add support for khr_materials_sheen during export

code/AssetLib/glTF2/glTF2AssetWriter.h

@@ -46,6 +46,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * glTF Extensions Support:
  *   KHR_materials_pbrSpecularGlossiness: full
  *   KHR_materials_unlit: full
+ *   KHR_materials_sheen: full
  */
 #ifndef GLTF2ASSETWRITER_H_INC
 #define GLTF2ASSETWRITER_H_INC

code/AssetLib/glTF2/glTF2AssetWriter.inl

@@ -417,6 +417,25 @@ namespace glTF2 {
           exts.AddMember("KHR_materials_unlit", unlit, w.mAl);
         }
 
+        if (m.materialSheen.isPresent) {
+            Value materialSheen(rapidjson::Type::kObjectType);
+
+            MaterialSheen &sheen = m.materialSheen.value;
+
+            WriteVec(materialSheen, sheen.sheenColorFactor, "sheenColorFactor", defaultSheenFactor, w.mAl);
+
+            if (sheen.sheenRoughnessFactor != 0.f) {
+                WriteFloat(materialSheen, sheen.sheenRoughnessFactor, "sheenRoughnessFactor", w.mAl);
+            }
+
+            WriteTex(materialSheen, sheen.sheenColorTexture, "sheenColorTexture", w.mAl);
+            WriteTex(materialSheen, sheen.sheenRoughnessTexture, "sheenRoughnessTexture", w.mAl);
+
+            if (!materialSheen.ObjectEmpty()) {
+                exts.AddMember("KHR_materials_sheen", materialSheen, w.mAl);
+            }
+        }
+
         if (!exts.ObjectEmpty()) {
             obj.AddMember("extensions", exts, w.mAl);
         }
@@ -808,6 +827,10 @@ namespace glTF2 {
             if (this->mAsset.extensionsUsed.KHR_materials_unlit) {
               exts.PushBack(StringRef("KHR_materials_unlit"), mAl);
             }
+
+            if (this->mAsset.extensionsUsed.KHR_materials_sheen) {
+                exts.PushBack(StringRef("KHR_materials_sheen"), mAl);
+            }
         }
 
         if (!exts.Empty())

code/AssetLib/glTF2/glTF2Exporter.cpp

@@ -714,6 +714,22 @@ void glTF2Exporter::ExportMaterials()
             mAsset->extensionsUsed.KHR_materials_unlit = true;
             m->unlit = true;
         }
+
+        bool hasMaterialSheen = false;
+        mat->Get(AI_MATKEY_GLTF_MATERIAL_SHEEN, hasMaterialSheen);
+
+        if (hasMaterialSheen) {
+            mAsset->extensionsUsed.KHR_materials_sheen = true;
+
+            MaterialSheen sheen;
+
+            GetMatColor(mat, sheen.sheenColorFactor, AI_MATKEY_GLTF_MATERIAL_SHEEN_COLOR_FACTOR);
+            mat->Get(AI_MATKEY_GLTF_MATERIAL_SHEEN_ROUGHNESS_FACTOR, sheen.sheenRoughnessFactor);
+            GetMatTex(mat, sheen.sheenColorTexture, AI_MATKEY_GLTF_MATERIAL_SHEEN_COLOR_TEXTURE);
+            GetMatTex(mat, sheen.sheenRoughnessTexture, AI_MATKEY_GLTF_MATERIAL_SHEEN_ROUGHNESS_TEXTURE);
+
+            m->materialSheen = Nullable<MaterialSheen>(sheen);
+        }
     }
 }