function rnd(nMax) {
	return Math.floor(Math.random() * nMax);
}

const RENDERER_WIDTH = 800;
const RENDERER_HEIGHT = 600;

const app = new PIXI.Application(
  RENDERER_WIDTH,
  RENDERER_HEIGHT,
  {backgroundColor : 0x1099bb}
);
document.body.appendChild(app.view);

const INITIAL_BUNNIES_AMOUNT = 10;
const bunnies = [];

function makeBunny(width = 20, height = 32) {
	const bunny = PIXI.Sprite.fromImage('examples/assets/bunny.png');

  	bunny.anchor.set(0.5);
  	bunny.width = width;
  	bunny.height = height;


 	bunny.body = new PIXI.Rectangle(0, 0, width, height);
    bunny.velocity = new PIXI.Point(0, 0);

  	bunnies.push(bunny);

  	return bunny;
}


function initialize() {
	for (let i = 0; i < INITIAL_BUNNIES_AMOUNT; i++) {
      const bunny = makeBunny();

      bunny.body.x = rnd(app.view.width);
      bunny.body.y = rnd(app.view.height);
      bunny.velocity = new PIXI.Point(rnd(10), rnd(10));

      app.stage.addChild(bunny);
	}
}

initialize();

app.ticker.add(function(delta) {
  	bunnies.forEach((b, i) => {
    	b.body.x = += b.velocity.x);
      	b.body.y = += b.velocity.y);


      	if (b.body.x >= RENDERER_WIDTH || b.body.x <= 0) {
          b.velocity.x *= -1;
        }
      	if (b.body.y >= RENDERER_HEIGHT || b.body.y <= 0) {
          b.velocity.y *= -1;
        }

      	b.x = b.body.x;
      	b.y = b.body.y;
    });
});