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# stepRate

The interval at which the vertex and its attributes are presented to the vertex function.

```
var stepRate: Int { get set }
```

## Discussion

The default value is `1`. The `stepRate` value, in conjunction with the [`stepFunction`](/documentation/Metal/MTLVertexBufferLayoutDescriptor/stepFunction) property, determines how often the function fetches new attribute data. The `stepRate` property is generally used when `stepFunction` is [`MTLVertexStepFunction.perInstance`](/documentation/Metal/MTLVertexStepFunction/perInstance). If `stepRate` is equal to `1`, new attribute data is fetched for every instance; if `stepRate` is equal to `2`, new attribute data is fetched for every two instances, and so forth.

---

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