zajc information 47 glöps
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- level: user
- personal:
- first name: Marin
- last name: Saric
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- demozoo: profile
- 4k Amiga OCS/ECS 4 seasons by Binary
- What an incredible 4k intro for an OCS Amiga 500! This looked beyond awesome on the big screen!
Voxels are a rare sight on A500, and 4k voxels are unheard of.
Technically, the fact that the landscape is tilting and that there's some serious color management makes an impressive 4k even more impressive, not to mention the custom replay routine, loader, etc. Rock on! - rulezadded on the 2024-04-03 14:56:24
- demo Amiga OCS/ECS sanity is dead by Rebels & Sanity
- Loving the drama, a great bit of scene history!
The whole text makes sense -- people who contribute to demoscene (gfx, music, code) wanted to kick others out.
Except... why would Mr. Pet, one of the demoscenes awesomest coders of all time get so angry?
You would think he would not just be informed by phone about this as without Mr. Pet there would be no Sanity as we have experienced... - rulezadded on the 2024-02-19 05:47:12
- 40k Amiga OCS/ECS Anniversary by Lazy Bones
- Huge thumbs up here for independently discovering (*), implementing and then popularizing the OCS 7-bitplane trick. A majority of rotozoomers on OCS today use some variation of this trick. Coyote did a write up that was posted on FIDONet and Usenet (comp.sys.amiga.misc and alt.sys.amiga.demos ).
The write up was so incredibly hard to find that I put up a pastebin here and also in the demozoo nfo here.
If anyone has a good place to mirror this, I think it is an little gem of Amiga democoding history.
Coyote/Lazybones discovered this trick in May 1993, probably during all-out coding for Move Any Mountain, to make it to the Revenge of Mr. Party 3
In his own words, from the textfile:
Quote:When you fill register $dff100 with value which has the number of
bitplanes specified as 7 (lo-res) something strange is going on. On screen
you will notice only 4 bitplanes but further checking has revealed to me
that there are still some differences from usual 4 bitplane mode.
When 7 bitplanes are 'opened' color index is 6 bit wide. (It would
be better to say 5 bit wide with halfbright enabled.) First 4 bits of color
index is fetched from BPL1DAT-BPL4DAT ($110 through $116) registers which
are filled through DMA channels. 5th and 6th bit of color index is taken
from BPL5DAT and BPL6DAT which are NOT disturbed by DMA. In other words,
you can put in, i.e. BPL5DAT value $aaaa and you will get at odd pixels on
screen color which is indexed as $10 trough $1f. (Same is with BPL6DAT,
value $aaaa would give you halfbright odd pixels.)
The benefit of this is accesing of all colors ($00-$1f) without
loosing speed of copper.
For mere mortals like me just getting into the Amiga: if you set BPLCON0 ($DFF100) to, say, $7200, you actually get the full EHB colorpalette (32 colors + 32 halfbrite colors), while Agnus occupies only 4 DMA slots to copy bitplanes 0 to 3. Only 4 DMA slots instead of 6 means your code runs faster during the time Agnus is fetching the bitplanes to display them. Four bitplanes gets you 16 colors, but then you can poke BPL5DAT and BPL6DAT via copper or cpu and actually get stuff on screen to use the extra 48 colors.
In practice, a standard 320x256 screen in 6 bitplanes (EHB or HAM mode) will have ~21% fewer words of chip/slow memory bus available for Amiga each 50Hz frame than the usual 16 color 4 bitplane mode (37608 vs 47848), once you take out some bandwidth for audio and memory refresh and count in all the bandwidth you get when Agnus is not working on displaying your gfx. Getting 21% more chip bus bandwidth might not seem like a lot, but even the CPU has to use this bandwidth to literally fetch your beautiful code, so in practice the slowdown is dramatic.
Poking BPL5DAT and BPL6DAT is slower than letting Agnus use DMA to fetch it. But again, you only do it when you need to, such as only poking a word per line for a cool background pattern ..
