XScreenSaver(1) 					      General Commands Manual						   XScreenSaver(1)

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] [-redoDelay seconds] [-size integer] [-ammann] [-no-ammann]

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.

       -redoDelay seconds
	       How long to wait between starting a completely new tiling.  Default 3 seconds.

       -ammann

       -no-ammann
	       Whether Ammann lines should be added.

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 (C) 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, pro-
       vided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice  appear  in  sup-
       porting 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.

X Version 11							     10-May-97							   XScreenSaver(1)