text: // The Nature of Code
  // Daniel Shiffman
  // http://natureofcode.com
  
  // Example 1-2: Bouncing Ball, with PVector!
  var position = new p5.Vector(100, 100);
  var velocity = new p5.Vector(5, 10);
  
  function setup() {
    createCanvas(windowWidth, windowHeight);
    background(255);
  }
  
  function draw() {
    noStroke();
    fill(55, 50);
    rect(0, 0, width, height);
  
    // Add the current speed to the position.
    position.add(velocity);
  
    if ((position.x > width) || (position.x < 0)) {
      velocity.x = velocity.x * -1;
    }
    if ((position.y > height) || (position.y < 0)) {
      velocity.y = velocity.y * -1;
    }
  
    // Display circle at x position
    stroke(0);
    fill(255, 255, 0);
    ellipse(position.x, position.y, 32, 32);
  }
  