vision factory twintris cracktro how too ....

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Hi  DBF Community ,

first post - first question  - 


Stormbringer comes with  this Cracktro remake for win 32 .

http://www.dbfinteractive.com/forum/index.php?topic=2350.0

its my favorite cracktro because the effects and the great sound .

my question is : how to program these color rotating lines  ?  (in the top  and the down from the blue circles)
using sin / cos ?

its only for interest  maybe someone show me the light ?

[Shockwave]

Hi Pre,

That effect is caused by an interference effect.
You just get an image which is made up of concentric circles and overlay it on top of another image which is the same.  As they move, it creates this interference effect.

Most of the time on the amiga they would draw these in different bitplanes so that when they overlap the colour can automatically change which gives another type of effect and makes the lines look like they are stretching.

You can generate lots of interesting effects using different patterns and this method

Welcome to DBF.

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hi Shockwave ,

sorry i mean the colored rotating frame  not the blue circles !

[Shockwave]

Ah, the twisting bars is a bit of an illusion.  On the Amiga you's use the copper to alter one of the colour registers (usually colour 0) as you went across the screen, you could move new values into the register every 8 pixels so you'd have a gradient coloured line, just by cycling these colours and having a few more lines below with the colours offset a bit gives this effect.

If you make the bars too wide then the effect won't work, but with a shallow gradient and a fairly narrow band you can make it look like it's twisting.

Here's some source code for one I made a long time ago in freebasic;

http://www.dbfinteractive.com/forum/index.php?topic=1555.msg23684#msg23684

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thx shockwave  ill will  look @ your code !

thx  agin

[Shockwave]

My pleasure

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got it 

[Shockwave]

Excellent