# roughness The amount the surface of the 3D object scatters reflected light. ``` var roughness: PhysicallyBasedMaterial.Roughness { get set } ``` ## Discussion The `roughness` property represents how much the surface of the entity scatters light it reflects. A material with a high roughness has a matte appearance, while one with a low roughness has a shiny appearance.  Specify this property using a to represent a uniform `roughness` for the entire entity, or a UV-mapped grayscale image that uses shades of gray to represent the roughness of different parts of the entity. When using an image, black pixels represent areas that have a low roughness and appear shiny, while white represents areas that have a high roughness and display a matte finish. If you initialize this property with a color image rather than a grayscale image, RealityKit only uses the intensity of the image’s red channel. The following example uses a single value to specify roughness: ```swift material.roughness = PhysicallyBasedMaterial.Roughness(floatLiteral: 0.0) ``` The following example uses an image to specify roughness: ```swift if let roughnessResource = try? TextureResource.load(named: "entity_roughness") { let roughness = MaterialParameters.Texture(roughnessResource) material.roughness = PhysicallyBasedMaterial.Roughness(texture:roughness) } ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)