---
title: instancedAccelerationStructures
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtlinstanceaccelerationstructuredescriptor/instancedaccelerationstructures
---

# instancedAccelerationStructures

The bottom-level acceleration structures that instances use in the instance acceleration structure .

## Declaration

```swift
var instancedAccelerationStructures: [any MTLAccelerationStructure]? { get set }
```

## Discussion

Discussion Each instance in the instance descriptor buffer has an index into this array, specifying which acceleration structure to use for that instance.

## See Also

### Related Documentation

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

### Specifying the instance structures

- [instanceDescriptorType](metal/mtlinstanceaccelerationstructuredescriptor/instancedescriptortype.md)
- [MTLAccelerationStructureInstanceDescriptorType](metal/mtlaccelerationstructureinstancedescriptortype.md)