Merge pull request #3198 from Autodesk/bailp/EMSUSD-190/lost-light

EMSUSD-190 fix for lights after edit-as-Maya

lib/mayaUsd/fileio/primUpdaterManager.cpp

@@ -1135,7 +1135,7 @@ bool PrimUpdaterManager::mergeToUsd(
     auto ufeUsdItem = Ufe::Hierarchy::createItem(pulledPath.pop());
     auto hier = Ufe::Hierarchy::hierarchy(ufeUsdItem);
     if (TF_VERIFY(hier)) {
-        scene.notify(Ufe::SubtreeInvalidate(hier->defaultParent()));
+        scene.notify(Ufe::SubtreeInvalidate(hier->parent()));
     }
     progressBar.advance();
 
@@ -1401,7 +1401,7 @@ bool PrimUpdaterManager::discardPrimEdits(const Ufe::Path& pulledPath)
     auto ufeUsdItem = Ufe::Hierarchy::createItem(pulledPath);
     auto hier = Ufe::Hierarchy::hierarchy(ufeUsdItem);
     if (TF_VERIFY(hier)) {
-        scene.notify(Ufe::SubtreeInvalidate(hier->defaultParent()));
+        scene.notify(Ufe::SubtreeInvalidate(hier->parent()));
     }
     progressBar.advance();
 

lib/mayaUsd/ufe/ProxyShapeHierarchy.cpp

@@ -332,10 +332,23 @@ ProxyShapeHierarchy::reorderCmd(const Ufe::SceneItemList& orderedList) const
 
 Ufe::SceneItem::Ptr ProxyShapeHierarchy::defaultParent() const
 {
-    // The default parent is the root of the USD scene.
-    // Since the proxy shape corresponds to the USD root prim,
-    // therefore we implement the default parent as the proxy shape itself.
-    return UsdSceneItem::create(sceneItem()->path(), getUsdRootPrim());
+    // The documentation for defaultParent() stipulate that it should return
+    // where this node should be inserted to be added back. The proxy shape need
+    // to be inserted under its Maya shape node, which is its default parent,
+    // so we return that.
+    //
+    // It used to return the USD virtual root prim, but that caused problem since
+    // the UFE path pointed to a Maya node (the proxy shape) and the default parent
+    // was a USD object, leading to a contradiction. In particular, it became
+    // impossible to create a UFE Hiearchy interface from that default parent: its
+    // path indicated it was in the Maya run-time, yet its scene item claimed to
+    // be in the USD run-time.
+    //
+    // As far as I can tell, the defaultParent function is only used when reparenting
+    // nodes that lacked a parent, to figure a default location where to insert them.
+    //
+    // The PrimUpdaterManager also used to call it, but it no longer does.
+    return parent();
 }
 
 #endif // UFE_V2_FEATURES_AVAILABLE