let px, py;

​

let showNorm = false;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

​

  x = width / 2;

  y = height / 2;

  px = x;

  py = y;

​

  background(0);

  strokeWeight(3);

}

​

function draw() {

​

  if (keyIsPressed) {

    showNorm = !showNorm;

  }

​

  x = random(-5, 5) + mouseX;

  y = random(-5, 5) + mouseY;

​

  stroke(255);

  line(x, y, px, py);

​

  px = x;

  py = y;

​

​

  if (showNorm) {

    stroke(255, 0, 0);

    line(mouseX, mouseY, pmouseX, pmouseY);

  }

​

}

​

function mousePressed() {

  clear();

  background(0);

}