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.TH XScreenSaver 1 "10-May-97" "X Version 11"
.SH NAME
penrose - draws quasiperiodic tilings
.SH SYNOPSIS
.B penrose
[\-display \fIhost:display.screen\fP] [\-foreground \fIcolor\fP] [\-background \fIcolor\fP] [\-window] [\-root] [\-mono] [\-install] [\-visual \fIvisual\fP] [\-ncolors \fIinteger\fP] [\-delay \fImicroseconds\fP] [\-size \fIinteger\fP] [\-ammann] [\-no\-ammann]
[\-fps]
.SH DESCRIPTION
The \fIpenrose\fP 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.
.SH OPTIONS
.I penrose
accepts the following options:
.TP 8
.B \-window
Draw on a newly-created window. This is the default.
.TP 8
.B \-root
Draw on the root window.
.TP 8
.B \-mono
If on a color display, pretend we're on a monochrome display.
.TP 8
.B \-install
Install a private colormap for the window.
.TP 8
.B \-visual \fIvisual\fP
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.
.TP 8
.B \-ncolors \fIinteger\fP
How many colors should be used (if possible). Default 64.
The colors are chosen randomly.
.TP 8
.B \-size \fIinteger\fP
How big the tiles should be. Default 40 pixels.
.TP 8
.B \-delay \fImilliseconds\fP
How long (in 1/1,000,000'ths of a second) to wait between drawing each
tile. Default 10,000 or .01 seconds.
.TP 8
.B \-ammann
.TP 8
.B \-no\-ammann
Whether Ammann lines should be added.
.TP 8
.B \-fps
Display the current frame rate and CPU load.
.SH ENVIRONMENT
.PP
.TP 8
.B DISPLAY
to get the default host and display number.
.TP 8
.B XENVIRONMENT
to get the name of a resource file that overrides the global resources
stored in the RESOURCE_MANAGER property.
.SH SEE ALSO
.BR X (1),
.BR xscreensaver (1),
.BR xlock (1)
.SH COPYRIGHT
Copyright \(co 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.
.SH AUTHOR
Timo Korvola <tkorvola@dopey.hut.fi>, 1996.
Ability to run standalone or with \fIxscreensaver\fP added by
Jamie Zawinski <jwz@jwz.org>, 10-May-97.
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