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# MTLAccelerationStructureGeometryDescriptor

A base class for descriptors that contain geometry data to convert into a ray-tracing acceleration structure.

```
class MTLAccelerationStructureGeometryDescriptor
```

## Overview

Don’t use this base class directly. Use one of the derived classes instead, as  [`MTLAccelerationStructure`](/documentation/Metal/MTLAccelerationStructure) describes.

## Topics

### Specifying base geometry properties

[`label`](/documentation/Metal/MTLAccelerationStructureGeometryDescriptor/label)

A label for the geometry structure, suitable for debugging.

[`intersectionFunctionTableOffset`](/documentation/Metal/MTLAccelerationStructureGeometryDescriptor/intersectionFunctionTableOffset)

An index into the intersection table for determining which intersection function Metal calls when it intersects a ray with the acceleration structure.

[`opaque`](/documentation/Metal/MTLAccelerationStructureGeometryDescriptor/opaque)

A Boolean value that determines whether the geometry data in the acceleration structure needs to skip triangle-intersection tests.

[`allowDuplicateIntersectionFunctionInvocation`](/documentation/Metal/MTLAccelerationStructureGeometryDescriptor/allowDuplicateIntersectionFunctionInvocation)

A Boolean value that indicates whether Metal calls the ray-intersection test more than once per primitive on the structure.

## See Also

[`MTLAccelerationStructureMotionTriangleGeometryDescriptor`](/documentation/Metal/MTLAccelerationStructureMotionTriangleGeometryDescriptor)

A description of a list of triangle primitives, as motion keyframe data, to turn into an acceleration structure.

[`MTLAccelerationStructureMotionBoundingBoxGeometryDescriptor`](/documentation/Metal/MTLAccelerationStructureMotionBoundingBoxGeometryDescriptor)

A description of a list of bounding boxes, as motion keyframe data, to turn into an acceleration structure.


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