diff --git a/panda/src/pgraph/geomNode.I b/panda/src/pgraph/geomNode.I
index c70af9100a..640988b903 100644
--- a/panda/src/pgraph/geomNode.I
+++ b/panda/src/pgraph/geomNode.I
@@ -28,6 +28,17 @@ get_num_geoms() const {
   return cdata->get_geoms()->size();
 }
 
+
+////////////////////////////////////////////////////////////////////
+//     Function: GeomNode::get_num_geoms
+//       Access: Public
+//  Description: Returns the number of geoms in the node.
+////////////////////////////////////////////////////////////////////
+INLINE void GeomNode::
+set_preserved(bool value){
+  _preserved = value;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: GeomNode::get_geom
 //       Access: Public
diff --git a/panda/src/pgraph/geomNode.cxx b/panda/src/pgraph/geomNode.cxx
index 097d663f0c..37eb523f84 100644
--- a/panda/src/pgraph/geomNode.cxx
+++ b/panda/src/pgraph/geomNode.cxx
@@ -45,6 +45,7 @@ GeomNode(const string &name) :
   PandaNode(name)
 {
   // GeomNodes have a certain set of bits on by default.
+  _preserved = false;
   set_into_collide_mask(get_default_collide_mask());
 }
 
@@ -56,7 +57,8 @@ GeomNode(const string &name) :
 GeomNode::
 GeomNode(const GeomNode &copy) :
   PandaNode(copy),
-  _cycler(copy._cycler)
+  _cycler(copy._cycler),
+  _preserved(copy._preserved)
 {
 }
 
@@ -222,6 +224,46 @@ xform(const LMatrix4f &mat) {
   transformer.transform_vertices(this, mat);
 }
 
+
+////////////////////////////////////////////////////////////////////
+//     Function: GeomNode::safe_to_flatten
+//       Access: Public, Virtual
+//  Description: Transforms the contents of this node by the indicated
+//               matrix, if it means anything to do so.  For most
+//               kinds of nodes, this does nothing.
+//
+//               For a GeomNode, this does the right thing, but it is
+//               better to use a GeomTransformer instead, since it
+//               will share the new arrays properly between different
+//               GeomNodes.
+////////////////////////////////////////////////////////////////////
+bool GeomNode::
+safe_to_flatten() const {
+  if(_preserved)
+    return false;
+  return true;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: GeomNode::safe_to_combine
+//       Access: Public, Virtual
+//  Description: Transforms the contents of this node by the indicated
+//               matrix, if it means anything to do so.  For most
+//               kinds of nodes, this does nothing.
+//
+//               For a GeomNode, this does the right thing, but it is
+//               better to use a GeomTransformer instead, since it
+//               will share the new arrays properly between different
+//               GeomNodes.
+////////////////////////////////////////////////////////////////////
+bool GeomNode::
+safe_to_combine() const {
+  if(_preserved)
+    return false;
+  return true;
+}
+
+
 ////////////////////////////////////////////////////////////////////
 //     Function: GeomNode::combine_with
 //       Access: Public, Virtual
diff --git a/panda/src/pgraph/geomNode.h b/panda/src/pgraph/geomNode.h
index ec05708c70..ffb91dd2e4 100644
--- a/panda/src/pgraph/geomNode.h
+++ b/panda/src/pgraph/geomNode.h
@@ -57,7 +57,12 @@ public:
   virtual bool is_renderable() const;
   virtual CollideMask get_legal_collide_mask() const;
 
+  virtual bool safe_to_flatten() const;
+  virtual bool safe_to_combine() const;
+
 PUBLISHED:
+
+  INLINE void set_preserved(bool value);
   INLINE int get_num_geoms() const;
   INLINE const Geom *get_geom(int n) const;
   INLINE Geom *get_unique_geom(int n);
@@ -98,6 +103,8 @@ public:
   };
 
 private:
+
+  bool _preserved;
   typedef RefCountObj< pvector<GeomEntry> > GeomList;
   typedef pmap<const InternalName *, int> NameCount;