# init(floatLiteral:) Creates an object from a single value. ``` init(floatLiteral value: Float) ``` ## Parameters `value` The reflectiveness value for the material. ## Discussion In physically based rendering, the `metallic` property represents the reflectiveness of an entity. This initializer creates a new object that passes a single metallic value to your custom shader functions but doesn’t pass a texture. The following Swift code shows how to specify reflectiveness using a single value for the entire entity: ```swift material.roughness = PhysicallyBasedMaterial.Roughness(floatLiteral: 0.0) ``` 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. The following Metal code shows how to retrieve the value set in this initializer in your surface shader and use it: ```other // Retrieve the metallic scale from the CustomMaterial. float metallic = params.material_constants().metallic_scale(); // Set the roughness value using the metallic scale value. 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)