Remove Eye Lerping from engine. (#2371)

Robust.Client/GameObjects/EntitySystems/EyeUpdateSystem.cs

@@ -7,8 +7,10 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.Input;
 using Robust.Shared.Input.Binding;
 using Robust.Shared.IoC;
+using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
+using Robust.Shared.Timing;
 
 #nullable enable
 
@@ -18,26 +20,8 @@ namespace Robust.Client.GameObjects
     /// Updates the position of every Eye every frame, so that the camera follows the player around.
     /// </summary>
     [UsedImplicitly]
-    internal class EyeUpdateSystem : EntitySystem
+    public class EyeUpdateSystem : EntitySystem
     {
-        [Dependency] private readonly IEyeManager _eyeManager = default!;
-        [Dependency] private readonly IMapManager _mapManager = default!;
-        [Dependency] private readonly IPlayerManager _playerManager = default!;
-
-        private TransformComponent? _lastParent;
-        private TransformComponent? _lerpTo;
-        private Angle LerpStartRotation;
-        private float _accumulator;
-
-        public bool IsLerping { get => _lerpTo != null; }
-
-        // How fast the camera rotates in radians / s
-        private const float CameraRotateSpeed = MathF.PI;
-        // PER THIS AMOUNT OF TIME MILLISECONDS
-        private const float CameraRotateTimeUnit = 1.2f;
-        // Safety override
-        private const float _lerpTimeMax = CameraRotateTimeUnit + 0.4f;
-
         /// <inheritdoc />
         public override void Initialize()
         {
@@ -65,77 +49,6 @@ namespace Robust.Client.GameObjects
         /// <inheritdoc />
         public override void FrameUpdate(float frameTime)
         {
-            var currentEye = _eyeManager.CurrentEye;
-
-            // TODO: Content should have its own way of handling this. We should have a default behavior that they can overwrite.
-
-            EntityUid tempQualifier = _playerManager.LocalPlayer?.ControlledEntity ?? EntityUid.Invalid;
-            var playerTransform = (tempQualifier != EntityUid.Invalid ? EntityManager.GetComponent<TransformComponent>(tempQualifier) : null);
-
-            if (playerTransform == null) return;
-
-            var gridId = playerTransform.GridID;
-
-            TransformComponent parent;
-            if (gridId != GridId.Invalid &&
-                _mapManager.GetGrid(gridId).GridEntityId is var gridEnt &&
-                EntityManager.EntityExists(gridEnt))
-                parent = EntityManager.GetComponent<TransformComponent>(gridEnt);
-            else
-            {
-                parent = EntityManager.GetComponent<TransformComponent>(
-                    _mapManager.GetMapEntityId(playerTransform.MapID));
-            }
-
-            // Make sure that we don't fire the vomit carousel when we spawn in
-            if (_lastParent is null)
-                _lastParent = parent;
-
-            // Set a default for target rotation
-            var parentRotation = -parent.WorldRotation;
-            // Reuse current rotation when stepping into space
-            if (parent.GridID == GridId.Invalid)
-                parentRotation = currentEye.Rotation;
-
-            // Handle grid change in general
-            if (_lastParent != parent)
-                _lerpTo = parent;
-
-            // And we are up and running!
-            if (_lerpTo is not null)
-            {
-                // Handle a case where we have beeing spinning around, but suddenly got off onto a different grid
-                if (parent != _lerpTo) {
-                    LerpStartRotation = currentEye.Rotation;
-                    _lerpTo = parent;
-                    _accumulator = 0f;
-                }
-
-                _accumulator += frameTime;
-
-                var changeNeeded = (float) (LerpStartRotation - parentRotation).Theta;
-
-                var changeLerp = _accumulator / (Math.Abs(changeNeeded % MathF.PI) / CameraRotateSpeed * CameraRotateTimeUnit);
-
-                currentEye.Rotation = Angle.Lerp(LerpStartRotation, parentRotation, changeLerp);
-
-                // Either we have overshot, or we have taken way too long on this, emergency reset time
-                if (changeLerp > 1.0f || _accumulator >= _lerpTimeMax)
-                {
-                    _lastParent = parent;
-                    _lerpTo = null;
-                    _accumulator = 0f;
-                }
-            }
-
-            // We are just fine, or we finished a lerp (and probably overshot)
-            if (_lerpTo is null)
-            {
-                currentEye.Rotation = parentRotation;
-                LerpStartRotation = parentRotation;
-            }
-
-
             foreach (var eyeComponent in EntityManager.EntityQuery<EyeComponent>(true))
             {
                 eyeComponent.UpdateEyePosition();

