MAYA-106486 Handle UV linkage on material export

lib/mayaUsd/fileio/shading/shadingModeExporterContext.h

@@ -94,7 +94,12 @@ class UsdMayaShadingModeExportContext
     /// targeting a subset of the bound prim's faces.
     /// If the list of faceIndices is empty, it means the assignment targets
     /// all the faces in the bound prim or the entire bound prim.
-    typedef std::pair<SdfPath, VtIntArray> Assignment;
+    struct Assignment
+    {
+        SdfPath    boundPrimPath;
+        VtIntArray faceIndices;
+        TfToken    shapeName;
+    };
 
     /// Vector of assignments.
     typedef std::vector<Assignment> AssignmentVector;
@@ -104,17 +109,22 @@ class UsdMayaShadingModeExportContext
     MAYAUSD_CORE_PUBLIC
     AssignmentVector GetAssignments() const;
 
-    /// Use this function to create a UsdShadeMaterial prim at the "standard"
-    /// location.  The "standard" location may change depending on arguments
-    /// that are passed to the export script.
+    /// Use this function to create a UsdShadeMaterial prim at a "standard"
+    /// location computed by browsing the \p assignmentsToBind
+    MAYAUSD_CORE_PUBLIC
+    UsdPrim MakeStandardMaterialPrim(
+        const AssignmentVector& assignmentsToBind,
+        const std::string&      name = std::string()) const;
+
+    /// Use this function to bind a UsdShadeMaterial prim to all assignments provided.
     ///
     /// If \p boundPrimPaths is not NULL, it is populated with the set of
     /// prim paths that were bound to the created material prim, based on the
     /// given \p assignmentsToBind.
     MAYAUSD_CORE_PUBLIC
-    UsdPrim MakeStandardMaterialPrim(
+    void BindStandardMaterialPrim(
+            const UsdPrim & materialPrim,
             const AssignmentVector& assignmentsToBind,
-            const std::string& name=std::string(),
             SdfPathSet* const boundPrimPaths=nullptr) const;
 
     MAYAUSD_CORE_PUBLIC

lib/mayaUsd/fileio/shading/shadingModePxrRis.cpp

@@ -301,9 +301,8 @@ class PxrRisShadingModeExporter : public UsdMayaShadingModeExporter {
             return;
         }
 
-        UsdPrim materialPrim = context.MakeStandardMaterialPrim(assignments,
-                                                                std::string(),
-                                                                boundPrimPaths);
+        UsdPrim materialPrim = context.MakeStandardMaterialPrim(assignments);
+        context.BindStandardMaterialPrim(materialPrim, assignments, boundPrimPaths);
         UsdShadeMaterial material(materialPrim);
         if (!material) {
             return;

lib/mayaUsd/fileio/shading/shadingModeUseRegistry.cpp

@@ -329,11 +329,7 @@ class UseRegistryShadingModeExporter : public UsdMayaShadingModeExporter
                 return;
             }
 
-            UsdPrim materialPrim =
-                context.MakeStandardMaterialPrim(
-                    assignments,
-                    std::string(),
-                    boundPrimPaths);
+            UsdPrim materialPrim = context.MakeStandardMaterialPrim(assignments, std::string());
             UsdShadeMaterial material(materialPrim);
             if (!material) {
                 return;
@@ -381,6 +377,8 @@ class UseRegistryShadingModeExporter : public UsdMayaShadingModeExporter
                 material,
                 UsdShadeTokens->displacement,
                 renderContext);
+
+            context.BindStandardMaterialPrim(materialPrim, assignments, boundPrimPaths);
         }
 };
 

lib/mayaUsd/fileio/utils/meshReadUtils.cpp

@@ -245,13 +245,12 @@ namespace
         MString uvSetName(primvarName.GetText());
         bool createUVSet = true;
 
