Provided by: xscreensaver-data_5.36-1ubuntu1_amd64 
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.