Quadrille.cellLength = 20;
let board = true;
let quadrille;

function setup() {
  createCanvas(400, 400);
  quadrille = createQuadrille(20, 20);
  quadrille.fill('cyan', 'red');  // create a chessboard pattern with given colors
}

function draw() {
  background('black');
  drawQuadrille(quadrille, { tileDisplay: board ? 0 : Quadrille.tileDisplay });
}

function mouseClicked() {
  board = !board;
  board ? quadrille.fill('cyan', 'red') : quadrille.clear();
}

function keyPressed() {
  board = !board;
  board ? quadrille.fill('cyan', 'red') : quadrille.clear();
}