function preload(){

negative = loadImage('negative.gif')

}

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(negative)

  fill(255, 0, 0)

  ellipse(150, 230, 10)

  fill(0, 0, 255)

  ellipse(160, 230, 10)

  fill(0, 255, 0)

  ellipse(150, 230, 10)

  if (mouseIsPressed){

  background(255)}

}