---
title: MTLVertexStepFunction.perPatch
framework: metal
role: symbol
role_heading: Case
path: metal/mtlvertexstepfunction/perpatch
---

# MTLVertexStepFunction.perPatch

The post-tessellation vertex function fetches data based on the patch index of the patch.

## Declaration

```swift
case perPatch
```

## See Also

### Step functions

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