init(texture:)
Creates an object from an image texture.
Declaration
init(texture: CustomMaterial.Texture? = nil)Parameters
- texture:
A UV-mapped image texture that defines the entity’s exposure to ambient light.
Discussion
Ambient occlusion represents the entity’s exposure to ambient light. This function creates a new ambient occlusion object from a UV-mapped image texture.
Specify ambient occlusion by using a UV-mapped image called an ambient occlusion map. A value of black (0.0) represents parts of the model that receive less ambient light because that part of the model is a crevice, dent, or recessed area, or because another part of the same entity is preventing ambient light from reaching it. Ambient occlusion values of white (1.0) represent flat portions of the model that receive full ambient light. You generate ambient occlusion maps by using a 3D software package.
The ambient occlusion texture is available in the material’s surface shader, but RealityKit doesn’t render ambient occlusion unless the surface shader calls params.surface().set_ambient_occlusion().
The following Metal code shows how to use the ambient occlusion texture in a surface shader function:
// Retrieve the entity's texture coordinates.
float2 uv = params.geometry().uv0();
// Entities loaded from USDZ or .reality files have texture coordinates
// with a flipped y-axis. This adjusts for that.
uv.y = 1.0 - uv.y;
// Sample the ambient occlusion texture and use it to set the
// ambient occlusion value to use during rendering.
auto tex = params.textures();
half metallic = tex.ambient_occlusion().sample(textureSampler, uv).r;
params.surface().set_ambient_occlusion(metallic);