Shaders exports should be bound to a material #2047 (#2097)

CHANGELOG.md

@@ -38,6 +38,7 @@
 - [usd#2082](https://github.com/Autodesk/arnold-usd/issues/2082) - Support arnold cameras in hydra
 - [usd#2084](https://github.com/Autodesk/arnold-usd/issues/2084) - Imagers should be applied to all drivers
 - [usd#2086](https://github.com/Autodesk/arnold-usd/issues/2086) - Compute FOV in the procedural and hydra in a similar manner
+- [usd#2047](https://github.com/Autodesk/arnold-usd/issues/2047) - Shaders exports should be bound to a material
 
 ### Bug fixes
 - [usd#1961](https://github.com/Autodesk/arnold-usd/issues/1961) - Random curves width in Hydra when radius primvars are authored

libs/common/constant_strings.h

@@ -345,6 +345,9 @@ ASTR(log_flags_console);
 ASTR(log_flags_file);
 ASTR(mask);
 ASTR(MATERIALX_NODE_DEFINITIONS);
+ASTR(material_surface);
+ASTR(material_displacement);
+ASTR(material_volume);
 ASTR(matrix);
 ASTR(matrix_multiply_vector);
 ASTR(matte);

libs/translator/writer/prim_writer.cpp

@@ -555,6 +555,29 @@ std::string UsdArnoldPrimWriter::GetArnoldNodeName(const AtNode* node, const Usd
         name = ss.str();
     }
 
+    _SanitizePrimName(name);
+
+    // If we need to strip a hierarchy from the arnold node's name,
+    // we need to find if this node name starts with the expected hierarchy
+    // and do it before prefixing it with the scope
+    const std::string &stripHierarchy = writer.GetStripHierarchy();
+    if (!stripHierarchy.empty()) {
+        if (TfStringStartsWith(name, stripHierarchy)) {
+            name = name.substr(stripHierarchy.size());
+        }
+    }
+    name = writer.GetScope() + name;
+
+    const AtNodeEntry* nodeEntry = AiNodeGetNodeEntry(node);
+    // Drivers should always be under the scope /Render/Products
+    if (AiNodeEntryGetType(nodeEntry) == AI_NODE_DRIVER) {
+        name = writer.GetRenderProductsScope().GetString() + name;
+    } 
+
+    return name;
+}
+void UsdArnoldPrimWriter::_SanitizePrimName(std::string &name)
+{
     std::locale loc;    
 
     // We need to determine which parameters must be converted to underscores
@@ -578,27 +601,7 @@ std::string UsdArnoldPrimWriter::GetArnoldNodeName(const AtNode* node, const Usd
             i++;
         }
     }
-
-    // If we need to strip a hierarchy from the arnold node's name,
-    // we need to find if this node name starts with the expected hierarchy
-    // and do it before prefixing it with the scope
-    const std::string &stripHierarchy = writer.GetStripHierarchy();
-    if (!stripHierarchy.empty()) {
-        if (TfStringStartsWith(name, stripHierarchy)) {
-            name = name.substr(stripHierarchy.size());
-        }
-    }
-    name = writer.GetScope() + name;
-
-    const AtNodeEntry* nodeEntry = AiNodeGetNodeEntry(node);
-    // Drivers should always be under the scope /Render/Products
-    if (AiNodeEntryGetType(nodeEntry) == AI_NODE_DRIVER) {
-        name = writer.GetRenderProductsScope().GetString() + name;
-    } 
-
-    return name;
 }
-
 // Ensure a connected node is properly translated, handle the output attributes,
 // and return its name
 static inline std::string GetConnectedNode(UsdArnoldWriter& writer, AtNode* target, int outComp = -1)
@@ -1215,7 +1218,7 @@ static void processMaterialBinding(AtNode* shader, AtNode* displacement, UsdPrim
     if (materialPath != "/")
         writer.SetStripHierarchy(materialPath);
 
