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Demos Amiga Demoscene Archive Forum / Coding / Nexus 7 Raytrace Scroller

 

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Toffeeman
Member
#1 - Posted: 31 Aug 2006 00:21
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You guys have been excellent in telling me how some demo effects work.

So you know my next question ;0) How did this impressive scroller work at 50hz on a stock A1200 ? I can see the vertical lines of the text are just copied down from the font but how did he texture map the font in the first place ? I'm guessing theres some serious precalcing/predrawn stuff involved.

Thanks
sp_
Member
#2 - Posted: 15 Sep 2006 00:54 - Edited
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Here is my guess.
(I haven't seen the effect in many years)

1, Hardware scrolling pr vertical lines in different speeds using the copper with a static looping txture.

2. The rendered scroller is in 1 bitplane probobly using the cpu to plot the outline of the font and blitter to fill.

3. The "3d effect" is done by setting the modulo to -80 (320/80) in the copper in the even bitplanes.

4. Probobly dual playfield mode or a clever palette settings.

This can be done on the a500..
sp_
Member
#3 - Posted: 15 Sep 2006 12:30
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probobly point 2. is even simpler.

2. The rendered scroller is in 1 bitplane using scroll registers and moving 1 letter at a time.

The hardware scroll registers on aga have bether precition than on ecs. So you are able to scroll in a higher resolution. So the effect might look smoother on AGA than ECS chipset.
sp_
Member
#4 - Posted: 21 Sep 2006 17:56
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maybe not hardware scrolling. I rewatched the effect now. probobly a 3 bitplane generated txturemap anim with a 1 bpl realtime 3d font plotter.. Many ways to code this.
z5_
Member
#5 - Posted: 1 Feb 2007 13:02
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@sp_:
Hyde commented on Bitfellas that you were spot on in your guess on how the scroller was done :o)
Toffeeman
Member
#6 - Posted: 1 Feb 2007 20:10
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Can you post a link please z5 ?
z5_
Member
#7 - Posted: 1 Feb 2007 20:28
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bitfellas mindcandy thread see last post by Hyde where he links to this thread.

 

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A.D.A. Amiga Demoscene Archive, Version 3.0