It occurs to me that there is another major use for this cubic pattern: as a
'cubic' environnment map. (Maybe that was the original reason for its creation?)

Fot distant environmment maps that envelop a scene--as for radiosity use or
reflections-- I always use a sphere or hemisphere as the object, with a texture
or suitable photograph on it. But 'cubic'-shaped maps can also be used. (I've
never worked with computer games or GPU processing, but it looks like cubic maps
are the main technique used there, not spherical maps.) One of the reasons seems
to be that a cubic map makes better use of the texture's pixels-- less
distortion when mapping the original texture onto the cube faces vs. the inner
surface of a sphere.

I came across an old Paul Bourke article that explains it better...

http://paulbourke.net/miscellaneous/cubemaps/

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