-    TfToken arnoldContext("arnold");
+    const TfToken arnoldContext("arnold");
     if (shader) {
         // Write the surface shader under the material's scope.
         // Here we only want to consider the last name in the prim 

libs/translator/writer/prim_writer.h

@@ -76,6 +76,9 @@ class UsdArnoldPrimWriter {
     void _WriteMatrix(UsdGeomXformable &xform, const AtNode *node, UsdArnoldWriter &writer);
     void _WriteMaterialBinding(
         const AtNode *node, UsdPrim &prim, UsdArnoldWriter &writer, AtArray *shidxsArray = nullptr);
+
+    static void _SanitizePrimName(std::string &name);
+
     std::unordered_set<std::string> _exportedAttrs; // list of arnold attributes that were exported
 
     float _motionStart;

libs/translator/writer/write_shader.cpp

@@ -82,4 +82,40 @@ void UsdArnoldWriteShader::Write(const AtNode *node, UsdArnoldWriter &writer)
     }
     // Ensure all shaders have an output attribute
     prim.CreateAttribute(str::t_outputs_out, SdfValueTypeNames->Token, false);
+
+    if (!(writer.GetMask() & AI_NODE_SHAPE)) {
+        // If shapes are not exported and a material is specified for this shader, let's create it
+        AtString materialName;
+        bool isDisplacement = false;
+        // material_surface / material_displacement / material_volume are user data 
+        // authored by the arnold plugins when a shader library is exported, so that 
+        // materials can be restored at import. We can use this to create the
+        // USD material primitives #2047
+        if (AiNodeLookUpUserParameter(node, str::material_surface)) {
+            materialName = AiNodeGetStr(node, str::material_surface);
+        } else if (AiNodeLookUpUserParameter(node, str::material_displacement)) {
+            materialName = AiNodeGetStr(node, str::material_displacement);
+            isDisplacement = true;
+        } else if (AiNodeLookUpUserParameter(node, str::material_volume)) {
+            // Note that volume assignments are treated the same way as
+            // surface shader assignments in our usd support
+            materialName = AiNodeGetStr(node, str::material_volume);
+        }
+
+        if (!materialName.empty()) {
+            std::string matName(materialName.c_str());
+            _SanitizePrimName(matName);
+            std::string mtlScope = writer.GetScope() + writer.GetMtlScope();
+            writer.CreateScopeHierarchy(SdfPath(mtlScope));
+            matName = mtlScope + matName;
+            UsdShadeMaterial mat = UsdShadeMaterial::Define(writer.GetUsdStage(), SdfPath(matName));
+            const TfToken arnoldContext("arnold");
+            std::string shaderOutput = prim.GetPath().GetString() + std::string(".outputs:out");
+            UsdShadeOutput matOutput = (isDisplacement) ? 
+                mat.CreateDisplacementOutput(arnoldContext) : 
+                mat.CreateSurfaceOutput(arnoldContext);
+
+            matOutput.ConnectToSource(SdfPath(shaderOutput));
+        }
+    }
 }

testsuite/test_2047/README

@@ -0,0 +1,7 @@
+Shaders exports should be bound to a material
+
+See #2047
+
+author: sebastien ortega
+
+PARAMS: {'resaved':'usda'}

