory<T>(CopyPixelsDelegate<T> callback, UIBox2i? subRegion = null) where T : unmanaged, IPixel<T>;
     }
 }

Robust.Client/Graphics/Overlays/IOverlayManager.cs

@@ -1,22 +1,29 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using JetBrains.Annotations;
 using Robust.Shared.Timing;
 
 namespace Robust.Client.Graphics
 {
+
     [PublicAPI]
     public interface IOverlayManager
     {
-        void AddOverlay(Overlay overlay);
-        void RemoveOverlay(string id);
-        bool HasOverlay(string id);
+        bool AddOverlay(Overlay overlay);
 
-        Overlay GetOverlay(string id);
-        T GetOverlay<T>(string id) where T : Overlay;
+        bool RemoveOverlay(Overlay overlay);
+        bool RemoveOverlay(Type overlayClass);
+        bool RemoveOverlay<T>() where T : Overlay;
 
-        bool TryGetOverlay(string id, [NotNullWhen(true)] out Overlay? overlay);
-        bool TryGetOverlay<T>(string id, [NotNullWhen(true)] out T? overlay) where T : Overlay;
+        bool TryGetOverlay(Type overlayClass, out Overlay? overlay);
+        bool TryGetOverlay<T>(out T? overlay) where T : Overlay;
+
+        Overlay GetOverlay(Type overlayClass);
+        T GetOverlay<T>() where T : Overlay;
+
+        bool HasOverlay(Type overlayClass);
+        bool HasOverlay<T>() where T : Overlay;
 
         IEnumerable<Overlay> AllOverlays { get; }
     }

Robust.Client/Graphics/Overlays/Overlay.cs

@@ -1,118 +1,105 @@
-using System;
-using System.Collections.Generic;
-using JetBrains.Annotations;
 using Robust.Shared.IoC;
+using JetBrains.Annotations;
 using Robust.Shared.Timing;
+using Robust.Shared.Enums;
+using System;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Maths;
+using Robust.Shared.Utility;
 
 namespace Robust.Client.Graphics
 {
     /// <summary>
-    ///     An overlay is used for fullscreen drawing in the game, for example parallax.
+    ///     An overlay is used for fullscreen drawing in the game. This can range from drawing parallax to a full screen shader.
     /// </summary>
     [PublicAPI]
     public abstract class Overlay
     {
+
         /// <summary>
-        ///     The ID of this overlay. This is used to identify it inside the <see cref="IOverlayManager"/>.
+        ///     Determines when this overlay is drawn in the rendering queue.
         /// </summary>
-        public string ID { get; }
-
-        public virtual bool AlwaysDirty => false;
-        public bool IsDirty => AlwaysDirty || _isDirty;
-        public bool Drawing { get; private set; }
-
         public virtual OverlaySpace Space => OverlaySpace.ScreenSpace;
 
+        /// <summary>
+        ///     If set to true, <see cref="ScreenTexture"/> will be set to the current frame (at the moment before the overlay is rendered). This can be costly to performance, but
+        ///     some shaders will require it as a passed in uniform to operate.
+        /// </summary>
+        public virtual bool RequestScreenTexture => false;
+
+        /// <summary>
+        ///     If <see cref="RequestScreenTexture"> is true, then this will be set to the texture corresponding to the current frame. If false, it will always be null.
+        /// </summary>
+        public Texture? ScreenTexture = null;
+
+        /// <summary>
+        ///    Overlays on the same OverlaySpace will be drawn from lowest ZIndex to highest ZIndex. As an example, ZIndex -1 will be drawn before ZIndex 2.
+        ///    This value is 0 by default. Overlays with same ZIndex will be drawn in an random order.
+        /// </summary>
+        public int? ZIndex { get; set; }
+
         protected IOverlayManager OverlayManager { get; }
 
-        public int? ZIndex { get; set; }
+        private bool Disposed = false;
 
-        public virtual bool SubHandlesUseMainShader { get; } = true;
-
-        private bool _isDirty = true;
-
-        private readonly List<DrawingHandleBase> TempHandles = new();
-
-        private bool Disposed;
-
-        protected Overlay(string id)
+        public Overlay()
         {
             OverlayManager = IoCManager.Resolve<IOverlayManager>();
-            ID = id;
         }
 
