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# readVertices(at:_:)

Reads the current contents of a vertex buffer synchronously on the CPU.

```
final func readVertices<R, E>(at index: Int, _ body: (RawSpan) throws(E) -> R) throws(E) -> R where E : Error, R : ~Copyable
```

## Parameters

`index`

The vertex buffer index to read.

`body`

A closure that receives a read-only span over the buffer’s bytes.

## Discussion

You pass a closure that receives a read-only span representing the contents of the vertex buffer.
This span is valid only for the duration of the closure.

> Throws: Any error thrown by `body`.

---

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