OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Viewing Model

For the time being, it is important to keep thinking in terms of three-dimensional coordinates while making many of the decisions that determine what is drawn on the screen. It is too early to start thinking about which pixels need to be drawn. Instead, try to visualize three-dimensional space. It is later, after the viewing transformations are completed, after the subjects of this chapter, that pixels will enter the discussion.