penrose(6x) XScreenSaver manual penrose(6x)
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 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.
-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.
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, 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.
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