-        public void Dispose()
-        {
-            if (Disposed)
-            {
-                return;
-            }
-
-            Dispose(true);
-            Disposed = true;
-            GC.SuppressFinalize(this);
-        }
-
-        ~Overlay()
-        {
-            Dispose(false);
-        }
-
-        protected virtual void Dispose(bool disposing)
-        {
+        /// <summary>
+        ///     If this function returns true, the target framebuffer will be wiped before applying this overlay to it.
+        /// </summary>
+        public virtual bool OverwriteTargetFrameBuffer(){
+            return false;
         }
 
         /// <summary>
         /// Draws this overlay to the current space.
         /// </summary>
-        /// <param name="handle">Current drawing handle that the overlay should be drawing with. Do not hold a reference to this in the overlay.</param>
-        /// <param name="currentSpace">Current space that is being drawn. This function is called for every space that was set up in initialization.</param>
-        protected abstract void Draw(DrawingHandleBase handle, OverlaySpace currentSpace);
-
-        public void Dirty()
-        {
-            _isDirty = true;
-        }
+        protected internal abstract void Draw(in OverlayDrawArgs args);
 
         protected internal virtual void FrameUpdate(FrameEventArgs args) { }
 
-        internal void ClydeRender(IRenderHandle renderHandle, OverlaySpace currentSpace)
+        ~Overlay() {
+            Dispose();
+        }
+
+        public void Dispose() {
+            if (Disposed)
+                return;
+            else
+                DisposeBehavior();
+        }
+
+        protected virtual void DisposeBehavior(){
+            Disposed = true;
+            GC.SuppressFinalize(this);
+        }
+
+
+        internal void ClydeRender(
+            IRenderHandle renderHandle,
+            OverlaySpace currentSpace,
+            IViewportControl? vpControl,
+            IClydeViewport vp,
+            in UIBox2i screenBox,
+            in Box2 worldBox)
         {
             DrawingHandleBase handle;
-            if (currentSpace == OverlaySpace.WorldSpace)
-                handle = renderHandle.DrawingHandleWorld;
-            else
+            if (currentSpace == OverlaySpace.ScreenSpace || currentSpace == OverlaySpace.ScreenSpaceBelowWorld)
+            {
+                DebugTools.AssertNotNull(vpControl);
                 handle = renderHandle.DrawingHandleScreen;
+            }
+            else
+            {
+                handle = renderHandle.DrawingHandleWorld;
+            }
 
-            Draw(handle, currentSpace);
+            var args = new OverlayDrawArgs(currentSpace, vpControl, vp, handle, screenBox, worldBox);
+
+            Draw(args);
         }
     }
-
-
-    /// <summary>
-    ///     Determines in which canvas layers an overlay gets drawn.
-    /// </summary>
-    [Flags]
-    public enum OverlaySpace : byte
-    {
-        /// <summary>
-        ///     Used for matching bit flags.
-        /// </summary>
-        None = 0b0000,
-
-        /// <summary>
-        ///     This overlay will be drawn in the UI root, thus being in screen space.
-        /// </summary>
-        ScreenSpace = 0b0001,
-
-        /// <summary>
-        ///     This overlay will be drawn in the world root, thus being in world space.
-        /// </summary>
-        WorldSpace = 0b0010,
-
-        /// <summary>
-        ///     Drawn in screen coordinates, but behind the world.
-        /// </summary>
-        ScreenSpaceBelowWorld = 0b0100,
-    }
 }