-        if (primvarName == UsdUtilsGetPrimaryUVSetName()) {
+        if (primvarName == UsdUtilsGetPrimaryUVSetName() && UsdMayaReadUtil::ReadSTAsMap1()) {
             // We assume that the primary USD UV set maps to Maya's default 'map1'
             // set which always exists, so we shouldn't try to create it.
             uvSetName = UsdMayaMeshPrimvarTokens->DefaultMayaTexcoordName.GetText();
             createUVSet = false;
-        } else if (!hasDefaultUVSet) {
-            // If map1 still exists, we rename and re-use it:
+        } else if (!hasDefaultUVSet) {            // If map1 still exists, we rename and re-use it:
             MStringArray uvSetNames;
             meshFn.getUVSetNames(uvSetNames);
             if (uvSetNames[0] == UsdMayaMeshPrimvarTokens->DefaultMayaTexcoordName.GetText()) {
@@ -633,7 +632,7 @@ UsdMayaMeshReadUtils::assignPrimvarsToMesh(const UsdGeomMesh& mesh,
             || (UsdMayaReadUtil::ReadFloat2AsUV() && typeName == SdfValueTypeNames->Float2Array)) {
             const TfToken fullName = primvar.GetPrimvarName();
             if (fullName == UsdMayaMeshPrimvarTokens->DefaultMayaTexcoordName
-                || fullName == UsdUtilsGetPrimaryUVSetName()) {
+                || (fullName == UsdUtilsGetPrimaryUVSetName() && UsdMayaReadUtil::ReadSTAsMap1())) {
                 hasDefaultUVSet = true;
             }
         }

lib/mayaUsd/fileio/utils/meshWriteUtils.cpp

@@ -828,11 +828,10 @@ UsdMayaMeshWriteUtils::writeUVSetsAsVec2fPrimvars(const MFnMesh& meshFn,
             continue;
         }
 
-        // XXX: We should be able to configure the UV map name that triggers this
-        // behavior, and the name to which it exports.
-        // The UV Set "map1" is renamed st. This is a Pixar/USD convention.
+        // Rename "map1" as "st" to follow Pixar/USD convention if requested.
         TfToken setName(uvSetNames[i].asChar());
-        if (setName == UsdMayaMeshPrimvarTokens->DefaultMayaTexcoordName.GetText()) {
+        if (setName == UsdMayaMeshPrimvarTokens->DefaultMayaTexcoordName.GetText()
+            && UsdMayaWriteUtil::WriteMap1AsST()) {
             setName = UsdUtilsGetPrimaryUVSetName();
         }
 

lib/mayaUsd/fileio/utils/readUtil.cpp

@@ -65,6 +65,20 @@ UsdMayaReadUtil::ReadFloat2AsUV()
     return readFloat2AsUV;
 }
 
+TF_DEFINE_ENV_SETTING(
+    MAYAUSD_IMPORT_PRIMARY_UV_SET_AS_MAP1,
+    false,
+    "Translates the primary UV set in USD to the map1 UV set in Maya. "
+    "When disabled, UV set names are translated directly (st in USD becomes st in Maya).");
+
+bool
+UsdMayaReadUtil::ReadSTAsMap1()
+{
+    static const bool readSTAsMap1 = 
+        TfGetEnvSetting(MAYAUSD_IMPORT_PRIMARY_UV_SET_AS_MAP1);
+    return readSTAsMap1;
+}
+
 MObject
 UsdMayaReadUtil::FindOrCreateMayaAttr(
         const SdfValueTypeName& typeName,

lib/mayaUsd/fileio/utils/readUtil.h

@@ -42,6 +42,11 @@ struct UsdMayaReadUtil
     MAYAUSD_CORE_PUBLIC
     static bool ReadFloat2AsUV();
 
+    /// Returns whether the environment setting for renaming st TexCoord to map1
+    /// is set to true
+    MAYAUSD_CORE_PUBLIC
+    static bool ReadSTAsMap1();
+
     /// Given the \p typeName and \p variability, try to create a Maya attribute
     /// on \p depNode with the name \p attrName.
     /// If the \p typeName isn't supported by this function, raises a runtime

lib/mayaUsd/fileio/utils/writeUtil.cpp

@@ -81,6 +81,11 @@ TF_DEFINE_ENV_SETTING(
     "TexCoord2d, TexCoord3h, TexCoord3f, TexCoord3d and their associated "
     "Array types)");
 
+TF_DEFINE_ENV_SETTING(
+    MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET,
+    false,
+    "Translates the map1 UV set in Maya to the primary UV set in USD. "
+    "When disabled, UV set names are translated directly (map1 in Maya becomes map1 in USD).");
 
 static
 bool
@@ -130,6 +135,14 @@ UsdMayaWriteUtil::WriteUVAsFloat2()
     return writeUVAsFloat2;
 }
 
+bool
+UsdMayaWriteUtil::WriteMap1AsST()
+{
+    static const bool writeMap1AsST =
+        TfGetEnvSetting(MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET);
+    return writeMap1AsST;
+}
+
 /* static */
 UsdAttribute
 UsdMayaWriteUtil::GetOrCreateUsdAttr(

lib/mayaUsd/fileio/utils/writeUtil.h

@@ -54,6 +54,11 @@ struct UsdMayaWriteUtil
     MAYAUSD_CORE_PUBLIC
     static bool WriteUVAsFloat2();
 
