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# heapAccelerationStructureSizeAndAlign(size:)

Returns the size and alignment, in bytes, of an acceleration structure if you create it from a heap.

```
func heapAccelerationStructureSizeAndAlign(size: Int) -> MTLSizeAndAlign
```

## Parameters

`size`

The size of an acceleration structure, in bytes.

## Return Value

An [`MTLSizeAndAlign`](/documentation/Metal/MTLSizeAndAlign) instance

## Discussion

Use this method to help estimate an appropriate size for a new heap before you create it.

---

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