​

function setup() { 

  createCanvas(windowWidth, windowHeight);

    noStroke();

} 

​

function draw() { 

  if(isField) {

    fill(0);

    rect(random(width), random(height), width/100,  width/100);

  }

  else {

    fill(255);

    rect(0, 0, width, height);

    if(random(1) < 0.01) {

      fill(0);

      rect(0, 0, width, height);

    }

  }

}

​

function mousePressed(){

 isField = ! isField; 

}