​

​

function setup() {

  createCanvas(400, 400);

​

  for (let i = 0; i < 20; i++) {

    balls.push(new Ball(width / 2, height / 2, random(-2,2), random(-2,2)));

  }

}

​

​

function draw() {

  background(220);

​

  for (let ball of balls) {

    ball.move();

    ball.bounce();

    ball.drawBall();

  }

}

​

​

class Ball {

  constructor(x, y, xSpeed, ySpeed) {

    this.x = x;

    this.y = y;

    this.xSpeed = xSpeed;

    this.ySpeed = ySpeed;

  }

​

  move() {

    this.x += this.xSpeed;

    this.y += this.ySpeed;

  }

​

  bounce() {

    if (this.x > width - 20 || this.x < 20) {

      this.xSpeed *= -1;

    }

    if (this.y > height - 20 || this.y < 20) {

      this.ySpeed *= -1;

    }

  }

​

  drawBall() {

    ellipse(this.x, this.y, 40, 40);

  }

}

​