Revision 2024

[arcanist]

Originally Posted by Marconelly

You'll love the Automated Raster Machine and Branching Off 64k intros
https://www.pouet.net/prod.php?which=96545
https://www.pouet.net/prod.php?which=96549

Ah, that's the stuff. Never change, Amiga scene!

[Toffee]

Probably my favorite moment from Revision 2024:-

[ Show youtube player ]

2 minutes 50 in. A500 1*1 pixel 50hz bitmap rotator. Beautiful!

[h0ffman]

Yes, Jobbo has had all of us Amiga coders scratching our heads on this one!.

[a/b]

It looks like improved Brian the Lion and Sanity zoomrot, without zooming. Meaning someone finally sat down and cracked the numbers to figure out how to modify shearing coefficients to eliminate distortions and a need for "zooming".
This was already discussed at least once here, so in short: 3 shearing passes, you shift rows/columns/rows to achive perfect 2D rotation. You start by simply skipping the first shear and adjusting the other two to compensate. Third shear is done with copper (modulos+scroll) without modifiying the image and this enables the second shear (copy columns with blitter) to be completely incremental, so you only have to blit at most half of the picture each frame (simple d=a). And in the third shear you also pretend to zoom and shrink the picture vertically to fix distortions because adjusted coefficients don't cut it. Brian did this better, more optimized code and no unneeded blits, but Sanity also had other stuff on the screen, so that's that.
You achieve -45 to +45 rotation with that, and use 4 pre-rotated copies (0/90/180/270).

But maybe I got it wrong :P, in any case props.

[Marconelly]

But it does zoom (zoom-down only as far as I can tell)? I wasn't aware this effect was never before done on A500. To me it looked pretty similar to Brian the Lion title screen logo effect which also rotates and zooms-down in a very similar way, and as far as I can tell Brian's logo is also 1 pixel effect and has 14 colors too - or I guess 14 shades of blue color. Brian's logo rotation does look more glitchy around the edges so maybe it's 2x2 effect, hidden slightly by the fact the logo has no sharp edges? In this demo, the rotation does look very clean.

In any case, that demo was my favorite overall of Amiga demo compo, I think it should have won. My second favorite Amiga demo effect was seeing mandelbulb on 060 in the 2nd placed demo, but it is very small on the screen.

[PARALAX]

And here is our summary of the best demos from the PC, Amiga and Oldskool Compo from our livestream last saturday: [ Show youtube player ]

[PascalDe73]

Glubble in Correct ADF Format (for a real Amiga) In The Zone