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cobbpg
Registered: Jan 2022
Posts: 6 |
Earliest examples of EOR fillers?
What are the earliest known instances of vertical EOR fill routines either in demos or in games? I know that at least Stunt Car Racer uses the technique to draw the sky under the opponent four pixels at a time. |
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trident
Registered: May 2002
Posts: 91 |
very cool! so that may be the first instance of an eor filler in a c64 demo!
@mixer: do you have any insight into the thinking behind bx's code? such as if the idea or incorporating the eor fill came from experience with amiga coding? |
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Ninja
Registered: Jan 2002
Posts: 411 |
trident: read the production notes of that demo |
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Mixer
Registered: Apr 2008
Posts: 443 |
@trident, the production notes have some details on it as Ninja mentioned. |
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trident
Registered: May 2002
Posts: 91 |
awesome! this is the relevant part from the production notes:
> Idea for EOR filler was inveted by CLF when he was doing his Amiga 3d routines.
so i guess that confirms the hypothesis that the eor filler technique that got popular in c64 demos originated with the amiga's blitter fill techniques.
the eor fill technique from stunt car racer was quite a bit earlier though, but since the game was released on the amiga as well as the c64, it isn't impossible that the amiga inspired the c64 eor fill in that case as well.
does anyone know where the amiga blitter designers may have picked up idea for the eor fill? it feels like there should be a siggraph paper from the 1970s that pioneered it, but they can be difficult to find since the early terminology wasn't always consistent with later uses. |
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Mixer
Registered: Apr 2008
Posts: 443 |
A lot of the CG stuff was imagined or demonstrated late 60's and early 70's(cool demos in Youtube), but I would not be surprised if the origins of rasterization goes back all the way to the time of the loom. |
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cobbpg
Registered: Jan 2022
Posts: 6 |
As far as I know, Stunt Car Racer was developed on the C64 first, then Crammond did the Amiga port, which renders the world in a completely different way. It's possible that knowing about the blitter was an inspiration, but in the end there are many innovations in that engine that are a lot more complex than the EOR trick, so he could have just figured it out in isolation to solve that particular problem.
One very relevant paper I found was "The Edge Flag Algorithm—A Fill Method for Raster Scan Displays" (Ackland and Weste, 1981), which basically describes the idea of plotting edges with just one pixel per scanline, then applying the EOR transformation horizontally. Apparently they even built a hardware implementation.
All earlier papers I could find with a cursory search usually talk about other methods (mostly generating spans from ordered edges or flood filling variants). The above paper does refer to an earlier publication discussing "parity check" algorithms, but those are also more complex and have to look at other neighbours as well to handle various corner cases. |
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Mixer
Registered: Apr 2008
Posts: 443 |
Those Agkland and Weste seem to be Bell Labs employees, so this may be relevant:
https://www.youtube.com/watch?v=98EyJG-xmu4 |
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trident
Registered: May 2002
Posts: 91 |
that ackland and weste paper definitely sounds like it could be the original origin! unfortunately i can't seem to find a pdf copy right now (and don't have ieee xplore access either). |
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ChristopherJam
Registered: Aug 2004
Posts: 1402 |
Effluvium was very late (2004), but it does use a horizontal EOR fill, which apparently isn't the "usual" way to do it - so I've no idea how much prior art there is there. |
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cobbpg
Registered: Jan 2022
Posts: 6 |
Quoting tridentthat ackland and weste paper definitely sounds like it could be the original origin! unfortunately i can't seem to find a pdf copy right now (and don't have ieee xplore access either).
Yeah, I could only find the paper through the popular alternative route...
So we have one example of monochrome fill from as early as 1989, and multicolour with glenz from 1992. I wonder how far back the latter idea goes. Is megademo 8 the earliest one from the Amiga scene? |
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