let angleDirection = 1

let angleSpeed = .005

​

function setup() {

  createCanvas(120, 120)

}

​

function draw() {

  background(220)

  translate(20, 25)

  rotate(angle)

  strokeWeight(12)

  line(0, 0, 40, 0)

  translate(40, 0)

  rotate(angle * 2)

  strokeWeight(5)

  line(0, 0, 30, 0)

  translate(30, 0)

  rotate(angle * 2.5)

  strokeWeight(3)

  line(0, 0, 20, 0)

  angle += angleSpeed * angleDirection

  if (angle > QUARTER_PI || angle < 0)

    angleDirection *= -1

}