Add a "mtl" scope when authoring usd materials #1486 (#1517)

Autodesk · May 5, 2023 · 777f0f1 · 777f0f1
1 parent 0f43465
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Showing 8 changed files with 52 additions and 25 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Feature
 - [usd#1492](https://github.com/Autodesk/arnold-usd/issues/1492) - Add Arnold render status and estimated render time to viewport annotation
 - [usd#1499](https://github.com/Autodesk/arnold-usd/issues/1499) - Add support for camera filtermap and uv_remap
+- [usd#1486](https://github.com/Autodesk/arnold-usd/issues/1486) - Add a "Mtl" scope for materials when authoring usd files
 
 ### Build
 - [usd#1480](https://github.com/Autodesk/arnold-usd/issues/1480) - Allow to specify a testsuite output folder

diff --git a/common/constant_strings.h b/common/constant_strings.h
@@ -332,6 +332,7 @@ ASTR(missing);
 ASTR(missing_texture_color);
 ASTR(motion_end);
 ASTR(motion_start);
+ASTR(mtl_scope);
 ASTR(mtlx);
 ASTR(multiply);
 ASTR(name);

diff --git a/procedural/main.cpp b/procedural/main.cpp
@@ -377,6 +377,12 @@ scene_write
         if (AiParamValueMapGetStr(params, str::scope, &scope))
             writer->SetScope(std::string(scope.c_str()));
 
+        AtString mtlScope;
+        if (!AiParamValueMapGetStr(params, str::mtl_scope, &mtlScope))
+            mtlScope = AtString("/mtl");
+
+        writer->SetMtlScope(std::string(mtlScope.c_str()));
+
         AtString defaultPrim;
         if (AiParamValueMapGetStr(params, str::defaultPrim, &defaultPrim))
             writer->SetDefaultPrim(std::string(defaultPrim.c_str()));

diff --git a/testsuite/test_0138/data/test.cpp b/testsuite/test_0138/data/test.cpp
@@ -27,7 +27,7 @@ int main(int argc, char **argv)
         AiMsgError("/beautiful/scope/my/cone/name doesn't exist");
         success = false;
     }
-    if (!AiNodeLookUpByName(nullptr, "/beautiful/scope/lambert1/lambert1")) {
+    if (!AiNodeLookUpByName(nullptr, "/beautiful/scope/mtl/lambert1/lambert1")) {
         AiMsgError("/beautiful/scope/lambert1 doesn't exist");
         success = false;
     }

diff --git a/testsuite/test_0208/data/test.cpp b/testsuite/test_0208/data/test.cpp
@@ -16,20 +16,20 @@ int main(int argc, char **argv)
     AiParamValueMapDestroy(params);
     AiEnd();
 
-    std::vector<std::string> includeList = {"/aiStandard3/aiStandard3", 
-                                            "/aiStandard3/checker",
-                                            "/aiStandard3displacementShader1/aiStandard3",
-                                            "/aiStandard3displacementShader1/checker",
-                                            "/aiStandard3displacementShader1/displacementShader1",
-                                            "/aiStandard3displacementShader1/bulge1",
-                                            "/aiStandard3displacementShader2/aiStandard3",
-                                            "/aiStandard3displacementShader2/checker",
-                                            "/aiStandard3displacementShader2/displacementShader2",
-                                            "/aiStandard3displacementShader2/noise1",
-                                            "/aiStandard5displacementShader3/aiStandard5",
-                                            "/aiStandard5displacementShader3/displacementShader3",
-                                            "/aiStandard5displacementShader3/checker1_cc",
-                                            "/aiStandard5displacementShader3/checker1",
+    std::vector<std::string> includeList = {"/mtl/aiStandard3/aiStandard3", 
+                                            "/mtl/aiStandard3/checker",
+                                            "/mtl/aiStandard3displacementShader1/aiStandard3",
+                                            "/mtl/aiStandard3displacementShader1/checker",
+                                            "/mtl/aiStandard3displacementShader1/displacementShader1",
+                                            "/mtl/aiStandard3displacementShader1/bulge1",
+                                            "/mtl/aiStandard3displacementShader2/aiStandard3",
+                                            "/mtl/aiStandard3displacementShader2/checker",
+                                            "/mtl/aiStandard3displacementShader2/displacementShader2",
+                                            "/mtl/aiStandard3displacementShader2/noise1",
+                                            "/mtl/aiStandard5displacementShader3/aiStandard5",
+                                            "/mtl/aiStandard5displacementShader3/displacementShader3",
+                                            "/mtl/aiStandard5displacementShader3/checker1_cc",
+                                            "/mtl/aiStandard5displacementShader3/checker1",
                                             "/place2dTexture1_u",
                                             "/place2dTexture1_v",
                                             "/place2dTexture1",

diff --git a/testsuite/test_1457/data/test.cpp b/testsuite/test_1457/data/test.cpp
@@ -18,9 +18,9 @@ int main(int argc, char **argv)
     AiBegin();
     AiSceneLoad(nullptr, "scene.usda", nullptr);
 
