let lx, rx, ty, by;

​

function setup() {

  createCanvas(800, 600);

  background(20);

  // 1st argument: x-coordinate of the rectangle

  // 2nd argument: y-coordinate of the rectangle

  // 3rd argument: width of the rectangle

  // 4th argument: height of the rectangle

  x = width / 2;

  y = height / 2;

  w = width / 2;

  h = height / 2;

  lx = x - w / 2;

  rx = x + w / 2;

  ty = y - h / 2;

  by = y + h / 2;

  rectMode(CENTER);

}

​

function draw() {

​

  //draw with rect()

  // noStroke();

  // rect(x, y, w, h);

​

​

  //draw with vertex()

  beginShape(QUADS);

  vertex(lx, ty);

  vertex(rx, ty);

  vertex(rx, by);

  vertex(lx, by);

  endShape();

​

}