Fix OpenVDB fieldName in hydra & assign default volume shader in USD #…

…2239 #2240 (#2241)
Autodesk · Feb 19, 2025 · c4cd82b · c4cd82b
1 parent 50589e8
commit c4cd82b
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Showing 11 changed files with 603 additions and 28 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,7 @@
 - [usd#2148](https://github.com/Autodesk/arnold-usd/issues/2248) - Leverage new Shared Arrays API in the render delegate.
 - [usd#2227](https://github.com/Autodesk/arnold-usd/issues/2227) - Hydra procedural breaks the Arnold logging settings
 - [usd#2228](https://github.com/Autodesk/arnold-usd/issues/2228) - Release usd stage after the hydra procedural translation
+- [usd#2240](https://github.com/Autodesk/arnold-usd/issues/2240) - Default volume shader should be assigned in the usd procedural
 - [usd#2242](https://github.com/Autodesk/arnold-usd/issues/2242) - Support HDARNOLD_DEBUG_SCENE env var in the hydra procedural
 
 ### Bug fixes
@@ -19,6 +20,7 @@
 - [usd#2224](https://github.com/Autodesk/arnold-usd/issues/2224) - Fix warning "HdArnoldDriverMain is already installed" 
 - [usd#2234](https://github.com/Autodesk/arnold-usd/issues/2234) - Fix warning "Selected hydra renderer doesn't support prim type 'RenderSettings'" 
 - [usd#2232](https://github.com/Autodesk/arnold-usd/issues/2232) - Fix incorrect husk render of left handed indexed meshes with normals.
+- [usd#2239](https://github.com/Autodesk/arnold-usd/issues/2239) - OpenVDB asset with explicit fieldName does not render in hydra
 
 ## Pending Feature release
 

diff --git a/libs/render_delegate/volume.cpp b/libs/render_delegate/volume.cpp
@@ -179,6 +179,7 @@ const HtoAFnSet _GetHtoAFunctionSet()
 TF_DEFINE_PRIVATE_TOKENS(_tokens,
     (openvdbAsset)
     (filePath)
+    (fieldName)
 );
 // clang-format on
 
@@ -221,7 +222,7 @@ void HdArnoldVolume::Sync(
             sceneDelegate->GetRenderIndex().GetSprim(HdPrimTypeTokens->material, materialId));
         auto* volumeShader =
             material != nullptr ? material->GetVolumeShader() : _renderDelegate->GetFallbackVolumeShader();
-        _ForEachVolume([&](HdArnoldShape* s) { AiNodeSetPtr(s->GetShape(), str::shader, volumeShader); });
+        _ForEachVolume([&](HdArnoldShape* s) { if (volumeShader) AiNodeSetPtr(s->GetShape(), str::shader, volumeShader); else AiNodeResetParameter(s->GetShape(), str::shader); });
     }
 
     auto transformDirtied = false;
@@ -295,16 +296,23 @@ void HdArnoldVolume::_CreateVolumes(const SdfPath& id, HdSceneDelegate* sceneDel
             if (path.empty()) {
                 path = assetPath.GetAssetPath();
             }
+            TfToken fieldName = field.fieldName;
+            const auto fieldNameValue = sceneDelegate->Get(field.fieldId, _tokens->fieldName);
+            if (fieldNameValue.IsHolding<TfToken>()) {
+                const TfToken &fieldNameToken = fieldNameValue.UncheckedGet<TfToken>();
+                if (!fieldNameToken.IsEmpty())
+                    fieldName = fieldNameToken;
+            }
             if (TfStringStartsWith(path, "op:")) {
                 auto& fields = houVdbs[path];
-                if (std::find(fields.begin(), fields.end(), field.fieldName) == fields.end()) {
-                    fields.push_back(field.fieldName);
+                if (std::find(fields.begin(), fields.end(), fieldName) == fields.end()) {
+                    fields.push_back(fieldName);
                 }
                 continue;
             }
             auto& fields = openvdbs[path];
-            if (std::find(fields.begin(), fields.end(), field.fieldName) == fields.end()) {
-                fields.push_back(field.fieldName);
+            if (std::find(fields.begin(), fields.end(), fieldName) == fields.end()) {
+                fields.push_back(fieldName);
             }
         }
     }

