RCS $Id: README,v 1.13 1994/06/02 17:19:20 tuna Exp $ README file for xearth, version 0.92 Kirk Lauritz Johnson 1 June 1994 WHAT IS IT? Xearth sets the X root window an image of the Earth, as seen from your favorite vantage point in space, correctly shaded for the current position of the Sun. By default, xearth updates the displayed image every five minutes; the time between updates can be changed using either X resources or a command line option. Xearth can also render directly into PPM and GIF files instead of drawing in the root window; see the man page for details. See the HISTORY file for a list of changes since versions 0.5 and 0.92. IMPORTANT! This version of xearth (version 0.92) is an evolution of the only version(s) of xearth that I ever released (versions 0.5, 0.9, and 0.91). Unfortunately, some net.weenies chose to make some minor mods (and introduce bugs!) and "release" a bogus version 0.6 without even notifying or consulting with me; this may be the version of xearth that you are currently using. Some of the command line options supported in the bogus version 0.6 (e.g, those having to do with "geostatic") don't exist in this version -- their functionality (and more!) is available through other means. In addition, the meaning and syntax of some of the xearth command line options have changed, so you should probably give the new man page a good reading if things don't seem to be working as you expect. MAJOR CAVEAT This version of xearth (version 0.92) supports both one- and eight-bit framebuffers. Systems with other than one- and eight-bit framebuffers are only "supported" (indirectly) to the extent that xearth can generate PPM and GIF files that can be fed directly into your favorite image viewer (e.g., xv, xloadimage). WHERE TO GET IT? The latest-and-greatest version of xearth should be available via anonymous ftp from cag.lcs.mit.edu:/pub/tuna (or, for those web surfers out there, via a link from the xearth WWW home page http://cag-www.lcs.mit.edu/~tuna/xearth/index.html). NOTES If you are trying to build xearth under SunOS 4.x using /bin/cc, make sure to read the section of the INSTALL file entitled "BUILDING UNDER SUNOS 4.x" regarding a compiler bug. There are a number of improvements that I'd love to make, but I really should be working on my thesis instead of hacking on this. The map information used in xearth was derived from the "CIA World Data Bank II map database," as taken from some "cbd" files that were apparently originally generated by Brian Reid at DECWRL. Running in the background on a Sun 4/110, xearth requires around 30 CPU seconds each time it redraws an image in the root window. With the default time-between-redraws of 300 seconds, I hardly even notice the extra CPU load. Your mileage may vary, of course, especially on slower machines. The Graphics Interchange Format(c) is the Copyright property of CompuServe Incorporated. GIF(sm) is a Service Mark property of CompuServe Incorporated. Thanks to Jamie Zawinski for suggesting that I look at his xscreensaver package for a good example of how to use the resource and command line option parts of Xt; his code saved me piles of lossage. Kudos to Jef Poskanzer for his excellent PBMPLUS toolkit. IDEAS FOR FUTURE WORK Support for other visual classes and depths. Better error recovery (better than "assert()", anyway). Add options/resources that specify colors other than the default green, blue, red, white, and black. Add hooks for user-specified marker locations. Code for tracking real-life orbits ("-pos hubble"). Support for supersampling/antialiasing. AUTHOR Kirk Johnson Patches, bug reports, and suggestions are welcome, although I can't guarantee that I'll get around to doing anything about them in a timely fashion. LEGAL STUFF Copyright (C) 1989, 1990, 1993, 1994 by Kirk Lauritz Johnson Portions of the xearth source code, as marked, are: Copyright (C) 1989, 1990, 1991 by Jim Frost Copyright (C) 1992 by Jamie Zawinski Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. The author makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.