private void delPluginSphere(string pluginName)
 {
     OgreWindow.Instance.pause();
     try
     {
         MaterialPtr ptrMat = MaterialManager.Singleton.GetByName(sphereNamePrefix + "_SphereMaterial_" + pluginName);
         ptrMat.Unload();
         MaterialManager.Singleton.Remove(ptrMat.Handle);
         ptrMat.Dispose();
         MeshPtr ptrMesh = MeshManager.Singleton.GetByName(sphereNamePrefix + "_SphereMesh_" + pluginName);
         ptrMesh.Unload();
         MeshManager.Singleton.Remove(ptrMesh.Handle);
         ptrMesh.Dispose();
         OgreWindow.Instance.mSceneMgr.DestroyEntity(sphereNamePrefix + "_SphereEntity_" + pluginName);
         OgreWindow.Instance.mSceneMgr.DestroySceneNode(sphereNamePrefix + "_SphereSceneNode_" + pluginName);
     }
     catch (Exception ex)
     {
         log("error deleting plugin sphere: " + ex.ToString());
     }
     OgreWindow.Instance.unpause();
 }