---
title: MTLVertexStepFunction.perInstance
framework: metal
role: symbol
role_heading: Case
path: metal/mtlvertexstepfunction/perinstance
---

# MTLVertexStepFunction.perInstance

The vertex function regularly fetches new attribute data for a number of instances that is determined by stepRate.

## Declaration

```swift
case perInstance
```

## See Also

### Step functions

- [MTLVertexStepFunction.constant](metal/mtlvertexstepfunction/constant.md)
- [MTLVertexStepFunction.perVertex](metal/mtlvertexstepfunction/pervertex.md)
- [MTLVertexStepFunction.perPatch](metal/mtlvertexstepfunction/perpatch.md)
- [MTLVertexStepFunction.perPatchControlPoint](metal/mtlvertexstepfunction/perpatchcontrolpoint.md)