---
title: "init(named:in:)"
framework: realitykit
role: symbol
role_heading: Initializer
path: "realitykit/custommaterial/postlightingshader/init(named:in:)"
---

# init(named:in:)

Creates a post-lighting shader object from a named function in a Metal library.

## Declaration

```swift
init(named name: String, in library: any MTLLibrary)
```

## Parameters

- `name`: The name of the post-lighting shader function.
- `library`: The Metal library that contains the function.

## Discussion

Discussion To create a post-lighting  shader for a custom material, create a Metal file in your Xcode project. Prefix the function with the keyword [[stitchable]]. The function needs to take two parameters, one of type realitykit::post_lighting_parameters, and the other an arbitrary pointer to valid data. Here’s what a minimal post-lighting shader function looks like: #include <metal_stdlib> #include <RealityKit/RealityKit.h>

// Specify the current default namespace as metal so our code // doesn't have to to prefix Metal Standard Library symbols. using namespace metal;

[[stitchable]] void myPostLightingShader(realitykit::post_lighting_parameters params const void *customParams) {    // Calculate post-lighting effect. } To create a custom material using this shader, get a reference to your app’s Metal library: guard let device = MTLCreateSystemDefaultDevice() else {     fatalError("Error creating default metal device.") } guard let library = maybeDevice.makeDefaultLibrary() else {     fatalError("Error creating default metal library") } Once you have a reference to your Metal library, use it to create the surface shader reference: let postLightingShader = CustomMaterial.PostLightingShader(     named: "myPostLightingShader",     in: library ) important: RealityKit loads post-lighting shader functions by name, so name your post-lighting shader uniquely and to exactly match the named parameter. For more information on creating custom materials and writing shader functions, see Modifying RealityKit rendering using custom materials.