---
title: mask
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtlaccelerationstructuremotioninstancedescriptor/mask
---

# mask

A mask for testing ray-tracing rays with a scene’s geometry, which applies to the next acceleration-structure motion instance you create with the descriptor.

## Declaration

```swift
var mask: UInt32
```

## See Also

### Customizing intersection and hit tests for the instance

- [intersectionFunctionTableOffset](metal/mtlaccelerationstructuremotioninstancedescriptor/intersectionfunctiontableoffset.md)
- [options](metal/mtlaccelerationstructuremotioninstancedescriptor/options.md)