oh and btw to render your minimap, you could use GL Framebuffers and then as a pre-process before you start the render loop, put your camera into orthographic projection, place it in the middle of your world, set the width and height to the bounds of the world and then render the whole lot into the Framebuffer (yes might take a fraction of a second to complete but you don't need to do it every frame). then you have a texture (or renderbuffer etc) in truecolour of your entire map that you can render as a textured quad (or blit the render buffer etc). You might want to exclude things from this map render pass that you don't want visible on the map, like say walkways across roads that might result in spidery grid like patterns on the image.