Support duplicate blendshape target names

lib/mayaUsd/fileio/writeJobContext.h

@@ -27,6 +27,7 @@
 #include <maya/MDagPath.h>
 #include <maya/MFnDependencyNode.h>
 #include <maya/MObjectHandle.h>
+#include <maya/MPlugArray.h>
 
 #include <memory>
 #include <vector>

lib/mayaUsd/utils/util.cpp

@@ -187,7 +187,7 @@ std::string UsdMayaUtil::GetMayaNodeName(const MObject& mayaNode)
     return nodeName.asChar();
 }
 
-MString UsdMayaUtil::GetUniqueNameOfDAGNode(const MObject& node)
+MString UsdMayaUtil::GetUniqueNameOfDagNode(const MObject& node)
 {
     if (!TF_VERIFY(!node.isNull() && node.hasFn(MFn::kDagNode))) {
         return MString();

lib/mayaUsd/utils/util.h

@@ -174,7 +174,7 @@ std::string GetMayaNodeName(const MObject& mayaNode);
  * @return      The name as a Maya string.
  */
 MAYAUSD_CORE_PUBLIC
-MString GetUniqueNameOfDAGNode(const MObject& node);
+MString GetUniqueNameOfDagNode(const MObject& node);
 
 /// Gets the Maya MObject for the node named \p nodeName.
 MAYAUSD_CORE_PUBLIC

lib/usd/translators/meshWriter.cpp

@@ -275,6 +275,8 @@ TF_DEFINE_PRIVATE_TOKENS(
 );
 // clang-format on
 
+MPlugArray PxrUsdTranslators_MeshWriter::mBlendShapesAnimWeightPlugs;
+
 PxrUsdTranslators_MeshWriter::PxrUsdTranslators_MeshWriter(
     const MFnDependencyNode& depNodeFn,
     const SdfPath&           usdPath,
@@ -291,7 +293,16 @@ PxrUsdTranslators_MeshWriter::PxrUsdTranslators_MeshWriter(
     }
 }
 
-void PxrUsdTranslators_MeshWriter::PostExport() { cleanupPrimvars(); }
+void PxrUsdTranslators_MeshWriter::PostExport()
+{
+    cleanupPrimvars();
+    if (this->mBlendShapesAnimWeightPlugs.length() != 0) {
+        // NOTE: (yliangsiew) Really, clearing it once is enough, but due to the constraints on what
+        // should go in the WriteJobContext, there's not really a better place to put this cache for
+        // now.
+        this->mBlendShapesAnimWeightPlugs.clear();
+    }
+}
 
 bool PxrUsdTranslators_MeshWriter::writeAnimatedMeshExtents(
     const MObject&     deformedMesh,
@@ -463,6 +474,13 @@ bool PxrUsdTranslators_MeshWriter::writeMeshAttrs(
             }
         } else {
             // NOTE: (yliangsiew) This is going to get called once for each time sampled.
+            // Why do we do this later? Currently, it's because the block above needs to
+            // run across _all_ meshes first, so that we build the entire array of
+            // blendshapes being exported ahead of time (the above block is run for each
+            // prim at the default time sample before running it on each anim. time
+            // sample) and the plugs that they're associated with. Then here, now knowing
+            // the entirety of the shapes that are meant to be exported, we can go ahead
+            // and write the animation for each of them.
             if (!_skelInputMesh.isNull()) {
                 bStat = this->writeBlendShapeAnimation(usdTime);
                 if (!bStat) {
@@ -473,6 +491,9 @@ bool PxrUsdTranslators_MeshWriter::writeMeshAttrs(
                         return bStat;
                     }
                 }
+                // NOTE: (yliangsiew) Also write out the "default" weights for the blendshapes,
+                // to cover static blendshapes (i.e. non-animated targets.)
+                bStat = this->writeBlendShapeAnimation(UsdTimeCode::Default());
             }
         }
     }

lib/usd/translators/meshWriter.h

@@ -37,7 +37,6 @@
 #include <maya/MBoundingBox.h>
 #include <maya/MFnDependencyNode.h>
 #include <maya/MFnMesh.h>
-#include <maya/MPlugArray.h>
 #include <maya/MString.h>
 
 #include <set>
@@ -75,12 +74,18 @@ class PxrUsdTranslators_MeshWriter : public UsdMayaPrimWriter
     bool    writeBlendShapeAnimation(const UsdTimeCode& usdTime);
     bool    writeAnimatedMeshExtents(const MObject& deformedMesh, const UsdTimeCode& usdTime);
 
+    /// Used to cache the animated blend shape weight plugs that need to be
+    /// sampled per-frame.  Becuase UsdSkelBlendShape stores animation in an
+    /// array that encompasses _all_ targets at the SkelRoot level, we cache out
+    /// blendshape weight plugs across repeated invocations of the meshWriter,
+    /// so that we know which plugs to sample when we start writing out the
+    /// animation. This shared cache is eventually cleared in PostExport() of
+    /// each meshWriter.
+    static MPlugArray mBlendShapesAnimWeightPlugs;
+
     /// Input mesh before any skeletal deformations, cached between iterations.
     MObject _skelInputMesh;
 
-    /// The animated plugs of any blendshape nodes involved in mesh deformation.
-    MPlugArray _animBlendShapeWeightPlugs;
-
     /// The previous sample for the mesh extents. Cached between iterations.
     VtVec3fArray _prevMeshExtentsSample;