---
title: stepFunction
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/lowlevelmeshresource/layout/stepfunction
---

# stepFunction

Determines how the vertex shader steps through the data in this layout.

## Declaration

```swift
var stepFunction: MTLVertexStepFunction { get set }
```

## Discussion

Discussion Set to .perInstance to supply per-instance data (for example, per-instance color or transform) from a vertex buffer rather than a separate instancing buffer. Defaults to .perVertex. Corresponds to MTLVertexBufferLayoutDescriptor.stepFunction.

## See Also

### Configuring vertex stepping

- [stepRate](realitykit/lowlevelmeshresource/layout/steprate.md)