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

@@ -31,10 +31,16 @@ NodeItem GroupNodeParser::compute()
   graph = group_graph.get();
 #endif
 
-  NodeItem out =
+  NodeItem out = GroupOutputNodeParser(graph,
-      GroupOutputNodeParser(
+                                       depsgraph_,
-          graph, depsgraph_, material_, node_out, socket_out_, to_type_, this, export_image_fn_)
+                                       material_,
-          .compute_full();
+                                       node_out,
+                                       socket_out_,
+                                       to_type_,
+                                       this,
+                                       use_group_default_,
+                                       export_image_fn_)
+                     .compute_full();
 
 #ifdef USE_MATERIALX_NODEGRAPH
   /* We have to be in NodeParser's graph_, therefore copying output */
@@ -121,6 +127,9 @@ NodeItem GroupInputNodeParser::compute()
   }
   return create_input(in_name(), value);
 #else
+  if (use_group_default_) {
+    return group_parser_->get_input_value(socket_out_->index(), to_type_);
+  }
   return group_parser_->get_input_link(socket_out_->index(), to_type_);
 #endif
 }

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

@@ -71,6 +71,7 @@ MaterialX::DocumentPtr export_to_materialx(Depsgraph *depsgraph,
                              NodeItem::Type::Material,
                              nullptr,
                              NodeItem(doc.get()),
+                             false,
                              export_image_fn};
       output_node->typeinfo->materialx_fn(&data, output_node, nullptr);
     }
@@ -82,6 +83,7 @@ MaterialX::DocumentPtr export_to_materialx(Depsgraph *depsgraph,
                                 nullptr,
                                 NodeItem::Type::Material,
                                 nullptr,
+                                false,
                                 export_image_fn)
           .compute_error();
     }
@@ -94,6 +96,7 @@ MaterialX::DocumentPtr export_to_materialx(Depsgraph *depsgraph,
                               nullptr,
                               NodeItem::Type::Material,
                               nullptr,
+                              false,
                               export_image_fn)
         .compute();
   }

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

@@ -21,6 +21,7 @@ NodeParser::NodeParser(MaterialX::GraphElement *graph,
                        const bNodeSocket *socket_out,
                        NodeItem::Type to_type,
                        GroupNodeParser *group_parser,
+                       bool use_group_default,
                        ExportImageFunction export_image_fn)
     : graph_(graph),
       depsgraph_(depsgraph),
@@ -29,6 +30,7 @@ NodeParser::NodeParser(MaterialX::GraphElement *graph,
       socket_out_(socket_out),
       to_type_(to_type),
       group_parser_(group_parser),
+      use_group_default_(use_group_default),
       export_image_fn_(export_image_fn)
 {
 }
@@ -199,7 +201,9 @@ NodeItem NodeParser::get_default(const bNodeSocket &socket, NodeItem::Type to_ty
   return res.convert(to_type);
 }
 
-NodeItem NodeParser::get_input_link(const bNodeSocket &socket, NodeItem::Type to_type)
+NodeItem NodeParser::get_input_link(const bNodeSocket &socket,
+                                    NodeItem::Type to_type,
+                                    bool use_group_default)
 {
   const bNodeLink *link = socket.link;
   if (!(link && link->is_used())) {
@@ -225,6 +229,7 @@ NodeItem NodeParser::get_input_link(const bNodeSocket &socket, NodeItem::Type to
                            link->fromsock,
                            to_type,
                            group_parser_,
+                           use_group_default,
                            export_image_fn_)
         .compute_full();
   }
@@ -236,6 +241,7 @@ NodeItem NodeParser::get_input_link(const bNodeSocket &socket, NodeItem::Type to
                                 link->fromsock,
                                 to_type,
                                 group_parser_,
+                                use_group_default,
                                 export_image_fn_)
         .compute_full();
   }
@@ -248,15 +254,21 @@ NodeItem NodeParser::get_input_link(const bNodeSocket &socket, NodeItem::Type to
     return empty();
   }
 
-  NodeParserData data = {
+  NodeParserData data = {graph_,
-      graph_, depsgraph_, material_, to_type, group_parser_, empty(), export_image_fn_};
+                         depsgraph_,
+                         material_,
+                         to_type,
+                         group_parser_,
+                         empty(),
+                         use_group_default,
+                         export_image_fn_};
   from_node->typeinfo->materialx_fn(&data, const_cast<bNode *>(from_node), link->fromsock);
   return data.result;
 }
 
 NodeItem NodeParser::get_input_value(const bNodeSocket &socket, NodeItem::Type to_type)
 {
-  NodeItem res = get_input_link(socket, to_type);
+  NodeItem res = get_input_link(socket, to_type, true);
   if (!res) {
     res = get_default(socket, to_type);
   }

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

@@ -33,6 +33,7 @@ class NodeParser {
   const bNodeSocket *socket_out_;
   NodeItem::Type to_type_;
   GroupNodeParser *group_parser_;
+  bool use_group_default_;
   ExportImageFunction export_image_fn_;
 
  public:
@@ -43,6 +44,7 @@ class NodeParser {
              const bNodeSocket *socket_out,
              NodeItem::Type to_type,
              GroupNodeParser *group_parser,
+             bool use_group_default,
              ExportImageFunction export_image_fn);
   virtual ~NodeParser() = default;
 
@@ -71,7 +73,9 @@ class NodeParser {
 
  private:
   NodeItem get_default(const bNodeSocket &socket, NodeItem::Type to_type);
-  NodeItem get_input_link(const bNodeSocket &socket, NodeItem::Type to_type);
+  NodeItem get_input_link(const bNodeSocket &socket,
+                          NodeItem::Type to_type,
+                          bool use_group_default = false);
   NodeItem get_input_value(const bNodeSocket &socket, NodeItem::Type to_type);
 };
 
@@ -103,6 +107,7 @@ struct NodeParserData {
   NodeItem::Type to_type;
   GroupNodeParser *group_parser;
   NodeItem result;
+  bool use_group_default;
   ExportImageFunction export_image_fn;
 };
 
@@ -130,6 +135,7 @@ struct NodeParserData {
                                     out, \
                                     d->to_type, \
                                     d->group_parser, \
+                                    d->use_group_default, \
                                     d->export_image_fn) \
                     .compute_full(); \
   }