let y = 0;

let spacing = 20;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(0);

  ellipseMode(CORNER);

}

​

function draw() {

​

  stroke(255);

  if (random(1) < 0.5) {

    line(x, y, x + spacing, y + spacing);

  } else {

    line(x, y + spacing, x + spacing, y);

  }

​

  x += spacing;

​

  if (x > width) {

    x = 0;

    y += spacing;

  }

​

  if (y > height) {

    noLoop();

  }

}