              WXtrackGL - simple 3D Satellite Prediction

Purpose:

An add-on to WXtrack enabling realistic 3D display of satellite orbits and
current ground position.  Using this tool may provide you with a greater
understanding of orbital mechanics, and it is fun to watch satellites and the 
International Space Station (ISS) coming into and out of view.


Installation, Files & Running:

Extract all files from the Zip file to a location of you choice, and run
WXtrackGL.exe.

You may need one other library file, but you should already have this if you 
have installed the prerequisite WXtrack:

If you don't already have Borland's run-time library, you will also need to 
download the file VCL50.zip from any site offering it.  For example:
  www.satsignal.net  --> Software, Runtime Libraries

Extract the file VCL50.BPL and copy it to your Windows System folder (e.g. 
\Windows\System or \WinNT\System32).  Do not overwrite newer versions with 
old.

There is information on analysing any "Missing DLL" messages at:
  www.satsignal.net  --> Software, Runtime Libraries


Usage notes:

With all the maximum quality options set, this program can use a lot of CPU
each cycle.  There are 5 seconds between each update.  It is up to you to
find settings for quality that suit your system, but not steal too many CPU 
cycles from any other application you wish to run.

As a general comment, I read that many implemenations of OpenGL on Windows 
are not particularly good.  Having said that, this program does not stretch
OpenGL to anything like its limits, so you should be OK.  Be aware that 
OpenGL was an add-on to the original version of Windows 95, and the update 
may be found at the following URL.  Only apply this patch if you need it!

  http://support.microsoft.com/support/kb/articles/Q154/8/77.asp

One person has found that the program fails to auto-update after 5 - 10 
minutes of running, but I cannot reproduce this problem.  Another found that 
an old S3 Trio64V+PCI(765) 2MB worked fine, but a more modern 3DFX Voodoo 
Banshee AGP videocard with 16MB of memory would only work at 256 colours!  The 
latest hardware drivers and version 2.0 of WXtrackGL cured that problem.  In 
version V2.0.0 onwards I sometimes see a black area at the bottom of display 
when the window is maximised.

The program has been tested sucessfully at the following screen settings:

  - 800 x 600 small fonts
  - 1024 x 768 small fonts
  - 1024 x 768 large fonts

If you have a card that does not like the high resolution bitmap built into
the program you may pace a file named UserMapGL.jpg in the folder and it will 
be read instead of the built-in image.  This can be a .JPG or .BMP file, and 
it should be 512 x 256 pixels.  A sample is provided as _UserMapGL.jpg.  Note 
the need to invert this image.  However, you will only save ~1MB this way.


Notes:

The program is written for Borland's Delphi 5.01, but you do not need access 
to Delphi to run WXtrack.  The program has been developed on Windows NT 4.0
and runs on Windows NT, 2000, 95B, 98 etc.

WXtrack should first be installed on your system to generate information for 
this program, although this is not essential.


Release information:

2000 Dec 25  V1.0.0  First experimental version
2000 Dec 26  V1.0.2  Get satellites and rotations working
                     Release as experimental version for comment
2000 Dec 30  V1.0.4  Add earth gridlines
                     Add satellite vectors
                     Locate scene updates within try..finally..end blocks
                     Add home viewpoint
2001 Jan 04  V1.0.6  Allow choice of primary satellite
                     Add Satellite and FlySatellite viewpoints
                     Add optional orbit display
                     Add display quality choice
                     Add topography on off
                     Add read of user-supplied .BMP and .JPG images
                     Add mouse control of rotation
                     Add choice of WXtrack's 3 banks
                     Add status bar with various readouts
                     Add mouse-over for satellite name on status bar
                     Add maximised support
                     Don't show geostationary trails, confuses & slows display
                     Reduce brightnesses with topography to improve clarity
                     Trap error with colour index
                     Trap error when primary satellite is unspecified in WXtrack
                     Remove requirement for GLScene.BPL
2001 Jan 28  V2.0.0  Add File open to read a set of Keplers
                     Add manual time control, with cascade secs -> mins etc.
                     Take name of Kepler file as parameter, e.g. gps-ops.txt
                     Change trails to dark grey solid instead of broken white
                     Make program work without WXtrack in a limited way
                     Move to GLScene V0.8 RC2
                     Update earth texture filters
                     Add floating point exception as "Run Handled"
                     Try to program round FP exceptions


Support:

This program is provided "as is", without any support from me.  
There is a self-help mailing list at www.egroups.com/subscribe/SatSignal 
where other users of the software may be contacted.


Program Status & Distribution:

This is a fun program ONLY!!!  However, the internal calculations are highly
accurate.

This program is freeware, and remains copyright of David J Taylor, Edinburgh, 
2000-2001.  Whilst I cannot answer queries relating to the use of this 
program, I'd value any comments or suggestions for improvements you may have.  
If you report a problem, be sure to include the exact program version number 
(from the Help, About command), and the details of the operating system, video 
adapter and display mode you are using.  Frequently you can cure problems
yourself by changing to a different display mode.

This program may be freely distributed providing its origin and the 
copyright of the program and helper libraries are strictly observed.

Basic source code is available via e-mail on request


Acknowledgements:

Many routines were modified from Dr TS Kelso's invaluable SGP4 routines, 
used with permission, which are:
  Copyright (c)  1991-2000, Dr TS Kelso, All Rights Reserved
  E-mail:   tskelso@celestrak.com
  Web site: www.celestrak.com

Dr TS Kelso's site at: www.celestrak.com/NORAD/elements/ provides the orbital 
elements, and is your source for up to the minute data.  For the sort of 
display accuracy in this program, getting new Kepler data once a month should 
be adequate, except where powered vehicles such as the Shuttle and perahps 
the ISS are required, as they will change orbits with every thruster firing!

GLScene is a library of OpenGL-based 3D rendering and animation components 
for Borland Delphi which is Open Source under Mozilla Public License.  

  Maintained by Eric Grange (egrange@infonie.fr)
  http://www.lischke-online.de/GLScene.html

A suggestion Justin Priami actually triggered me into action, and many folks
on the SatSignal mailing list have made valuable suggestions.

Many thanks to Paul Holder for his valiant efforts at tracking the FP error.


Contacting the author:

Web site:            www.satsignal.net
E-mail:              davidtaylor@writeme.com
Software self-help:  http://www.egroups.com/subscribe/SatSignal
2001 Jan 28