Robust.Client/Graphics/Overlays/OverlayDrawArgs.cs

@@ -0,0 +1,65 @@
+using JetBrains.Annotations;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Enums;
+using Robust.Shared.Maths;
+
+namespace Robust.Client.Graphics
+{
+    /// <summary>
+    ///     Parameters passed to <see cref="Overlay.Draw"/>.
+    /// </summary>
+    [PublicAPI]
+    public readonly ref struct OverlayDrawArgs
+    {
+        /// <summary>
+        ///     The overlay space that currently is being rendered for.
+        /// </summary>
+        public readonly OverlaySpace Space;
+
+        /// <summary>
+        ///     The viewport control that is rendering this viewport.
+        ///     Only available for screen-space overlays.
+        /// </summary>
+        public readonly IViewportControl? ViewportControl;
+
+        /// <summary>
+        ///     The viewport that is rendering this viewport.
+        /// </summary>
+        public readonly IClydeViewport Viewport;
+
+        /// <summary>
+        ///     The drawing handle that you can draw with.
+        /// </summary>
+        public readonly DrawingHandleBase DrawingHandle;
+
+        /// <summary>
+        ///     The screen-space coordinates available to render within.
+        ///     Relevant for screen-space overlay rendering.
+        /// </summary>
+        public readonly UIBox2i ViewportBounds;
+
+        /// <summary>
+        ///     AABB enclosing the area visible in the viewport.
+        /// </summary>
+        public readonly Box2 WorldBounds;
+
+        public DrawingHandleScreen ScreenHandle => (DrawingHandleScreen) DrawingHandle;
+        public DrawingHandleWorld WorldHandle => (DrawingHandleWorld) DrawingHandle;
+
+        public OverlayDrawArgs(
+            OverlaySpace space,
+            IViewportControl? viewportControl,
+            IClydeViewport viewport,
+            DrawingHandleBase drawingHandle,
+            in UIBox2i viewportBounds,
+            in Box2 worldBounds)
+        {
+            Space = space;
+            ViewportControl = viewportControl;
+            Viewport = viewport;
+            DrawingHandle = drawingHandle;
+            ViewportBounds = viewportBounds;
+            WorldBounds = worldBounds;
+        }
+    }
+}

Robust.Client/Graphics/Overlays/OverlayManager.cs

@@ -1,13 +1,15 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using Robust.Shared.Log;
 using Robust.Shared.Timing;
 
 namespace Robust.Client.Graphics
 {
     internal class OverlayManager : IOverlayManagerInternal
     {
-        private readonly Dictionary<string, Overlay> _overlays = new();
+        private readonly Dictionary<Type, Overlay> _overlays = new Dictionary<Type, Overlay>();
+        public IEnumerable<Overlay> AllOverlays => _overlays.Values;
 
         public void FrameUpdate(FrameEventArgs args)
         {
@@ -17,59 +19,80 @@ namespace Robust.Client.Graphics
             }
         }
 
-        public void AddOverlay(Overlay overlay)
+        public bool AddOverlay(Overlay overlay)
         {
-            if (_overlays.ContainsKey(overlay.ID))
-            {
-                throw new InvalidOperationException($"We already have an overlay with ID '{overlay.ID}'");
+            if(_overlays.ContainsKey(overlay.GetType()))
+                return false;
+            _overlays.Add(overlay.GetType(), overlay);
+            return true;
+        }
+
+
+
+        public bool RemoveOverlay(Type overlayClass)
+        {
+            if(!overlayClass.IsSubclassOf(typeof(Overlay))){
+                Logger.Error("RemoveOverlay was called with arg: " + overlayClass.ToString() + ", which is not a subclass of Overlay!");
+                return false;
             }
-
-            _overlays.Add(overlay.ID, overlay);
+            return _overlays.Remove(overlayClass);
         }
 
-        public Overlay GetOverlay(string id)
-        {
-            return _overlays[id];
+        public bool RemoveOverlay<T>() where T : Overlay{
+            return RemoveOverlay(typeof(T));
         }
 
-        public T GetOverlay<T>(string id) where T : Overlay
-        {
-            return (T) GetOverlay(id);
+        public bool RemoveOverlay(Overlay overlay) {
+            return _overlays.Remove(overlay.GetType());
         }
 
-        public bool HasOverlay(string id)
-        {
-            return _overlays.ContainsKey(id);
-        }
 
-        public void RemoveOverlay(string id)
+
+
+
+        public bool TryGetOverlay(Type overlayClass, [NotNullWhen(true)] out Overlay? overlay)
         {
-            if (!_overlays.TryGetValue(id, out var overlay))
-            {
-                return;
+            overlay = null;
+            if (!overlayClass.IsSubclassOf(typeof(Overlay))){
+                Logger.Error("TryGetOverlay was called with arg: " + overlayClass.ToString() + ", which is not a subclass of Overlay!");
+                return false;
             }
-
-            overlay.Dispose();
-            _overlays.Remove(id);
+            return _overlays.TryGetValue(overlayClass, out overlay);
         }
 
