Part 6. Main menu scene and its sub-scenes:

In the previous articles, we successfully implemented resources manager, scene management system, and created the splash screen scene. Now we will take care of creating the menu scene and its sub scene(s) - (refer to the class diagram included in the article number 2)

1. Loading Menu scene resources:

• First of all, we will need a background, lets use this one:

• we will also need 2 buttons, play and options, lets use these:

• create fields for menu texture, and texture regions:

public ITextureRegion menu_background_region;
public ITextureRegion play_region;
public ITextureRegion options_region;
    
private BuildableBitmapTextureAtlas menuTextureAtlas;

• load assets inside the previously created loadMenuGraphics() method:

BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/menu/");
menuTextureAtlas = new BuildableBitmapTextureAtlas(activity.getTextureManager(), 1024, 1024, TextureOptions.BILINEAR);
menu_background_region = BitmapTextureAtlasTextureRegionFactory.createFromAsset(menuTextureAtlas, activity, "menu_background.png");
play_region = BitmapTextureAtlasTextureRegionFactory.createFromAsset(menuTextureAtlas, activity, "play.png");
options_region = BitmapTextureAtlasTextureRegionFactory.createFromAsset(menuTextureAtlas, activity, "options.png");
       
try 
{
    this.menuTextureAtlas.build(new BlackPawnTextureAtlasBuilder<IBitmapTextureAtlasSource, BitmapTextureAtlas>(0, 1, 0));
    this.menuTextureAtlas.load();
} 
catch (final TextureAtlasBuilderException e)
{
        Debug.e(e);
}

We are creating a buildable bitmap texture atlas  so we do not have to specify positions of particular graphics inside texture. Okay, our menu assets loading code is done.

2. Creating menu scene:

• inside getSceneType() return the proper scene type:

@Override
public SceneType getSceneType()
{
    return SceneType.SCENE_MENU;
}

• inside onBackPressed() put the code responsible for closing our app.

@Override
public void onBackKeyPressed()
{
    System.exit(0);
}

• lets create a background for our menu scene, create the new method createBackground() 

private void createBackground()
{
    attachChild(new Sprite(400, 240, resourcesManager.menu_background_region, vbom)
    {
        @Override
        protected void preDraw(GLState pGLState, Camera pCamera) 
        {
            super.preDraw(pGLState, pCamera);
            pGLState.enableDither();
        }
    });
}

• execute this method, inside the createScene() method.

@Override
public void createScene()
{
    createBackground();
}

private MenuScene menuChildScene;
private final int MENU_PLAY = 0;
private final int MENU_OPTIONS = 1;

private void createMenuChildScene()
{
    menuChildScene = new MenuScene(camera);
    menuChildScene.setPosition(400, 240);
    
    final IMenuItem playMenuItem = new ScaleMenuItemDecorator(new SpriteMenuItem(MENU_PLAY, resourcesManager.play_region, vbom), 1.2f, 1);
    final IMenuItem optionsMenuItem = new ScaleMenuItemDecorator(new SpriteMenuItem(MENU_OPTIONS, resourcesManager.options_region, vbom), 1.2f, 1);
    
    menuChildScene.addMenuItem(playMenuItem);
    menuChildScene.addMenuItem(optionsMenuItem);
    
    menuChildScene.buildAnimations();
    menuChildScene.setBackgroundEnabled(false);
    
    playMenuItem.setPosition(playMenuItem.getX(), playMenuItem.getY() + 10);
    optionsMenuItem.setPosition(optionsMenuItem.getX(), optionsMenuItem.getY() - 110);
    
    menuChildScene.setOnMenuItemClickListener(this);
    
    setChildScene(menuChildScene);
}

We are creating two sprite menu items, for our two buttons (play & options) we also use scale menu item decorator, which makes our menu items animated (they are being scaled up while touched) it's a really easy effect, you may easily create your own, it's more than enough for the purpose of this tutorial though. We are also adding those menu items to the menu scene, and positioning those menu items, to looks good with our background.

Now simply execute this method inside createScene() method.

@Override
public void createScene()
{
     createBackground();
     createMenuChildScene();
}

public boolean onMenuItemClicked(MenuScene pMenuScene, IMenuItem pMenuItem, float pMenuItemLocalX, float pMenuItemLocalY)
{
        switch(pMenuItem.getID())
        {
        case MENU_PLAY:
            return true;
        case MENU_OPTIONS:
            return true;
        default:
            return false;
    }
}

Leave it like that for now, we will create menu button actions later. 

3. Initializing, handling menu scene displaying:

• open our SceneManager and create method responsible for creating menu scene.

public void createMenuScene()
{
    ResourcesManager.getInstance().loadMenuResources();
    menuScene = new MainMenuScene();
    setScene(menuScene);
    disposeSplashScene();
}

• Open your activity, to execute this method inside on populate scene

public void onPopulateScene(Scene pScene, OnPopulateSceneCallback pOnPopulateSceneCallback) throws IOException
{
    mEngine.registerUpdateHandler(new TimerHandler(2f, new ITimerCallback() 
    {
        public void onTimePassed(final TimerHandler pTimerHandler) 
        {
            mEngine.unregisterUpdateHandler(pTimerHandler);
            SceneManager.getInstance().createMenuScene();
        }
    }));
    pOnPopulateSceneCallback.onPopulateSceneFinished();
}