penrose(6) XScreenSaver manual penrose(6)

NAME

penrose - draws quasiperiodic tilings

SYNOPSIS

penrose [--display host:display.screen] [--foreground color]
[--background color] [--window] [--root] [--window-id number][--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 within
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.

--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
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.

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,
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.

X Version 11 6.09 (07-Jun-2024) penrose(6)