emissiveColor
The color of light this material emits.
Declaration
var emissiveColor: CustomMaterial.EmissiveColor { get set }Discussion
With physically based rendering (PBR), you can give entities in RealityKit the appearance of emitting light. Use this property to simulate real-world objects that glow, such as objects with LEDs or computer screens. To enable light emission from a material, set emissiveIntensity to a value greater than zero, then specify a color (other than black) using this property. You can specify a single emissive color for the entire material, or use a UV-mapped image texture to use different colors for different parts of the entity.
With custom materials, RealityKit doesn’t use emissiveColor automatically to render your entity. Call params.surface().set_emissive_color() from your surface shader, otherwise RealityKit renders no light emission.
The following example assigns a tint color to the emissiveColor property, without a texture:
self.emissiveColor = PhysicallyBasedMaterial.EmissiveColor(color: .red)This next example uses a texture to specify the emissiveColor property:
if let emissiveResource = try? TextureResource.load(named: "entity_emissive") {
let emissiveMap = MaterialParameters.Texture(emissiveResource)
material.emissiveColor = .init(texture: emissiveMap)
}This Metal code shows how to access the emissive color tint in your shader functions:
half3 emissiveTint = (half3)params.material_constants().emissive_color();The following Metal code demonstrates how to sample the emissive color texture for the current fragment:
// Get the entity's primary texture coordinates.
float2 uv = params.geometry().uv0();
// Flip the y-axis. You only need to do this for entities you load from
// USDZ or .reality files.
uv.y = 1.0 - uv.y;
// Sample the emissive color texture to get the value for this fragment.
auto tex = params.textures();
half3 emissiveColor = (half3)tex.emissive_color()
.sample(textureSampler, uv).rgb;