let sx, sy, ex, ey;

let sxspeed, syspeed, exspeed, eyspeed;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  init();

  stroke(255);

}

​

function draw() {

  background(0);

  sx += sxspeed;

  sy += syspeed;

  ex += exspeed;

  ey += eyspeed;

  line(sx, sy, ex, ey);

}

​

function init() {

  // Left

  if (random(1) > 0.75) {

    sx = random(-width, 0);

    sy = random(height);

    ex = random(-width, 0);

    ey = random(height);

    sxspeed = random(0, 2 * r);

    syspeed = random(-r, r);

    exspeed = random(0, 2 * r);

    eyspeed = random(-r, r);

​

  }

  // Right

  else if (random(1) > 0.5) {

    sx = random(width, width *2);

    sy = random(height);

    ex = random(width, width *2);

    ey = random(height);

    sxspeed = random(-2 * r, 0);

    syspeed = random(-r, r);

    exspeed = random(-2 * r, 0);

    eyspeed = random(-r, r);

  }

  // Top

  else if (random(1) > 0.25) {

    sx = random(width);

    sy = random(-height, 0);

    ex = random(width);

    ey = random(-height, 0);

    sxspeed = random(-r, r);

    syspeed = random(0, 2 * r);

    exspeed = random(-r, r);

    eyspeed = random(0, 2 * r);

  }

  // Bottom

  else {

    sx = random(width);

    sy = random(height, height * 2);

    ex = random(width);

    ey = random(height, height * 2);

    sxspeed = random(-r, r);

    syspeed = random(-2 * r, 0);

    exspeed = random(-r, r);

    eyspeed = random(-2 * r, 0);

  }

}

​

function mousePressed() {

  r = 10*mouseX / width;

  init();

  print("HI", sx, sxspeed);

}