Handle 'inverse roughness' flag.

src/fbx/Fbx2Raw.cpp

@@ -249,7 +249,8 @@ static void ReadMesh(
             toVec3f(fbxMatInfo->emissive),
             fbxMatInfo->emissiveIntensity,
             fbxMatInfo->metallic,
-            fbxMatInfo->roughness));
+            fbxMatInfo->roughness,
+            fbxMatInfo->invertRoughnessMap));
       } else {
         FbxTraditionalMaterialInfo* fbxMatInfo =
             static_cast<FbxTraditionalMaterialInfo*>(fbxMaterial.get());

src/fbx/materials/3dsMaxPhysicalMaterial.cpp

@@ -65,9 +65,6 @@ std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::reso
     roughness = 1.0f - roughness;
   }
 
-  // TODO: turn this into a normal map through simple numerial differentiation
-  const auto* bumpMap = getTex("bump");
-
   std::string unsupported;
   const auto addUnsupported = [&](const std::string bit) {
     if (!unsupported.empty()) {
@@ -76,6 +73,12 @@ std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::reso
     unsupported += bit;
   };
 
+  // TODO: turn this into a normal map through simple numerial differentiation
+  const auto* bumpMap = getTex("bump");
+  if (bumpMap != nullptr) {
+    addUnsupported("bump map");
+  }
+
   // TODO: bake transparency > 0.0f into the alpha of baseColor?
   double transparency = getValue(props, "transparency", 0.0);
   const auto* transparencyMap = getTex("transparency");
@@ -157,6 +160,7 @@ std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::reso
 
   res->texMetallic = metalnessMap;
   res->texRoughness = roughnessMap;
+  res->invertRoughnessMap = invertRoughness;
 
   res->emissive = emissiveColor;
   res->emissiveIntensity = emissiveWeight;

src/fbx/materials/RoughnessMetallicMaterials.hpp

@@ -35,6 +35,7 @@ struct FbxRoughMetMaterialInfo : FbxMaterialInfo {
   const FbxDouble metallic;
   const FbxDouble roughness;
 
+  FbxBool invertRoughnessMap = false;
   FbxDouble baseWeight = 1;
   FbxVector4 emissive = FbxVector4(0, 0, 0, 1);
   FbxDouble emissiveIntensity = 1;

src/gltf/Raw2Gltf.cpp

@@ -276,7 +276,13 @@ ModelData* Raw2Gltf(
               },
               "ao_met_rough",
               [&](const std::vector<const TextureBuilder::pixel*> pixels) -> TextureBuilder::pixel {
-                return {{(*pixels[0])[0], (*pixels[2])[0], (*pixels[1])[0], 1}};
+                const float occlusion = (*pixels[0])[0];
+                const float metallic = (*pixels[1])[0];
+                const float roughness = (*pixels[2])[0];
+                return {{occlusion,
+                         props->invertRoughnessMap ? 1.0f - roughness : roughness,
+                         metallic,
+                         1}};
               },
               false);
 

src/raw/RawModel.hpp

@@ -234,18 +234,21 @@ struct RawMetRoughMatProps : RawMatProps {
       const Vec3f&& emissiveFactor,
       float emissiveIntensity,
       float metallic,
-      float roughness)
+      float roughness,
+      bool invertRoughnessMap)
       : RawMatProps(shadingModel),
         diffuseFactor(diffuseFactor),
         emissiveFactor(emissiveFactor),
         emissiveIntensity(emissiveIntensity),
         metallic(metallic),
-        roughness(roughness) {}
+        roughness(roughness),
+        invertRoughnessMap(invertRoughnessMap) {}
   const Vec4f diffuseFactor;
   const Vec3f emissiveFactor;
   const float emissiveIntensity;
   const float metallic;
   const float roughness;
+  const bool invertRoughnessMap;
 
   bool operator==(const RawMatProps& other) const override {
     if (RawMatProps::operator==(other)) {