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Old 27 January 2012, 21:01   #41
Photon's Avatar
Join Date: Nov 2004
Location: Hult / Sweden
Posts: 4,296
Originally Posted by Mrs Beanbag View Post
I think a real starfield is possible using the blitter. The blitter can plot a lot of points in a frame by clever use of line mode
Stopped reading here. Did you notice the filled circles in the starfield? Inventing effects is not about could and probably. It's about constantly testing ideas and seeing all but a few fail. Hehe. Apart from this, line mode is very slow on OCS and AGA, and no CPU can make it faster, so I can save you one test.

Why not enlighten people by showing what can be done instead? It's basically demo making in a nutshell - the opposite of making speculations.

Sine in 4 blits per 16px was done in summer of 1990. Perhaps before. I say no more.


Let me make some speculations that are more fruitful I think.

I've seen some porridge-pixel handcammed "newly rediscovered" old demos, one of them was very impressive but turned out to be an anim played from harddisk, ie. not possible on stock A500/1MB. OCS is really quite capable if given the same CPU, memory and storage options usually available for AGA/060, but that would not really be a sane platform Anyway, AGA just doubles the colors and palette depth and does nothing else.

It's impossible to tell anything definite from the potato-shaped video. But a very educated guess as to how it would be done on OCS is:

1) Background is basically the highlight of this intro (unless it looks like crap when run). Looks like 1 bitplane+vertical coppershade, leaving 3 for sine+buffershadows and 1 for the copperbars covering bg (you can also shuffle colors and decrease BPLCON by 1, but since 1 shadowbuffer has the same color as the copperbars it's the former). Even with this video quality, I can judge that the bg is not an anim that repeats. Odds are not bad that it's real circular 1bpl vectorbobs on a repeating star-anim - and of course you would see that instantly on a real Amiga instead of on crappy video. That's why videos of demos don't count.

2) The rest is no problem. The framerate and resolution of the sine non-scroller is impossible to judge, but 50 fps/1px is no problem. No offset on the shadows and no scrolling, but that's not a problem either. The sinebuffer is quite small so no clearing trick needed.

Horizontally shaded copperbars are pretty nice but even with 6 bitplanes they would shade nicely at 16px horiz resolution, in fact there are so few colorsteps between green and cyan that the visible resolution would have to be made coarser, 32px or higher.

Gotta agree with Stingray's "nothing special" this time. I think you get a bit fooled by that one perhaps doesn't really see it properly with the low video quality and assume it's a bad video of a flawlessly running demo, which it could indeed be, and which is understandable. But what you see is possible without tricks, and of course it's possible on OCS. So suspecting the source is not necessary in this case.

Infobox on YT apologized for the music but apart from lacking any memorable melody I think the sound overall was nice and Kraftwerkish and adds to the intro

If someone finds this, remember that BitWorld are keen on archiving it for the future! We have 29000 demos and counting...

We wouldn't mind a newly made OCS intro, but of course if it's some Python+SDL test code you'd have to go elsewhere

Last edited by Photon; 27 January 2012 at 21:47.
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