---
title: MTLAccelerationStructureUserIDInstanceDescriptor
framework: metal
role: symbol
role_heading: Structure
path: metal/mtlaccelerationstructureuseridinstancedescriptor
---

# MTLAccelerationStructureUserIDInstanceDescriptor

A description of an instance in an instanced geometry acceleration structure, with the instance including a user identifier for the instance.

## Declaration

```swift
struct MTLAccelerationStructureUserIDInstanceDescriptor
```

## Topics

### Creating an instance descriptor

- [init()](metal/mtlaccelerationstructureuseridinstancedescriptor/init().md)
- [init(transformationMatrix:options:mask:intersectionFunctionTableOffset:accelerationStructureIndex:userID:)](metal/mtlaccelerationstructureuseridinstancedescriptor/init(transformationmatrix:options:mask:intersectionfunctiontableoffset:accelerationstructureindex:userid:).md)

### Specifying the instance

- [accelerationStructureIndex](metal/mtlaccelerationstructureuseridinstancedescriptor/accelerationstructureindex.md)

### Specifying the instance transform

- [transformationMatrix](metal/mtlaccelerationstructureuseridinstancedescriptor/transformationmatrix.md)

### Customizing intersection and hit tests for the instance

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

### Specifying the user identifier

- [userID](metal/mtlaccelerationstructureuseridinstancedescriptor/userid.md)

## Relationships

### Conforms To

- [Sendable](swift/sendable.md)

## See Also

### Instance descriptors

- [MTLAccelerationStructureInstanceDescriptor](metal/mtlaccelerationstructureinstancedescriptor.md)
- [MTLAccelerationStructureMotionInstanceDescriptor](metal/mtlaccelerationstructuremotioninstancedescriptor.md)
- [MTLAccelerationStructureInstanceOptions](metal/mtlaccelerationstructureinstanceoptions.md)
- [MTL4IndirectInstanceAccelerationStructureDescriptor](metal/mtl4indirectinstanceaccelerationstructuredescriptor.md)
- [MTLIndirectInstanceAccelerationStructureDescriptor](metal/mtlindirectinstanceaccelerationstructuredescriptor.md)
- [MTLIndirectAccelerationStructureInstanceDescriptor](metal/mtlindirectaccelerationstructureinstancedescriptor.md)
- [MTLIndirectAccelerationStructureMotionInstanceDescriptor](metal/mtlindirectaccelerationstructuremotioninstancedescriptor.md)