From 3806d4b59f2f995148ed876bb0b9681d3130f281 Mon Sep 17 00:00:00 2001
From: David Vierra <codewarrior@hawaii.rr.com>
Date: Sun, 4 Jan 2015 15:46:40 -1000
Subject: [PATCH] Destroy lists when removing children from rendergraph, make
 parent link a weakref to avoid cyclic refs/gc

---
 src/mcedit2/rendering/rendergraph.py | 22 +++++++++++++++++++++-
 src/mcedit2/rendering/scenegraph.py  | 15 ++++++++++++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/mcedit2/rendering/rendergraph.py b/src/mcedit2/rendering/rendergraph.py
index 0373139..43e7169 100644
--- a/src/mcedit2/rendering/rendergraph.py
+++ b/src/mcedit2/rendering/rendergraph.py
@@ -4,6 +4,7 @@
 from __future__ import absolute_import, division, print_function
 import collections
 import logging
+import weakref
 from OpenGL import GL
 import numpy
 from mcedit2.rendering import cubes
@@ -24,11 +25,23 @@ class RenderNode(object):
         self.displayList = DisplayList()          # Recompiled whenever this node's scenegraph node is dirty
                                                   # or node gains or loses children
         self.childNeedsRecompile = True
-        self.parent = None
 
     def __repr__(self):
         return "%s(%s)" % (self.__class__.__name__, self.sceneNode)
 
+    _parent = None
+    @property
+    def parent(self):
+        if self._parent:
+            return self._parent()
+
+    @parent.setter
+    def parent(self, value):
+        if value:
+            self._parent = weakref.ref(value)
+        else:
+            self._parent = value
+
     def addChild(self, node):
         self.children.append(node)
         self._addChild(node)
@@ -99,6 +112,12 @@ class RenderNode(object):
     def drawSelf(self):
         pass
 
+    def destroyLists(self):
+        for child in self.children:
+            child.destroyLists()
+        self.displayList.destroy()
+
+
 
 class RenderstateRenderNode(RenderNode):
     def draw(self):
@@ -362,6 +381,7 @@ def updateChildren(renderNode):
 
     for dc in deadChildren:
         renderNode.removeChild(dc)
+        dc.destroyLists()
 
     for index, sceneChild in enumerate(sceneNode.children):
         renderChild = renderNode.childrenBySceneNode.get(sceneChild)
diff --git a/src/mcedit2/rendering/scenegraph.py b/src/mcedit2/rendering/scenegraph.py
index 93d834e..f7e9ef2 100644
--- a/src/mcedit2/rendering/scenegraph.py
+++ b/src/mcedit2/rendering/scenegraph.py
@@ -3,6 +3,7 @@
 """
 from __future__ import absolute_import, division, print_function
 import logging
+import weakref
 
 from mcedit2.rendering import rendergraph
 
@@ -20,11 +21,23 @@ class Node(object):
         self._dirty = True
         self.childrenChanged = False
         self.descendentChildrenChanged = False
-        self.parent = None
 
     def __repr__(self):
         return "%s(visible=%s, children=%d)" % (self.__class__.__name__, self.visible, len(self._children))
 
+    _parent = None
+    @property
+    def parent(self):
+        if self._parent:
+            return self._parent()
+
+    @parent.setter
+    def parent(self, value):
+        if value:
+            self._parent = weakref.ref(value)
+        else:
+            self._parent = value
+
     def touchChildren(self):
         node = self
         node.childrenChanged = True