Help: Sphere Rotation

http://www.html5gamedevs.com/topic/18119-sphere-rotation/

by chongdashu

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/phaser/2.4.4/phaser.js"></script>

JavaScript

/**
 * Credits: Images:
   - texture: http://pics-about.space/nasa-world-map-texture?p=1
   - sphere: http://www.devbattles.com/en/sand/post-1881-Rotation_of_planets_in_space_on_HTML5_JavaScript
   - HTML5GameDevs.com Forum members: chg, weratius.
 */


preload = function () {
    game.load.crossOrigin = 'anonymous';
    game.load.image("texture", "http://i.imgur.com/G4xEZx3.jpg");
    game.load.image("sphere", "http://i.imgur.com/cyz54kw.png");
    game.load.image("button", "http://i.imgur.com/oS5Q1Jx.png");

    this.game.world.setBounds(-game.world.width / 2, -game.world.height / 2,
    game.world.width, game.world.height);

};

create = function () {
    var ball = game.add.sprite(0, 0);
    var texture1 = game.make.sprite(0, 0, "texture");
    var texture2 = game.make.sprite(0, 0, "texture");

    var mask = game.add.graphics(0, 0);
    mask.beginFill(0xFFFFFF);
    mask.drawCircle(0, 0, 250);

    ball.mask = mask;

    this.rotation = Phaser.Math.degToRad(-15);

    texture1.anchor.set(0.5, 0.5);
    texture2.anchor.set(0.5, 0.5);

    ball.addChild(texture1);
    ball.addChild(texture2);

    texture1.rotation = this.rotation;
    texture2.rotation = this.rotation;

    texture1.x += texture1.width / 2 * Math.cos(this.rotation);
    texture2.x -= texture1.width / 2 * Math.cos(this.rotation);
    texture1.y += texture1.width / 2 * Math.sin(this.rotation);
    texture2.y -= texture1.width / 2 * Math.sin(this.rotation);

    this.texture1 = texture1;
    this.texture2 = texture2;

    this.speed = 1;

    var sphere = game.add.sprite(0, 0, "sphere");
    sphere.anchor.set(0.5, 0.5);

    // debug


    this.textMask = game.add.text(-300, 102, "Toggle Mask", {
        fill: "white",
        font: "10pt Arial"
    });
    this.buttonMask = game.add.button(-200, 100, 'button',

    function () {
        ball.mask = ball.mask ? null : mask;
    });

    this.textShadow = game.add.text(-300, 132, "Toggle Shadow", {
        fill: "white",
        font: "10pt...