function setup() {

  createCanvas(600, 400);

  for (let i = 0; i < 4; i++) {

    bubbles.push(new Bubble(random(width), random(height)));

  }

}

​

function draw() {

  background(0);

  for (let bubble of bubbles) {

    for (let b of bubbles) {

      bubble.otherBub(b);

    }

    bubble.show();

    bubble.grow();

  }

}

​

class Bubble {

  constructor(x, y) {

    this.x = x;

    this.y = y;

    this.d = 1;

    this.growing = true;

  }

  show() {

    noFill();

    stroke(255);

    circle(this.x, this.y, this.d);

  }

  grow() {

    if (this.edges()) {

      if (this.growing) {

        this.d += 1;

      }

    }

  }

  edges() {

    return (

      this.x + this.d / 2 < width &&

      this.x - this.d / 2 > 0 &&

      this.y + this.d / 2 < height &&

      this.y - this.d / 2 > 0

    );

  }

  otherBub(other) {

    let d = dist(this.x, this.y, other.x, other.y);

    if (d < this.d/2+other.d/2) {

      this.growing = false;

    } else {

      this.growing = true;

    }

  }

}

​