-        public bool TryGetOverlay(string id, [NotNullWhen(true)] out Overlay? overlay)
-        {
-            return _overlays.TryGetValue(id, out overlay);
-        }
-
-        public bool TryGetOverlay<T>(string id, [NotNullWhen(true)] out T? overlay) where T : Overlay
-        {
-            if (_overlays.TryGetValue(id, out var value))
-            {
-                overlay = (T) value;
+        public bool TryGetOverlay<T>([NotNullWhen(true)] out T? overlay) where T : Overlay {
+            overlay = null;
+            if(_overlays.TryGetValue(typeof(T), out Overlay? toReturn)){
+                overlay = (T)toReturn;
                 return true;
             }
-
-            overlay = default;
             return false;
         }
 
-        public IEnumerable<Overlay> AllOverlays => _overlays.Values;
+
+
+
+        public Overlay GetOverlay(Type overlayClass) {
+            return _overlays[overlayClass];
+        }
+
+        public T GetOverlay<T>() where T : Overlay {
+            return (T)_overlays[typeof(T)];
+        }
+
+
+
+
+
+        public bool HasOverlay(Type overlayClass) {
+            if (!overlayClass.IsSubclassOf(typeof(Overlay)))
+                Logger.Error("HasOverlay was called with arg: " + overlayClass.ToString() + ", which is not a subclass of Overlay!");
+            return _overlays.ContainsKey(overlayClass);
+        }
+
+        public bool HasOverlay<T>() where T : Overlay  {
+            return _overlays.ContainsKey(typeof(T));
+        }
+
     }
 }

Robust.Client/Graphics/RSI/RSI.State.cs

@@ -19,10 +19,10 @@ namespace Robust.Client.Graphics
         public sealed class State : IRsiStateLike
         {
             // List of delays for the frame to reach the next frame.
-            private readonly float[] Delays;
+            public readonly float[] Delays;
 
             // 2D array for the texture to use for each animation frame at each direction.
-            private readonly Texture[][] Icons;
+            public readonly Texture[][] Icons;
 
             internal State(Vector2i size, StateId stateId, DirectionType direction, float[] delays, Texture[][] icons)
             {

Robust.Client/Graphics/RSI/RSISchema.json

@@ -1,47 +0,0 @@
-{
-    "$schema": "http://json-schema.org/draft-04/schema#",
-    "title": "RSI Image Format Validation Schema V1",
-    "description": "Robust Station Image",
-    "type": "object",
-    "definitions": {
-        "size": {
-            "type": "object",
-            "properties": {
-                "x": {"type": "integer", "minimum": 1},
-                "y": {"type": "integer", "minimum": 1}
-            },
-            "required": ["x","y"]
-        },
-        "directions": {
-            "type": "integer",
-            "enum": [1,4,8]
-        },
-        "state": {
-            "type": "object",
-            "properties": {
-                "name": {"type": "string"},
-                "flags": {"type": "object"}, //To be de-serialized as a Dictionary
-                "directions": {"$ref": "#/definitions/directions"},
-                "delays": {
-                    "type": "array",
-                    "minItems": 1,
-                    "items": {
-                        "type": "array",
-                        "items": {"type": "number", "minimum": 0, "exclusiveMinimum": true} //number == float
-                    }
-                }
-            },
-            "required": ["name"] //'delays' is marked as optional in the spec
-        }
-    },
-    "properties": {
-        "version": {"type": "integer", "minimum": 1, "maximum": 1},
-        "size": {"$ref": "#/definitions/size"},
-        "states": {
-            "type": "array",
-            "items": {"$ref": "#/definitions/state"},
-            "minItems": 1
-        }
-    },
-    "required": ["version","size","states"]
-}

Robust.Client/Graphics/ScreenshotType.cs

@@ -1,8 +1,13 @@
 namespace Robust.Client.Graphics
 {
+    /// <summary>
+    ///     Types of screenshots to take, at various stages of the render pipeline.
+    /// </summary>
     public enum ScreenshotType : byte
     {
-        BeforeUI,
-        AfterUI
+        /// <summary>
+        ///     Final framebuffer that will be presented to the window.
+        /// </summary>
+        Final
     }
 }

