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Overdrive 2 Effect Write-Up: Pushing Polygons on the Mega Drive

category: code [glöplog]
 
It took a bit longer than anticipated, but I finally finished the write-up of the effect I did for Overdrive 2: https://jix.one/pushing-polygons-on-the-mega-drive/
added on the 2017-05-16 21:12:57 by jix jix
awesome stuff
added on the 2017-05-16 21:28:52 by psenough psenough
Good work. Thanks for sharing.
added on the 2017-05-17 06:52:14 by Adok Adok
wow, great writeup!
added on the 2017-05-17 07:00:07 by wbc\\bz7 wbc\\bz7
Thanks!
added on the 2017-05-17 10:26:08 by sol_hsa sol_hsa
I wonder if the "polygon codec" routines on C64 (for example) work similarly, and what are the differences?

Demos that come to mind:
- Wok Zombie by FLT
- Sphaeristerium by Horizon & Triad & Instinct
- Second Reality by Smash Design
If I´m not totally wrong the mentioned C64 demos all use somehow lossless or lossy compressed precalced chars/tiles. No polygon drawing is happening there.

The C64-"engine" closest to the one described above is used in the first screen of Fantasmolytic

The differences are:

- The polygon coverage handling is done realtime, because it would be hard to precalc that, if you want to drive the movement of the buildings by music. Algo behind it is close to what Doom/DukeNukem do on PC.
- The C64 Version works 90° rotated. The "fringe"-buffer is not left-right oriented, but top-down. Because the C64 multicolor pixels have 2x1 aspect-ratio. So line interpolation and coverage handling is done in half the resolution.
added on the 2017-05-17 13:49:00 by axis^oxy axis^oxy
In Wok Zombie the frames are stored as lines and dots, and then its an eor filler.
BB Image
added on the 2017-05-17 21:41:47 by hollowman hollowman
Thanks for sharing, that's a really informative and detailed write up, and i was thinking that it can be applied to any old-skool system (tile based, bitmapped or whatever)
added on the 2017-05-17 21:57:39 by DanLemon DanLemon
Now just want to know how all the crazy effects in Overdrive II (zooming plasma, tilting greets etc..) were done :D
added on the 2017-05-17 21:58:20 by DanLemon DanLemon
Maybe the time has come to precalc the vertex transform, culling and what will fit in a reasonable amount of memory on Amiga aswell now. Those metaballs on the recent bomb demo made me want to precalc the shit out of those metaball vertices. Vertex compression is also a noble art.
added on the 2017-05-18 13:17:27 by rloaderro rloaderro
Err.. yes I wanted to say thanks for the great article!
added on the 2017-05-18 13:46:03 by rloaderro rloaderro
Thanks for the writeup!
added on the 2017-05-22 23:00:37 by Sdw Sdw

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