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Index › Programming Questions & Help › Programs › Fading Lines
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Fading Lines (Read 690 times)
CaptainBeyond
Fading Lines
Aug 22nd, 2009, 9:23pm  
Hi. I was reading the examples and trying to draw a line that will fade way begining from one of its point and vanishing more and more parts until the other point is reached. Something like the way the "comet"´s tail fades on the Reflection1 Example that comes with processing. I couldn´t figure out how to do this on processing. Does anyone have any suggestion about this algorithm?

Thanks
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Cedric
Re: Fading Lines
Reply #1 - Aug 22nd, 2009, 10:59pm  
you can easily achieve this effect by drawing semitransparent rects instead of background();

read more about this "hack" : http://processing.org/hacks/hacks:fading

if you have more objects and want the fading only on one of them its getting more complicated and you have to do something like this.

old example, but hope it gives you an idea:

Code:
void setup(){
  size(400,400);
  background(255);
  frameRate(40);

  for(int i=0; i<anzahl; i++){
    oldX[i] = 0;
    oldY[i] = 0; 
  }
}

int anzahl=9;
float[] oldX = new float[anzahl];
float[] oldY = new float[anzahl];

void draw(){
 
 float[] tmpX = new float[anzahl];
 float[] tmpY = new float[anzahl];
  for(int i=0; i<anzahl-1; i++){
    tmpX[i+1] = oldX[i];
    tmpY[i+1] = oldY[i];
   }
   tmpX[0]=mouseX;
   tmpY[0]=mouseY;
   
   oldX=tmpX;
   oldY=tmpY;
    
 background(255);
  for(int i=0; i<anzahl-1; i++){

   stroke(255/anzahl*i);
   strokeWeight(10+20*(1-i/float(anzahl)));
    line(oldX[i],oldY[i],oldX[i+1],oldY[i+1]);

  }
}


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