Robust.Client/Graphics/Shaders/Params.cs

@@ -1,33 +0,0 @@
-namespace Robust.Client.Graphics
-{
-    public enum ShaderParamType : byte
-    {
-        // Can this even happen?
-        Void = 0,
-        Bool,
-        BVec2,
-        BVec3,
-        BVec4,
-        UInt,
-        /// <summary>
-        ///     While Godot supports all (u)int vectors,
-        ///     It doesn't specify which is used from get params.
-        ///     So ivec2, ivec3, ivec4... are all this guy.
-        /// </summary>
-        IntVec,
-        Int,
-        Float,
-        Vec2,
-        Vec3,
-        Vec4,
-        Mat2,
-        Mat3,
-        Mat4,
-        /// <summary>
-        ///     Godot supports u, i and b samplers too,
-        ///     but we can't tell in code.
-        /// </summary>
-        Sampler2D,
-        SamplerCube
-    }
-}

Robust.Client/Graphics/Shaders/ShaderPrototype.cs

@@ -19,7 +19,7 @@ namespace Robust.Client.Graphics
         [Dependency] private readonly IResourceCache _resourceCache = default!;
 
         [ViewVariables]
-        [field: DataField("id", required: true)]
+        [DataField("id", required: true)]
         public string ID { get; } = default!;
 
         private ShaderKind Kind;

Robust.Client/IBaseClient.cs

@@ -70,5 +70,15 @@ namespace Robust.Client
         ///     Disconnects the connected BaseClient from a remote server.
         /// </summary>
         void DisconnectFromServer(string reason);
+
+        /// <summary>
+        ///     Starts the single player mode.
+        /// </summary>
+        void StartSinglePlayer();
+
+        /// <summary>
+        ///     Stops the single player mode.
+        /// </summary>
+        void StopSinglePlayer();
     }
 }

Robust.Client/IGameControllerInternal.cs

@@ -7,6 +7,8 @@ namespace Robust.Client
 {
     internal interface IGameControllerInternal : IGameController
     {
+        GameControllerOptions Options { get; }
+        bool ContentStart { get; set; }
         void SetCommandLineArgs(CommandLineArgs args);
         bool LoadConfigAndUserData { get; set; }
         bool Startup(Func<ILogHandler>? logHandlerFactory = null);
@@ -18,4 +20,4 @@ namespace Robust.Client
         void MouseWheel(MouseWheelEventArgs mouseWheelEventArgs);
         void OverrideMainLoop(IGameLoop gameLoop);
     }
-}
+}

Robust.Client/Input/Events.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Text;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Input
@@ -58,6 +59,7 @@ namespace Robust.Client.Input
         }
 
         public uint CodePoint { get; }
+        public Rune AsRune => new Rune(CodePoint);
     }
 
     public class KeyEventArgs : ModifierInputEventArgs

Robust.Client/Input/IInputManager.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using Robust.Client.UserInterface;
 using Robust.Shared.Input;
 using Robust.Shared.Input.Binding;
 using Robust.Shared.Maths;
@@ -14,6 +15,16 @@ namespace Robust.Client.Input
     {
         bool Enabled { get; set; }
 
+        /// <summary>
+        ///     Relay a key event that hit a viewport further down the input stack.
+        /// </summary>
+        /// <remarks>
+        ///     This is ONLY intended to be used in key handler from viewport controls.
+        /// </remarks>
+        /// <param name="control">The viewport control that relayed the input.</param>
+        /// <param name="eventArgs">The key event args triggering the input.</param>
+        void ViewportKeyEvent(Control? control, BoundKeyEventArgs eventArgs);
+
         Vector2 MouseScreenPosition { get; }
 
         BoundKeyMap NetworkBindMap { get; }
@@ -60,12 +71,12 @@ namespace Robust.Client.Input
         /// <summary>
         ///     UIKeyBindStateChanged is called when a keybind is found.
         /// </summary>
-        event Func<BoundKeyEventArgs, bool> UIKeyBindStateChanged;
+        event Func<BoundKeyEventArgs, bool>? UIKeyBindStateChanged;
 
         /// <summary>
         ///     If UIKeyBindStateChanged did not handle the BoundKeyEvent, KeyBindStateChanged is called.
         /// </summary>
-        event Action<BoundKeyEventArgs> KeyBindStateChanged;
+        event Action<ViewportBoundKeyEventArgs>? KeyBindStateChanged;
 
