状态更改后，Android libGDX没有背景精灵

Question

I want to adjust the texture in my game to diffrent screens sizes, so I try to add ExtendViewport into my viewport , but Whenever I try change the states the background is not loaded. For the first time everything works fine, but whenever I try to set another state Ive got blank screen (I try with the same State instance to exclude the code errors)

STATE

public abstract class State {

protected OrthographicCamera camera;
protected  GameStateManager gsm;
protected Viewport viewport;
public State(GameStateManager gsm) {
    this.gsm = gsm;
    camera = new OrthographicCamera();
    viewport = new ExtendViewport(GAME_SIZE_WIDTH * aspectRatio, GAME_SIZE_HEIGHT, camera);
    viewport.apply();

    camera.position.set(GAME_SIZE_WIDTH / 2, GAME_SIZE_HEIGHT / 2, 0);
     }
public  abstract void handleInput();
public abstract void update(float dt);
public abstract void render (SpriteBatch sb);
public abstract void dispose();
public abstract void resize(int width, int height) ;
}

Menu State

public class MenuState extends State{


    private Sprite background;
    private Sprite playButton;

    public MenuState(GameStateManager gsm) {
        super(gsm);

        background =new Sprite(new Texture(Gdx.files.internal("back.jpg")));
        background.setSize(GAME_SIZE_WIDTH,GAME_SIZE_HEIGHT);
        background.setPosition(0,0);

        playButton=new Sprite(new Texture("play.png"));
        playButton.setSize(40,30);
        playButton.setPosition(GAME_SIZE_WIDTH/2-playButton.getWidth()/2,GAME_SIZE_HEIGHT/2-playButton.getHeight()/2);
    }



    @Override
    public void render(SpriteBatch sb) {
        sb.setProjectionMatrix(camera.combined);
        sb.begin();
        background.draw(sb);
        playButton.draw(sb);
        sb.end();
    }

    @Override
    public void dispose() {
        playButton.getTexture().dispose();
        background.getTexture().dispose();
    }

    @Override
    public void resize(int width, int height) {
        viewport.update(width,height);
        camera.position.set(GAME_SIZE_WIDTH / 2, GAME_SIZE_HEIGHT / 2, 0);
    }
    @Override
    public void handleInput() {
    if(Gdx.input.justTouched()) {
        gsm.set(new MenuState(gsm));}
    }
    @Override
    public void update(float dt) {
        handleInput();
    }
}

GameStateManager

public class GameStateManager {

private Stack<State> states;

public GameStateManager() {
    states=new Stack<State>();

}

public void push(State state){
    states.push(state);
}
public void pop(){
    states.pop().dispose();
}
public void set(State state){
    states.pop().dispose();
    states.push(state);
}
public void update(float dt){
    states.peek().update(dt);
}

public void render(SpriteBatch sb){
    states.peek().render(sb);
}
public  void resize(int width, int height){
    states.peek().resize(width,height);
}}

Answer 1

Problem is simple, you're not updating viewport of new State so update that with your screen width and height.

First time when Game Start resize method of State called by ApplicationListener class in this way.

ApplicationListener 's resize(,) -> GameStateManager 's resize(,) -> State 's resize(,)

After that resize( , ) of State or GameStateManager never called.

so simply change set() method of your GameStateManager .

public void set(State state){
    state.resize((int)states.peek().viewport.getScreenWidth(),(int)states.peek().viewport.getScreenHeight());
    states.pop().dispose();
    states.push(state);
}