diff --git a/libs/translator/reader/read_geometry.cpp b/libs/translator/reader/read_geometry.cpp
@@ -203,10 +203,10 @@ static inline void _ReadGenericShape(const UsdPrim &prim, UsdArnoldReaderContext
     // If requested, we can read the material bindings
     if (readMaterial) {
         int derivedType = AiNodeEntryGetDerivedType(AiNodeGetNodeEntry(node));
-        // For volumes & procedurals, we do not assign a default shader 
+        // For volumes, we do not assign a default shader 
         // as it could cause problems in Arnold
         ReadMaterialBinding(prim, node, context, 
-            derivedType != AI_NODE_SHAPE_PROCEDURAL && derivedType != AI_NODE_SHAPE_VOLUME);
+            derivedType != AI_NODE_SHAPE_PROCEDURAL);
     }
 
     if (AiNodeIs(node, str::polymesh)) {

diff --git a/libs/translator/reader/reader.cpp b/libs/translator/reader/reader.cpp
@@ -97,6 +97,7 @@ UsdArnoldReader::UsdArnoldReader(AtUniverse *universe, AtNode *procParent)
           _threadCount(1),
           _mask(AI_NODE_ALL),
           _defaultShader(nullptr),
+          _defaultVolumeShader(nullptr),
           _hasRootPrim(false),
           _readStep(READ_NOT_STARTED),
           _purpose(UsdGeomTokens->render),
@@ -819,35 +820,44 @@ void UsdArnoldReader::ClearNodes()
     _nodes.clear();
     _nodeNames.clear();
     _defaultShader = nullptr; // reset defaultShader
+    _defaultVolumeShader = nullptr; 
 }
 
 void UsdArnoldReader::CreateViewportRegistry(AtProcViewportMode mode, const AtParamValueMap* params) {
     delete _readerRegistry;
     _readerRegistry = new UsdArnoldViewportReaderRegistry(mode, params);
 }
 
-AtNode *UsdArnoldReader::GetDefaultShader()
+AtNode *UsdArnoldReader::GetDefaultShader(bool isVolume)
 {
+    AtNode *node = nullptr;
     // Eventually lock the mutex
     LockReader();
-
-    if (_defaultShader == nullptr) {
-        // The default shader doesn't exist yet, let's create a standard_surface,
-        // which base_color is linked to a user_data_rgb that looks up the user data
-        // called "displayColor". This way, by default geometries that don't have any
-        // shader assigned will appear as in hydra.
-        _defaultShader = AiNode(_universe, AtString("standard_surface"), AtString("_default_arnold_shader"), _procParent);
-        AtNode *userData = AiNode(_universe, AtString("user_data_rgb"), AtString("_default_arnold_shader_color"), _procParent);
-        _nodes.push_back(_defaultShader);
-        _nodes.push_back(userData);
-        AiNodeSetStr(userData, str::attribute, AtString("displayColor"));
-        AiNodeSetRGB(userData, str::_default, 1.f, 1.f, 1.f); // neutral white shader if no user data is found
-        AiNodeLink(userData, str::base_color, _defaultShader);
+    if (isVolume) {
+        if (_defaultVolumeShader == nullptr) {
+            // The default volume shader doesn't exist yet, let's create a standard_volume,
+            _defaultVolumeShader = AiNode(_universe, AtString("standard_volume"), AtString("_fallbackVolume"), _procParent);
+            _nodes.push_back(_defaultVolumeShader);
+        }
+        node = _defaultVolumeShader;
+    } else {
+        if (_defaultShader == nullptr) {
+            // The default shader doesn't exist yet, let's create a standard_surface,
+            // which base_color is linked to a user_data_rgb that looks up the user data
+            // called "displayColor". This way, by default geometries that don't have any
+            // shader assigned will appear as in hydra.
+            _defaultShader = AiNode(_universe, AtString("standard_surface"), AtString("_default_arnold_shader"), _procParent);
+            AtNode *userData = AiNode(_universe, AtString("user_data_rgb"), AtString("_default_arnold_shader_color"), _procParent);
+            _nodes.push_back(_defaultShader);
+            _nodes.push_back(userData);
+            AiNodeSetStr(userData, str::attribute, AtString("displayColor"));
+            AiNodeSetRGB(userData, str::_default, 1.f, 1.f, 1.f); // neutral white shader if no user data is found
+            AiNodeLink(userData, str::base_color, _defaultShader);
+        }
+        node = _defaultShader;
     }
-
     UnlockReader();
-
-    return _defaultShader;
+    return node;
 }
 