Robust.Client/GameObjects/EntitySystems/TransformSystem.cs

@@ -14,7 +14,7 @@ namespace Robust.Client.GameObjects
     ///     Handles interpolation of transform positions.
     /// </summary>
     [UsedImplicitly]
-    internal sealed class TransformSystem : SharedTransformSystem
+    public sealed class TransformSystem : SharedTransformSystem
     {
         // Max distance per tick how far an entity can move before it is considered teleporting.
         // TODO: Make these values somehow dependent on server TPS.

Robust.Client/Graphics/ClientEye/EyeManager.cs

@@ -32,14 +32,20 @@ namespace Robust.Client.Graphics
         public IEye CurrentEye
         {
             get => _currentEye ?? _defaultEye;
-            set => _currentEye = value;
+            set
+            {
+                var old = _currentEye;
+                _currentEye = value;
+
+                _entityManager.EventBus.RaiseEvent(EventSource.Local, new CurrentEyeChangedEvent(old, _currentEye));
+            }
         }
 
         public IViewportControl MainViewport { get; set; } = default!;
 
         public void ClearCurrentEye()
         {
-            _currentEye = _defaultEye;
+            CurrentEye = _defaultEye;
         }
 
         void IEyeManager.Initialize()
@@ -146,4 +152,16 @@ namespace Robust.Client.Graphics
             return MainViewport.ScreenToMap(point);
         }
     }
+
+    public class CurrentEyeChangedEvent : EntityEventArgs
+    {
+        public IEye? Old { get; }
+        public IEye New { get; }
+
+        public CurrentEyeChangedEvent(IEye? oldEye, IEye newEye)
+        {
+            Old = oldEye;
+            New = newEye;
+        }
+    }
 }

Robust.Server/GameObjects/EntitySystems/TransformSystem.cs

@@ -2,7 +2,7 @@ using Robust.Shared.GameObjects;
 
 namespace Robust.Server.GameObjects
 {
-    internal sealed class TransformSystem : SharedTransformSystem
+    public sealed class TransformSystem : SharedTransformSystem
     {
 
     }

Robust.Shared.Maths/Angle.cs

@@ -229,12 +229,16 @@ namespace Robust.Shared.Maths
         /// </summary>
         public static Angle Lerp(in Angle a, in Angle b, float factor)
         {
-            var degA = MathHelper.RadiansToDegrees(Reduce(a));
-            var degB = MathHelper.RadiansToDegrees(Reduce(b));
-            var delta = MathHelper.Mod((degB - degA), 360);
-            if (delta > 180)
-                delta -= 360;
-            return new Angle(MathHelper.DegreesToRadians(degA + delta * MathHelper.Clamp(factor, 0, 1)));
+            return a + ShortestDistance(a, b) * factor;
+        }
+
+        /// <summary>
+        ///     Returns the shortest distance between two angles.
+        /// </summary>
+        public static Angle ShortestDistance(in Angle a, in Angle b)
+        {
+            var delta = (b - a) % Math.Tau;
+            return 2 * delta % Math.Tau - delta;
         }
 
         /// <summary>

Robust.Shared/GameObjects/Systems/SharedTransformSystem.cs

@@ -8,7 +8,7 @@ using Robust.Shared.Utility;
 
 namespace Robust.Shared.GameObjects
 {
-    internal abstract class SharedTransformSystem : EntitySystem
+    public abstract class SharedTransformSystem : EntitySystem
     {
         [Dependency] private readonly IMapManager _mapManager = default!;