# materialsCRC

> An array of Material CRC and instance id pairs generated by RayTracingAccelerationStructure.CullInstances when using RayTracingInstanceCullingFlags.ComputeMaterialsCRC flag.

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine.Rendering](/engine/6000.5/script-reference/unityengine/rendering.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
public RayTracingInstanceMaterialCRC[] materialsCRC
```

### Remarks

The array can be used for example to compute a composite CRC of all Materials and reset the convergence during path tracing if the user changed a Material property or Materials used in path tracing were created or deleted.

Additional Resources: [Material.ComputeCRC()](/engine/6000.5/script-reference/unityengine/material/computecrc.md), [HashUtilities](/engine/6000.5/script-reference/unityengine/hashutilities.md).