Occlusion/Roughness/Metalness texture packing rethink

.gitignore

@@ -5,3 +5,8 @@ npm/fbx2gltf/node_modules/
 npm/tests/node_modules/
 npm/tests/test/*.js
 npm/tests/test/*.js.map
+build
+sdk
+.vscode
+Pipfile
+Pipfile.lock

README.md

@@ -308,6 +308,19 @@ that route should be digested propertly by FBX2glTF.
 (A happy note: Allegorithmic's Substance Painter also exports Stingray PBS,
 when hooked up to Maya.)
 
+When processing PBR materials, this converter will always pack Occlusion,
+Roughness, and Metallness into a single combined ORM texture, with each parameter
+being in the R, G and, B channels respectively. If you specify a texture in any
+of the Stingray material slots, a full ORM will be generated; if you leave all 3
+blank, then no ORM texture will be assigned.
+
+* Should you specify different textures for each, then they will
+  be merged into their respective channels. Any missing textures will be
+  defaulted to: Occlusion 1, Roughness 0, and Metallness 0. Note, all textures
+  must have the same dimensions.
+* Should you specify the same texture in all 3 slots, then the texture will
+  be assumed to already be a packed ORM, and will be used as-is.
+
 ## Draco Compression
 
 The tool will optionally apply [Draco](https://github.com/google/draco)

src/gltf/Raw2Gltf.cpp

@@ -261,41 +261,96 @@ ModelData* Raw2Gltf(
            */
           RawMetRoughMatProps* props = (RawMetRoughMatProps*)material.info.get();
 
-          // determine if we need to generate a combined map
+          // determine if we need to generate a combined map, or if we only have 1 map to pass through
           bool hasMetallicMap = material.textures[RAW_TEXTURE_USAGE_METALLIC] >= 0;
           bool hasRoughnessMap = material.textures[RAW_TEXTURE_USAGE_ROUGHNESS] >= 0;
           bool hasOcclusionMap = material.textures[RAW_TEXTURE_USAGE_OCCLUSION] >= 0;
-          bool atLeastTwoMaps = hasMetallicMap ? (hasRoughnessMap || hasOcclusionMap)
-                                               : (hasRoughnessMap && hasMetallicMap);
-          if (!atLeastTwoMaps) {
-            // this handles the case of 0 or 1 maps supplied
+
+          auto texturesAreSame = [&](RawTextureUsage a, RawTextureUsage b) -> bool {
+            // note: at this point the usages will be different, so we can't just compare indexes
+            return StringUtils::CompareNoCase(
+                raw.GetTexture(material.textures[a]).fileLocation,
+                raw.GetTexture(material.textures[b]).fileLocation ) == 0;
+          };
+
+          bool isPassThroughTexture = hasOcclusionMap && hasRoughnessMap && hasMetallicMap;
+          if (isPassThroughTexture) {
+            isPassThroughTexture =
+                texturesAreSame(RAW_TEXTURE_USAGE_METALLIC, RAW_TEXTURE_USAGE_ROUGHNESS) &&
+                texturesAreSame(RAW_TEXTURE_USAGE_METALLIC, RAW_TEXTURE_USAGE_OCCLUSION);
+          }
+
+          auto textureName = [&](RawTextureUsage usage){
+            int index = material.textures[usage];
+            if (index >= 0) {
+              return raw.GetTexture(index).name.c_str();
+            } else {
+              return "<empty>";
+            }
+          };
+
+          if (!(hasMetallicMap || hasRoughnessMap || hasOcclusionMap)) {
+            // no data, assume it's a material that just relies on the uniform properties
+            aoMetRoughTex = nullptr;
+            if (verboseOutput) {
+              fmt::printf("Material %s: no ORM textures detected\n", material.name.c_str() );
+            }
+          }
+          else if (isPassThroughTexture) {
+            // this handles the case where the same map is assigned to all the channels
             aoMetRoughTex = hasMetallicMap
                 ? simpleTex(RAW_TEXTURE_USAGE_METALLIC)
                 : (hasRoughnessMap
-                       ? simpleTex(RAW_TEXTURE_USAGE_ROUGHNESS)
-                       : (hasOcclusionMap ? simpleTex(RAW_TEXTURE_USAGE_OCCLUSION) : nullptr));
+                    ? simpleTex(RAW_TEXTURE_USAGE_ROUGHNESS)
+                    : (hasOcclusionMap
+                        ? simpleTex(RAW_TEXTURE_USAGE_OCCLUSION)
+                        : nullptr));
+            if (verboseOutput) {
+              if (aoMetRoughTex) {
+                fmt::printf("Material %s: detected single ORM texture: %s\n", material.name.c_str(), aoMetRoughTex->name.c_str());
+              } else {
+                fmt::printf("Material %s: no ORM textures detected\n", material.name.c_str() );
+              }
+            }
           } else {
-            // otherwise merge occlusion into the red channel, metallic into blue channel, and
-            // roughness into the green, of a new combinatory texture
+            /* otherwise we always have to create a new texture that merges
+             *   occlusion into the red channel
+             *   roughness into the green
+             *   metallic into blue channel
+             * with defaults for any unspecified channels
+             */
             aoMetRoughTex = textureBuilder.combine(
                 {
                     material.textures[RAW_TEXTURE_USAGE_OCCLUSION],
-                    material.textures[RAW_TEXTURE_USAGE_METALLIC],
                     material.textures[RAW_TEXTURE_USAGE_ROUGHNESS],
+                    material.textures[RAW_TEXTURE_USAGE_METALLIC],
                 },
                 "ao_met_rough",
                 [&](const std::vector<const TextureBuilder::pixel*> pixels)
                     -> TextureBuilder::pixel {
-                  const float occlusion = (*pixels[0])[0];
-                  const float metallic = (*pixels[1])[0] * (hasMetallicMap ? 1 : props->metallic);
-                  const float roughness =
-                      (*pixels[2])[0] * (hasRoughnessMap ? 1 : props->roughness);
+                  /**
+                   * note: we're picking the channels from the sources aligned with where they're going
+                   *   just in case they were authored that way. This makes an existing ORM texture
+                   *   "pass through", and has no effect on a grey single type texture.
+                   */
+                  const float occlusion = hasOcclusionMap ? (*pixels[0])[0] : 1;
+                  const float roughness = (*pixels[1])[1] * (hasRoughnessMap ? 1 : props->roughness);
+                  const float metallic = (*pixels[2])[2] * (hasMetallicMap ? 1 : props->metallic);
                   return {{occlusion,
                            props->invertRoughnessMap ? 1.0f - roughness : roughness,
                            metallic,
                            1}};
                 },
                 false);
+            if ( aoMetRoughTex && verboseOutput ) {
+              fmt::printf("Material %s: detected multiple ORM textures, combined: [%s, %s, %s] into [%s]\n",
+                material.name.c_str(),
+                textureName(RAW_TEXTURE_USAGE_OCCLUSION),
+                textureName(RAW_TEXTURE_USAGE_ROUGHNESS),
+                textureName(RAW_TEXTURE_USAGE_METALLIC),
+                aoMetRoughTex->name.c_str()
+              );
+            }
           }
           baseColorTex = simpleTex(RAW_TEXTURE_USAGE_ALBEDO);
           diffuseFactor = props->diffuseFactor;