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Forums > C64 Coding > Earliest examples of EOR fillers?
2024-06-20 21:02
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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2024-06-23 19:29
Mixer

Registered: Apr 2008
Posts: 443
@trident, the production notes have some details on it as Ninja mentioned.
2024-06-23 19:49
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.
2024-06-23 20:43
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.
2024-06-23 20:52
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.
2024-06-23 20:57
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
2024-06-24 14:15
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).
2024-06-24 15:20
ChristopherJam

Registered: Aug 2004
Posts: 1403
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.
2024-06-24 18:20
cobbpg

Registered: Jan 2022
Posts: 6
Quoting trident
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).


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?
2024-06-24 18:31
Bansai

Registered: Feb 2023
Posts: 40
Good youtube link. Neil Weste wrote this book that I remember from my undergrad days, so he was probably involved with the hardware design as well. Those guys in the research labs back then had their fingers in everything.

https://www.amazon.com/Principles-CMOS-VLSI-Design-Weste/dp/020..
2024-06-24 19:31
Jetboy

Registered: Jul 2006
Posts: 265
Quote: Quoting trident
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).


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?


Amiga Demoscene Archive lists Wild Copper as the only demo released in 1988
https://ada.untergrund.net/?p=demos&y=1988&c=0&h=0&v=0
So according to them it is the oldest. Is it? Definitely one of the first i have seen. Megademo 8 was released in 1990, so there were some major demos released prior to it, ie. RSI Megademo, Budbrains, etc.

Of course very first was BOING! But it was made by the Amiga Developers - so i'm not sure if it qualifies as Amiga scene production, but maybe it should?

As for EOR fillers, i'm not sure who was first, but in the second half of 90's it was a common knowledge that EORfill is the way.
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