Fix eye zoom lerp (#19377)

Content.Client/Eye/EyeLerpingSystem.cs

@@ -1,11 +1,10 @@
-using Content.Shared.Follower.Components;
+using System.Numerics;
 using Content.Shared.Movement.Components;
 using Content.Shared.Movement.Systems;
+using JetBrains.Annotations;
 using Robust.Client.GameObjects;
-using Robust.Client.Graphics;
 using Robust.Client.Physics;
 using Robust.Client.Player;
-using Robust.Shared.Collections;
 using Robust.Shared.Timing;
 
 namespace Content.Client.Eye;
@@ -15,9 +14,10 @@ public sealed class EyeLerpingSystem : EntitySystem
     [Dependency] private readonly IPlayerManager _playerManager = default!;
     [Dependency] private readonly IGameTiming _gameTiming = default!;
     [Dependency] private readonly SharedMoverController _mover = default!;
+    [Dependency] private readonly SharedTransformSystem _transform = default!;
 
     // Convenience variable for for VV.
-    [ViewVariables]
+    [ViewVariables, UsedImplicitly]
     private IEnumerable<LerpingEyeComponent> ActiveEyes => EntityQuery<LerpingEyeComponent>();
 
     public override void Initialize()
@@ -59,8 +59,14 @@ public sealed class EyeLerpingSystem : EntitySystem
         lerpInfo.LastRotation = lerpInfo.TargetRotation;
         lerpInfo.ManuallyAdded |= !automatic;
 
+        lerpInfo.TargetZoom = component.Zoom;
+        lerpInfo.LastZoom = lerpInfo.TargetZoom;
+
         if (component.Eye != null)
+        {
             component.Eye.Rotation = lerpInfo.TargetRotation;
+            component.Eye.Zoom = lerpInfo.TargetZoom;
+        }
     }
 
     public void RemoveEye(EntityUid uid)
@@ -107,9 +113,29 @@ public sealed class EyeLerpingSystem : EntitySystem
         {
             lerpInfo.LastRotation = lerpInfo.TargetRotation;
             lerpInfo.TargetRotation = GetRotation(uid, xform);
+
+            lerpInfo.LastZoom = lerpInfo.TargetZoom;
+            lerpInfo.TargetZoom = UpdateZoom(uid, frameTime);
         }
     }
 
+    private Vector2 UpdateZoom(EntityUid uid, float frameTime, EyeComponent? eye = null, ContentEyeComponent? content = null)
+    {
+        if (!Resolve(uid, ref content, ref eye, false))
+            return Vector2.One;
+
+        var diff = content.TargetZoom - eye.Zoom;
+
+        if (diff.LengthSquared() < 0.00001f)
+        {
+            return content.TargetZoom;
+        }
+
+        var change = diff * 8f * frameTime;
+
+        return eye.Zoom + change;
+    }
+
     /// <summary>
     /// Does the eye need to lerp or is its rotation matched.
     /// </summary>
@@ -138,7 +164,7 @@ public sealed class EyeLerpingSystem : EntitySystem
         // if not tied to a mover then lock it to map / grid
         var relative = xform.GridUid ?? xform.MapUid;
         if (relative != null)
-            return -Transform(relative.Value).WorldRotation;
+            return -_transform.GetWorldRotation(relative.Value);
 
         return Angle.Zero;
     }
@@ -151,6 +177,19 @@ public sealed class EyeLerpingSystem : EntitySystem
 
         while (query.MoveNext(out var entity, out var lerpInfo, out var eye, out var xform))
         {
+            // Handle zoom
+            var zoomDiff = Vector2.Lerp(lerpInfo.LastZoom, lerpInfo.TargetZoom, tickFraction);
+
+            if ((zoomDiff - lerpInfo.TargetZoom).Length() < lerpMinimum)
+            {
+                eye.Zoom = lerpInfo.TargetZoom;
+            }
+            else
+            {
+                eye.Zoom = zoomDiff;
+            }
+
+            // Handle Rotation
             TryComp<InputMoverComponent>(entity, out var mover);
 
             // This needs to be recomputed every frame, as if this is simply the grid rotation, then we need to account for grid angle lerping.