A question about the levels themselves.

There has been a question about the levels that I have been itching to be answered but I never seem to any information about it or it is completely confusing in techno-bable.

The question is: How are the basic (just the walls, floors/ground and ceiling/skyboxs) levels textured?

Thanks for your help in advance as this had been bothering for a longest time.

For a long time (relatively) one had to use UV textures for the best results. Now, if your graphics card supports GLSL you have many more options, because much more of the options listed under materials work real-time. Though it still comes down to uv textures.