NAME

       grav - draws a simple orbital simulation

SYNOPSIS

       grav  [--display host:display.screen] [--foreground color] [--background color] [--window]
       [--root] [--window-id number][--mono] [--install] [--visual  visual]  [--ncolors  integer]
       [--delay microseconds] [--count integer] [--decay] [--no-decay] [--trail] [--no-trail]

       [--fps]

DESCRIPTION

       The grav program draws a simple orbital simulation

OPTIONS

       grav accepts the following options:

       --window
               Draw on a newly-created window.  This is the default.

       --root  Draw on the root window.

       --window-id number
               Draw on the specified window.

       --mono  If on a color display, pretend we're on a monochrome display.

       --install
               Install a private colormap for the window.

       --visual visual
               Specify  which visual to use.  Legal values are the name of a visual class, or the
               id number (decimal or hex) of a specific visual.

       --ncolors integer
               How many colors should be used (if possible).  Default 64.  The colors are  chosen
               randomly.

       --count integer
               Default 12.

       --decay

       --no-decay
               Whether orbits should decay.

       --trail

       --no-trail
               Whether  the objects should leave trails behind them (makes it look vaguely like a
               cloud-chamber.

       --fps   Display the current frame rate and CPU load.

ENVIRONMENT

       DISPLAY to get the default host and display number.

       XENVIRONMENT
               to get the name of a resource file that overrides the global resources  stored  in
               the RESOURCE_MANAGER property.

       XSCREENSAVER_WINDOW
               The window ID to use with --root.

SEE ALSO

       X(1), xscreensaver(1), xlock(1)

COPYRIGHT

       Copyright © 1993 by Greg Bowering.

       Permission  to  use,  copy, modify, and distribute this software and its documentation for
       any purpose and without fee is hereby granted, provided that the  above  copyright  notice
       appear in all copies and that both that copyright notice and this permission notice appear
       in supporting documentation.

AUTHOR

       Greg Bowering <gb@pobox.com>, 1993.

       Ability to run standalone or with xscreensaver  added  by  Jamie  Zawinski  <jwz@jwz.org>,
       10-May-97.