let ballsize=10

  function setup() {

  createCanvas(400, 400);

}

​

function draw() {

   background=(255)

  fill (255,0,0)

      strokeWeight(0)

  // arc(height/2, width/2, ballsize, ballsize, 0, PI);

 translate(width / 2, height / 2);

 rotate(PI / 3.0);

  fill (220, 0, 100)

    arc(0, 0, ballsize, ballsize, 0, PI);

  grow=1

  ballsize=ballsize+grow

   if (ballsize<=0){

  grow=grow -1;

  }

  if (ballsize>=100){

  print('done')

    grow=-grow

  }

  print (ballsize)

}