invisible flag should not eliminate collision solids

pandatool/src/mayaegg/mayaNodeTree.cxx

@@ -258,6 +258,17 @@ get_egg_group(MayaNodeDesc *node_desc) {
         egg_group->add_object_type(object_type);
       }
 
+      // Is the node flagged to be invisible?  If it is, and is has no
+      // other egg flags, it is implicitly tagged "backstage", so it
+      // won't get converted.  (But it might be an invisible collision
+      // solid, which is why we do this only if it has no other egg
+      // flags.)
+      bool visible = true;
+      get_bool_attribute(dag_object, "visibility", visible);
+      if (!visible && egg_group->get_num_object_types() == 0) {
+        egg_group->add_object_type("backstage");
+      }
+
       // We treat the object type "billboard" as a special case: we
       // apply this one right away and also flag the group as an
       // instance.

pandatool/src/mayaegg/mayaToEggConverter.cxx

@@ -534,15 +534,9 @@ process_model_node(MayaNodeDesc *node_desc) {
   }
 
   MObject node = dag_path.transform(&status);
-
-  bool visible;
-  if (!get_bool_attribute(node, "visibility", visible)) {
-    if (mayaegg_cat.is_debug()) {
-      mayaegg_cat.debug()
-        << "Couldn't get visibility attribute for " << dag_node.name()
-        << "\n";
-    }
-    visible = true;
+  if (!status) {
+    status.perror("dag_path.transform()");
+    return false;
   }
 
   string path = dag_path.fullPathName().asChar();
@@ -556,11 +550,6 @@ process_model_node(MayaNodeDesc *node_desc) {
         << " (animated)";
     }
 
-    if (!visible) {
-      mayaegg_cat.debug(false)
-        << " (invisible)";
-    }
-
     mayaegg_cat.debug(false) << "\n";
   }
 
@@ -572,13 +561,6 @@ process_model_node(MayaNodeDesc *node_desc) {
       get_joint_transform(dag_path, egg_group);
     }
 
-  } else if (!visible) {
-    if (mayaegg_cat.is_debug()) {
-      mayaegg_cat.debug()
-        << "Ignoring invisible node " << path
-        << "\n";
-    }
-
   } else if (dag_node.inUnderWorld()) {
     if (mayaegg_cat.is_debug()) {
       mayaegg_cat.debug()