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

Limitations of the Classic Lighting Model

The classic lighting model works pretty well at what it tries to do: modeling the surface reflection properties, modeling each light, combining them together to modulate an underlying color, and getting a pretty realistic approximation of what color is scattered and reflected. Yet, there are some important things missing.

Shadows are a big item. We lit each surface as if it was the only surface present, with no other objects blocking the path of the lights to the surface. We will provide techniques for shadowing later in this chapter.

Another big missing item is accurate ambient lighting. If you look around a room, you won’t see a constant level of ambient lighting. Corners, for example, are darker than ...