Fix stack overflow when using recursion with nested scene animations

#519

Source/Editor/GUI/Timeline/SceneAnimationTimeline.cs

@@ -26,6 +26,7 @@ namespace FlaxEditor.GUI.Timeline
 
         private SceneAnimationPlayer _player;
         private bool _showSelected3dTrack = true;
+        internal Guid _id;
 
         /// <summary>
         /// Gets or sets the animation player actor used for the timeline preview.

Source/Editor/GUI/Timeline/Tracks/NestedSceneAnimationTrack.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.IO;
+using System.Linq;
 using FlaxEngine;
 
 namespace FlaxEditor.GUI.Timeline.Tracks
@@ -122,5 +123,22 @@ namespace FlaxEditor.GUI.Timeline.Tracks
         : base(ref options)
         {
         }
+
+        /// <inheritdoc />
+        protected override void OnAssetChanged()
+        {
+            if (Asset)
+            {
+                var refs = Asset.GetReferences();
+                var id = ((SceneAnimationTimeline)Timeline)._id;
+                if (Asset.ID == id || refs.Contains(id))
+                {
+                    Asset = null;
+                    throw new Exception("Cannot use nested scene animation (recursion).");
+                }
+            }
+
+            base.OnAssetChanged();
+        }
     }
 }

Source/Editor/Windows/Assets/SceneAnimationWindow.cs

@@ -852,6 +852,7 @@ namespace FlaxEditor.Windows.Assets
                 _isWaitingForTimelineLoad = false;
 
                 // Load timeline data from the asset
+                _timeline._id = OriginalAsset.ID;
                 _timeline.Load(_asset);
 
                 // Setup

Source/Engine/Animations/SceneAnimations/SceneAnimationPlayer.cpp

@@ -192,7 +192,8 @@ void SceneAnimationPlayer::Tick(float dt)
     _cameraCutCam = nullptr;
 
     // Tick the animation
-    Tick(anim, time, dt, 0);
+    CallStack callStack;
+    Tick(anim, time, dt, 0, callStack);
 #if !BUILD_RELEASE
     if (_tracksDataStack.Count() != 0)
     {
@@ -486,9 +487,12 @@ bool SceneAnimationPlayer::TickPropertyTrack(int32 trackIndex, int32 stateIndexO
     return true;
 }
 
-void SceneAnimationPlayer::Tick(SceneAnimation* anim, float time, float dt, int32 stateIndexOffset)
+void SceneAnimationPlayer::Tick(SceneAnimation* anim, float time, float dt, int32 stateIndexOffset, CallStack& callStack)
 {
     const float fps = anim->FramesPerSecond;
+#if !BUILD_RELEASE || USE_EDITOR
+    callStack.Add(anim);
+#endif
 
     // Update all tracks
     for (int32 j = 0; j < anim->Tracks.Count(); j++)
@@ -546,7 +550,20 @@ void SceneAnimationPlayer::Tick(SceneAnimation* anim, float time, float dt, int3
                     return;
                 }
 
-                Tick(nestedAnim, mediaTime, dt, stateIndexOffset);
+#if !BUILD_RELEASE || USE_EDITOR
+                // Validate recursive call
+                if (callStack.Contains(nestedAnim))
+                {
+                    LOG(Warning,
+                        "Recursive nested scene animation. Animation {0} for nested track {1} on actor {2}.",
+                        callStack.Last()->ToString(),
+                        nestedAnim->ToString(),
+                        ToString());
+                    return;
+                }
+#endif
+
+                Tick(nestedAnim, mediaTime, dt, stateIndexOffset, callStack);
             }
             break;
         }

Source/Engine/Animations/SceneAnimations/SceneAnimationPlayer.h

@@ -202,7 +202,8 @@ private:
 
     void Restore(SceneAnimation* anim, int32 stateIndexOffset);
     bool TickPropertyTrack(int32 trackIndex, int32 stateIndexOffset, SceneAnimation* anim, float time, const SceneAnimation::Track& track, TrackInstance& state, void* target);
-    void Tick(SceneAnimation* anim, float time, float dt, int32 stateIndexOffset);
+    typedef Array<SceneAnimation*, FixedAllocation<8>> CallStack;
+    void Tick(SceneAnimation* anim, float time, float dt, int32 stateIndexOffset, CallStack& callStack);
     void Tick();
     void OnAnimationModified();
     void ResetState();