RotoScope (a new demo effect?)

[va!n]

Hi guys! here is a graphic effect i coded for a coding competition by a german pb forum. deadline was 30.sep.2007 @ 23:59... Here is what i come up with... (i don't know to have seen that kind of fx before. runs in 800x600x32)  zip cointains exe and full sources...

[Jim]

Good effect, and definitely Karma+ for posting source.

Also, I'm very pleased to see that your degrees to radians function is accurate to 18 decimal places, 0.017453292500000002, that's down to the attometer level, about 1 quintillionth of a degree , or one billion, billion, billionth of a pixel

Jim

[p01]

Kaleidoscope are not new to the scene
Also using a rotozoom to "feed" it is rather obvious as it produces many rotating patterns. See KaleidoSkop, a 256b intro by Beetle / 3SC in 2000 or in a loop, an insane 1k intro on C64 by Ate Bit in 2006

Kudos for sharing the source.

[benny!]

Love the kaleidoscope fx, va!n. Nice one. Good luck with your entry in the competition.

[Shockwave]

That is a pretty good effect, I'd like to wish you good luck in the competition!

Looking at the source I am sure that it can be optimised quite a lot more.
The two matrix constants can be computed outside the loop;

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    MO1= COS (THETA)
    MO2= SIN (THETA)


And then inside the loop;

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        ONE AXIS OF ROTATION
        XXX=X(L)
        YYY=Y(L)
       
        X(L) = MO1 * XXX - MO2 * YYY
        Y(L) = MO1 * YYY + MO2 * XXX


Which is probably still not the way I'd go about making this effect, but it would be a little faster than it is at the moment.

If I had to code this in software I'd make a very quick and dirty linear texture mapping routine, there would be no problem with warping of textures because there is no Z Co-ordinate.

But anyway I'll STFU now, the effect looks nice and the best of luck with the comp

[p01]

Dunno the langage used here but surely you can replace:

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While lTexturePixelX < 0 : lTexturePixelX = lTexturePixelX + 255 : Wend
While lTexturePixelY < 0 : lTexturePixelY = lTexturePixelY + 255 : Wend

If lTexturePixelX > 255 : lTexturePixelX = lTexturePixelX - 255 : EndIf
If lTexturePixelY > 255 : lTexturePixelY = lTexturePixelY - 255 : EndIfby something like:

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lTexturePixelX &= 255
lTexturePixelY &= 255

Also in a rotozoom, the slope is continous, therefore the inner ( X ) loop can be summed up to:

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xLoopX += xLoopDeltaX
xLoopY += xLoopDeltaXAnd the outer ( Y ) loop to:

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xLoopX = ( yLoopX += yLoopDeltaX )
xLoopY = ( yLoopY += yLoopDeltaY )

HTH

[taj]

The effect is very pleasing on the eyes. Karma++ for source.

[Stonemonkey]

Nice one Va!n, goodluck with the compo.

[va!n]

compo is running atm at www.purebasic-lounge.de ^^

[Shockwave]

Good luck mate

[DeXtr0]

Great code and great Idea.
I'm not sure if I have seen this before but I think I have.

However well done. Karma ++ and good luck with the competition !

Keep us informed about your position (after the votings) 

Cheers,
DeX