// Daniel Shiffman

// http://natureofcode.com

​

// A reference to our box2d world

let world;

​

// A list for all of our particles

let particles = [];

​

// An object to describe a Windmill (two bodies and one joint)

let windmill;

​

function setup() {

​

  createCanvas(640, 360);

  createP("Click mouse to toggle motor.\nMotor: OFF");

​

  // Initialize box2d physics and create the world

  world = createWorld();

​

  // Make the windmill at an x,y position

  windmill = new Windmill(width / 2, 175);

}

​

function draw() {

  background(0);

​

  // We must always step through time!

  let timeStep = 1.0 / 30;

  // 2nd and 3rd arguments are velocity and position iterations

  world.Step(timeStep, 10, 10);

​

  if (random(1) < 0.1) {

    let sz = random(4, 8);

    particles.push(new Particle(random(width / 2 - 100, width / 2 + 100), -20, sz));

  }

​

​

  // Display all the pairs

  for (let i = particles.length - 1; i >= 0; i--) {

    particles[i].display();

    if (particles[i].done()) {

      particles.splice(i, 1);

    }

  }

​

  // Draw the windmill

  windmill.display();

​

  let status = "OFF";

  if (windmill.motorOn()) status = "ON";

​

}

​

function mousePressed() {

  windmill.toggleMotor();

​

  let status = "OFF";

  if (windmill.motorOn()) status = "ON";

  txt.html("Click mouse to toggle motor.\nMotor: " + status);

}