         IEnumerable<BoundKeyFunction> DownKeyFunctions { get; }
 

Robust.Client/Input/InputManager.cs

@@ -42,6 +42,8 @@ namespace Robust.Client.Input
         [Dependency] private readonly IReflectionManager _reflectionManager = default!;
         [Dependency] private readonly IUserInterfaceManagerInternal _userInterfaceManagerInternal = default!;
 
+        private bool _currentlyFindingViewport;
+
         private readonly List<KeyBindingRegistration> _defaultRegistrations = new();
 
         private readonly Dictionary<BoundKeyFunction, InputCmdHandler> _commands =
@@ -68,7 +70,7 @@ namespace Robust.Client.Input
         public event Func<BoundKeyEventArgs, bool>? UIKeyBindStateChanged;
 
         /// <inheritdoc />
-        public event Action<BoundKeyEventArgs>? KeyBindStateChanged;
+        public event Action<ViewportBoundKeyEventArgs>? KeyBindStateChanged;
 
         public IEnumerable<BoundKeyFunction> DownKeyFunctions => _bindings
             .Where(x => x.State == BoundKeyState.Down)
@@ -329,36 +331,67 @@ namespace Robust.Client.Input
 
         private bool SetBindState(KeyBinding binding, BoundKeyState state, bool uiOnly = false)
         {
-            binding.State = state;
+            // christ this crap *is* re-entrant thanks to PlacementManager and
+            // I honestly have no idea what the best solution here is.
+            DebugTools.Assert(!_currentlyFindingViewport, "Re-entrant key events??");
 
-            var eventArgs = new BoundKeyEventArgs(binding.Function, binding.State,
-                new ScreenCoordinates(MouseScreenPosition), binding.CanFocus);
-
-            var handled = UIKeyBindStateChanged?.Invoke(eventArgs);
-            if (state == BoundKeyState.Up
-                || !(handled == true || eventArgs.Handled)
-                && !uiOnly)
+            try
             {
-                var cmd = GetInputCommand(binding.Function);
-                // TODO: Allow input commands to still get forwarded to server if necessary.
-                if (cmd != null)
+                // This is terrible but anyways.
+                // This flag keeps track of "did a viewport fire the key up for us" so we know we don't do it again.
+                _currentlyFindingViewport = true;
+
+                binding.State = state;
+
+                var eventArgs = new BoundKeyEventArgs(binding.Function, binding.State,
+                    new ScreenCoordinates(MouseScreenPosition), binding.CanFocus);
+
+                // UI returns true here into blockPass if it wants to prevent us from giving input events
+                // to the viewport, but doesn't want it hard-handled so we keep processing possible key actions.
+                var blockPass = UIKeyBindStateChanged?.Invoke(eventArgs);
+                if ((state == BoundKeyState.Up || (!(blockPass == true || eventArgs.Handled) && !uiOnly))
+                    && _currentlyFindingViewport)
                 {
-                    if (state == BoundKeyState.Up)
-                    {
-                        cmd.Disabled(null);
-                    }
-                    else
-                    {
-                        cmd.Enabled(null);
-                    }
+                    ViewportKeyEvent(null, eventArgs);
+                }
+
+                return eventArgs.Handled;
+            }
+            finally
+            {
+                _currentlyFindingViewport = false;
+            }
+        }
+
+        public void ViewportKeyEvent(Control? viewport, BoundKeyEventArgs eventArgs)
+        {
+            _currentlyFindingViewport = false;
+
+            var cmd = GetInputCommand(eventArgs.Function);
+            // TODO: Allow input commands to still get forwarded to server if necessary.
+            if (cmd != null)
+            {
+                // Out-of-simulation input event
+                if (eventArgs.State == BoundKeyState.Up)
+                {
+                    cmd.Disabled(null);
                 }
                 else
                 {
-                    KeyBindStateChanged?.Invoke(eventArgs);
+                    cmd.Enabled(null);
                 }
             }
+            else
+            {
+                var viewportEventArgs = new ViewportBoundKeyEventArgs(eventArgs, viewport);
+                // In-simulation input event (through content to InputSystem)
+                KeyBindStateChanged?.Invoke(viewportEventArgs);
 
-            return eventArgs.Handled;
+                if (viewportEventArgs.KeyEventArgs.Handled)
+                {
+                    eventArgs.Handle();
+                }
+            }
         }
 
         private bool PackedMatchesPressedState(PackedKeyCombo packed)

