---
title: instanceDescriptorType
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtl4instanceaccelerationstructuredescriptor/instancedescriptortype
---

# instanceDescriptorType

The type of instance descriptor that the instance descriptor buffer references.

## Declaration

```swift
var instanceDescriptorType: MTLAccelerationStructureInstanceDescriptorType { get set }
```

## Discussion

Discussion This value determines the layout Metal expects for the structs the instance descriptor buffer contains: MTLAccelerationStructureInstanceDescriptorType.indirect: Use the MTLIndirectAccelerationStructureInstanceDescriptor struct layout. MTLAccelerationStructureInstanceDescriptorType.indirectMotion: Use the MTLIndirectAccelerationStructureMotionInstanceDescriptor struct layout. The default value is MTLAccelerationStructureInstanceDescriptorType.indirect.