updated 2001/07/12
Computerwelt 2
(aka GBAwelt)

Computerwelt 2

History
The idea of this demo dates from the days when I had an Amiga.I'm sure anybody can  remember a demodisk by Wild Copper where a text did a "circular scrolling". I've spent ages wondering how they did it and one day I found ! I did my own (lame) version of this demo and tried to improve it a bit. I added a planet and the text went elliptic (instead of circular).

The GBA version
A few years later I discovered the Gameboy Advance. A demo competition was initiated by Subice, the ADD. I decided to adapt my old Amiga demo to the GBA. It was a good exercise, I've learnt many things. The algorithms are very different, as the Amiga works with bitplanes and the GBA works with pixel. The final version must be about 50 times faster than the first one... It was a good test to have a rough estimation of the power of the GBA.

Here are some tech facts for those who are interested:

The demo is written in C and compiled to Thumb with the ARM SDT 250 eval.
It worked perfect, at 60 FPS,  the first time I could check it on a real GBA :-)
The display loop runs in fast WRAM, while it uses some data i had to leave in slow RAM and ROM. Note that if I had left the code in ROM, it would be kind of twice slower at best...
No DMA, no interrupt.
Press right trigger to view CPU charge. I could make it faster but as it's already perfectly smooth I don't care. Time to do something else !
Wait for the text to finish for greatest madness.
Download
Considering that the ADD seems to be cancelled,or at least delayed for a few months, I'll give away my demo.
Well, here it is :)
I haven't included the sources yet, one day maybe...

IMPORTANT UPDATE !!!
Well, some of you may have noticed I'm a big lamer... or blind... I've realized today the demo ran only at 30 FPS ! A few hours of hard work later, I've now reached a perfect 60 FPS. I do now compile to Arm and not Thumb, which makes the code located in WRAM even faster.
What's cool is that the source code is much smaller and cleaner. The timing also varies much less than with the previous version.
What sucks is that it's now a bit too fast and it's hard to read the text *<8o)
Anyway, here's the new version if you want to train your eyeballs... Again, press the right trigger, the tiny little green band shows the few milliseconds that save me... a close shave...
 

Thanks
I would like to thank a few people who made this demo possible:

DevPsx
WayneKerr
Eloist
Lemon
Joat
Marat
Wild Copper
D.O.C.
Visoly
and of course ARM and Nintendo.
Read the scrolltext for more greetz ! Feedbacks welcome.


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