​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  let redness= false

  background(220);

   noStroke ();

  if (redness) { 

  fill("red");

    rect(0,0, width/3, height);

  }

  if (mouseX >= 0 && mouseX <= width/3 && mouseY > 0 && mouseY < height) {

    noStroke ();

    fill("red");

    rect(0,0, width/3, height);

  } 

 else {

    fill(0);

  }

}

​

​