-! A few of the hacks require OpenGL, and will only be built if you have it.
-! If your vendor doesn't provide real OpenGL, you might want to consider
-! building MesaGL, which is a free implementation -- GL is way cool.
-!
-! Note that those hacks (gears, superquadratics, morph3d, cage, moebius,
-! stairs, pipes, sproingies, and rubik) tend to work best on a visual *half*
-! as deep as the depth of the screen, since that way, they can do
-! double-buffering -- try it and see, but you will probably find that you
-! should specify the deepest visual that is half as deep as the screen.
-!
-! For example, on a screen that supports both 24-bit TrueColor and 12-bit
-! PseudoColor, the 12-bit visual will probably work best (this is true of
-! base-model SGI Indys: the 0x29 visual is the one you want.) Oddly, on SGI
-! O2s, (machines that have serious hardware support for GL) the 12-bit
-! PseudoColor visual looks awful (you get a black and white, flickery image.)
-! On these machines, the visual you want turns out to be 0x31 -- this is but
-! one of the eight 15-bit TrueColor visuals (yes, 8, and yes, 15) that O2s
-! provide. This is the only visual that works properly -- as far as xdpyinfo
-! is concerned, all of the 15-bit TrueColor visuals are identical, but some
-! flicker like mad, and some have deeply weird artifacts (hidden surfaces
-! show through!) I suppose these other visuals must be tied to some arcane
-! hardware feature... Your mileage, therefore, may vary dramatically.
-!