# Sandbox.SceneAnimationSystem.BoneFrame

```csharp
int BoneFrame { get; set; }
```

Incremented once per frame when bones are updated. Lets per-frame bone caches - like
[Sandbox.SkinnedModelRenderer.BoneWorldTransforms](/api/Sandbox.SkinnedModelRenderer/BoneWorldTransforms) - know when they're stale without re-reading
the skeleton more than once per frame.

Declared in [Sandbox.SceneAnimationSystem](/api/Sandbox.SceneAnimationSystem).
Assembly: `Sandbox.Engine`.