​

function setup () {

  createCanvas (innerWidth, innerWidth)

}

​

function draw () {

  background ('purple')

  if (frameCount % 25 == 0 && risers.length < 8) {

    risers.push (new Riser (innerWidth / 10, 200, color('tomato')))

  }

  risers.forEach (r => r.increment ())

  risers.forEach (r => r.show ())

  const third = width / 3

  const half  = width / 2

  for (let i = 0; i < 256; i++) {

    const period = i / 255

    const y_pos = third + third * period

    const angle = (period + (frameCount / 255)) * PI * 2

    const x_pos =  half + (third - 100) * sin (angle)

    fill (i)

    noStroke ()

    ellipse (x_pos, y_pos, third)

  }

}