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

# clearcoatRoughness

The degree to which an entity’s clear, shiny coating scatters light to create soft highlights.

## Declaration

```swift
var clearcoatRoughness: CustomMaterial.ClearcoatRoughness { get set }
```

## Discussion

Discussion An entity in RealityKit can display a clearcoat, which is a separate layer of transparent specular highlights used to simulate a clear coating, like on a car or the surface of lacquered objects. This property allows you to specify a clearcoat roughness value to indicate how much the clearcoat scatters light that bounces off of it, which softens and disperses the highlights. You can specify a single value that applies to the entire material, or you can supply a UV-mapped image texture containing different roughness values for different parts of the entity. This value is available in your surface shader. RealityKit won’t render a clearcoat with roughness unless your surface shader calls both params.surface().set_clearcoat_roughness() and params.surface().set_clearcoat() with a value greater than 0.0. The following Swift code demonstrates setting the clearcoatRoughness using a single value: material.clearcoatRoughness = .init(floatLiteral: 0.5) This example shows how to set the clearcoatRoughness using a UV-mapped image: if let clearcoatRoughnessResource = try? TextureResource.load(named: "entity_cc_roughness") {     let ccRoughnessMap = MaterialParameters.Texture(clearcoatRoughnessResource)     material.clearcoat = .init(texture: ccRoughnessMap) } With custom materials, RealityKit only renders a clearcoat if lightingModel is CustomMaterial.LightingModel.clearcoat and the material’s surface shader function calls params.surface().set_clearcoat(). To specify clearcoatRoughness, your surface shader function needs to also call params.surface().set_clearcoat_roughness(). The following Metal code demonstrates using clearcoat and clearcoatRoughness in a surface shader, replicating the behavior of the PhysicallyBasedMaterial shader: // Retrieve the clearcoat scale and roughness from the CustomMaterial. float clearcoatScale = params.material_constants().clearcoat_scale(); float clearcoatRoughnessScale = params.material_constants().clearcoat_roughness_scale();

// Retrieve the entity's texture coordinates. float2 uv = params.geometry().uv0();

// Entities loaded from a USDZ or .reality file use texture coordinates with // a flipped y-axis. This compensates for that. uv.y = 1.0 - uv.y;

// Sample a value from the clearcoat and clearcoat roughness textures. auto tex = params.textures(); half clearcoat = tex.clearcoat().sample(textureSampler, uv).r; half clearcoatRoughness = tex.clearcoat_roughness().sample(textureSampler, uv).r;

// Multiply the scale and sampled texture value from the clearcoat and // assign  the result. clearcoat *= clearcoatScale; params.surface().set_clearcoat(clearcoat);

// Multiply the scale and sampled texture value from the clearcoat roughness // and assign the result. clearcoatRoughness *= clearcoatRoughnessScale; params.surface().set_clearcoat_roughness(clearcoatRoughness);

## See Also

### Setting the core properties

- [baseColor](realitykit/custommaterial/basecolor-swift.property.md)
- [roughness](realitykit/custommaterial/roughness-swift.property.md)
- [metallic](realitykit/custommaterial/metallic-swift.property.md)
- [normal](realitykit/custommaterial/normal-swift.property.md)
- [emissiveColor](realitykit/custommaterial/emissivecolor-swift.property.md)
- [ambientOcclusion](realitykit/custommaterial/ambientocclusion-swift.property.md)
- [specular](realitykit/custommaterial/specular-swift.property.md)
- [clearcoat](realitykit/custommaterial/clearcoat-swift.property.md)
- [clearcoatNormal](realitykit/custommaterial/clearcoatnormal-swift.property.md)