GP2JAM - Grand Prix 2 JAM to BMP Converter

Copyright (c) 1996 Trevor Kellaway (100331.2330@compuserve.com)

V1.0 18th Aug 1996

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Introduction
Grand Prix 2 (GP2) from Microprose stores its image files in a unique format, these files have the extension '.JAM' (referred to as 'JAM' files).

GP2JAM is a DOS program which converts GP2 JAM files to .BMP files and back again. You will find these images in \GP2\GAMEJAMS\ on your hard disk (or CD-ROM drive).

This version of GP2JAM supports the car image JAM files, thus you can convert from a WILLIAMS.JAM file to a WILLIAMS.BMP. You can now use your favourite bitmap editor to modify the image and save it. Next you would convert the WILLIAMS.BMP back to WILLIAMS.JAM.

Installation
This distribution should include the following files: 
	GP2JAM.TXT	A text version of the help file.
	GP2JAM.HTM	An HTML version of the help file.
	GP2JAM.EXE	The converter program.

Copy GP2JAM.EXE to any directory on your hard disk, I recommend that you create a new directory (say '\JAM'), you can then keep all your updated JAMs and BMPs there without cluttering up the game directories (this also allows you to reinstall the game without losing your images).

Quick Start
Here is a quick tutorial on how to start painting the Williams.

Change directory to where you put GP2JAM.EXE ('\JAM'). Convert the Williams JAM file to a bitmap by typing the following at a DOS command prompt: 

	GP2JAM -j\GP2\GAMEJAMS\WILLIAMS.JAM

This should create a WILLIAMS.BMP in the current directory (Note: If the game is stored on a different drive then add the appropriate drive letter at the front of the filename).

Now startup your favourite bitmap editor (Paint Shop Pro is a good one, much better than Windows/W95 Paintbrush) and load the WILLIAMS.BMP. You should see a picture of the different panels of the car. Paint the car and then save the WILLIAMS.BMP again.

Now back at the DOS prompt convert the file back to a JAM: 

	GP2JAM -bWILLIAMS.BMP -j\GP2\GAMEJAMS\WILLIAMS.JAM

That should be it. Startup GP2 and admire your work!

Important
All of the JAM files have a unique identity (ID) encoded in them so you can't copy a WILLIAMS.JAM over the top of say a BENETTON.JAM, you will get a transparent car! GP2JAM will always display the actual JAM ID when converting to help you identify which file you are manipulating, this only becomes useful if you start renaming the JAM files in your directory (don't rename the games JAM files!).
Usage
GP2JAM [-h?v] [-y] [-bFILENAME.BMP] [-jFILENAME.JAM]

     -h|-?         Display this usage message.
     -v            Display the version number & contact information.

     -jFNAME.JAM	Set the JAM filename to be 'FNAME.JAM'.
     -bFNAME.BMP	Set the BMP filename to be 'FNAME.BMP'.

     -y            Automatically answer all questions with 'Yes'.
When converting from a JAM to BMP you need only specify the JAM filename: 
	GP2JAM -jWILLIAMS.JAM
This will automatically create a WILLIAMS.BMP (based on the JAM ID), if the WILLIAMS.BMP file already exists you will be asked if you wish to overwrite it. You can turn off these prompts by using the '-y' option which will automatically respond 'Yes' to all prompts.

If you wanted to use a different bitmap filename specify it after the JAM filename: 

	GP2JAM -jWILLIAMS.JAM -bCAR1.BMP
To convert back from a BMP to a JAM file you must specify both filenames and the BMP filename must be first: 
	GP2JAM -bWILLIAMS.BMP -jWILLIAMS.JAM -y
This will update the existing WILLIAMS.JAM file (Note: the '-y' option was present to automatically respond to the overwrite prompt).

You can display the usage message by starting GP2JAM either with no command line options, or use either '-?', or '-h'.

To find out which version of GP2JAM you have use the '-v' option, this also displays the author's E-mail address and web site URL.

Bitmaps and Palettes
When you first convert an original game JAM file GP2JAM may display the following warning: 
 'Warning: The image contains unique colours which can't be mapped to GP2JAM's
 standard palette, these will be mapped to the nearest colour available.'
Don't worry about this, GP2JAM uses a different fixed palette to that of the cars in the game and maps the game colours to the nearest available ones in its palette. When you perform a later update of a car you've edited previously you won't get this warning.

When saving the BMP image don't change the colour depth (256) or change the image size. You can use any of the colours from the fixed palette (the first 192) but *don't* change the palette as this is fixed by the game and the BMP just contains a copy (changing the palette won't have any effect in the game). Make sure you save the bitmap RGB encoded (not RLE or OS/2 encoded).

Don't over paint the background (dull green) colour or move any of the car parts. A good way to paint large areas is to use the selective colour eraser tool which is available in most good painting packages.

The BMP has several small rectangles which are all one colour, these are the suspension arms.

Known Problems
GP2JAM has been tested with the European GP2 V1.0b and works fine in VGA and SVGA. It should also work for the other language versions but I haven't tried these yet.

This version of GP2JAM currently only supports the car JAM files. The cockpit view from a car will display the original game colour as this information seems to be encoded in the GP2.EXE file rather than the car JAM file.

Car Sets
Please *don't* send me the results of your painting, I'll get swamped with file E-mails otherwise! I won't be producing any car sets (I just write the converter, I never actually use it!), but I'm sure some good ones will quickly be available on the web.

Checkout Dave Gymer's web site and this will probably soon have some links on it:

http://www.gamesdomain.co.uk/dgymer/f1gp/

Note: The JAM files don't compress at all, so if possible when creating a car set include the BMP files as they do compress (I recommend you create a JAMS.ZIP and a BMP.ZIP then the downloader can choose which one to download, the BMP.ZIP will be much smaller than the JAMS.ZIP).

Future Updates
The next version of GP2JAM will support the driver's helmets. Subsequent versions may support the advertising boards and possibly other objects around the track. Keep an eye on my web page.
History
V1.0 18th Aug 1996	Initial version.
			Only supports car JAM files.
E-mail / Further Info
Please send any suggestions, comments, or bug reports (include the version of GP2JAM you are using) to the author Trevor Kellaway at: 
CompuServe:    [100331,2330]
Internet:      100331.2330@compuserve.com
The current version of GP2JAM will always be available on my web page along with the current version of this help file.

http://ourworld.compuserve.com/homepages/tkellaway/

It should also be available on Compuserve in GO SPRTSIMS, Lib #14 (Racing Circuits) as GP2JAM.ZIP.

This program may be freely copied and distributed, as long as it is not modified in any way, no fee is charged and this file is always included. This program is provided "as is" with no warranties expressed or implied. The author will not be held responsible for any losses incurred, either directly or indirectly by the use of this program.

This is *not* an Microprose product. If you have problems with the game then try it without using this program.

The author has no connection with Geoff Crammond or Microprose.

E-mail: Trevor Kellaway (100331.2330@compuserve.com)