.TH grav 6x "6.08 (10-Oct-2023)" "X Version 11" "XScreenSaver manual"
.SH NAME
grav \- draws a simple orbital simulation
.SH SYNOPSIS
.B grav
[\-\-display \fIhost:display.screen\fP] [\-\-foreground \fIcolor\fP]
[\-\-background \fIcolor\fP] [\-\-window] [\-\-root]
[\-\-window\-id \fInumber\fP][\-\-mono] [\-\-install] [\-\-visual \fIvisual\fP] [\-\-ncolors \fIinteger\fP] [\-\-delay \fImicroseconds\fP] [\-\-count \fIinteger\fP] [\-\-decay] [\-\-no\-decay] [\-\-trail] [\-\-no\-trail]

[\-\-fps]
.SH DESCRIPTION
The \fIgrav\fP program draws a simple orbital simulation
.SH OPTIONS
.I grav
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 \-\-window\-id \fInumber\fP
Draw on the specified 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 \-\-count \fIinteger\fP
Default 12.
.TP 8
.B \-\-decay
.TP 8
.B \-\-no\-decay
Whether orbits should decay.

.TP 8
.B \-\-trail
.TP 8
.B \-\-no\-trail
Whether the objects should leave trails behind them (makes it look vaguely
like a cloud-chamber.

.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.
.TP 8
.B XSCREENSAVER_WINDOW
The window ID to use with \fI\-\-root\fP.
.SH SEE ALSO
.BR X (1),
.BR xscreensaver (1),
.BR xlock (1)
.SH COPYRIGHT
Copyright \(co 1993 by Greg Bowering.

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
Greg Bowering <gb@pobox.com>, 1993.

Ability to run standalone or with \fIxscreensaver\fP added by 
Jamie Zawinski <jwz@jwz.org>, 10-May-97.