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

Orthographic Viewing Model

Sometimes, a perspective view is not desired, and an orthographic view is used instead. This type of projection is used by applications for architectural blueprints and computer-aided design, where it’s crucial to maintain the actual sizes of objects and the angles between them as they’re projected. This could be done simply by ignoring one of the x, y, or z coordinates, letting the other two coordinates give two-dimensional locations. You would do that, of course, after orienting the objects and the scene with model-view transformations, as with the camera model. But, in the end, you will still need to locate and scale the resulting model for display in normalized device coordinates. The transformation for this is ...