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# geometryDescriptors

Associates the array of geometry descriptors that comprise this primitive acceleration structure.

```
var geometryDescriptors: [MTL4AccelerationStructureGeometryDescriptor]? { get set }
```

## Discussion

If you enable keyframe motion by setting property [`motionKeyframeCount`](/documentation/Metal/MTL4PrimitiveAccelerationStructureDescriptor/motionKeyframeCount) to a value greater than `1`, then
all geometry descriptors this array references need to be motion geometry descriptors and have a number of
primitive buffers equals to [`motionKeyframeCount`](/documentation/Metal/MTL4PrimitiveAccelerationStructureDescriptor/motionKeyframeCount).

Example of motion geometry descriptors include: [`MTL4AccelerationStructureMotionTriangleGeometryDescriptor`](/documentation/Metal/MTL4AccelerationStructureMotionTriangleGeometryDescriptor),
[`MTL4AccelerationStructureMotionBoundingBoxGeometryDescriptor`](/documentation/Metal/MTL4AccelerationStructureMotionBoundingBoxGeometryDescriptor), [`MTL4AccelerationStructureMotionCurveGeometryDescriptor`](/documentation/Metal/MTL4AccelerationStructureMotionCurveGeometryDescriptor).

---

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