function setup() {
  createCanvas(windowWidth, windowHeight)

  angleMode(DEGREES)
  rectMode(CENTER)
}

function draw() {
  background(10, 20, 30)
  noFill()

  translate(width / 2, height / 2 - 50)

  for (var i = 0; i < 200; i++) {
    push()

    rotate(sin(frameCount + i) * 100)

    var r = map(sin(frameCount), -1, 1, 50, 255)
    var g = map(cos(frameCount / 2), -1, 1, 50, 255)
    var b = map(sin(frameCount / 4), -1, 1, 50, 255)

    stroke(r, g, b)

    rect(0, 0, 600 - i * 3, 600 - i * 3, 200 - i)

    pop()
  }
}