let u = 0,

    k = 2;

​

let x = [0, 0], 

    y = [0, 0];

​

function setup() {

  createCanvas(400, 400);

  background(30);

  i = TWO_PI / 300;

}

​

function draw() {

  translate(width/2, height/2)

  stroke(200)

  strokeWeight(4)

  let r = width * 0.49 * cos(k*u)

  x[1] = r * cos(u)

  y[1] = r * sin(u)

  if (u > 0) {

    line(x[0], y[0], x[1], y[1])

    if (floor(u / TWO_PI) == 1) {

      background(30)

      u = 0

      k += 2

    }

  }

  x[0] = x[1]

  y[0] = y[1]

  u += i

}