Fix issue with Storm and rendering custom nodes that use texture coor…

…dinates

This issue is specific to custom nodes that use the <texcoord> node in their
defining nodegraph and either re-use that nodes output or are a multioutput
node.

This change removes the addition of the 'index' input to the network
interface, and in Storm sets the texture coordinate primvar type as
Vector2 regardless of the node's output type.

Previously, we were adding the 'index' input to the network interface which
means that the second time we come across this node we have an input
that is not a part of the nodedef. This means that when we pass it to
MaterialX for shadergen it is not able to correctly identify the node. Also,
in Storm when we gather the primvar information for the glslfx header,
we use the node's output type for the texture coordinates, which is not
likely to be a vector2 type, and for multioutput nodes specifically it
causes shadergen to completely fail.

(Internal change: 2341878)

pxr/imaging/hdMtlx/hdMtlx.cpp

@@ -35,7 +35,9 @@ PXR_NAMESPACE_OPEN_SCOPE
 
 TF_DEFINE_PRIVATE_TOKENS(
     _tokens,
-    (index)
+    (texcoord)
+    (geompropvalue)
+    (filename)
 );
 
 static mx::FileSearchPath
@@ -184,12 +186,12 @@ HdMtlxConvertToString(VtValue const& hdParameterValue)
 }
 
 static bool
-_ContainsTexcoordNode(mx::NodeDefPtr const& mxNodeDef)
+_UsesTexcoordNode(mx::NodeDefPtr const& mxNodeDef)
 {
     mx::InterfaceElementPtr impl = mxNodeDef->getImplementation();
     if (impl && impl->isA<mx::NodeGraph>()) {
         mx::NodeGraphPtr nodegraph = impl->asA<mx::NodeGraph>();
-        if (nodegraph->getNodes("texcoord").size() != 0) {
+        if (!nodegraph->getNodes(_tokens->texcoord).empty()) {
             return true;
         }
     }
@@ -275,7 +277,7 @@ _AddMaterialXNode(
     // MaterialX nodes that use textures can have more than one filename input
     if (mxHdData) {
         for (mx::InputPtr const& mxInput : mxNodeDef->getActiveInputs()) {
-            if (mxInput->getType() == "filename") {
+            if (mxInput->getType() == _tokens->filename) {
                 // Save the corresponding Mx and Hydra names for ShaderGen
                 mxHdData->mxHdTextureMap[mxNodeName].insert(mxInput->getName());
                 // Save the path to adjust parameters after for ShaderGen
@@ -285,7 +287,7 @@ _AddMaterialXNode(
     }
 
     // MaterialX primvar node
-    if (mxNodeCategory == "geompropvalue") {
+    if (mxNodeCategory == _tokens->geompropvalue) {
         if (mxHdData) {
             // Save the path to have the primvarName declared in ShaderGen
             mxHdData->hdPrimvarNodes.insert(hdNodePath);
@@ -294,14 +296,8 @@ _AddMaterialXNode(
 
     // Stdlib MaterialX texture coordinate node or a custom node that 
     // uses a texture coordinate node
-    if (mxNodeCategory == "texcoord" || _ContainsTexcoordNode(mxNodeDef)) {
+    if (mxNodeCategory == _tokens->texcoord || _UsesTexcoordNode(mxNodeDef)) {
         if (mxHdData) {
-            // Make sure it has the index parameter set.
-            if (std::find(hdNodeParamNames.begin(), hdNodeParamNames.end(), 
-                _tokens->index) == hdNodeParamNames.end()) {
-                netInterface->SetNodeParameterValue(
-                    hdNodeName, _tokens->index, VtValue(0));
-            }
             // Save the path to have the textureCoord name declared in ShaderGen
             mxHdData->hdPrimvarNodes.insert(hdNodePath);
         }

pxr/imaging/hdSt/materialXFilter.cpp

@@ -495,10 +495,9 @@ _UpdatePrimvarNodes(
             (*mxHdPrimvarDefaultValueMap)[primvarName] = defaultPrimvarValue;
         }
 
-        // Texcoord nodes will have an index parameter set
-        primvarNameIt = hdPrimvarNode.parameters.find(_tokens->index);
-        if (primvarNameIt != hdPrimvarNode.parameters.end()) {
-            // Get the sdr node for the texcoord node
+        else {
+            // Other primvar nodes will be either a texcoord node or a  
+            // custom node that uses a texcoord node. 
             SdrRegistry &sdrRegistry = SdrRegistry::GetInstance();
             const SdrShaderNodeConstPtr sdrTexCoordNode = 
                 sdrRegistry.GetShaderNodeByIdentifierAndType(
@@ -511,12 +510,7 @@ _UpdatePrimvarNodes(
                 texCoordName = metadata[SdrNodeMetadata->Primvars];
             }
 
-            // Figure out the mx typename
-            mx::NodeDefPtr mxNodeDef = mxDoc->getNodeDef(
-                    hdPrimvarNode.nodeTypeId.GetString());
-            if (mxNodeDef) {
-                (*mxHdPrimvarMap)[texCoordName] = mxNodeDef->getType();
-            }
+            (*mxHdPrimvarMap)[texCoordName] = mx::Type::VECTOR2->getName();
         }
     }
 }