The title says all.
I would assume they are the geometry used to fake an atmosphere in a game. since there is no real “background” in an OpenGL window, you use large geometry to represent a distant sky and place it at a static position from the viewport.
Not to seem rude, but your last two questions, while valid, could easily have been answered from a number of sources, including www.gdmag.com and www.gamasutra.com . If you have any more questions about basic terminology of the industry, you might want to check there first. Otherwise, I believe the beginners forum is more appropriate.
[This message has been edited by lpVoid (edited 02-07-2001).]
A skybox, from a coder point of view, just a simple textured box with visible faces inside it.
The basic method in opengl is to draw the skybox with depth buffer cleared and depth testing disabled at the very beginning of the display function/callback.
During this stage changing the fov may give cool result.
Note that the 6 textures used for this should have been designed with skybox consideration.
There’s also the skydome tech which uses an hemisphere as geometry.
[This message has been edited by holocaust (edited 02-07-2001).]
About creating the textures for a skybox:
Create the enviroment you like in your favorite 3d package (Lightwave, 3d Studio Max etc). Maybe som mountains and clouds.
It is very simple to render it just set frame aspect ratio to 1.0, FOV to 90 vertical and 90 horizontal (should be the same with aspect ratio 1.0). and render 512x512 pixel views of front, right, back, left, top and bottom.
Use the images as textures on the inside of a box and squeeze it into your OpengGL app.