+    /// Returns whether the environment setting for renaming map1 TexCoord to st
+    /// is set to true
+    MAYAUSD_CORE_PUBLIC
+    static bool WriteMap1AsST();
+
     /// Given an \p attrPlug, try to create a USD attribute on \p usdPrim with
     /// the name \p attrName. Note, it's value will not be set.
     ///

lib/mayaUsd/python/wrapReadUtil.cpp

@@ -92,6 +92,8 @@ void wrapReadUtil()
     class_<This>("ReadUtil", no_init)
         .def("ReadFloat2AsUV", This::ReadFloat2AsUV)
         .staticmethod("ReadFloat2AsUV")
+        .def("ReadSTAsMap1", This::ReadSTAsMap1)
+        .staticmethod("ReadSTAsMap1")
         .def("FindOrCreateMayaAttr", _FindOrCreateMayaAttr,
             (arg("typeName"), arg("variability"), arg("nodeName"),
              arg("attrName"), arg("attrNiceName")=std::string()))

lib/mayaUsd/python/wrapWriteUtil.cpp

@@ -50,6 +50,8 @@ void wrapWriteUtil()
     class_<This>("WriteUtil", no_init)
         .def("WriteUVAsFloat2", This::WriteUVAsFloat2)
         .staticmethod("WriteUVAsFloat2")
+        .def("WriteMap1AsST", This::WriteMap1AsST)
+        .staticmethod("WriteMap1AsST")
         .def("GetVtValue", _GetVtValue)
         .staticmethod("GetVtValue")
     ;

lib/mayaUsd/render/mayaToHydra/shadingModeExporter.cpp

@@ -132,8 +132,8 @@ class MtohShadingModeExporter : public UsdMayaShadingModeExporter {
             context.GetAssignments();
         if (assignments.empty()) { return; }
 
-        UsdPrim materialPrim = context.MakeStandardMaterialPrim(
-            assignments, std::string(), boundPrimPaths);
+        UsdPrim materialPrim = context.MakeStandardMaterialPrim(assignments);
+        context.BindStandardMaterialPrim(materialPrim, assignments, boundPrimPaths);
         UsdShadeMaterial material(materialPrim);
         if (!material) { return; }
 

lib/usd/translators/shading/usdFileTextureWriter.cpp

@@ -33,6 +33,7 @@
 #include <pxr/usd/sdf/types.h>
 #include <pxr/usd/usdShade/input.h>
 #include <pxr/usd/usdShade/output.h>
+#include <pxr/usd/usdShade/material.h>
 #include <pxr/usd/usdShade/shader.h>
 #include <pxr/usd/usdUtils/pipeline.h>
 #include <pxr/usdImaging/usdImaging/tokens.h>
@@ -170,11 +171,35 @@ PxrUsdTranslators_FileTextureWriter::PxrUsdTranslators_FileTextureWriter(
     primvarReaderShaderSchema.CreateIdAttr(
         VtValue(_tokens->UsdPrimvarReader_float2));
 
-    // XXX: We'll eventually need to to determine which UV set to use if we're
-    // not using the default (i.e. "map1" in Maya -> "st" in USD).
-    primvarReaderShaderSchema.CreateInput(
+    UsdShadeInput varnameInput = primvarReaderShaderSchema.CreateInput(
         _tokens->varname,
-        SdfValueTypeNames->Token).Set(UsdUtilsGetPrimaryUVSetName());
+        SdfValueTypeNames->Token);
+
+    // We expose the primvar reader varname attribute to the material to allow
+    // easy specialization based on UV mappings to geometries:
+    SdfPath          materialPath = GetUsdPath().GetParentPath();
+    UsdShadeMaterial materialSchema(GetUsdStage()->GetPrimAtPath(materialPath));
+    while (!materialSchema && !materialPath.IsEmpty()) {
+        materialPath = materialPath.GetParentPath();
+        materialSchema = UsdShadeMaterial(GetUsdStage()->GetPrimAtPath(materialPath));
+    }
+
+    if (materialSchema) {
+        TfToken inputName(
+            TfStringPrintf("%s:%s", depNodeFn.name().asChar(), _tokens->varname.GetText()));
+        UsdShadeInput materialInput
+            = materialSchema.CreateInput(inputName, SdfValueTypeNames->Token);
+        materialInput.Set(UsdUtilsGetPrimaryUVSetName());
+        varnameInput.ConnectToSource(materialInput);
+        // Note: This needs to be done for all nodes that require UV input. In
+        // the UsdPreviewSurface case, the file node is the only one, but for
+        // other Maya nodes like cloth, checker, mandelbrot, we will also need
+        // to resolve the UV channels. This means traversing UV inputs until we
+        // find the unconnected one that implicitly connects to uvSet[0] of the
+        // geometry, or an explicit uvChooser node connecting to alternate uvSets.
+    } else {
+        varnameInput.Set(UsdUtilsGetPrimaryUVSetName());
+    }
 
