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NAME

       penrose - draws quasiperiodic tilings

SYNOPSIS

       penrose  [-display  host:display.screen] [-foreground color] [-background color] [-window]
       [-root] [-mono] [-install]  [-visual  visual]  [-ncolors  integer]  [-delay  microseconds]
       [-size integer] [-ammann] [-no-ammann]

       [-fps]

DESCRIPTION

       The penrose program draws quasiperiodic tilings.

       See  Onoda,  Steinhardt,  DiVincenzo  and  Socolar  in  Phys.  Rev. Lett. 60, #25, 1988 or
       Strandburg in Computers in Physics, Sep/Oct 1991.

       This implementation uses the simpler version of the growth algorithm, i.e., if  there  are
       no  forced  vertices,  a  randomly  chosen  tile  is added to a randomly chosen vertex (no
       preference for those 108 degree angles).

       There are two essential differences to the algorithm presented in the  literature:  First,
       we  do  not  allow  the  tiling to enclose an untiled area.  Whenever this is in danger of
       happening, we just do not add the tile, hoping for a better random choice the  next  time.
       Second,  when  choosing a vertex randomly, we will take one that lies withing the viewport
       if available.  If this seems to cause enclosures in the forced rule case,  we  will  allow
       invisible vertices to be chosen.

       Tiling  is  restarted  whenever  one  of  the  following  happens: there are no incomplete
       vertices within the viewport or the tiling has extended a window's length beyond the  edge
       of the window horizontally or vertically or forced rule choice has failed 100 times due to
       areas about to become enclosed.

       Although quasiperiodic tilings are produced, the tiles themselves are  not  penrose  tiles
       (darts  and  kites).  In  contrast to penrose tiles, these tiles can be arranged to form a
       periodic tiling.

OPTIONS

       penrose accepts the following options:

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

       -root   Draw on the root 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.

       -size integer
               How big the tiles should be.  Default 40 pixels.

       -delay milliseconds
               How long (in 1/1,000,000'ths of a second)  to  wait  between  drawing  each  tile.
               Default 10,000 or .01 seconds.

       -ammann

       -no-ammann
               Whether Ammann lines should be added.

       -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.

SEE ALSO

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

COPYRIGHT

       Copyright © 1996 by Timo Korvola.

       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

       Timo Korvola <tkorvola@dopey.hut.fi>, 1996.

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