Support both pbrSpecGlos and materials_specular

code/AssetLib/glTF2/glTF2Asset.h

@@ -44,6 +44,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * glTF Extensions Support:
  *   KHR_materials_pbrSpecularGlossiness full
+ *   KHR_materials_specular full
  *   KHR_materials_unlit full
  *   KHR_lights_punctual full
  *   KHR_materials_sheen full
@@ -718,6 +719,7 @@ const vec4 defaultBaseColor = { 1, 1, 1, 1 };
 const vec3 defaultEmissiveFactor = { 0, 0, 0 };
 const vec4 defaultDiffuseFactor = { 1, 1, 1, 1 };
 const vec3 defaultSpecularFactor = { 1, 1, 1 };
+const vec3 defaultSpecularColorFactor = { 0, 0, 0 };
 const vec3 defaultSheenFactor = { 0, 0, 0 };
 const vec3 defaultAttenuationColor = { 1, 1, 1 };
 
@@ -761,6 +763,16 @@ struct PbrSpecularGlossiness {
     void SetDefaults();
 };
 
+struct MaterialSpecular {
+    float specularFactor;
+    vec3 specularColorFactor;
+    TextureInfo specularTexture;
+    TextureInfo specularColorTexture;
+
+    MaterialSpecular() { SetDefaults(); }
+    void SetDefaults();
+};
+
 struct MaterialSheen {
     vec3 sheenColorFactor;
     float sheenRoughnessFactor;
@@ -818,6 +830,9 @@ struct Material : public Object {
     //extension: KHR_materials_pbrSpecularGlossiness
     Nullable<PbrSpecularGlossiness> pbrSpecularGlossiness;
 
+    //extension: KHR_materials_specular
+    Nullable<MaterialSpecular> materialSpecular;
+
     //extension: KHR_materials_sheen
     Nullable<MaterialSheen> materialSheen;
 
@@ -1098,6 +1113,7 @@ public:
     //! Keeps info about the enabled extensions
     struct Extensions {
         bool KHR_materials_pbrSpecularGlossiness;
+        bool KHR_materials_specular;
         bool KHR_materials_unlit;
         bool KHR_lights_punctual;
         bool KHR_texture_transform;
@@ -1112,6 +1128,7 @@ public:
 
         Extensions() :
                 KHR_materials_pbrSpecularGlossiness(false), 
+                KHR_materials_specular(false), 
                 KHR_materials_unlit(false), 
                 KHR_lights_punctual(false), 
                 KHR_texture_transform(false), 

code/AssetLib/glTF2/glTF2Asset.inl

@@ -1236,7 +1236,7 @@ inline void Material::Read(Value &material, Asset &r) {
     ReadMember(material, "alphaCutoff", this->alphaCutoff);
 
     if (Value *extensions = FindObject(material, "extensions")) {
-        if (r.extensionsUsed.KHR_materials_pbrSpecularGlossiness) {
+        if (r.extensionsUsed.KHR_materials_pbrSpecularGlossiness) {  //TODO: Maybe ignore this if KHR_materials_specular is also defined
             if (Value *curPbrSpecularGlossiness = FindObject(*extensions, "KHR_materials_pbrSpecularGlossiness")) {
                 PbrSpecularGlossiness pbrSG;
 
@@ -1250,6 +1250,19 @@ inline void Material::Read(Value &material, Asset &r) {
             }
         }
         
+        if (r.extensionsUsed.KHR_materials_specular) {
+            if (Value *curMatSpecular = FindObject(*extensions, "KHR_materials_specular")) {
+                MaterialSpecular specular;
+
+                ReadMember(*curMatSpecular, "specularFactor", specular.specularFactor);
+                ReadTextureProperty(r, *curMatSpecular, "specularTexture", specular.specularTexture);
+                ReadMember(*curMatSpecular, "specularColorFactor", specular.specularColorFactor);
+                ReadTextureProperty(r, *curMatSpecular, "specularColorTexture", specular.specularColorTexture);
+
+                this->materialSpecular = Nullable<MaterialSpecular>(specular);
+            }
+        }
+
         // Extension KHR_texture_transform is handled in ReadTextureProperty
 
         if (r.extensionsUsed.KHR_materials_sheen) {
@@ -1337,6 +1350,12 @@ inline void PbrSpecularGlossiness::SetDefaults() {
     glossinessFactor = 1.0f;
 }
 
+inline void MaterialSpecular::SetDefaults() {
+    //KHR_materials_specular properties
+    SetVector(specularColorFactor, defaultSpecularColorFactor);
+    specularFactor = 0.f;
+}
+
 inline void MaterialSheen::SetDefaults() {
     //KHR_materials_sheen properties
     SetVector(sheenColorFactor, defaultSheenFactor);
@@ -2018,6 +2037,7 @@ inline void Asset::ReadExtensionsUsed(Document &doc) {
     }
 
