message: Reduce number of texture lookups in gltf_viewer.
diff: @@ -139,8 +139,9 @@ std::string shaderFromConfig(MaterialConfig config) {
  if (!config.unlit) {
  shader += R"SHADER(
  - material.roughness = materialParams.roughnessFactor * texture(materialParams_metallicRoughnessMap, metallicRoughnessUV).g;
  - material.metallic = materialParams.metallicFactor * texture(materialParams_metallicRoughnessMap, metallicRoughnessUV).b;
  + vec4 metallicRoughness = texture(materialParams_metallicRoughnessMap, metallicRoughnessUV);
  + material.roughness = materialParams.roughnessFactor * metallicRoughness.g;
  + material.metallic = materialParams.metallicFactor * metallicRoughness.b;
  material.ambientOcclusion = texture(materialParams_aoMap, aoUV).r;
  material.emissive = texture(materialParams_emissiveMap, emissiveUV);
  material.emissive.rgb *= materialParams.emissiveFactor.rgb;
  