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calcLightSpecular in the anisotropic GGX chunk took roughness as (1 - gloss)^2 and then squared it again for alphaRoughness, so at and ab were built from perceptual roughness to the fourth power. The Khronos KHR_materials_anisotropy reference derives them from alphaRoughness = perceptualRoughness^2, so anisotropic highlights came out too narrow. Compute alphaRoughness directly in both the GLSL and WGSL chunks. Fixed playcanvas#9511
getReflDir in reflDirAniso computed the bend roughness as sqrt(1 - gloss), i.e. sqrt(perceptualRoughness). The glTF Sample Renderer's getIBLRadianceAnisotropy is called with perceptualRoughness itself, so glossy anisotropic materials were bent less than they should be. Use 1 - gloss in both the GLSL and WGSL chunks, and cover it in the anisotropy chunk test alongside the alphaRoughness check. Fixes playcanvas#9511
drakeo338
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Description
This covers both parts of the issue, in the GLSL and WGSL chunks.
The anisotropic GGX chunk squared
(1 - gloss)^2again, soatandabcame from perceptualRoughness^4. It now usesalphaRoughness = (1 - gloss)^2directly.reflDirAnisobent the reflection normal withsqrt(1 - gloss); it now uses1 - gloss, matching the referencegetIBLRadianceAnisotropy.It is a visible change: anisotropic highlights get noticeably wider and less intense, and glossy anisotropic reflections bend more. A new unit test evaluates the roughness lines of all four chunks; it fails on main and passes here.
npm testandnpm run lintare clean.#9513 covers the separate isotropic bug (#9510).
Fixes #9511
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