Agfdhyk

I am trying to change the opacity of my strokes, but not sure how do it in HSB color mode. Or, if I switch to RGB mode how do I make the color change over time?

Here is my code: (Any help would be appreciated)

float rainbow=0;

int dir=1;



void setup() {

  size(600, 600);

  background(0);

  colorMode(HSB, 255);

 } 



void draw() {

  if ( rainbow < 255 && dir==1) {

     rainbow++;

  }



  if ( rainbow > 0 && dir==-1) {

    rainbow--;

  }



  if ( rainbow == 255) {

    dir*= -1;

  }



  if ( rainbow == 0) {

    dir*= -1;

  }



  stroke(rainbow, 255, 200);

  line(mouseX,mouseY,width/2,height/2); 



  if (mousePressed){

  stroke(rainbow, 255, 200);

  line(mouseX,mouseY,0,mouseX);

  }



  if (mousePressed){

  stroke(rainbow, 100, 200);

  line(mouseX,mouseY,600,mouseX);

  }

}

You can give the stroke() or fill() functions a fourth parameter for the opacity. Here's a simple example:

void setup(){

  size(500, 500);

  colorMode(HSB, 255);

  background(255);

}



void draw(){

  fill(0, 255, 200, 100);

  ellipse(mouseX, mouseY, 20, 20);

}

Note that you can also use RGB mode and modify the R, G, and B arguments over time as well. This is going to be a little more complicated than cycling through HSB values, but you can create any pattern you want. Here's a simple example:

float r = 0;

float g = 0;

float b = 0;



float deltaR = 1;

float deltaG = 2;

float deltaB = 4;



void setup(){

  size(500, 500);

  background(255);

}



void draw(){



  r += deltaR;

  g += deltaG;

  b += deltaB;



  if(r < 0 || r > 255){

    deltaR *= -1;

    r = constrain(r, 0, 255);

  }



  if(g < 0 || g > 255){

   deltaG *= -1;

   g = constrain(g, 0, 255);

  }



  if(b < 0 || b > 255){

    deltaB *= -1;

    b = constrain(b, 0, 255);

  }



  fill(r, g, b);

  ellipse(mouseX, mouseY, 20, 20);

}