Visdom II by JAC! [web]
screenshot added by JAC! on 2012-03-13 20:48:55
platform :
type :
release date : march 1993
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popularity : 51%
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alltime top: #17851
added on the 2012-03-13 20:48:55 by JAC! JAC!

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On Friday, this demo is going to be 19 years old. That's why I decided to finally release the fixed single file version I promised in 1993 :-)

It was created during 6 months or military service isolation in Karlsruhe using my Amiga 500 cross development system and my Atari XL stored in big wooden box. An extraordinary situation which made this demo possible. I still love the raster split logo, the wiggle, impres and the cool tune by Karsten Schmidt. All effects run at full 50 FPS, so you best watch it in emu or on the real iron.

- Raster Split Logo - 9 colors out of 128 at 160 pixels per line, 60 lines high, animated in waves
- Wiggle - 32 colors out of 256 at 80 pixels per line, 128 lines high, sin sin x movement
- ImpRes - 16 colors out of 128 at 160 pixels per line, 128 lines high, sin x/sin y movement

This was the first demo to exploit the GTIA bug which became the basis for many new graphics modes. Apart from Silly Things, this is the demo I am >>really<< proud of. Those were the days!
added on the 2012-03-13 20:49:43 by JAC! JAC!
Do you have a handy link to somewhere that describes the GTIA bug (especially if it will make sense to someone who never coded on the Atari 8bits :)? I love reading that kind of stuff.
added on the 2012-03-13 20:53:19 by xeron xeron
Of course: The GITA bug is a half pixel right shift which appears in mode 10 (lores with indexed palette) due to the additional delay caused by the palette lookup. It allows interlaced modes which mix 16 colors/16|8 luminances at virtually 160px. How I found it is described here. The graphics modes which are built on it are described in HIP FAQ and here.
added on the 2012-03-13 21:43:04 by JAC! JAC!
early atari 8bit love needs a thumb.
rulez added on the 2012-03-14 10:40:56 by wysiwtf wysiwtf
Cute and colorful demo, and the story about finding the bug was a fun read too
rulez added on the 2012-03-14 10:46:45 by britelite britelite
Cool story, bro!
rulez added on the 2012-03-14 13:30:14 by rez rez
Very colourfull!
rulez added on the 2012-03-14 14:02:04 by baah baah
Army Coding!
rulez added on the 2012-03-14 14:13:17 by Optimus Optimus
rulez added on the 2012-03-14 14:16:06 by Pandafox Pandafox
rulez added on the 2012-03-14 21:33:45 by ltk_tscc ltk_tscc
Nice and colorfull. Looks more like an 80s Amiga Demo than an Atari XL!
rulez added on the 2012-03-14 23:09:41 by RA RA
Jesus... 1996 when I was putting together the HIP FAQ??? I am getting old.

This part of the Halle Project Mega Demo was a big inspiration for my 800 coding. Jac produced such a fluent demo with little details here and there and is polished. good to see the single part released and with complete source code. it seems that military service is very "time consuming" ;)

rulez added on the 2012-03-16 14:27:06 by Heaven/TQA Heaven/TQA
rulez added on the 2015-08-02 11:39:02 by miker miker

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