尝试使用 LibGDX 在 flappy bird android 游戏中为硬币制作动画

Question

public class PlayState extends State {

private static final int TUBE_SPACING = 125;
private static final int TUBE_COUNT = 4;
private static final int GROUND_Y_OFFSET = -30;
private static final int COIN_SPACING = 100;
private static final int COIN_COUNT = 2;


public int SCORE = 0;

private Bird bird;
private Coin coin;

private Texture bg;
private Texture ground;
private Vector2 groundPos1, groundPos2;

private Array<Tube> tubes;

private Array<Coin> coins;

public PlayState(GameStateManager gsm) {
    super(gsm);
    bird = new Bird(50, 300);

    cam.setToOrtho(false, FlappyDemo.WIDTH / 2, FlappyDemo.HEIGHT / 2);
    bg = new Texture("bg.png");
    ground = new Texture("ground.png");
    groundPos1 = new Vector2(cam.position.x - cam.viewportWidth / 2, GROUND_Y_OFFSET);
    groundPos2 = new Vector2((cam.position.x - cam.viewportWidth / 2) + ground.getWidth(), GROUND_Y_OFFSET);

    tubes = new Array<Tube>();

    for(int i = 1; i <= TUBE_COUNT; i++){
        tubes.add(new Tube(i * (TUBE_SPACING + Tube.TUBE_WIDTH)));
    }

    coins = new Array<Coin>();
    for(int i = 1; i<= COIN_COUNT; i++){
        coins.add(new Coin(i * (COIN_SPACING + (Coin.COIN_WIDTH / 3))));
    }

}

@Override
protected void handleInput() {
    if(Gdx.input.justTouched()){
        bird.jump();
    }
}

@Override
public void update(float dt) {
    handleInput();
    updateGround();
    bird.update(dt);
    coin.update(dt);
    cam.position.x = bird.getPosition().x +80;
    updateCoin();
    updateTube();

    if(bird.getPosition().y <= ground.getHeight() + GROUND_Y_OFFSET){
        gsm.set(new MenuState(gsm));
        System.out.println("Score : "+SCORE);
    }
    cam.update();
}

@Override
public void render(SpriteBatch sb) {
    sb.setProjectionMatrix(cam.combined);
    sb.begin();
    sb.draw(bg, cam.position.x - (cam.viewportWidth / 2), 0);
    sb.draw(bird.getTexture(), bird.getPosition().x, bird.getPosition().y);
    for(Tube tube : tubes) {
        sb.draw(tube.getTopTube(), tube.getPosTopTube().x, tube.getPosTopTube().y);
        sb.draw(tube.getBottomTube(), tube.getPosBotTube().x, tube.getPosBotTube().y);
    }
    for(Coin coin : coins){
        sb.draw(coin.getTexture(), coin.getPosCoin().x, coin.getPosCoin().y);
    }
    sb.draw(ground, groundPos1.x, groundPos1.y);
    sb.draw(ground, groundPos2.x, groundPos2.y);
    sb.end();
}

@Override
public void dispose() {
    bg.dispose();
    bird.dispose();
    ground.dispose();
    for(Tube tube : tubes)
        tube.dispose();
    for(Coin coin : coins)
        coin.dispose();
    System.out.println("PlayState disposed");
}

private void updateGround(){
    if(cam.position.x - (cam.viewportWidth / 2) > groundPos1.x + ground.getWidth())
        groundPos1.add(ground.getWidth() * 2, 0);
    if(cam.position.x - (cam.viewportWidth / 2) > groundPos2.x + ground.getWidth())
        groundPos2.add(ground.getWidth() * 2, 0);
}

private void updateTube(){
    for(int i = 0; i< tubes.size; i++){
        Tube tube = tubes.get(i);

        if(cam.position.x - (cam.viewportWidth / 2) > tube.getPosTopTube().x + tube.getTopTube().getWidth()){
            tube.reposition(tube.getPosTopTube().x + ((Tube.TUBE_WIDTH + TUBE_SPACING) * TUBE_COUNT));
        }
        if(tube.collides(bird.getBounds())){
            gsm.set(new MenuState(gsm));
            System.out.println("Score : "+SCORE);
        }
    }
}

private void updateCoin(){
    for(int i = 0; i< coins.size; i++){
        Coin coin = coins.get(i);

        if(cam.position.x - (cam.viewportWidth / 2) > coin.getPosCoin().x + coin.getTexCoin().getWidth()){
            coin.reposition(coin.getPosCoin().x + ((Coin.COIN_WIDTH + COIN_SPACING) * COIN_COUNT));
        }
        if(coin.collides(bird.getBounds())){
            SCORE = SCORE + 10;
            System.out.println("Collided");
        }
    }
}

}

public class Coin {

public static final int COIN_WIDTH  = 32;
public static final int COIN_HEIGHT  = 32;
public static final int COIN_SCORE = 10;
private static final int FLUCTUATION = 150;
private static final int COIN_GAP = 100;

private Texture texCoin;
private Vector2 posCoin;
private Rectangle boundsCoin;
private Random randCoin;
private Animation coinAnimation;


public Coin(int x){
    texCoin = new Texture("Coin.png");
    randCoin = new Random();

    posCoin = new Vector2(x, randCoin.nextInt(Tube.TUBE_GAP) + COIN_GAP);
    coinAnimation = new Animation(new TextureRegion(texCoin), 3, 0.5f);
    boundsCoin = new Rectangle(x, posCoin.y, texCoin.getWidth() / 3, texCoin.getHeight());
}

public void update(float dt){
   try{
       coinAnimation.update(dt);
       posCoin.set(randCoin.nextInt(FLUCTUATION) + COIN_GAP, randCoin.nextInt(FLUCTUATION)+ Tube.TUBE_GAP);
       boundsCoin.setPosition(posCoin.x, posCoin.y);
   }catch(Exception e){
       System.out.println("Errrrrr!");
   }
}

public Texture getTexCoin() { return texCoin;}

public Vector2 getPosCoin() { return posCoin;}

public TextureRegion getTexture() {
    return coinAnimation.getFrame();
}

public void reposition(float x){
    posCoin.set(x, randCoin.nextInt(FLUCTUATION) + COIN_GAP);
    boundsCoin.setPosition(posCoin.x, posCoin.y);
}

public boolean collides(Rectangle coinBound){
    return coinBound.overlaps(boundsCoin);
}

public void dispose(){
    texCoin.dispose();
}

}

线程“LWJGL 应用程序”中的异常 java.lang.NullPointerException 在 com.games.flappy.statess.PlayState.update(PlayState.java:75) 在 com.games.flappy.statess.GameStateManager.update(GameStateManager.java:31) 在 com.games.flappy.FlappyDemo.render(FlappyDemo.java:37) 在 com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:223) 在 com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:124)

Answer 1

它会爆炸吗：

coin.update(dt);

你有一个硬币变量，但看起来你实际上并没有给它分配任何东西。您的其余代码作用于硬币数组，其中当然包含许多单独的硬币对象。但我认为 coin 变量没有引用任何东西吗？ （很难说第 75 行实际指向的是什么）