public void drawPolygons(Graphics2D g) {
polygonRenderer.startFrame(g);
// draw polygons in bsp tree (set z buffer)
((BSPRenderer) polygonRenderer).draw(g, bspTree);
// draw game object polygons (check and set z buffer)
gameObjectManager.draw(g, (GameObjectRenderer) polygonRenderer);
polygonRenderer.endFrame(g);
}
