pouët.net

http://www.pouet.net/prod.php?which=60835

What's the name of this effect, the effect shown in the screen-shot?

thanks

precalculated scanline.

I don't know, maybe X-rotator texture or something.

is it really precalculated?

raycasting

barrel rotator?

scanline textured skit-box rotator?

mode7?

scanline scalers, dunno

http://www.pouet.net/prod.php?which=1418

Absolutely not. A "mode 7" effect is when you have a background layer which you can rotate and scale freely around any angle or scale.

This effect, whatever it's called, if it even has a specific name that isn't just a technical explanation of what is, consists of adjusting just the y and optionally x position of a BG plane, without rotation or scaling. (and maaaaybe some vertical compression by mid-scanline X scroll register writes...)
Obviously, the BG plane needs to be filled with appropriate data for the effect to work.

This effect also exists in
Deus Ex Machina by Crest & Oxyron (C64, pouët, lazy yt link)
We Are New by Fairlight (C64, 2010, pouët, lazy yt link)
Cenotaph by Dual Crew and Shining (GBC, 2012, pouët, lazy yt link)

And, I'm sure, others.

Here's what the BG layer contains in Cenotaph to give an idea. The rest of the effect consists of scrolling and palette changes.



It would be interesting to find the earliest use of this type of effect, and if indeed it has a proper name.

Uhm, horizontal compression.

I forgot to add that Deus Ex Machina is from 2000.

Oh, and Dawnfall, 1995! I missed Weyland's link.

World of Commodore by Sanity from '92 perhaps?

I think it's in Optimum Fuckup too. (1992)

Jesterday aswell. I am pretty sure there were some lines about the origin of this effect in Tomcat's "The Brief History of the Computer Demoscene".

its the same as wobbler-effects like in this prod i did in 1994:
Sleepless Nights by Bonzai Bros
if you dont have an amiga-emulator, i am talking of the thing in the background of the screenshot. this intro has a lot of wobblers in some variations.

Optimum Fuckup actually uses copper to change the horizintal fine scrolling in addition. This way you can save a lot a memory because need precalced lines. Amigaaaaaaa! :-)

(replace "horizintal" by "horizontal", "a" by "of" and add "you" and "less". and add spell check to "submit" button)

sure, as if spellchecking would ever have worked as should!
try using windowsVoiceRecognitionSoftware to post a comment, same result ;)

also all those effects worked via copper on a500.
just have a pointer into your texture every scanline and alter it every frame. done!
if anyone is still wondering how the effects in my favourite copper-demo Total Triple Trouble (TTT.exe) by Rebels worked...same stuff, just used way better than ever before or after ;) and that gem was done in 1990

horizontal only texture mapping (HOTM)

hArdDy's method works if you have enough RAM, but on a stock 512kB A500 you could obtain the same effect by having a small set of prescaled images in RAM, and banging the $dff102 register multiple times every scanline to interpolate between these images.

Vertical scroller.

texture-scanline-alteration -> TSA!

the TSA in that cenotaph-demo just has 2 textures, to get the chessboard-feeling, also altering the color if the last 2 scanlines went another direction in y (yes, y, due to the changes in horizontal=x are done by looking up the texture on a different y-coordinate) than the one getting processed.
or maybe its just one texture and just negatived to get the chessboard!