let xspeed, yspeed;

let x, y;

let scl;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  xstart = 200;

  ystart = 355;

  scl = 0.5;

reset();

  xspeed = 2;

  yspeed = 3;

}

​

function reset() {

  x = xstart;

  y = ystart;

}

​

function draw() {

  background(0);

​

  x += xspeed * scl;

  y += yspeed * scl;

​

  stroke(255);

  line(xstart, ystart, x, y);

​

  if (x < 0 || x > width || y < 0 || y > height) {

    reset();

  }

}