KHR_materials_scatter

The pinned draft has an initial thin-wall rendering profile in the canonical PBR material shaders on WebGL2 and WebGPU.

The material must also declare KHR_materials_transmission. Transmission energy is split between specular transmission and diffuse scattering by scatterStrengthFactor, multiplied by the strength texture's alpha channel. The scattered energy exits through the forward and backward hemispheres in proportions (1 + g) / 2 and (1 - g) / 2. Its color comes from multiscatterColorFactor and the sRGB color texture, independently of base color. Existing UV selection and texture transforms apply.

Nonzero volume thickness is rejected. This profile does not implement volumetric transport, random walks, diffusion, or claim full draft conformance. The support registry therefore retains loader-only, and strict required-extension loading does not accept the draft as fully supported. Materials combining this extension with unlit, specular-glossiness, or diffuse transmission are rejected.

The shared feature example accepts feature="scatter". It loads the original Scatter Strength Thin-Walled reference from the proposal-author sample-assets branch. Model, Info, and Attributions tabs separate selection, explanation, and source credits. The CC BY 4.0 asset is loaded without material rewriting. Direct-light rendering does not claim pixel equivalence to upstream environment-lit references.