source/blender/io/usd/hydra/material.cc

@@ -81,8 +81,9 @@ void MaterialData::init()
     MaterialX::DocumentPtr doc = blender::nodes::materialx::export_to_materialx(
         scene_delegate_->depsgraph, (Material *)id);
     pxr::UsdMtlxRead(doc, stage);
-    pxr::UsdMtlxReadNodeGraphs(doc, stage);
 
+    /* Logging stage: creating lambda stage_str() for not to call stage->ExportToString()
+     * if log doesn't execute. */
     auto stage_str = [&stage]() {
       std::string str;
       stage->ExportToString(&str);

source/blender/nodes/shader/materialx/group_nodes.cc

@@ -20,29 +20,34 @@ NodeItem GroupNodeParser::compute()
     return res;
   }
 
+  MaterialX::GraphElement *graph = graph_;
+#ifdef USE_MATERIALX_NODEGRAPH
   std::string name = MaterialX::createValidName(ngroup->id.name);
   MaterialX::NodeGraphPtr group_graph = graph_->getChildOfType<MaterialX::NodeGraph>(name);
   if (!group_graph) {
     CLOG_INFO(LOG_MATERIALX_SHADER, 1, "<nodegraph name=%s>", name.c_str());
     group_graph = graph_->addChild<MaterialX::NodeGraph>(name);
   }
+  graph = group_graph.get();
+#endif
 
-  NodeItem out = GroupOutputNodeParser(group_graph.get(),
-                                       depsgraph_,
-                                       material_,
-                                       node_out,
-                                       socket_out_,
-                                       NodeItem::Type::Any,
-                                       this)
+  NodeItem out =
+      GroupOutputNodeParser(
+          graph, depsgraph_, material_, node_out, socket_out_, NodeItem::Type::Any, this)
           .compute_full();
 
+#ifdef USE_MATERIALX_NODEGRAPH
   /* We have to be in NodeParser's graph_, therefore copying output */
   res.output = out.output;
+#else
+  res = out;
+#endif
   return res;
 }
 
 NodeItem GroupOutputNodeParser::compute()
 {
+#ifdef USE_MATERIALX_NODEGRAPH
   Vector<NodeItem> values;
   for (auto socket_in : node_->input_sockets()) {
     NodeItem value = get_input_value(socket_in->index(), NodeItem::Type::Any);
@@ -59,12 +64,15 @@ NodeItem GroupOutputNodeParser::compute()
       outputs.append(create_output("output" + std::to_string(i + 1), values[i]));
     }
   }
-
   return outputs[socket_out_->index()];
+#else
+  return get_input_value(socket_out_->index(), NodeItem::Type::Any);
+#endif
 }
 
 NodeItem GroupOutputNodeParser::compute_full()
 {
+#ifdef USE_MATERIALX_NODEGRAPH
   NodeItem res = empty();
 
   /* Checking if output was already computed */
@@ -82,22 +90,29 @@ NodeItem GroupOutputNodeParser::compute_full()
 
   res = compute();
   return res;
+#else
+  return NodeParser::compute_full();
+#endif
 }
 
 NodeItem GroupInputNodeParser::compute()
 {
+#ifdef USE_MATERIALX_NODEGRAPH
   NodeItem value = group_parser_->get_input_value(socket_out_->index(), to_type_);
   if (value.value) {
     NodeItem constant = create_node("constant", value.type());
     constant.set_input("value", value);
     value = constant;
   }
-
   return create_input("input" + std::to_string(socket_out_->index() + 1), value);
+#else
+  return group_parser_->get_input_value(socket_out_->index(), to_type_);
+#endif
 }
 
 NodeItem GroupInputNodeParser::compute_full()
 {
+#ifdef USE_MATERIALX_NODEGRAPH
   NodeItem res = empty();
 
   /* Checking if output was already computed */
@@ -115,6 +130,9 @@ NodeItem GroupInputNodeParser::compute_full()
 
   res = compute();
   return res;
+#else
+  return NodeParser::compute_full();
+#endif
 }
 
 }  // namespace blender::nodes::materialx

source/blender/nodes/shader/materialx/group_nodes.h

@@ -6,11 +6,16 @@
 
 #include "node_parser.h"
 
+/* TODO: pxr::UsdMtlxRead() doesn't perform nodegraphs.
+ * Uncomment USE_MATERIALX_NODEGRAPH after fixing it. */
+/* #define USE_MATERIALX_NODEGRAPH */
+
 namespace blender::nodes::materialx {
 
 class GroupInputNodeParser;
 
 class GroupNodeParser : public NodeParser {
+  friend NodeParser;
   friend GroupInputNodeParser;
 
  public:

source/blender/nodes/shader/materialx/node_parser.cc

@@ -67,7 +67,18 @@ std::string NodeParser::node_name() const
   if (ELEM(to_type_, NodeItem::Type::BSDF, NodeItem::Type::EDF)) {
     name += "_" + NodeItem::type(to_type_);
   }
+#ifdef USE_MATERIALX_NODEGRAPH
   return MaterialX::createValidName(name);
+#else
+  std::string prefix;
+  GroupNodeParser *gr = group_parser_;
+  while (gr) {
+    const bNodeTree *ngroup = reinterpret_cast<const bNodeTree *>(gr->node_->id);
+    prefix = MaterialX::createValidName(ngroup->id.name) + "_" + prefix;
+    gr = gr->group_parser_;
+  }
+  return prefix + MaterialX::createValidName(name);
+#endif
 }
 
 NodeItem NodeParser::create_node(const std::string &category, NodeItem::Type type)