let y;

let x;

let w;

let vertical = 0;

​

function setupStick(){

  vertical = random([0, 1]);

  speed = random(3, 15);

  y = vertical ? height : random(height);

  x = !vertical ? 0 : random(width);

  w = random(50);

}

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background('#fff');

  noStroke();

  fill('#000');

  setupStick();

}

​

function draw() {

  rect(x, y, w, speed-1);

  if(vertical){

    if(y <= 0){

      setupStick();

    }else{

      y -= speed; 

    }

  }else{

    if(x >= width){

      setupStick();

    }else{

      x += speed; 

    }

  }

}