# init(scale:texture:) Creates an object from a color or texture. ``` init(scale: Float = 1.0, texture: CustomMaterial.Texture? = nil) ``` ## Parameters `scale` The reflectiveness value. `texture` An optional image texture. ## Discussion In physically based rendering, the `metallic` property represents the reflectiveness of an entity. This initializer creates a new object that passes a single scale value, a texture, or both to the material’s shader functions. The following code demonstrates creating a roughness object using this initializer: ```swift if let metallicResource = try? TextureResource.load(named: "metallic_roughness") { let metallic = MaterialParameters.Texture(metallicResource) customMaterial.roughness = .init(scale: 0.5, texture: metallic) } ``` With custom materials, the `texture` and `scale` properties you set on this property are available in your surface shader function, but RealityKit doesn’t automatically use them to render your entity. To render an entity with reflectiveness, set [`lightingModel`](/documentation/RealityKit/CustomMaterial/lightingModel-swift.property) to [`CustomMaterial.LightingModel.lit`](/documentation/RealityKit/CustomMaterial/LightingModel-swift.enum/lit) or [`CustomMaterial.LightingModel.clearcoat`](/documentation/RealityKit/CustomMaterial/LightingModel-swift.enum/clearcoat), and call `params.surface().set_metallic()` from its surface shader. To achieve the same metallic behavior as [`PhysicallyBasedMaterial`](/documentation/RealityKit/PhysicallyBasedMaterial), the surface shader function multiplies the metallic scale by the sampled value from the roughness texture, as the following Metal code demonstrates: ```other // Retrieve the metallic scale from the CustomMaterial. float metallicScale = params.material_constants().metallic_scale(); // Retrieve the entity's UV texture coordinates. float2 uv = params.geometry().uv0(); // Models loaded from USDZ or Reality Composer use UVs that are flipped // on the y-axis. This compensates for that. uv.y = 1.0 - uv.y; // Sample the texture based on the resulting UVs. auto tex = params.textures(); half metallic = tex.metallic().sample(textureSampler, uv).r; // Multiply the scale and the sampled value from the texture, and assign // the result to the shader's metallic property. metallic *= metallicScale; params.surface().set_metallic(metallic); ``` For more information on creating custom materials and writing shader functions, see [Modifying RealityKit rendering using custom materials](/documentation/RealityKit/modifying-realitykit-rendering-using-custom-materials). --- 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)