testsuite/test_2047/data/shaders.ass

@@ -0,0 +1,127 @@
+### exported: Thu Sep 12 08:53:34 2024
+### from:     Arnold 7.3.5.0 [6795639c] windows x86_64 clang-15.0.7 oiio-2.4.1 osl-1.13.0 vdb-11.0.0 adlsdk-8.0.7.50 clmhub-3.1.1.43 rlm-14.2.5 optix-8.0.0 2024/09/01 22:15:30
+### host app: MtoA 5.4.5 41e56b38 (master) Maya 2024
+### render_layer: defaultRenderLayer
+### user: blaines
+### scene: C:/arnold/mtoa/testsuite/test_0086/data/test.ma
+### meters_per_unit: 0.010000
+
+
+
+standard_surface
+{
+ name aiStandard5
+ base 0.699999988
+ base_color 0 1 0
+ specular 0
+ specular_roughness 0.4669047
+ specular_IOR 10
+ subsurface_radius 0.100000001 0.100000001 0.100000001
+ coat_roughness 0
+ coat_IOR 10
+ declare material_surface constant STRING
+ material_surface "aiStandard5SG"
+}
+
+range
+{
+ name displacementShader6
+ input checker3/cc.a
+ output_min -1
+ output_max 0
+ contrast_pivot 0
+ declare material_displacement constant STRING
+ material_displacement "aiStandard5SG"
+}
+
+checkerboard
+{
+ name checker3
+ color1 0 0 0
+ color2 1 1 1
+ u_frequency 16
+ v_frequency 16
+ u_offset 0
+ v_offset 0
+ filter_strength 0
+ uvset ""
+}
+
+color_correct
+{
+ name checker3/cc
+ input checker3
+ alpha_is_luminance on
+}
+
+standard
+{
+ name aiStandard3
+ Kd_color 1 0 0
+ declare material_surface constant STRING
+ material_surface "aiStandard3SG"
+}
+
+range
+{
+ name displacementShader4
+ input checker1
+ output_min 0
+ output_max 1
+ contrast_pivot 0
+ declare material_displacement constant STRING
+ material_displacement "aiStandard3SG"
+}
+
+checkerboard
+{
+ name checker1
+ color1 0 0 0
+ color2 1 1 1
+ u_frequency 4
+ v_frequency 4
+ u_offset 0
+ v_offset 0
+ filter_strength 0
+ uvset ""
+}
+
+standard
+{
+ name aiStandard4
+ Kd_color 0 0 1
+ declare material_surface constant STRING
+ material_surface "aiStandard4SG"
+}
+
+range
+{
+ name displacementShader5
+ input checker2/cc.a
+ output_min 0
+ output_max 1
+ contrast_pivot 0
+ declare material_displacement constant STRING
+ material_displacement "aiStandard4SG"
+}
+
+checkerboard
+{
+ name checker2
+ color1 0 0 0
+ color2 3 3 3
+ u_frequency 8
+ v_frequency 8
+ u_offset 0
+ v_offset 0
+ filter_strength 0
+ uvset ""
+}
+
+color_correct
+{
+ name checker2/cc
+ input checker2
+ alpha_is_luminance on
+}
+

testsuite/test_2047/data/test.py

@@ -0,0 +1,46 @@
+import os
+import sys
+
+sys.path.append(os.path.join(os.environ['ARNOLD_PATH'], 'python'))
+from arnold import *
+
+AiBegin()
+universe = AiUniverse()
+
+usdScene = 'shaders_resaved.usda'
+AiSceneLoad(universe, 'shaders.ass', None)
+params = AiParamValueMap()
+AiParamValueMapSetInt(params, 'mask', AI_NODE_SHADER)
+AiSceneWrite(universe, usdScene, params)
+AiEnd()
+
+expectedLines = ['def Scope "mtl"',
+				'def Material "aiStandard5SG"',
+				'token outputs:arnold:displacement.connect = </displacementShader6.outputs:out>',
+				'token outputs:arnold:surface.connect = </aiStandard5.outputs:out>',
+				'def Material "aiStandard3SG"',
+				'token outputs:arnold:displacement.connect = </displacementShader4.outputs:out>',
+				'token outputs:arnold:surface.connect = </aiStandard3.outputs:out>',
+				'def Material "aiStandard4SG"',
+				'token outputs:arnold:displacement.connect = </displacementShader5.outputs:out>',
+				'token outputs:arnold:surface.connect = </aiStandard4.outputs:out>']
+
+expectedLinesCount = len(expectedLines)
+currentLine = 0
+
+success = False
+with open(usdScene, 'r') as f:
+    lines = f.readlines()
+    for line in lines:
+        if expectedLines[currentLine] in line:
+            currentLine = currentLine + 1
+            if currentLine == expectedLinesCount:
+                success = True
+                break
+
+if not success:
+    print('Line not found in the output usd file:')
+    print(expectedLines[currentLine])
+    sys.exit(-1)
+
+print('SUCCESS')