Written by Dave Gerdes  USA-CERL   1990

This program is designed to use the GL library on Silicon Graphics
4D workstations.   It takes three GRASS cell maps as arguments. These
are expected to have data in the range of 0-255.  The three files
will be combined as Red, Green, and Blue components and displayed in 
SGI 24 bit color mode.  This is a nice alternative to i.composite/i.median.
You can also use the SGI 'gamma' command to modify the resultant image.

Let us know if you want to see more SGI programs in GRASS.  It is a wonderful
machine to work on, and has a lot of potential in the GIS arena.

    This command does NOT use the GRASS display window, but instead
creates its own.  The size of the window is dependant on the number of
rows and columns in the current GRASS 'region'.  Since the screen is 
something like 1100 by 1000 pixels, it would be wise to make sure that
the GRASS region is less than that size before running this command.
    Since this is not a GRASS display window, commands like d.what
and d.region will NOT work on it.  It is strictly for display 
purposes.