Or you use it to make your rotozoomer have 3x3 pixel elements as Coyote himself wrote in this post on EAB more than 15 years ago.
Cool stuff, especially when you think some teenager in this village, population 184 people, figured this out in 1993 with no modem and no access to Internet...
[*] Footnote: Stingray insightfully pointed out that Brainwalker/Skidrow first used this trick in his cool Megaroids intro in June 1991. In that intro the use-case is generating some dithering noise, whereas Coyote used it thoroughly in a rotozoomer and did a write up about it. - rulezadded on the 2024-02-07 10:05:52
- demo Amiga OCS/ECS Negative FX by Reality
- Isn't the Amiga crowd on here more often than not wistfully thinking about what could have been? Negative FX epitomizes that.
Why? Negative FX was the release everyone was anticipating at the Revenge of Mr. Party 3 in 1993.
Everyone who mattered in the Croatian Amiga scene was there. Alas, it was not meant to be, the trackloader just would not work and this became a stuff of legends (translation from a 24 year old usenet post): "The Reality group was the best - Bonefish and Hitcher code a killer demo and then at the party cannot get the trackloader working - and there you go Reality falls to pieces" and then later in the thread "Talk no more, getting tears in my eyes.. By the way, Bonefish ruled, he would put together incredible stuff"
In the end "Made in Croatia" by Binary won, and deservedly so. This was the peak year of the Croatian Amiga scene, so on the same compo you had Move any Mountain by far the first voxel landscape on Amiga 500, and The Image which, among other things, featured several environment mapped spheres..
That would be the end of this urban legend.. And you know how urban legends are like, yes, yes, he just finished realtime raytracing on C64 and the his dog ate the floppy, sure.... until bonefish awoke from hybernation and finished the thing in 2014, 21 years later. Yes, it was real, yes the demoscene missed out.
This was in the first half of 1993. But imagine how strong the compo would be if this was also one of the prods released there..
The music by Pete (Petar Dundov) is exquisite. Pete later became a a techno DJ and producer well known far outside of Croatia.. Sven Väth, Laurent Garnier, Josh Wink all have him on their playlists
As far as code, there is a lot of codeporn in here. From the initial zoom and copperchunky rotozoom, to super fast rotating landscape and generally very fast dot effects.. and of course the traveling 3d checkerboard is so nice to look at..
Negative FX could have easily been one of the best demos of 1993 and an evergreen on Amiga OCS. At least it's not an urban legend anymore and we get to enjoy it, many decades later... - rulezadded on the 2024-02-06 11:07:46
- 40k Amiga OCS/ECS 40k by Polaris
- Agree! There's a lot of atypical code here. The 1-bitplane dithered flat shading 3d routine , fast blitter-warping effects, shaded checkerboard.. Even the cube has a wireframe outline...
- rulezadded on the 2024-02-06 09:12:58
- 40k Amiga OCS/ECS Desire FM by Desire [web]
- Possibly the fastest C2P effects Amiga 500 has seen, sizecoded into 40k!! By far the biggest surprise of Gerp 2024! Fast paced, short (makes you want to watch it over and over) and so many cool effects that are extremely high performance on OCS.
Incredibly fast environment mapped sphere at 25-30 seconds in, super fast rotozoomer, morphing 3d dots (lots of them) and a cityscape that is faster and more detailed than the legendary one in Pygymy Projects / Extension
You should have seen the audience reaction live -- this is an intro no one expected!!! Eerily silent for some of the coolest effects, and then when everyone recovered from shock, applause, whistles and shouting at the end :)
Not to forget, uplifting fast paced music that matched well and nice graphics that were somehow also packed in 40k.
People were walking over to congratulate Gigabates afterwards. To me, this was the proof that the Amiga OCS scene is reviving in 2024. - rulezadded on the 2024-02-04 12:06:03
account created on the 2022-11-12 13:58:18