var iterations = 10;

​

function setup() {

  createCanvas(640, 480);

  // for (var i = 0; i < 10; i++) {

  //   balls[i] = new Circle(random(20, width - 20), random(20, height - 20), 10);

  // }

}

​

function mousePressed() {

  balls.push(new Circle(mouseX, mouseY, 20));

}

​

function draw() {

  background(0);

  if (frameCount % 20 == 0) {

    balls.push(new Circle(width / 2, height / 2, 20));

  }

  if (balls[0]) {

    for (var ball of balls) {

      var g = createVector(0, 0.25);

      ball.applyForce(g);

      for (var i = 0; i < iterations; i++) {

        ball.update();

      }

      for (var other of balls) {

        if (other != ball) {

          ball.collideCircle(other);

        }

      }

      ball.show();

    }

  }

}