Fix T68971: Copy As New Driver from Material node creates a bad reference.

NodeTree structures of materials and some other data blocks are
effectively node group data block objects that are contained inside
the parent block. Thus, direct references to them are only valid
while blender is running, and are lost on save.

Fix Copy As New Driver to create a reference that goes through
the owner data block, by adding a new runtime field to bNodeTree.

1 files changed, 2 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/node.c b/source/blender/blenkernel/intern/node.c
index 206c59c110a..59ffbbfea6f 100644
--- a/source/blender/blenkernel/intern/node.c
+++ b/source/blender/blenkernel/intern/node.c
@@ -1394,7 +1394,7 @@ void ntreeInitDefault(bNodeTree *ntree)
   ntree_set_typeinfo(ntree, NULL);
 }
 
-bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
+bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname, ID *owner)
 {
   bNodeTree *ntree;
 
@@ -1408,6 +1408,7 @@ bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
     ntree = MEM_callocN(sizeof(bNodeTree), "new node tree");
     *((short *)ntree->id.name) = ID_NT;
     BLI_strncpy(ntree->id.name + 2, name, sizeof(ntree->id.name));
+    ntree->owner = owner;
   }
 
   /* Types are fully initialized at this point,