-.TP 8
-.B OpenGL Programs and Visuals
-Some of the graphics demos included with xscreensaver make use of the
-OpenGL (or MesaGL) 3D library, if it is available. It is possible (even
-likely) that \fIxscreensaver\fP's notion of the ``\fIbest\fP'' visual is
-not quite right for these GL programs.
-
-The odd thing about GL programs is that, unlike normal X11 programs, they
-tend to work best on a visual \fIhalf\fP 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, for these particular programs, you should specify the
-deepest visual that is half as deep as the screen. (See the discussion
-of the \fBprograms\fP resource in the \fIConfiguration\fP section, above.)
-
-For example, on a screen that supports both 24-bit TrueColor and 12-bit
-PseudoColor visuals, 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.
-However, 0x31 is but \fIone\fP of the \fIeight\fP 15-bit TrueColor visuals
-(yes, 8, and yes, 15) that the O2 X server provides. This is the only visual
-that works properly: as far as
-.BR xdpyinfo (1)
-is concerned, all of the 15-bit TrueColor visuals are identical, but some
-flicker like mad, and some have deeply weird artifacts (such as hidden
-surfaces that show through, as if depth worked backwards!)
-
-I suppose these other visuals must be tied to some arcane hardware feature...
-If anyone would care to explain it to me, that would be great.