# PostProcessingPass.PrepareMaterialPropertyBlockDelegate

> The optional callback to prepare the material property block for the effect.

## Definition

* **Type:** Delegate
* **Namespace:** [UnityEngine.UIElements](/engine/6000.3/script-reference/unityengine/uielements.md)
* **Assembly:** UnityEngine.UIElementsModule

> **Warning:**
>
> **Deprecated.** This delegate will be removed. Use ApplyFilterPassSettingsDelegate instead.

```csharp
public delegate void PostProcessingPass.PrepareMaterialPropertyBlockDelegate(MaterialPropertyBlock mpb, FilterFunction func)
```