Rendering and User Input - Learning Game Physics with Bullet Physics and OpenGL - page 17

Tip
Note that we have already enabled this feature back in Chapter 1 , Building a
Game Application , when we called the glutInitDisplayMode() function.
The following diagram shows the working of double-buffering:
The command to swap these buffers in FreeGLUT is glutSwapBuffers() , and
the command to clear the backbuffer is glClear() . In order to clear the color value
of every pixel in the current buffer, we pass the value GL_COLOR_BUFFER_BIT into
glClear() . Both of these functions must be called inside the Idle() function,
which is automatically and repeatedly called by FreeGLUT whenever it's not busy
processing its own events. This is the moment where we should process our own
background tasks such as physics processing, object management, responding to
game events, and even rendering itself.