let r = 0;

let g = 0;

let b = 0;

​

let ballsize = 255;

//background color

let backR = 0;

let backG = 0;

let backB = 0;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

}

​

function draw() {

  background(backR, backG, backB);

  fill(r,g,b);

  ellipse(width/2, height/2, ballsize, ballsize);

  if (mouseIsPressed) {

    backR = random(255);

    backG = random(255);

    backB = random(255);

  }

}

​

function mousePressed() {

  r=random(255);

  g=random(255);

  b=random(255);

}