createCanvas(windowWidth, windowHeight);

  rectMode(CENTER)

}

​

function draw() {

  background(220);

  line(width/4,height/4,3*width/4,height/4);

  line(3*width/4,height/4,3*width/4,3*height/4);

  line(3*width/4,3*height/4,width/4,3*height/4);

  line(width/4,3*height/4,width/4,height/4);

}