let x;

let xSpeed = 3;

let ySpeed = 2;

let col=0;

let colSpeed=1;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  x = width / 2;

  y = height / 2;

}

​

function draw() {

  background(220);

  fill(col);

​

  circle(x, y, circleSize);

​

  x += xSpeed;

  y += ySpeed;

  col += colSpeed;

​

  if (x > width - circleSize / 2 || x < circleSize / 2 ) {

    xSpeed *= -1;

    colSpeed *= -1;

  }

​

  if (y > height - circleSize / 2 || y < circleSize / 2) {

    ySpeed *= -1;

    colSpeed *= -1;

  }

}

​