​

function setup() {

  createCanvas(windowWidth, windowHeight);

  rectMode(CENTER);

​

  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/4,3*width/4,3*height/4);

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

​

  //OR

  //rect(width / 2, height / 2, 0.1 * width, 0.1 *height);

  x1=width/4

  y1=height/4

  x2=3*width/4

  y2=height/4

  x3=3*width/4

  y3=3*height/4

  x4=width/4

  y4=3*height/4

}

​

function draw() {

  background(220);

​

  line(x1, y1, x2, y2);

  line(x2, y2, x3, y3);

  line(x3, y3, x4, y4);

  line(x4, y4, x1, y1);

​

}