The fog is quite useful to add realism to certain scenes or to help reducing the deepness of the field of vision. Because of the fact that the fog is computed at the fixed pipeline level, in the T&L and Texturing modules, it's necessary to know how to compute it when the rendering uses programmable shaders. The per-pixel fog permits to obtain a good visual quality but needs more GPU power.

• Red Book - chap.6: Blending, Antialiasing, Fog, and Polygon Offset
• Orange Book - chap.9 - part 6: Fog

I wish to thank Vincent Manuceau (aka 'Jusan' on oZone3D.Net forums) for the good work of translating my french text in english. I also wish to thank Benoît Rogez for the tutorial pre-release feedbacks. Thank you guys!