clearcoatNormal
Waviness and imperfections for the top clearcoat.
Declaration
var clearcoatNormal: CustomMaterial.ClearcoatNormal { 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 a clearcoat normal and add waviness and imperfections to the top clearcoat.
This example shows how to set the clearcoatNormal using a UV-mapped image:
if let clearcoatNormalTextureResource = try?
TextureResource.load(named: "entity_cc_normalMap") {
let ccNormalMap = CustomMaterial.Texture(clearcoatNormalTextureResource)
material.clearcoatNormal = .init(texture: ccNormalMap)
}With custom materials, RealityKit only renders a clearcoat if lightingModel is CustomMaterial.LightingModel.clearcoat and the material’s surface shader function calls params.surface().set_clearcoat(). To specify clearcoatNormal, your surface shader function also needs to call params.surface().set_clearcoat_normal().
The following Metal code demonstrates using clearcoat and clearcoatNormal in a surface shader, replicating the behavior of the PhysicallyBasedMaterial shader:
// Retrieve the entity's texture coordinates.
float2 uv = params.geometry().uv0();
// Entities loaded from a USDZ or .reality file use texture coordinates with
// a flipped y-axis. This compensates for that.
uv.y = 1.0 - uv.y;
// Sample a value from the clearcoat normal texture.
auto tex = params.textures();
half3 clearcoatNormal = realitykit::unpack_normal(tex.clearcoat_normal().sample(textureSampler, uv).rgb);
// assign the result.
params.surface().set_clearcoat_normal(clearcoatNormal);
params.surface().set_clearcoat(1.0);