---
title: MTLPrimitiveAccelerationStructureDescriptor
framework: metal
role: symbol
role_heading: Class
path: metal/mtlprimitiveaccelerationstructuredescriptor
---

# MTLPrimitiveAccelerationStructureDescriptor

A description of an acceleration structure that contains geometry primitives.

## Declaration

```swift
class MTLPrimitiveAccelerationStructureDescriptor
```

## Overview

Overview Metal provides acceleration structures with a two-level hierarchy. The bottom layer consists of primitive acceleration structures, which instance acceleration structures in the top level reference.

## Topics

### Specifying geometry

- [geometryDescriptors](metal/mtlprimitiveaccelerationstructuredescriptor/geometrydescriptors.md)

### Specifying motion behavior

- [motionKeyframeCount](metal/mtlprimitiveaccelerationstructuredescriptor/motionkeyframecount.md)
- [motionStartTime](metal/mtlprimitiveaccelerationstructuredescriptor/motionstarttime.md)
- [motionEndTime](metal/mtlprimitiveaccelerationstructuredescriptor/motionendtime.md)
- [motionStartBorderMode](metal/mtlprimitiveaccelerationstructuredescriptor/motionstartbordermode.md)
- [motionEndBorderMode](metal/mtlprimitiveaccelerationstructuredescriptor/motionendbordermode.md)
- [MTLMotionBorderMode](metal/mtlmotionbordermode.md)

## Relationships

### Inherits From

- [MTLAccelerationStructureDescriptor](metal/mtlaccelerationstructuredescriptor.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSCopying](foundation/nscopying.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Acceleration structures

- [Improving ray-tracing data access using per-primitive data](metal/improving-ray-tracing-data-access-using-per-primitive-data.md)
- [MTLAccelerationStructure](metal/mtlaccelerationstructure.md)
- [MTL4AccelerationStructureDescriptor](metal/mtl4accelerationstructuredescriptor.md)
- [MTLAccelerationStructureDescriptor](metal/mtlaccelerationstructuredescriptor.md)
- [MTL4PrimitiveAccelerationStructureDescriptor](metal/mtl4primitiveaccelerationstructuredescriptor.md)
- [MTL4InstanceAccelerationStructureDescriptor](metal/mtl4instanceaccelerationstructuredescriptor.md)
- [MTLInstanceAccelerationStructureDescriptor](metal/mtlinstanceaccelerationstructuredescriptor.md)
- [MTLAccelerationStructureCommandEncoder](metal/mtlaccelerationstructurecommandencoder.md)
- [MTLAccelerationStructureUsage](metal/mtlaccelerationstructureusage.md)
- [MTLAccelerationStructureRefitOptions](metal/mtlaccelerationstructurerefitoptions.md)