First cleaned-up, consistent physical material implementation.

There's still work to be done here, mainly:
 - Convert BUMP to NORMAL
 - Apply "roughness inversion" to roughness map

But it now informs the user of unsupported properties their model uses,
and generally works correctly!

src/fbx/materials/3dsMaxPhysicalMaterial.cpp

@@ -10,11 +10,14 @@
 #include "RoughnessMetallicMaterials.hpp"
 
 std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::resolve() const {
-  const FbxProperty topProp = fbxMaterial->FindProperty("3dsMax");
+  const FbxProperty topProp = fbxMaterial->FindProperty("3dsMax", false);
   if (topProp.GetPropertyDataType() != FbxCompoundDT) {
     return nullptr;
   }
-  const FbxProperty props = fbxMaterial->FindProperty("Parameters");
+  const FbxProperty props = topProp.Find("Parameters", false);
+  if (!props.IsValid()) {
+    return nullptr;
+  }
 
   FbxString shadingModel = fbxMaterial->ShadingModel.Get();
   if (!shadingModel.IsEmpty() && shadingModel != "unknown") {
@@ -26,29 +29,21 @@ std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::reso
 
   auto getTex = [&](std::string propName) -> const FbxFileTexture* {
     const FbxFileTexture* ptr = nullptr;
-
+    const FbxProperty texProp = props.Find((propName + "_map").c_str(), false);
-    const FbxProperty useProp = props.FindHierarchical((propName + "_map_on").c_str());
+    if (texProp.IsValid()) {
-    if (useProp.IsValid() && useProp.Get<bool>()) {
+      const FbxProperty useProp = props.Find((propName + "_map_on").c_str(), false);
-      const FbxProperty texProp = useProp.FindHierarchical((propName + "_map").c_str());
+      if (useProp.IsValid() && !useProp.Get<FbxBool>()) {
-      if (texProp.IsValid()) {
+        // skip this texture if the _on property exists *and* is explicitly false
-        ptr = texProp.GetSrcObject<FbxFileTexture>();
+        return nullptr;
-        if (ptr != nullptr && textureLocations.find(ptr) == textureLocations.end()) {
+      }
-          ptr = nullptr;
+      ptr = texProp.GetSrcObject<FbxFileTexture>();
-        }
+      if (ptr != nullptr && textureLocations.find(ptr) == textureLocations.end()) {
+        ptr = nullptr;
       }
-    } else if (verboseOutput && useProp.IsValid()) {
-      fmt::printf(
-          "Note: property '%s' of 3dsMax Physical material '%s' exists, but is flagged as 'off'.\n",
-          propName,
-          fbxMaterial->GetName());
     }
     return ptr;
   };
 
-  int materialMode = getValue(props, "material_mode", 0);
-  fmt::printf("Note: 3dsMax Physical material has material_mode = %d.\n", materialMode);
-
-  // baseWeight && baseColor
   FbxDouble baseWeight = getValue(props, "base_weight", 1.0);
   const auto* baseWeightMap = getTex("base_weight");
   FbxDouble4 baseCol = getValue(props, "base_color", FbxDouble4(0.5, 0.5, 0.5, 1.0));
@@ -58,49 +53,97 @@ std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::reso
   const auto* emissiveWeightMap = getTex("emission");
   FbxDouble4 emissiveColor = getValue(props, "emit_color", FbxDouble4(1, 1, 1, 1));
   const auto* emissiveColorMap = getTex("emit_color");
-  // TODO: emit_luminance, emit_kelvin?
 
-  // roughness & metalness: supported
   double roughness = getValue(props, "roughness", 0.0);
   const auto* roughnessMap = getTex("roughness");
   double metalness = getValue(props, "metalness", 0.0);
   const auto* metalnessMap = getTex("metalness");
 
-  // TODO: does invertRoughness affect roughness_map too?
+  // TODO: we need this to affect roughness map, too.
   bool invertRoughness = getValue(props, "inv_roughness", false);
   if (invertRoughness) {
     roughness = 1.0f - roughness;
   }
 
