private GameScreen() {
    this.superflu = SuperFlu.getInstance();
    stage = new Stage(Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), false);
    groupZones = new Group();
    groupVilles = new GroupVilles();
    groupTransferts = new Group();

    Texture backgroundTexture = superflu.manager.get("images/fond_carte.png", Texture.class);
    TextureRegion backgroundTextureRegion =
        new TextureRegion(backgroundTexture, VIRTUAL_WIDTH, VIRTUAL_HEIGHT);
    Image imgBackground = new Image(backgroundTextureRegion);
    imgBackground.touchable = false;
    stage.addActor(imgBackground);

    Texture carteTexture = superflu.manager.get("images/carte.png", Texture.class);
    TextureRegion carteTextureRegion =
        new TextureRegion(carteTexture, VIRTUAL_WIDTH, VIRTUAL_HEIGHT);
    Image carte = new Image(carteTextureRegion);
    carte.touchable = false;
    stage.addActor(carte);

    stage.addActor(groupZones);
    stage.addActor(groupVilles);
    stage.addActor(groupTransferts);

    stage.addActor(TransfertCreator.getInstance());

    Music softMusic = superflu.manager.get("music/soft.mp3", Music.class);
    softMusic.play();

    createEntities();
    Gdx.input.setInputProcessor(stage);

    stage.addActor(new GlobalStatsActor(gameLogic));
  }
 @Override
 public boolean keyDown(int key) {
   if (key == Keys.BACK) {
     SuperFlu.getInstance().setScreen(MainMenuScreen.getInstance());
     return true;
   }
   return false;
 }
  private AboutScreen() {
    stage = new Stage(Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), false);
    superflu = SuperFlu.getInstance();
    credits = superflu.manager.get("images/credits.png", Texture.class);

    Texture backgroundTexture = superflu.manager.get("images/fond_carte.png", Texture.class);
    TextureRegion backgroundTextureRegion =
        new TextureRegion(backgroundTexture, VIRTUAL_WIDTH, VIRTUAL_HEIGHT);
    Image imgBackground = new Image(backgroundTextureRegion);
    imgBackground.touchable = false;
    stage.addActor(imgBackground);

    stage.addActor(new Image(credits));
    stage.addActor(new Dna());
  }
 @Override
 public boolean touchDown(int arg0, int arg1, int arg2, int arg3) {
   SuperFlu.getInstance().setScreen(MainMenuScreen.getInstance());
   return true;
 }