     UsdShadeOutput primvarReaderOutput =
         primvarReaderShaderSchema.CreateOutput(

plugin/pxr/maya/lib/usdMaya/CMakeLists.txt

@@ -315,6 +315,7 @@ pxr_register_test(testUsdMayaUserExportedAttributes
         MAYA_DISABLE_CIP=1
         MAYA_NO_STANDALONE_ATEXIT=1
         MAYA_APP_DIR=<PXR_TEST_DIR>/maya_profile
+        MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET=1
 )
 
 pxr_install_test_dir(

test/lib/usd/translators/CMakeLists.txt

@@ -100,6 +100,7 @@ mayaUsd_add_test(testUsdExportUVSets
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     ENV
         "PIXMAYA_WRITE_UV_AS_FLOAT2=0"
+        "MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET=0"
 )
 set_property(TEST testUsdExportUVSets APPEND PROPERTY LABELS translators)
 
@@ -108,14 +109,43 @@ mayaUsd_add_test(testUsdExportUVSetsFloat
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     ENV
         "PIXMAYA_WRITE_UV_AS_FLOAT2=1"
+        "MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET=0"
 )
 set_property(TEST testUsdExportUVSetsFloat APPEND PROPERTY LABELS translators)
 
+mayaUsd_add_test(testUsdExportUVSetsST
+    PYTHON_MODULE testUsdExportUVSets
+    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    ENV
+        "PIXMAYA_WRITE_UV_AS_FLOAT2=0"
+        "MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET=1"
+)
+set_property(TEST testUsdExportUVSetsST APPEND PROPERTY LABELS translators)
+
+mayaUsd_add_test(testUsdExportUVSetMappings
+    PYTHON_MODULE testUsdExportUVSetMappings
+    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    ENV
+        "PIXMAYA_WRITE_UV_AS_FLOAT2=0"
+        "MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET=0"
+)
+set_property(TEST testUsdExportUVSetMappings APPEND PROPERTY LABELS translators)
+
+mayaUsd_add_test(testUsdExportUVSetMappingsST
+    PYTHON_MODULE testUsdExportUVSetMappings
+    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    ENV
+        "PIXMAYA_WRITE_UV_AS_FLOAT2=0"
+        "MAYAUSD_EXPORT_MAP1_AS_PRIMARY_UV_SET=1"
+)
+set_property(TEST testUsdExportUVSetMappingsST APPEND PROPERTY LABELS translators)
+
 mayaUsd_add_test(testUsdImportUVSets
     PYTHON_MODULE testUsdImportUVSets
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     ENV
         "PIXMAYA_READ_FLOAT2_AS_UV=0"
+        "MAYAUSD_IMPORT_PRIMARY_UV_SET_AS_MAP1=0"
 )
 set_property(TEST testUsdImportUVSets APPEND PROPERTY LABELS translators)
 
@@ -124,9 +154,19 @@ mayaUsd_add_test(testUsdImportUVSetsFloat
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     ENV
         "PIXMAYA_READ_FLOAT2_AS_UV=1"
+        "MAYAUSD_IMPORT_PRIMARY_UV_SET_AS_MAP1=0"
 )
 set_property(TEST testUsdImportUVSetsFloat APPEND PROPERTY LABELS translators)
 
+mayaUsd_add_test(testUsdImportUVSetsST
+    PYTHON_MODULE testUsdImportUVSets
+    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    ENV
+        "PIXMAYA_READ_FLOAT2_AS_UV=0"
+        "MAYAUSD_IMPORT_PRIMARY_UV_SET_AS_MAP1=1"
+)
+set_property(TEST testUsdImportUVSetsST APPEND PROPERTY LABELS translators)
+
 # Test using standardSurface, which was introduced in Maya 2020.
 if (MAYA_APP_VERSION VERSION_GREATER_EQUAL 2020)
     set(CUSTOM_TEST_SCRIPT_FILES