-  // TODO: attempt to bake transparency > 0.0f into the alpha of baseColour?
+  // TODO: turn this into a normal map through simple numerial differentiation
-  // double transparency = getValue(props, "transparency", 0.0);
-  // const auto* transparencyMap = getTex("transparency");
-
-  // SSS: not supported
-  // double scattering = getValue(props, "scattering", 0.0);
-  // const auto* scatteringMap = getTex("scattering");
-
-  // reflectivity: not supported
-  // double reflectivityWeight = getValue(props, "reflectivity", 1.);
-  // const auto* reflectivityWeightMap = getTex("reflectivity");
-  // FbxDouble4 reflectivityColor = getValue(props, "refl_color", FbxDouble4(1, 1, 1, 1));
-  // const auto* reflectivityColorMap = getTex("refl_color");
-
-  // coatings: not supported
-  // double coating = getValue(props, "coating", 0.0);
-
-  // diffuse roughness: not supported
-  // double diffuseRoughness = getValue(props, "diff_roughness", 0.);
-
-  // explicit brdf curve control: not supported
-  // bool isBrdfMode = getValue(props, "brdf_mode", false);
-
-  // anisotrophy: not supported
-  // double anisotropy = getValue(props, "anisotropy", 1.0);
-
-  // TODO: how the heck do we combine these to generate a normal map?
   const auto* bumpMap = getTex("bump");
-  // const auto* displacementMap = getTex("displacement");
+
+  std::string unsupported;
+  const auto addUnsupported = [&](const std::string bit) {
+    if (!unsupported.empty()) {
+      unsupported += ", ";
+    }
+    unsupported += bit;
+  };
+
+  // TODO: bake transparency > 0.0f into the alpha of baseColor?
+  double transparency = getValue(props, "transparency", 0.0);
+  const auto* transparencyMap = getTex("transparency");
+  if (transparency != 0.0 || transparencyMap != nullptr) {
+    addUnsupported("transparency");
+  }
+
+  // TODO: if/when we bake transparency, we'll need this
+  // double transparencyDepth = getValue(props, "trans_depth", 0.0);
+  // if (transparencyDepth != 0.0) {
+  //   addUnsupported("transparency depth");
+  // }
+  // double transparencyColor = getValue(props, "trans_color", 0.0);
+  // const auto* transparencyColorMap = getTex("trans_color");
+  // if (transparencyColor != 0.0 || transparencyColorMap != nullptr) {
+  //   addUnsupported("transparency color");
+  // }
+  // double thinWalledTransparency = getValue(props, "thin_walled", false);
+  // if (thinWalledTransparency) {
+  //   addUnsupported("thin-walled transparency");
+  // }
+
+  const auto* displacementMap = getTex("displacement");
+  if (displacementMap != nullptr) {
+    addUnsupported("displacement");
+  }
+
+  double reflectivityWeight = getValue(props, "reflectivity", 1.0);
+  const auto* reflectivityWeightMap = getTex("reflectivity");
+  FbxDouble4 reflectivityColor = getValue(props, "refl_color", FbxDouble4(1, 1, 1, 1));
+  const auto* reflectivityColorMap = getTex("refl_color");
+  if (reflectivityWeight != 1.0 || reflectivityWeightMap != nullptr ||
+      reflectivityColor != FbxDouble4(1, 1, 1, 1) || reflectivityColorMap != nullptr) {
+    addUnsupported("reflectivity");
+  }
+
+  double scattering = getValue(props, "scattering", 0.0);
+  const auto* scatteringMap = getTex("scattering");
+  if (scattering != 0.0 || scatteringMap != nullptr) {
+    addUnsupported("sub-surface scattering");
+  }
+
+  double coating = getValue(props, "coating", 0.0);
+  if (coating != 0.0) {
+    addUnsupported("coating");
+  }
+
+  double diffuseRoughness = getValue(props, "diff_roughness", 0.0);
+  if (diffuseRoughness != 0.0) {
+    addUnsupported("diffuse roughness");
+  }
+
+  bool isBrdfMode = getValue(props, "brdf_mode", false);
+  if (isBrdfMode) {
+    addUnsupported("advanced reflectance custom curve");
+  }
+
+  double anisotropy = getValue(props, "anisotropy", 1.0);
+  if (anisotropy != 1.0) {
+    addUnsupported("anisotropy");
+  }
+
+  if (verboseOutput && !unsupported.empty()) {
+    fmt::printf(
+        "Warning: 3dsMax Physical Material %s uses features glTF cannot express:\n  %s\n",
+        fbxMaterial->GetName(),
+        unsupported);
+  }
 
   std::unique_ptr<FbxRoughMetMaterialInfo> res(new FbxRoughMetMaterialInfo(
       fbxMaterial->GetName(),
@@ -115,8 +158,6 @@ std::unique_ptr<FbxRoughMetMaterialInfo> Fbx3dsMaxPhysicalMaterialResolver::reso
   res->texMetallic = metalnessMap;
   res->texRoughness = roughnessMap;
 
-  res->texNormal = bumpMap; // TODO LOL NO NONO
-
   res->emissive = emissiveColor;
   res->emissiveIntensity = emissiveWeight;
   res->texEmissive = emissiveColorMap;