let count = 12; 

let angles = [];

let colors = [];

let btn;

​

function setup() {

  createCanvas(400, 400);

  btn = createButton("save as GIF");

  btn.mousePressed(saveAsGIF);

  colors = [color(0, 255, 255), color(0, 255, 0), color(0, 0, 255)];

  for (let i=0; i<count; i++){

    angles[i] = (TWO_PI/count) * i;

    circles[i] = new Circle(angles[i], colors[i%3]);

  }

}

​

function draw() {

  background(0);

  translate(width/2, height/2);

  push();

  blendMode(DIFFERENCE);

  for (let i=0; i<count; i++){

    circles[i].update();

    circles[i].display();

  }

  pop();

}

function saveAsGIF() {

  saveGif('bgcircles.gif', 6);

}