Clean up anisotropy code in GltfLoader and pbrLighting

packages/engine/Source/Scene/GltfLoader.js

@@ -1543,9 +1543,9 @@ function loadMetallicRoughness(loader, metallicRoughnessInfo, frameState) {
 
 function loadSpecular(loader, specularInfo, frameState) {
  const {
- specularFactor,
+ specularFactor = Specular.DEFAULT_SPECULAR_FACTOR,
  specularTexture,
- specularColorFactor,
+ specularColorFactor = Specular.DEFAULT_SPECULAR_COLOR_FACTOR,
  specularColorTexture,
  } = specularInfo;
 
@@ -1560,7 +1560,6 @@ function loadSpecular(loader, specularInfo, frameState) {
  frameState
  );
  }
- // TODO: if not defined, should we leave the default values?
  specular.specularFactor = specularFactor;
  specular.specularColorFactor = fromArray(Cartesian3, specularColorFactor);
 
@@ -1617,21 +1616,18 @@ function loadMaterial(loader, gltfMaterial, frameState) {
  pbrSpecularGlossiness,
  frameState
  );
- } else {
- // TODO: should this branch exclude materials.unlit?
+ } else if (material.unlit === false) {
  if (defined(pbrMetallicRoughness)) {
  material.metallicRoughness = loadMetallicRoughness(
  loader,
  pbrMetallicRoughness,
  frameState
  );
  }
- if (defined(pbrSpecular)) {
- // TODO: not compatible with materials.unlit
+ if (defined(pbrSpecular && material.unlit === false)) {
  material.specular = loadSpecular(loader, pbrSpecular, frameState);
  }
- if (defined(pbrAnisotropy)) {
- // TODO: not compatible with materials.unlit
+ if (defined(pbrAnisotropy) && material.unlit === false) {
  material.anisotropy = loadAnisotropy(loader, pbrAnisotropy, frameState);
  }
  }

packages/engine/Source/Shaders/Builtin/Functions/pbrLighting.glsl

@@ -11,7 +11,7 @@ vec3 fresnelSchlick2(vec3 f0, vec3 f90, float VdotH)
  return f0 + (f90 - f0) * versineSquared * versineSquared * versine;
 }
 
-// TODO: add ifdef for GGX anisotropy methods
+#ifdef USE_ANISOTROPY
 /**
  * @param {float} roughness Material roughness (along the anisotropy bitangent)
  * @param {float} tangentialRoughness Anisotropic roughness (along the anisotropy tangent)
@@ -39,7 +39,7 @@ float GGX_anisotropic(float roughness, float tangentialRoughness, vec3 halfwayDi
  float w2 = roughnessSquared / dot(f, f);
  return roughnessSquared * w2 * w2 / czm_pi;
 }
-
+#else
 float smithVisibilityG1(float NdotV, float roughness)
 {
  // this is the k value for direct lighting.
@@ -62,6 +62,7 @@ float GGX(float roughness, float NdotH)
  float f = (NdotH * roughnessSquared - NdotH) * NdotH + 1.0;
  return roughnessSquared / (czm_pi * f * f);
 }
+#endif
 
 /**
  * Compute the diffuse and specular contributions using physically based
@@ -106,23 +107,8 @@ vec3 czm_pbrLighting(
  vec3 l = normalize(lightDirectionEC);
  vec3 h = normalize(v + l);
  vec3 n = normalEC;
- float NdotL = clamp(dot(n, l), 0.001, 1.0);
- float NdotV = abs(dot(n, v)) + 0.001;
- float NdotH = clamp(dot(n, h), 0.0, 1.0);
  float VdotH = clamp(dot(v, h), 0.0, 1.0);
 
- #ifdef USE_ANISOTROPY
- vec3 anisotropicT = pbrParameters.anisotropicT;
- vec3 anisotropicB = pbrParameters.anisotropicB;
- // TODO: multiply with TBN matrix to get anisotropic view, light, and half directions
- float TdotV = dot(anisotropicT, v);
- float BdotV = dot(anisotropicB, v);
- float TdotH = dot(anisotropicT, h);
- float BdotH = dot(anisotropicB, h);
- float TdotL = dot(anisotropicT, l);
- float BdotL = dot(anisotropicB, l);
- #endif
-
  vec3 f0 = pbrParameters.f0;
  float reflectance = max(max(f0.r, f0.g), f0.b);
  // Typical dielectrics will have reflectance 0.04, so f90 will be 1.0.
@@ -131,19 +117,24 @@ vec3 czm_pbrLighting(
  vec3 F = fresnelSchlick2(f0, f90, VdotH);
 
  #if defined(USE_SPECULAR)
- F *= pbrParameters.specularWeight;
+  F *= pbrParameters.specularWeight;
  #endif
 
  float alpha = pbrParameters.roughness;
  #ifdef USE_ANISOTROPY
+ mat3 tbn = mat3(pbrParameters.anisotropicT, pbrParameters.anisotropicB, n);
+ vec3 lightDirection = l * tbn;
+ vec3 viewDirection = v * tbn;
+ vec3 halfwayDirection = h * tbn;
  float anisotropyStrength = pbrParameters.anisotropyStrength;
  float tangentialRoughness = mix(alpha, 1.0, anisotropyStrength * anisotropyStrength);
- vec3 lightDirection = vec3(TdotL, BdotL, NdotL);
- vec3 viewDirection = vec3(TdotV, BdotV, NdotV);
  float G = smithVisibilityGGX_anisotropic(alpha, tangentialRoughness, lightDirection, viewDirection);
- vec3 halfwayDirection = vec3(TdotH, BdotH, NdotH);
  float D = GGX_anisotropic(alpha, tangentialRoughness, halfwayDirection);
+ float NdotL = clamp(lightDirection.z, 0.001, 1.0);
  #else
+ float NdotL = clamp(dot(n, l), 0.001, 1.0);
+ float NdotV = abs(dot(n, v)) + 0.001;
+ float NdotH = clamp(dot(n, h), 0.0, 1.0);
  float G = smithVisibilityGGX(alpha, NdotL, NdotV);
  float D = GGX(alpha, NdotH);
  #endif