# mask

> The ray tracing instance mask.

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine.Rendering](/engine/6000.6/script-reference/unityengine/rendering.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
public uint mask
```

### Remarks

During acceleration structure traversal, the GPU accepts or rejects geometry based on the instance mask and InstanceInclusionMask specified when you call the `TraceRay` HLSL function, or when you execute ray queries while calling the `TraceRayInline` HLSL function.