     CHECK_EXT(KHR_materials_pbrSpecularGlossiness);
+    CHECK_EXT(KHR_materials_specular);
     CHECK_EXT(KHR_materials_unlit);
     CHECK_EXT(KHR_lights_punctual);
     CHECK_EXT(KHR_texture_transform);

code/AssetLib/glTF2/glTF2AssetWriter.h

@@ -45,6 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * glTF Extensions Support:
  *   KHR_materials_pbrSpecularGlossiness: full
+ *   KHR_materials_specular: full
  *   KHR_materials_unlit: full
  *   KHR_materials_sheen: full
  *   KHR_materials_clearcoat: full

code/AssetLib/glTF2/glTF2AssetWriter.inl

@@ -418,6 +418,25 @@ namespace glTF2 {
           exts.AddMember("KHR_materials_unlit", unlit, w.mAl);
         }
 
+        if (m.materialSpecular.isPresent) {
+            Value materialSpecular(rapidjson::Type::kObjectType);
+            materialSpecular.SetObject();
+
+            MaterialSpecular &specular = m.materialSpecular.value;
+
+            if (specular.specularFactor != 0.f) {
+                WriteFloat(materialSpecular, specular.specularFactor, "specularFactor", w.mAl);
+                WriteTex(materialSpecular, specular.specularTexture, "specularTexture", w.mAl);
+            }
+            if (specular.specularColorFactor[0] != defaultSpecularColorFactor[0] && specular.specularColorFactor[1] != defaultSpecularColorFactor[1] && specular.specularColorFactor[2] != defaultSpecularColorFactor[2]) {
+                WriteVec(materialSpecular, specular.specularColorFactor, "specularColorFactor", w.mAl);
+                WriteTex(materialSpecular, specular.specularColorTexture, "specularColorTexture", w.mAl);
+            }
+
+            if (!materialSpecular.ObjectEmpty()) {
+                exts.AddMember("KHR_materials_specular", materialSpecular, w.mAl);
+        }
+
         if (m.materialSheen.isPresent) {
             Value materialSheen(rapidjson::Type::kObjectType);
 
@@ -915,6 +934,10 @@ namespace glTF2 {
               exts.PushBack(StringRef("KHR_materials_unlit"), mAl);
             }
 
+            if (this->mAsset.extensionsUsed.KHR_materials_specular) {
+                exts.PushBack(StringRef("KHR_materials_specular"), mAl);
+            }
+
             if (this->mAsset.extensionsUsed.KHR_materials_sheen) {
                 exts.PushBack(StringRef("KHR_materials_sheen"), mAl);
             }

code/AssetLib/glTF2/glTF2Exporter.cpp

@@ -644,7 +644,10 @@ bool glTF2Exporter::GetMatSpecGloss(const aiMaterial &mat, glTF2::PbrSpecularGlo
     bool result = false;
     // If has Glossiness, a Specular Color or Specular Texture, use the KHR_materials_pbrSpecularGlossiness extension
     // NOTE: This extension is being considered for deprecation (Dec 2020), may be replaced by KHR_material_specular
-
+    // This extension has been deprecated, only export with the specific flag enabled, defaults to false. Uses KHR_material_specular default.
+    if (mat.Get(AI_MATKEY_USE_GLTF_PBR_SPECULAR_GLOSSINESS) != AI_SUCCESS) {
+        return false;
+    }
     if (mat.Get(AI_MATKEY_GLOSSINESS_FACTOR, pbrSG.glossinessFactor) == AI_SUCCESS) {
         result = true;
     } else {
@@ -674,6 +677,24 @@ bool glTF2Exporter::GetMatSpecGloss(const aiMaterial &mat, glTF2::PbrSpecularGlo
     return result;
 }
 
+bool glTF2Exporter::GetMatSpecular(const aiMaterial &mat, glTF2::MaterialSpecular &specular) {
+    // Specular requires either/or
+    if (GetMatColor(mat, specular.specularColorFactor, AI_MATKEY_COLOR_SPECULAR) != AI_SUCCESS && mat.Get(AI_MATKEY_SPECULAR_FACTOR, specular.specularFactor) != AI_SUCCESS) {
+        return false;
+    }
+
+    // default factors of zero disables specular, so do not export
+    if (specular.specularFactor == 0.0f && (specular.specularColorFactor[0] == defaultSpecularColorFactor[0] && specular.specularColorFactor[1] == defaultSpecularColorFactor[1] && specular.specularColorFactor[2] == defaultSpecularColorFactor[2])) {
+        return false;
+    }
+
+    // Add any appropriate textures
+    GetMatTex(mat, specular.specularTexture, aiTextureType_SPECULAR);
+    GetMatTex(mat, specular.specularColorTexture, aiTextureType_SPECULAR);
+
+    return true;
+}
+
 bool glTF2Exporter::GetMatSheen(const aiMaterial &mat, glTF2::MaterialSheen &sheen) {
     // Return true if got any valid Sheen properties or textures
     if (GetMatColor(mat, sheen.sheenColorFactor, AI_MATKEY_SHEEN_COLOR_FACTOR) != aiReturn_SUCCESS) {
@@ -816,7 +837,7 @@ void glTF2Exporter::ExportMaterials() {
 
