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Atari ST - The Snowman
Converted To OpenGL By Jeff Molofee ( NeHe )
http://nehe.gamedev.net - 2002
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This was one of my favorite Atari ST demos back in the day. I toyed with the
idea of porting it to the PC many years ago, but always ran into problems
trying to grab both the graphics and the sounds from this demo.
The original soundtrack is a raw audio format. Sounded raspy on my Atari Ste
and just as bad using Steem (emulator). After converting the audio I was
happy to hear that the quality of the sample is not really all that bad. The
resulting WAV file sounds good, and is almost the exact same size as the
original audio file. The audio file is the only file from the original Atari
ST demo that must be replaced. I didn't feel like making a player :(
The video was a completely different story, and took many hours of late night
coding and many more hours reading documentation from the net. The file
snowbit1.neo contains the text you see on either side of the animation. NEO
for those of you that have never heard of it is an Atari ST format created
by an art program called NeoChrome.
NeoChrome is not all that complex. However, it's a 4bpp image with a
resolution of 320x200. Not exactly an OpenGL friendly format. The bits are
reversed, and each palette index is created by calculating the bits on all
4 bitplanes per pixel (alot of work). Alot of struggling, alot of reading
the NEO specs and alot more struggling. Many hours later, I finished coding
a basic loader able to convert the image to a 24bit RGB format. YAY!!!
The video file snowmain.dat was a little trickier. I wasn't really sure what
type of data was in the file. I spent almost an entire day trying to extract
data. I went through the entire file with a hex editor at least 20 times. I
searched the net for information on the "grabber" software mentioned on the
main screen. In the long run, I discovered that the data inside this file is
actually NeoChrome images without the header (YAY again!!!). 75 images to be
exact. Each image 160x100x4bpp. Which means each image is 16000/2 bytes or
8000 bytes. 8000*75=600000 which is exactly the size of snowmain.dat.
I wrote a quick console application to rip all the images from the file. I
did this in order to map out each frame and so I could grab the colors from
each frame using Adobe. The exported files are .IFF format... a nice AMIGA
format that is very similar to .NEO. Instead of every bitplane being stored
one after another, .IFF's store each bitplane on a seperate line. Plus
Irfanview loads .IFF files (more good news).
After extracting the data, building a palette, resampling the sound, and
coding the NeoChrome loader, I started on the animation. More work! It turns
out that the 75 frames of animation are not in order, and some frames are used
multiple times. I actually had to watch the original demo at 10% speed in
order to write out a list of which frame to display and how long to keep it on
the screen.
All in all, it was a long process, but like any project I pushed myself, and
learned alot of new things in the process. I hope you enjoy the port as much
as I do!
* It's interesting to note that there is a frame of animation (frame 13) that
is not used in the demo. It's a single picture of a house. Not sure if
the original coder forgot to include it or if it's just one of them
mysteries :)
Please share this file with as many people as you can. Hopefully this demo
motivates other Atari fans out there. It would be nice to see some of the
classics brought to life on the PC!
As mentioned above, if you already have the ST version of this demo... copy
The Snowman.exe into the directory. This demo works with the original
Atari ST files!
** HUGE RESPECT to the original coders!!!
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Original Readme Follows
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Welcome to The Snowman, a Christmas demo brought to you directly from the
Atari Land of Plenty -- West Germany.
This demo was created using ST Replay 4 to digitize the music and The Grabber
to digitize and animate the graphics.
This demo requires a color monitor, double-sided drive and at least one meg of
memory to run. YOU MUST FORMAT THE DISK TO 82 TRACK, 10 SECTORS as the files
are over 800K when unarced.
Simply unarc to the double sided disk, create an AUTO folder and copy RUN.PRG
into this folder. Then, simply reboot with your newly-created disk in
Drive A.
Brought to you from:
ST VISION International User Group
Postfach 1651
D-6070 LANGEN
West Germany
via
Unicorn Publications (makers of Atari Interface Magazine)
3487 Braeburn Circle
Ann Arbor, MI 48108
(313) 973-8825
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