Robust.Client/Input/ViewportBoundKeyEventArgs.cs

@@ -0,0 +1,17 @@
+using Robust.Client.UserInterface;
+using Robust.Shared.Input;
+
+namespace Robust.Client.Input
+{
+    public sealed class ViewportBoundKeyEventArgs
+    {
+        public BoundKeyEventArgs KeyEventArgs { get; }
+        public Control? Viewport { get; }
+
+        public ViewportBoundKeyEventArgs(BoundKeyEventArgs keyEventArgs, Control? viewport)
+        {
+            KeyEventArgs = keyEventArgs;
+            Viewport = viewport;
+        }
+    }
+}

Robust.Client/Map/ClientMapManager.cs

@@ -1,92 +1,23 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameStates;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Network;
-using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 
-namespace Robust.Shared.Map
+namespace Robust.Client.Map
 {
-    internal partial class MapManager
+    internal class ClientMapManager : MapManager, IClientMapManager
     {
         [Dependency] private readonly INetManager _netManager = default!;
 
-        public GameStateMapData? GetStateData(GameTick fromTick)
-        {
-            var gridDatums = new Dictionary<GridId, GameStateMapData.GridDatum>();
-            foreach (var grid in _grids.Values)
-            {
-                if (grid.LastModifiedTick < fromTick)
-                {
-                    continue;
-                }
-
-                var chunkData = new List<GameStateMapData.ChunkDatum>();
-                foreach (var (index, chunk) in grid.GetMapChunks())
-                {
-                    if (chunk.LastModifiedTick < fromTick)
-                    {
-                        continue;
-                    }
-
-                    var tileBuffer = new Tile[grid.ChunkSize * (uint) grid.ChunkSize];
-
-                    // Flatten the tile array.
-                    // NetSerializer doesn't do multi-dimensional arrays.
-                    // This is probably really expensive.
-                    for (var x = 0; x < grid.ChunkSize; x++)
-                    {
-                        for (var y = 0; y < grid.ChunkSize; y++)
-                        {
-                            tileBuffer[x * grid.ChunkSize + y] = chunk.GetTile((ushort)x, (ushort)y);
-                        }
-                    }
-
-                    chunkData.Add(new GameStateMapData.ChunkDatum(index, tileBuffer));
-                }
-
-                var gridDatum =
-                    new GameStateMapData.GridDatum(chunkData.ToArray(), new MapCoordinates(grid.WorldPosition, grid.ParentMapId));
-
-                gridDatums.Add(grid.Index, gridDatum);
-            }
-
-            var mapDeletionsData = _mapDeletionHistory.Where(d => d.tick >= fromTick).Select(d => d.mapId).ToList();
-            var gridDeletionsData = _gridDeletionHistory.Where(d => d.tick >= fromTick).Select(d => d.gridId).ToList();
-            var mapCreations = _mapCreationTick.Where(kv => kv.Value >= fromTick && kv.Key != MapId.Nullspace)
-                .Select(kv => kv.Key).ToArray();
-            var gridCreations = _grids.Values.Where(g => g.CreatedTick >= fromTick && g.ParentMapId != MapId.Nullspace).ToDictionary(g => g.Index,
-                grid => new GameStateMapData.GridCreationDatum(grid.ChunkSize, grid.SnapSize));
-
-            // no point sending empty collections
-            if (gridDatums.Count        == 0)  gridDatums        = default;
-            if (gridDeletionsData.Count == 0)  gridDeletionsData = default;
-            if (mapDeletionsData.Count  == 0)  mapDeletionsData  = default;
-            if (mapCreations.Length     == 0)  mapCreations      = default;
-            if (gridCreations.Count     == 0)  gridCreations     = default;
-
-            // no point even creating an empty map state if no data
-            if (gridDatums == null && gridDeletionsData == null && mapDeletionsData == null && mapCreations == null && gridCreations == null)
-                return default;
-
-            return new GameStateMapData(gridDatums?.ToArray(), gridDeletionsData?.ToArray(), mapDeletionsData?.ToArray(), mapCreations?.ToArray(), gridCreations?.ToArray());
-        }
-
-        public void CullDeletionHistory(GameTick uptoTick)
-        {
-            _mapDeletionHistory.RemoveAll(t => t.tick < uptoTick);
-            _gridDeletionHistory.RemoveAll(t => t.tick < uptoTick);
-        }
-
         public void ApplyGameStatePre(GameStateMapData? data)
         {
-            DebugTools.Assert(_netManager.IsClient, "Only the client should call this.");
-
             // There was no map data this tick, so nothing to do.
             if(data == null)
                 return;
@@ -125,8 +56,7 @@ namespace Robust.Shared.Map
                         continue;
                     }
 