-    const static AtString shaderName("/test/aiStandardSurface1/aiStandardSurface1");
+    const static AtString shaderName("/mtl/test/aiStandardSurface1/aiStandardSurface1");
     AtNode *shader = AiNodeLookUpByName(nullptr, shaderName);
-    const static AtString noiseName("/test/aiStandardSurface1/my_noise");
+    const static AtString noiseName("/mtl/test/aiStandardSurface1/my_noise");
     AtNode *noise = AiNodeLookUpByName(nullptr, noiseName);
     bool success = (shader != nullptr && noise != nullptr);
     AiEnd();

diff --git a/translator/writer/prim_writer.cpp b/translator/writer/prim_writer.cpp
@@ -1107,21 +1107,26 @@ void UsdArnoldPrimWriter::_WriteMatrix(UsdGeomXformable& xformable, const AtNode
 
 static void processMaterialBinding(AtNode* shader, AtNode* displacement, UsdPrim& prim, UsdArnoldWriter& writer)
 {
-    std::string shaderName = (shader) ? UsdArnoldPrimWriter::GetArnoldNodeName(shader, writer) : "";
-    std::string dispName = (displacement) ? UsdArnoldPrimWriter::GetArnoldNodeName(displacement, writer) : "";
-
+
     // Special case : by default when no shader is assigned, the shader that is returned
     // is the arnold default shader "ai_default_reflection_shader". Since it's an implicit node that
     // isn't exported to arnold, we don't want to consider it
     static const std::string ai_default_reflection_shader = "ai_default_reflection_shader";
     if (shader && std::string(AiNodeGetName(shader)) == ai_default_reflection_shader) {
         shader = nullptr;
-        shaderName = "";
     }
 
     if (shader == nullptr && displacement == nullptr)
         return; // nothing to export
 
+    const std::string scope = writer.GetScope();
+    std::string mtlScope = scope + writer.GetMtlScope();
+    writer.SetScope("");
+    const std::string stripHierarchy = writer.GetStripHierarchy();
+
+    std::string shaderName = (shader) ? UsdArnoldPrimWriter::GetArnoldNodeName(shader, writer) : "";
+    std::string dispName = (displacement) ? UsdArnoldPrimWriter::GetArnoldNodeName(displacement, writer) : "";
+
 #if PXR_VERSION >= 2002
     UsdShadeMaterial mat = UsdShadeMaterialBindingAPI(prim).ComputeBoundMaterial();
 #else
@@ -1137,7 +1142,7 @@ static void processMaterialBinding(AtNode* shader, AtNode* displacement, UsdPrim
         // per combination of surface shader + displacement instead of duplicating it
         // for every geometry.
         if (!shaderName.empty()) {
-            materialName = shaderName;
+            materialName = mtlScope + shaderName;
             if (!dispName.empty()) {
                 size_t namePos = dispName.find_last_of('/');
                 materialName += (namePos == std::string::npos) ? dispName : dispName.substr(namePos + 1);
@@ -1162,10 +1167,9 @@ static void processMaterialBinding(AtNode* shader, AtNode* displacement, UsdPrim
     // one arnold shader could eventually be duplicated in the usd file if he's used with
     // different displacement shaders. We also need to strip the material's parent hierarchy 
     // from each shader name, otherwise the scope might appear twice under the shaders
-    const std::string scope = writer.GetScope();
-    const std::string stripHierarchy = writer.GetStripHierarchy();
+
     writer.SetScope(materialName);
-    std::string materialPath = TfGetPathName(materialName);
+    std::string materialPath = TfGetPathName(shaderName);
     if (materialPath != "/")
         writer.SetStripHierarchy(materialPath);
 

diff --git a/translator/writer/writer.h b/translator/writer/writer.h
@@ -89,6 +89,20 @@ class UsdArnoldWriter {
                 _scope = _scope.substr(0, _scope.length() - 1);            
         }
 
+    }
+    const std::string &GetMtlScope() const {return _mtlScope;}
+    void SetMtlScope(const std::string &scope) {
+        _mtlScope = scope;
+        if (!_mtlScope.empty()) { 
+            // First character needs to be a slash
+            if (_mtlScope[0] != '/')
+                _mtlScope = std::string("/") + _mtlScope;
+            // Last character should *not* be slash, otherwise we could have 
+            // double slashes in the nodes names, which can crash usd
+            if (_mtlScope.back() == '/')
+                _mtlScope = _mtlScope.substr(0, _mtlScope.length() - 1);            
+        }
+
     }
     const std::string &GetStripHierarchy() const {return _stripHierarchy;}
     void SetStripHierarchy(const std::string &s) {
@@ -201,6 +215,7 @@ class UsdArnoldWriter {
     std::unordered_set<std::string> _exportedNodes; // List of node names that were exported (including material scope)
     std::unordered_set<const AtNode *> _exportedShaders; // list of shader nodes that were exported
     std::string _scope;                // scope in which the primitives must be written
+    std::string _mtlScope;             // specific scope for materials (on top of the eventual generic scope)
     std::string _stripHierarchy;       // When writing out a primitive, strip a given hierarchy from the arnold node name
     bool _allAttributes;               // write all attributes to usd prims, even if they're left to default
     UsdTimeCode _time;                 // current time required by client code