let speed =0.9; 

let y = 0

let ac = 0.01;

​

 let bl

​

function setup() {

  createCanvas(400, 400, WEBGL);

    background(220);

}

​

function draw() {

​

​

  fill(0+x)

  circle(0, 0, x)

  if ( x >= 20 && x < 50){

​

    speed = speed

    ac = ac 

  //  ac = ac

  }

   else { 

   speed = -speed

      ac = -ac

​

  }

   point(-200+y, x) 

​

  x = x + speed+ac

 y = y + 0.6

  ac = ac+ac

}