Dark Bit Factory & Gravity

PROGRAMMING => General coding questions => Topic started by: pre on July 29, 2012

Title: vision factory twintris cracktro how too ....
Post by: pre on July 29, 2012

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 (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 ?

Title: Re: vision factory twintris cracktro how too ....
Post by: Shockwave on July 29, 2012

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.

Title: Re: vision factory twintris cracktro how too ....
Post by: pre on July 29, 2012

hi Shockwave ,

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

Title: Re: vision factory twintris cracktro how too ....
Post by: Shockwave on July 30, 2012

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

Title: Re: vision factory twintris cracktro how too ....
Post by: pre on July 30, 2012

thx shockwave  ill will  look @ your code !

thx  agin

Title: Re: vision factory twintris cracktro how too ....
Post by: Shockwave on July 31, 2012

My pleasure :)

Title: Re: vision factory twintris cracktro how too ....
Post by: pre on August 02, 2012

got it  ;D

Title: Re: vision factory twintris cracktro how too ....
Post by: Shockwave on August 04, 2012

Excellent :)