KHRMaterialsAnisotropy

KHR_materials_anisotropy defines anisotropy (directionally-dependent reflections) on a PBR material.

Figure: Effect of each color channel in the anisotropyTexture. Left to right: the full anisotropy texture, filling the red channel with black, filling the green channel with black, filling the blue channel with black. Source: Khronos Group & Wayfair.

This extension defines the anisotropic property of a material as observable with brushed metals for instance. An asymmetric specular lobe model is introduced to allow for such phenomena. The visually distinct feature of that lobe is the elongated appearance of the specular reflection. For a single punctual light source, the specular reflection will eventually degenerate into a zero width line in the limit, that is where the material is fully anisotropic, as opposed to be fully isotropic in which case the specular reflection is radially symmetric.

Properties:

• Anisotropy

Example

The KHRMaterialsAnisotropy class provides a single ExtensionProperty type, Anisotropy, which may be attached to any Material instance. For example:

import { KHRMaterialsAnisotropy, Anisotropy } from '@gltf-transform/extensions';

// Create an Extension attached to the Document.
const anisotropyExtension = document.createExtension(KHRMaterialsAnisotropy);

// Create an Anisotropy property.
const anisotropy = anisotropyExtension.createAnisotropy()
    .setAnisotropyStrength(1.0)
    .setAnisotropyRotation(Math.PI / 4);

// Attach the property to a Material.
material.setExtension('KHR_materials_anisotropy', anisotropy);