---
title: "init(floatLiteral:)"
framework: realitykit
role: symbol
role_heading: Initializer
path: "realitykit/custommaterial/roughness-swift.struct/init(floatliteral:)"
---

# init(floatLiteral:)

Creates an object to specify the amount of roughness, using a single value that applies to the entire material.

## Declaration

```swift
init(floatLiteral value: Float)
```

## Parameters

- `value`: The roughness value.

## Discussion

Discussion The roughness property represents how much the surface of the entity scatters light that it reflects. A material with a high roughness has a matte appearance, and one with a low roughness has a shiny appearance.

The following Swift code shows how to specify roughness using a single value for the entire entity: material.roughness = PhysicallyBasedMaterial.Roughness(floatLiteral: 0.0) With custom materials, the roughness value is available in your surface shader; however, RealityKit doesn’t use it automatically to render the entity. To render an entity with roughness, the material’s lightingModel needs to be CustomMaterial.LightingModel.lit or CustomMaterial.LightingModel.clearcoat, and call params.surface().set_roughness() from its surface shader function. The following Metal code shows how to retrieve the roughness value set using this initializer in your surface shader:     // Retrieve the roughness scale from the CustomMaterial.     float roughnessScale = params.material_constants().roughness_scale();

// Set the roughness value using the roughness scale.     params.surface().set_roughness(roughnessScale); For more information on creating custom materials and writing shader functions, see Modifying RealityKit rendering using custom materials.

## See Also

### Creating a roughness object

- [init(scale:texture:)](realitykit/custommaterial/roughness-swift.struct/init(scale:texture:).md)
- [init(_:)](realitykit/custommaterial/roughness-swift.struct/init(_:).md)