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Old 22 October 2017, 19:13   #1
Blueberry
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Checkerboard Challenge

At Revision 2017, we were blessed with the SEGA Mega Drive demo Overdrive 2 by Titan, which among other things contains a very nice checkerboard effect ( [ Show youtube player ]) with (as far as I can tell) 8 zooming layers.

It occurred to me that this ought to have been a classic record-beating effect on the Amiga - who can make one with the most simultaneously visible layers?

But this doesn't seem to be the case. The best one I could find is in the relatively recent 15 Years of Fame by Up Rough. It ( [ Show youtube player ]) has 4 layers, but is not fullscreen. Cyberlogik by Alcatraz and TRSI contains a nice, 3-layer one ( [ Show youtube player ]), but this is an AGA demo. Groovy! by Lemon. has a 2-layer, rotated one ( [ Show youtube player ]).

With the Amiga's 6 bitplanes, you would think that at least 6 layers should be achievable, right?

I discussed the situation with Britelite, and we agreed that this needs to be rectified. Hence this challenge. The rules are:

- Minimum resolution 320 x 256.
- 50 fps on Amiga 500 with 512k chip ram and 512k slow ram.
- Single file, i.e. no streaming of data from disk.
- Layers move independently of each other in both X and Y.
- Layers move fully in Z (zoom), but not necessarily independently.
- Layers are able to have colors that are all different.

The challenge showdown is set to take place at Gerp 2018. You are of course welcome to meet the challenge by releasing a checkerboard zoomer later on, but if you want your release to have the full novelty factor and be part of the main showdown, Gerp is the place.

Last edited by Blueberry; 22 October 2017 at 20:31. Reason: Youtube links don't show link text
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Old 23 October 2017, 00:43   #2
Galahad/FLT
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hmmmmmmmm
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Old 26 October 2017, 01:15   #3
coder76
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Nice demo! Many people have wondered what are the advantages with a planar display.. well here is one, which you don't get with a chunky display. Namely, you can have each bitplane operate independently of each other. In this case you need to copy graphics only into a single bitplane for each layer, and arrange the palette properly so that overlaps dont produce wrong color on display. There is a reduction in usable colors of course, with 4 bitplanes, it's only 4 colors, but more, if you want bitplane overlaps to show in various colors.

With AGA, you can produce even better effects, as there is 8 planes available. And there is no need to use precisely 8 layers with 8 planes, but one can use bitplane groups, like 2+1+5, and have a various amount of layers with various amount of colors.
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Old 26 October 2017, 01:18   #4
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Quote:
Originally Posted by coder76 View Post
Nice demo! Many people have wondered what are the advantages with a planar display.. well here is one, which you don't get with a chunky display. Namely, you can have each bitplane operate independently of each other. In this case you need to copy graphics only into a single bitplane for each layer, and arrange the palette properly so that overlaps dont produce wrong color on display. There is a reduction in usable colors of course, with 4 bitplanes, it's only 4 colors, but more, if you want bitplane overlaps to show in various colors.

With AGA, you can produce even better effects, as there is 8 planes available. And there is no need to use precisely 8 layers with 8 planes, but one can use bitplane groups, like 2+1+5, and have a various amount of layers with various amount of colors.
And a sprite layer or two on AGA as well, 64wide sprites
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