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.

COPYRIGHT

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.