public ProximityMap(SearchFunctionDelegate <T> searchFunc,
                            AddObjectsFunctionDelegate <T> findFunc,
                            float fWorldSize,
                            int nMaxDepth,
                            Vector3 v3Center,
                            object searchableData,
                            GraphicsDevice device)
        {
            m_searchFunc = searchFunc;
            m_findFunc   = findFunc;

            OctTreeNode <T> .InitialiseGraphics(device);

            m_octreeRoot = new OctTreeNode <T>(nMaxDepth, 0, fWorldSize, v3Center, findFunc, searchableData);
        }