Custom extension to support anisotropy factor and anisotropic rotation/direction map in GLTF/GLB
Export anisotropy factor and texture from PBS materials supported by cycles
To install, put the plugin directory in the addons folder of your blender installation.
For Mac its /Applications/Blender.app/Contents/Resources/2.92/scripts/addons
Import with custom GLTF loader extension. Adds the parameters and loaded texture to material userData. Change extension name if needed.
Register:
gltfLoader.register((p)=>new GLTFMaterialsAnisotropyExtension(p))Functions for adding anisotropy in Physical shader in threejs. Code taken mostly from filament. (Links in code)
const rotMap: ITexture | undefined = material.materialObject.userData?.anisotropyRotationMap
const bsdfs = glsl`
#include <bsdfs>
//#if ANISOTROPY_ENABLED
${randomHelpers}
${anisotropyBsdf}
` + (rotMap ? getTexelDecoding('anisotropyRotationMap', rotMap, renderer.capabilities.isWebGL2) : '')
shader.fragmentShader = shader.fragmentShader.replace('#include <bsdfs>', bsdfs)
shader.fragmentShader = shader.fragmentShader.replace('#include <lights_fragment_begin>', ShaderChunk.lights_fragment_begin)
shader.fragmentShader = shader.fragmentShader
.replace('IncidentLight directLight;', anisotropyTBN + 'IncidentLight directLight;')
.replaceAll('RE_Direct( directLight, geometry, material, reflectedLight )',
'RE_Direct( directLight, geometry, material, reflectedLight, anisotropicT, anisotropicB )')
// eslint-disable-next-line @typescript-eslint/naming-convention
const lights_physical_pars_fragment = ShaderChunk.lights_physical_pars_fragment
.replace('void RE_Direct_Physical( const in IncidentLight directLight, const in GeometricContext geometry, const in PhysicalMaterial material, inout ReflectedLight reflectedLight ) {',
'void RE_Direct_Physical( const in IncidentLight directLight, const in GeometricContext geometry, const in PhysicalMaterial material, inout ReflectedLight reflectedLight, const in vec3 anisotropicT, const in vec3 anisotropicB ) {')
.replace('BRDF_GGX( directLight.direction, geometry.viewDir, geometry.normal, material.specularColor, material.specularF90, material.roughness )',
'BRDF_GGX_Anisotropy( directLight.direction, geometry.viewDir, geometry.normal, material.specularColor, material.specularF90, material.roughness, anisotropicT, anisotropicB )')
shader.fragmentShader = shader.fragmentShader.replace('#include <lights_physical_pars_fragment>', lights_physical_pars_fragment)
// eslint-disable-next-line @typescript-eslint/naming-convention
const lights_fragment_maps = glsl`
#if defined( USE_ENVMAP )
vec3 anisotropyBentNormal = indirectAnisotropyBentNormal(geometry.normal, geometry.viewDir, material.roughness, anisotropicT, anisotropicB);
#endif
` + ShaderChunk.lights_fragment_maps
.replace('getIBLIrradiance( geometry.normal )',
'getIBLIrradiance( anisotropyBentNormal )')
.replace('getIBLRadiance( geometry.viewDir, geometry.normal, material.roughness )',
'getIBLRadiance( geometry.viewDir, anisotropyBentNormal, material.roughness )')
shader.fragmentShader = shader.fragmentShader.replace('#include <lights_fragment_maps>', lights_fragment_maps)
;(shader as any).vertexUvs = true
;(shader as any).vertexTangents = true