Fix stopping slot animations and playing the same frame

#1927

Source/Engine/Animations/Graph/AnimGraph.h

@@ -197,6 +197,7 @@ struct FLAXENGINE_API AnimGraphSlot
     float BlendOutTime = 0.0f;
     int32 LoopCount = 0;
     bool Pause = false;
+    bool Reset = false;
 };
 
 /// <summary>

Source/Engine/Animations/Graph/AnimGroup.Animation.cpp

@@ -2098,6 +2098,12 @@ void AnimGraphExecutor::ProcessGroupAnimation(Box* boxBase, Node* nodeBase, Valu
         auto& slot = slots[bucket.Index];
         Animation* anim = slot.Animation;
         ASSERT(slot.Animation && slot.Animation->IsLoaded());
+        if (slot.Reset)
+        {
+            // Start from the begining
+            slot.Reset = false;
+            bucket.TimePosition = 0.0f;
+        }
         const float deltaTime = slot.Pause ? 0.0f : context.DeltaTime * slot.Speed;
         const float length = anim->GetLength();
         const bool loop = bucket.LoopsLeft != 0;

Source/Engine/Level/Actors/AnimatedModel.cpp

@@ -494,6 +494,7 @@ void AnimatedModel::StopSlotAnimation(const StringView& slotName, Animation* ani
         if (slot.Animation == anim && slot.Name == slotName)
         {
             slot.Animation = nullptr;
+            slot.Reset = true;
             break;
         }
     }