-                    CreateGrid(gridData![gridId].Coordinates.MapId, gridId, creationDatum.ChunkSize,
-                        creationDatum.SnapSize);
+                    CreateGrid(gridData![gridId].Coordinates.MapId, gridId, creationDatum.ChunkSize);
                 }
             }
 
@@ -172,7 +102,7 @@ namespace Robust.Shared.Map
 
                     if (modified.Count != 0)
                     {
-                        GridChanged?.Invoke(this, new GridChangedEventArgs(grid, modified));
+                        InvokeGridChanged(this, new GridChangedEventArgs(grid, modified));
                     }
                 }
 
@@ -202,11 +132,11 @@ namespace Robust.Shared.Map
                         continue;
 
                     // get the existing client entity for the map.
-                    var cEntity = _entityManager.GetEntity(_mapEntities[mapId]);
+                    var cEntity = EntityManager.GetEntity(_mapEntities[mapId]);
 
                     // locate the entity that represents this map that was just sent to us
                     IEntity? sharedMapEntity = null;
-                    var mapComps = _entityManager.ComponentManager.EntityQuery<IMapComponent>(true);
+                    var mapComps = EntityManager.ComponentManager.EntityQuery<IMapComponent>(true);
                     foreach (var mapComp in mapComps)
                     {
                         if (!mapComp.Owner.Uid.IsClientSide() && mapComp.WorldMap == mapId)
@@ -251,12 +181,16 @@ namespace Robust.Shared.Map
                         continue;
 
                     // remove the existing client entity.
-                    var cEntity = _entityManager.GetEntity(grid.GridEntityId);
+                    var cEntity = EntityManager.GetEntity(grid.GridEntityId);
                     var cGridComp = cEntity.GetComponent<IMapGridComponent>();
-                    cGridComp.ClearGridId();
+
+                    // prevents us from deleting the grid when deleting the grid entity
+                    if(cEntity.Uid.IsClientSide())
+                        cGridComp.ClearGridId();
+
                     cEntity.Delete(); // normal entities are already parented to the shared comp, client comp has no children
 
-                    var gridComps = _entityManager.ComponentManager.EntityQuery<IMapGridComponent>(true);
+                    var gridComps = EntityManager.ComponentManager.EntityQuery<IMapGridComponent>(true);
                     foreach (var gridComp in gridComps)
                     {
                         if (gridComp.GridIndex == kvNewGrid.Key)

Robust.Client/Map/ClydeTileDefinitionManager.cs

@@ -16,7 +16,9 @@ namespace Robust.Client.Map
     {
         [Dependency] private readonly IResourceCache _resourceCache = default!;
 
-        public Texture TileTextureAtlas { get; private set; } = default!;
+        private Texture? _tileTextureAtlas;
+        
+        public Texture TileTextureAtlas => _tileTextureAtlas ?? Texture.Transparent;
 
         private readonly Dictionary<ushort, Box2> _tileRegions = new();
 
@@ -40,6 +42,11 @@ namespace Robust.Client.Map
         private void _genTextureAtlas()
         {
             var defList = TileDefs.Where(t => !string.IsNullOrEmpty(t.SpriteName)).ToList();
+
+            // If there are no tile definitions, we do nothing.
+            if (defList.Count <= 0)
+                return;
+
             const int tileSize = EyeManager.PixelsPerMeter;
 
             var dimensionX = (int) Math.Ceiling(Math.Sqrt(defList.Count));
@@ -77,7 +84,7 @@ namespace Robust.Client.Map
                         tileSize / w, tileSize / h));
             }
 
-            TileTextureAtlas = Texture.LoadFromImage(sheet, "Tile Atlas");
+            _tileTextureAtlas = Texture.LoadFromImage(sheet, "Tile Atlas");
         }
     }
 }