Renderworld only draws to the backbuffer. So you need the flip to swap the backbuffer with the frontbuffer, because as you probably know you only ever see the frontbuffer.
Usually you do not need to set the backbuffer every loop unless you are setting another buffer for some reason.
Oh and there are differences in the way windowed modes handle the two buffers. But usually you will not be aware of them.
Usually you do not need to set the backbuffer every loop unless you are setting another buffer for some reason.
Oh and there are differences in the way windowed modes handle the two buffers. But usually you will not be aware of them.