 // Process eventual light links info, and apply them to the 

diff --git a/libs/translator/reader/reader.h b/libs/translator/reader/reader.h
@@ -101,7 +101,8 @@ class UsdArnoldReader : public ProceduralReader {
     bool HasRootPrim() const {return _hasRootPrim;}
     const UsdPrim &GetRootPrim() const {return _rootPrim;}
 
-    AtNode *GetDefaultShader();
+    AtNode *GetDefaultShader(bool isVolume = false);
+
     AtNode *LookupNode(const char *name, bool checkParent = true)
     {
         auto it = _nodeNames.find(std::string(name));
@@ -222,6 +223,8 @@ class UsdArnoldReader : public ProceduralReader {
     std::unordered_map<std::string, UsdCollectionAPI> _shadowLinksMap;
 
     AtNode *_defaultShader;
+    AtNode *_defaultVolumeShader;
+
 
     bool _hasRootPrim;     // are we reading this stage based on a root primitive
     UsdPrim _rootPrim;     // eventual root primitive used to traverse the stage

diff --git a/libs/translator/reader/utils.cpp b/libs/translator/reader/utils.cpp
@@ -52,8 +52,26 @@ TF_DEFINE_PRIVATE_TOKENS(
     ((PrimvarsArnoldUvRemap, "primvars:arnold:uv_remap"))
     ((PrimvarsArnoldDeformKeys, "primvars:arnold:deform_keys"))
     ((PrimvarsArnoldTransformKeys, "primvars:arnold:transform_keys"))
+    ((PrimvarsArnoldStepSize, "primvars:arnold:step_size"))
 );
 
+static inline bool IsVolume(const AtNode* node, const UsdPrim& prim)
+{
+    if (AiNodeIs(node, str::volume))
+        return true;
+
+    if (AiNodeIs(node, str::polymesh)) {
+        // For mesh nodes, check if an attribute primvars:arnold:step_size exists in the usd primitive
+        UsdAttribute stepSizeAttr = prim.GetAttribute(_tokens->PrimvarsArnoldStepSize); 
+        if (stepSizeAttr && stepSizeAttr.HasAuthoredValue()) {
+            VtValue value;
+            if (stepSizeAttr.Get(&value))
+                return VtValueGetFloat(value) > AI_EPSILON;
+        }
+    }
+    return false;
+}
+
 bool HasConstantPrimvar(UsdArnoldReaderContext &context, const TfToken& name)
 {
     const std::vector<UsdGeomPrimvar>& primvars = context.GetPrimvars();
@@ -294,7 +312,7 @@ void ReadMaterialBinding(const UsdPrim &prim, AtNode *node, UsdArnoldReaderConte
         context.AddConnection(node, "shader", shaderPrim.GetPath().GetString(), 
             ArnoldAPIAdapter::CONNECTION_PTR);
     } else if (assignDefault) {
-        AiNodeSetPtr(node, str::shader, context.GetReader()->GetDefaultShader());
+        AiNodeSetPtr(node, str::shader, context.GetReader()->GetDefaultShader(IsVolume(node, prim)));
     }
 
     if (isPolymesh && dispPrim) {
@@ -333,7 +351,7 @@ void ReadSubsetsMaterialBinding(
         if (shaderPrim)
             shaderStr = shaderPrim.GetPath().GetString();
         else if (assignDefault) {
-            shaderStr = AiNodeGetName(context.GetReader()->GetDefaultShader());
+            shaderStr = AiNodeGetName(context.GetReader()->GetDefaultShader(IsVolume(node, prim)));
         }
         if (shaderStr.empty())
             shaderStr = "NULL";
@@ -387,7 +405,7 @@ void ReadSubsetsMaterialBinding(
         if (shaderPrim) {
             shaderStr = shaderPrim.GetPath().GetString();
         } else if (assignDefault) {
-            shaderStr = AiNodeGetName(context.GetReader()->GetDefaultShader());
+            shaderStr = AiNodeGetName(context.GetReader()->GetDefaultShader(IsVolume(node, prim)));
         } else {
             shaderStr = "NULL";
         }

diff --git a/testsuite/test_2239/README b/testsuite/test_2239/README
@@ -0,0 +1,7 @@
+Read UsdVolume asset with specific fieldName
+
+see #2239
+
+author: sebastien.ortega
+
+PARAMS: {'scene': 'test.usda', 'kick_params': '-frame 14 '}