         {
             // KHR_materials_pbrSpecularGlossiness extension
-            // NOTE: This extension is being considered for deprecation (Dec 2020)
+            // This extension has been deprecated, only export with the specific flag enabled, defaults to false. Uses KHR_material_specular default.
             PbrSpecularGlossiness pbrSG;
             if (GetMatSpecGloss(mat, pbrSG)) {
                 mAsset->extensionsUsed.KHR_materials_pbrSpecularGlossiness = true;
@@ -833,7 +854,12 @@ void glTF2Exporter::ExportMaterials() {
         } else {
             // These extensions are not compatible with KHR_materials_unlit or KHR_materials_pbrSpecularGlossiness
             if (!m->pbrSpecularGlossiness.isPresent) {
-                // Sheen
+                MaterialSpecular specular;
+                if (GetMatSpecular(mat, specular)) {
+                    mAsset->extensionsUsed.KHR_materials_specular = true;
+                    m->materialSpecular = Nullable<MaterialSpecular>(specular);
+                }
+
                 MaterialSheen sheen;
                 if (GetMatSheen(mat, sheen)) {
                     mAsset->extensionsUsed.KHR_materials_sheen = true;

code/AssetLib/glTF2/glTF2Exporter.h

@@ -76,6 +76,7 @@ struct OcclusionTextureInfo;
 struct Node;
 struct Texture;
 struct PbrSpecularGlossiness;
+struct MaterialSpecular;
 struct MaterialSheen;
 struct MaterialClearcoat;
 struct MaterialTransmission;
@@ -116,6 +117,7 @@ protected:
     aiReturn GetMatColor(const aiMaterial &mat, glTF2::vec4 &prop, const char *propName, int type, int idx) const;
     aiReturn GetMatColor(const aiMaterial &mat, glTF2::vec3 &prop, const char *propName, int type, int idx) const;
     bool GetMatSpecGloss(const aiMaterial &mat, glTF2::PbrSpecularGlossiness &pbrSG);
+    bool GetMatSpecular(const aiMaterial &mat, glTF2::MaterialSpecular &specular);
     bool GetMatSheen(const aiMaterial &mat, glTF2::MaterialSheen &sheen);
     bool GetMatClearcoat(const aiMaterial &mat, glTF2::MaterialClearcoat &clearcoat);
     bool GetMatTransmission(const aiMaterial &mat, glTF2::MaterialTransmission &transmission);

code/AssetLib/glTF2/glTF2Importer.cpp

@@ -283,8 +283,9 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
         aimat->AddProperty(&mat.alphaCutoff, 1, AI_MATKEY_GLTF_ALPHACUTOFF);
 
         // pbrSpecularGlossiness
-        if (mat.pbrSpecularGlossiness.isPresent) {
+        if (mat.pbrSpecularGlossiness.isPresent) { // TODO: Consider importing this only if KHR_materials_specular isn't also defined
             PbrSpecularGlossiness &pbrSG = mat.pbrSpecularGlossiness.value;
+            aimat->AddProperty(new int(1), 1, AI_MATKEY_USE_GLTF_PBR_SPECULAR_GLOSSINESS);
 
             SetMaterialColorProperty(r, pbrSG.diffuseFactor, aimat, AI_MATKEY_COLOR_DIFFUSE);
             SetMaterialColorProperty(r, pbrSG.specularFactor, aimat, AI_MATKEY_COLOR_SPECULAR);
@@ -307,6 +308,18 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
 
         aimat->AddProperty(&shadingMode, 1, AI_MATKEY_SHADING_MODEL);
 
+        // KHR_materials_specular
+        if (mat.materialSpecular.isPresent) {
+            MaterialSpecular &specular = mat.materialSpecular.value;
+            // Default values of zero disables Specular
+            if (std::memcmp(specular.specularColorFactor, defaultSpecularColorFactor, sizeof(glTFCommon::vec3)) != 0 || specular.specularFactor != 0.0f) {
+                SetMaterialColorProperty(r, specular.specularColorFactor, aimat, AI_MATKEY_COLOR_SPECULAR);
+                aimat->AddProperty(&specular.specularFactor, 1, AI_MATKEY_SPECULAR_FACTOR);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, specular.specularTexture, aimat, aiTextureType_SPECULAR);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, specular.specularColorTexture, aimat, aiTextureType_SPECULAR);
+            }
+        }
+
         // KHR_materials_sheen
         if (mat.materialSheen.isPresent) {
             MaterialSheen &sheen = mat.materialSheen.value;

include/assimp/material.h

@@ -1000,6 +1000,7 @@ extern "C" {
 // Specular Color.
 // Note: Metallic/Roughness may also have a Specular Color
 // AI_MATKEY_COLOR_SPECULAR
+#define AI_MATKEY_USE_PBR_SPECULAR_GLOSSINESS "$mat.useGltfPbrSpecularGlossiness", 0, 0
 #define AI_MATKEY_SPECULAR_FACTOR "$mat.specularFactor", 0, 0
 // Glossiness factor. 0.0 = Completely Rough, 1.0 = Perfectly Smooth
 #define AI_MATKEY_GLOSSINESS_FACTOR "$mat.glossinessFactor", 0, 0