Makes mobs visually float when weightless (#13391)

Content.Client/Gravity/FloatingVisualizerSystem.cs

@@ -0,0 +1,61 @@
+using Content.Shared.Gravity;
+using Robust.Client.GameObjects;
+using Robust.Client.Animations;
+using Robust.Shared.Animations;
+
+namespace Content.Client.Gravity;
+
+/// <inheritdoc/>
+public sealed class FloatingVisualizerSystem : SharedFloatingVisualizerSystem
+{
+    [Dependency] private readonly AnimationPlayerSystem AnimationSystem = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<FloatingVisualsComponent, AnimationCompletedEvent>(OnAnimationCompleted);
+    }
+
+    /// <inheritdoc/>
+    public override void FloatAnimation(EntityUid uid, Vector2 offset, string animationKey, float animationTime, bool stop = false)
+    {
+        if (stop)
+        {
+            AnimationSystem.Stop(uid, animationKey);
+            return;
+        }
+
+        var animation = new Animation
+        {
+            // We multiply by the number of extra keyframes to make time for them
+            Length = TimeSpan.FromSeconds(animationTime*2),
+            AnimationTracks =
+            {
+                new AnimationTrackComponentProperty
+                {
+                    ComponentType = typeof(SpriteComponent),
+                    Property = nameof(SpriteComponent.Offset),
+                    InterpolationMode = AnimationInterpolationMode.Linear,
+                    KeyFrames =
+                    {
+                        new AnimationTrackProperty.KeyFrame(Vector2.Zero, 0f),
+                        new AnimationTrackProperty.KeyFrame(offset, animationTime),
+                        new AnimationTrackProperty.KeyFrame(Vector2.Zero, animationTime),
+                    }
+                }
+            }
+        };
+
+        if (!AnimationSystem.HasRunningAnimation(uid, animationKey))
+            AnimationSystem.Play(uid, animation, animationKey);
+    }
+
+    private void OnAnimationCompleted(EntityUid uid, FloatingVisualsComponent component, AnimationCompletedEvent args)
+    {
+        if (args.Key != component.AnimationKey)
+            return;
+
+        FloatAnimation(uid, component.Offset, component.AnimationKey, component.AnimationTime, !component.CanFloat);
+    }
+}