“Now that you’ve read the preceding companion piece to this
article, “Preparing to Build a OpenGL Application,” you’re ready to
tackle rendering and drawing. Let’s jump right in to the details of
rendering.”
“The function registered as the Display (and usually Idle)
callback is where control is passed whenever it’s time to draw the
next frame of the display. For our program this is the
cbRenderScene() function, and it’s also where our motion
calculations are done.”
“In more advanced applications, physics calculations may be
executing in another process or be based on the actual amount of
time it took to render the last frame. This is necessary for
objects’ motions to be independent of frame-rate.”
“…OpenGL is the lowest-level, cross-platform, common
hardware accelerated 3D API available. The demo program we’ve
provided here should compile and run with only minor tweaking under
any Unix with OpenGL or a clone installed. It should also work
without much effort in a Windows- or Mac-based development
environment, although we haven’t tried that.“