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penrose(6)		      XScreenSaver manual		    penrose(6)

NAME
       penrose - draws quasiperiodic tilings

SYNOPSIS
       penrose	[--display  host:display.screen] [--foreground color] [--back-
       ground color] [--window]	[--root] [--window-id  number][--mono]	[--in-
       stall]  [--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 an-
       gles).

       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 within the view-
       port 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	verti-
       cally  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.

       --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.

       --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 draw-
	       ing 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.

       XSCREENSAVER_WINDOW
	       The window ID to	use with --root.

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		      6.09 (07-Jun-2024)		    penrose(6)

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