Відео

Amiga copper is 8px (with 4px precision) and it can use all colours. The ST needs 12px to do the same: move.w (an)+,(an). By lowering the number of colours (per scanline) it goes down to 8px as well: move.w register,(an). However, using the 68000 in the ST we can do some instruction pairing and get single columns of colours to 4px, this demo is using that trick quite a bit - it's limited but the overall look/impression is absolutely improved.

@@evldhs yes this was exactly this that baffled me no started to think how this could had been done on Amiga. If one could feed color reg with copper and cpu at same time but then I though that the bus must be blocked and timing issues. (Just pixel art guy with kind of tech knowledge so not a coder) Like sure one can do this “fake4px” with interlaced 4px cycle offset but it’s stellar really 8px. Works nice with soft stuff but for stuff like the logo not. Especially the first logo blew me away resolution wise! 💚💚💚 Btw are you the coder? (If so what is your scene name)

@@litjellyfish Evldhs is Evil from DHS. ;-) SPKR from SMFX did the code in this demo.

Not to forget Tom/SMFX, who did most of the code for the demo! 🙂

@@earx23 thanks. Should had been able to crack that one ;) Tbh I am totally lost and newbie regarding the Atari Scene. Even the Amiga scene I am pretty lost regarding tbh. Came back like three years ago from 30yearish year pause and so many new names and groups (and prods to catch up on) :) Also I must say sometimes I can be almost more impressed on some spectrum / Atari / C64 stuff. And it’s cool when some Atari coder comes and smack the fingers on Amiga coders. I mean even back in early 90s I know Amiga coders feared the 68000 skills of Atari coders even if they did not want to admit it :p Who are you btw? Haha / Iridon DCS/Nah-kolor

Yes they were.

It is perfectly fine to use handmade graphics stored in memory. Just not in bitplane (pixel) format. Everything is displayed using rasters of some sort, similar to how oldschool plasmas are done on ST. Everyone in the compo dug deep and went further than most have done before. Big <3 to all participants :)

Ofc it's possible to do pixel graphics in this mode, you just have to use a 8x1 canvas, because this is (normally) the minimum size of a '0bl pixel'.

@@evldhs sick, verynice

Not for this competition, there were no pixels allowed. Only background colour. The tech you talk of is used in other demos where it combines bitplane data and rapid colour switches. For example our demo from 2020: ua-cam.com/video/lm7D8gmEKJI/v-deo.html (spider screen, tunnel and rotozoom)

@@evldhs Yes, I did understand the competition rules :) I just was wondering how far this could be pushed. (4pixels?) Awesome!

It's smashing the background colour a bit yes. But no the black lines are not to save CPU. Just a lame coder doing a black line instead of special case loop (taken dbra is 4 cycles less blabla).

@@evldhs And still enough CPU time for some music and effects. Impressive!

A single register move to the colour register is 8 cycles, and when timing it's one cycle per pixel. There is also the ability to use a 12 cycle instruction to shift everything by 4 pixels.

ST, the compo was for 1 MB ST.

Ja, verkligen... och så fina de var! 🙂

@@dhedberg Och fortiga!!

@@PeranMe Ja, fortiga, men ändå städade! Skötsamma prickar!

Well there's no interlace here, but I guess you mean the empty scanlines in some of the screens. That's indeed to keep the stuff moving at 50 fps. Remember it's plain ST so no scanline addressing trickery possible (like on STe and other machines).

You're just need to rotate one point, others are obtained by symetry and interpolation. But you need an efficient projection routine.

I wrote a fullscreen orutine which can do muls. Never used it because it is way too slow.