​

function setup() {

  createCanvas(400, 400);

  frameRate(30)

  bubble = new Bubble(width/2, height/2, 30)

}

​

function draw() {

  background(30)

  bubble.show()

  bubble.shake(5)

}

class Bubble {

  constructor(x, y, r) {

    this.x = x

    this.y = y

    this.r = r

  }

  contains(x, y) {

    return this.r > dist(x, y, this.x, this.y)

  }

  show() {

    circle(this.x, this.y, this.r * 2) 

  }

  shake(bound) {

    this.x += random(-bound, bound)

    this.y += random(-bound, bound)

  }

  restrict(x, y, w, h) {

    this.x = constrain(this.x, x, x + w)

    this.y = constrain(this.y, y, y + h)

  }

}