let angle = 0

let motion = 1

const speed = 0.05

​

let centerX

let centerY

​

function setup() {

  createCanvas(600, 600);

  centerX = width / 2

  centerY = height / 2

}

​

function draw() {

  // background(220);

​

  ellipse(width / 2, height / 2, 10, 10)

​

  var x = centerX + radius * sin(angle)

  var y = centerY + radius * cos(angle)

  ellipse(x, y, 50, 50)

  if (radius >= 150 && motion === 1) {

    motion = -1

  } else if (radius <= 0) {

    motion = 1

  }

  radius+= motion

  angle = angle + speed

}