​

var speed = 2;

​

var shape = 200;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  circle(x, 200, shape);

  // translate(200, 200);

  x = x + speed;

  if (x + 50 > width || x - 50 < 0) {

    speed *= -1;

  }

​

  if (speed > 0) {

    if (x > width / 2) {

      shape = map(x, 0, width, 200, 100);

    } else {

      shape = map(x, 0, width, 100, 200);

    }

  } else {

    if (x > width / 2) {

      shape = map(x, 0, width, 50, 100);

    } else {

      shape = map(x, 0, width, 100, 50);

    }

  }

}

​

// if () {}

​