---
title: custom
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/custommaterial/custom-swift.property
---

# custom

User-defined properties for the material’s shader functions.

## Declaration

```swift
var custom: CustomMaterial.Custom { get set }
```

## Discussion

Discussion Use a CustomMaterial.Custom object to send custom data to your shader functions. A custom object can hold a texture or a vector value, or both. Both the texture and vector value are available in your shader functions. note: Unlike other CustomMaterial properties, you don’t need to create a CustomMaterial.Custom object for your material. All CustomMaterial objects have one by default; you just need to set the value property, texture property, or both. The following code demonstrates how to use the custom property to pass a vector to your shader functions: // Specify a custom vector to pass to the shader functions. customMaterial.custom.value = [0.25, 0.25, 0.25, 1.0] You can also use it to pass up to four scalar values instead of a vector: let customValue1: Float = 0.25 let customValue2: Float = 0.75 customMaterial.custom.value[0] = customValue1 customMaterial.custom.value[1] = customValue2 The custom property can also include a texture. The following code demonstrates how to add a texture to the custom property: if let theResource = try? TextureResource.load(named: "MyCustomTexture") {     let myTexture = CustomMaterial.Texture(theResource)     customMaterial.custom.texture = .init(myTexture) } The following Metal code shows how to retrieve the custom vector in a shader function: float4 myCustomVector = params.uniforms().custom_parameter(); The following Metal code shows how to retrieve individual values from the custom vector in your shader functions: float firstCustomValue = params.uniforms().custom_parameter()[0]; float secondCustomValue = params.uniforms().custom_parameter()[1]; Here’s how to retrieve the custom texture in your shader functions: float voronoiColor = params.textures()     .custom().sample(textureSampler, UV).r;

## See Also

### Setting shader properties

- [program](realitykit/custommaterial/program-swift.property.md)
- [lightingModel](realitykit/custommaterial/lightingmodel-swift.property.md)
- [withMutableUniforms(ofType:_:)](realitykit/custommaterial/withmutableuniforms(oftype:_:).md)
- [withMutableUniforms(ofType:stage:_:)](realitykit/custommaterial/withmutableuniforms(oftype:stage:_:).md)