clearcoat
The transparent highlights that simulate a clear, shiny coating on an entity.
Declaration
var clearcoat: CustomMaterial.Clearcoat { get set }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 clearcoat using a single Float that applies to the entire material, or a UV-mapped grayscale image to provide different values for different parts of an entity.
The following example specifies clearcoat using a single value:
material.clearcoat = .init(floatLiteral: 0.8)This example shows how to specify clearcoat using a UV-mapped image texture:
if let clearcoatResource = try? TextureResource.load(named:
"entity_clearcoat") {
let clearcoatMap = MaterialParameters.Texture(clearcoatResource)
material.clearcoat = .init(texture: clearcoatMap)
}With custom materials, RealityKit doesn’t automatically use the values you set for this property to render your entity. The values from this property are available to the custom material’s surface shader, but it doesn’t render a clearcoat unless the custom material’s lightingModel is CustomMaterial.LightingModel.clearcoat and the surface shader calls params.surface().set_clearcoat().
The following Metal code demonstrates how to retrieve the scale and texture from this property, and use them to enable clearcoat rendering.
// Retrieve the clearcoat scale from the CustomMaterial.
float clearcoatScale = params.material_constants().clearcoat_scale();
// Retrieve the entity's texture coordinates.
float2 uv = params.geometry().uv0();
// Models loaded from USDZ or .reality files use texture coordinates with a
// flipped y-axis. This compensates for that.
uv.y = 1.0 - uv.y;
// Sample the clearcoat texture using the texture coordinates.
auto tex = params.textures();
half clearcoat = tex.clearcoat().sample(textureSampler, uv).r;
// Multiply the scale and sampled value from the texture, and assign
// the result.
clearcoat *= clearcoatScale;
params.surface().set_clearcoat(clearcoat);