3D Demo Preview screen

[ComSoft6128]

French demo likely from the early nineties.
Just the great opening screen here, unfortunately the rest of the demo causes the OSSC to lose sync and no sync = no video.
I really like this screen & the accompanying music and that's why you are seeing it.

The full demo came in for some criticism at Pouet.net:
https://www.pouet.net/prod.php?which=1836

Links:
https://cpcrulez.fr/demostestDO_3d_demo_preview.htm
https://www.cpc-power.com/index.php?page=detail&num=7421
https://demozoo.org/groups/8318/

Not emulated - original hardware and software.
Please note that  the aspect ratio for this YouTube video is 16:9 but the CPC monitor
has an aspect ratio of 4:3 so you may wish to adjust your viewing device accordingly.

[Gryzor]

Now I wanna see the whole thing 

I don't understand the style of criticism; indeed maybe it's not a great demo, but those hostile comments? I don't get it. 

[MaV]

I love the "pre-calculated!" bit. It gets me every time. As if the CPC or any other 8 bit machine was capable of realtime 50Hz vector graphics. Either it's impressive and precalculated or it is a few pixels in realtime. The whole demo scene does it like that. Choose your poison.

[Optimus]

I used to like it at the time, for the starting screen, the presentation with the rasters and big messages, then it ended up with a small amount of dots in a loop, as people say precalcualted. With such amount one can do realtime for sure, we have seen in few other demos.

[martin464]

Mav, what about that spinning gameboy on the 3d bits demo and the spinning bat logo, that's another technique - drive CRTC directly bypass screen ram. wish i could see some source code for that. does this count as precalculated if they're using a template for the image? i just mean, isn't this a technique different from the usual ones? That bat logo and gameboy blew me away wish they do more like this

[tronic]

Mav, what about that spinning gameboy on the 3d bits demo and the spinning bat logo, that's another technique - drive CRTC directly bypass screen ram. wish i could see some source code for that. does this count as precalculated if they're using a template for the image? i just mean, isn't this a technique different from the usual ones? That bat logo and gameboy blew me away wish they do more like this

Hi,
Already posted it somewhere else but...
See here some very basic tests (and not exhaustive...) on this "almost same" technical... :
https://z80live.amstrad.info/edit/GQufxj9uuQjjczmfn
https://z80live.amstrad.info/edit/EenmF7REYnmg2KhMF
https://z80live.amstrad.info/edit/wyyjumueWEJkeEArc
https://z80live.amstrad.info/edit/unJysTiKoC3S3KJc4
https://z80live.amstrad.info/edit/nLQnhzucb5iuNL2Ag

And some tiny-tools/explanations/source-code to do it by yourself, available there :
https://uptobox.com/kb6ujgg9fegk

+++
Tronic/GPA.

[martin464]

thanks tronic just what i was looking for

ps i suppose this method is always 50 FPS, I mean you can't stop once you started or the image will fade, or could you only write it every 'n' times a second without flickering? then you'd have more chance to do other stuff in between..?

[martin464]

um, can i ask something, like how does this actually work?

i'm not sure if it's simply drawing the frames by changing video start/end ram address (cause i see the frames are in ram)
or is it doing something more?

cause I see the CRTC and Gate Array get outed to a lot as well (bank switching or video related?), and there's lots of ram copying going on
i would say i was close to getting it but actually... no i'm not!

[MaV]

Mav, what about that spinning gameboy on the 3d bits demo and the spinning bat logo, that's another technique - drive CRTC directly bypass screen ram. wish i could see some source code for that. does this count as precalculated if they're using a template for the image? i just mean, isn't this a technique different from the usual ones? That bat logo and gameboy blew me away wish they do more like this

Late answer. For some reason the alert went off just today (or I was blind the whole time.)

My comment was a bit out of context. You need to read the pouet thread to understand what Gryzor above my post talks about, because there is criticism in the pouet thread about the demo, and I refer to one specific comment on pouet that specifically calls out the precalculation as if this were a bad thing. Every time I'm reading something like that I wonder if these guys have any idea what it takes to do anything like that in realtime.

I'm fine with anything that gives the illusion that a computer that can't even fill the screen brute force in one frame is capable of much more. Every technique that can achieve that is good.

[pelrun]

Some people in the demoscene have a rigid idea of what a "real" demo is and anything else is lame and should be banned. Mostly I think that's because they liked specific demos which didn't win compos and are trying to come up with justifications why the winning demos didn't deserve it.

Of course, the best demos all cheat, that's what makes them more than just a exercise in Turing completeness. And compos aren't objective measures of merit anyway - my local parties who accept remote entries always get multiple serious entries from sceners in the EU who think it'll be easier to get a 1st here... only to be knocked out by a troll party demo made by the locals on the bus on the way to the venue.

I learned to ignore compos that claim to be "objective" when I watched the Meteoriks judges tie themselves in knots trying to justify overlooking Logon's Run in the outstanding technical category - it's clear they knew it was wrong but they wanted the shiny Titan demo to get the win.

[Anthony Flack]

Haha, "cheating". The whole point of a demo is to use clever tricks! Do people expect actual magic?

Yeah, I'm not impressed unless you do something that's outright impossible.