cocos2dx3.3开发FlappyBird总结十二：状态层设计

状态层是比较复杂的了，状态层需要与游戏层通信，因此也需要为游戏层先设计一个代理类，以便状态层遵守游戏层的代理，这样游戏层就可以在游戏开始、得分、结束时，告诉状态层做出相应的状态表现了。

游戏层的代理类：

/**
 * The delegate between status layer and game layer
 */
class GameStatusDelegate {
public:
  /**
   * When the game start, this method will be called
   */
  virtual void onGameStart() = 0;

  /**
   * During paying, after the score changed, this method will be called
   *
   * @param score The latest score
   */
  virtual void onGamePlaying(int score) = 0;

  /**
   * When game is over, this method will be called
   *
   * @param currentScore Current game score
   * @param historyBestScore The best score in the history of the player
   */
  virtual void onGameEnd(int currentScore, int historyBestScore) = 0;
};

只有三个方法，分别对应游戏开始、玩家得分、游戏结束。

那么状态层需要遵守代理：

/**
 *The status layer,showing the status information
 * in the game.
 */
class StatusLayer : public cocos2d::Layer, public GameStatusDelegate 

遵守代理后，必须声明代理中的方法：

  /**
   * Override from GameStatusDelegate
   *
   * @see GameStatusDelegate declaration.
   */
  void onGameStart(void);
  void onGamePlaying(int score);
  void onGameEnd(int currentScore, int historyBestScore);

如果不声明，会编译不通过的，这是必须实现的。
这个层中，有四种精灵需要控制：

 cocos2d::Sprite *_getReadySprite;
  cocos2d::Sprite *_tutorialSprite;
  cocos2d::Node *_scoreNode;
  cocos2d::Sprite *_blinkSprite;

分别对应GetReady、指导图、得分、闪屏图

在初始化时，先邓加载0~9数字精灵：

bool StatusLayer::init() {
  if (!Layer::init()) {
    return false;
  }

  // preload number sprite frames to memory
  ScoreNumber::getInstance()->loadNumber(kScoreNumberFont.c_str(), "font_0%02d", 48);
  ScoreNumber::getInstance()->loadNumber(kScoreNumberScore.c_str(), "number_score_%02d", 0);

  // At the first time, the game is ready to play
  this->showGameStatus(kGameStateReady);

  return true;
}

关于数字特效类ScoreNumber，后面再单独说明。

这个类中最重要的显示状态方法：

void StatusLayer::showGameStatus(GameState status, int currentScore, int historyBestScore) {
  auto size = Director::getInstance()->getVisibleSize();
  auto origin = Director::getInstance()->getVisibleOrigin();

  switch (status) {
    case kGameStateReady: {
      const char *scoreName = kScoreNumberFont.c_str();
      _scoreNode = ScoreNumber::getInstance()->convert(scoreName, currentScore);
      _scoreNode->setPosition(origin.x + size.width / 2, origin.y + size.height * 5 / 6);
      this->addChild(_scoreNode);

      _getReadySprite = Sprite::createWithSpriteFrame(AtlasLoader::getInstance()->getSpriteFrame("text_ready"));
      _getReadySprite->setPosition(origin.x + size.width / 2, origin.y + size.height * 2 / 3);
      this->addChild(_getReadySprite);

      _tutorialSprite = Sprite::createWithSpriteFrame(AtlasLoader::getInstance()->getSpriteFrame("tutorial"));
      _tutorialSprite->setPosition(origin.x + size.width / 2, origin.y + size.height * 1 / 2);
      this->addChild(_tutorialSprite);
    }
      break;
    case kGameStateStarted: {
      _getReadySprite->runAction(FadeOut::create(0.4f));
      _tutorialSprite->runAction(FadeOut::create(0.4f));
    }
      break;
    case kGameStateOver: {
      _currentScore = currentScore;
      _bestScore = historyBestScore;

      if (_currentScore > _bestScore) {
        _bestScore = _currentScore;
        _isNewRecord = true;
      } else {
        _isNewRecord = false;
      }

      this->removeChild(_scoreNode);

      // Game over
      auto overSprite = Sprite::createWithSpriteFrame(AtlasLoader::getInstance()->getSpriteFrame("text_game_over"));
      auto size = Director::getInstance()->getVisibleSize();
      auto origin = Director::getInstance()->getVisibleOrigin();

      overSprite->setPosition(origin.x + size.width / 2, origin.y + size.height * 2 / 3);
      this->addChild(overSprite);

      // Add animation
      auto fadein = FadeIn::create(0.5f);
      auto actionDone = CallFunc::create(std::bind(&StatusLayer::showScorePanel, this));
      auto sequence = Sequence::createWithTwoActions(fadein, actionDone);
      overSprite->stopAllActions();
      overSprite->runAction(sequence);
    }
      break;
    default:
      break;
  }
}

如果状态为ready，即准备状态，
准备状态图：

状态为kGameStateStarted，表示开始游戏时，
_getReadySprite->runAction(FadeOut::create(0.4f));
_tutorialSprite->runAction(FadeOut::create(0.4f));
只是添加淡出效果

状态为游戏结束时，显示游戏结束：

当游戏结束的时候，显示Game Over 精灵，然后添加淡入淡出的动画，来显示得分结果显示面板和重玩、机会按钮，
不过这里并没有实现机会使用按钮，因此此功能就留给喜欢研究扩展的朋友吧。

刷新得分面板用户得分函数，从0到玩家得分，有一个动画的过程，

void StatusLayer::refreshScoreUpdate(float delta) {
  const int kCurrentSpriteTag = 100;
  if (this->getChildByTag(kCurrentSpriteTag)) {
    this->removeChildByTag(kCurrentSpriteTag);
  }

  const char *score = kScoreNumberScore.c_str();
  _scoreNode = ScoreNumber::getInstance()->convert(score, _tmpScore, kGravityDirectionRight);
  _scoreNode->setAnchorPoint(Vec2(1, 0));

  auto size = Director::getInstance()->getVisibleSize();
  auto origin = Director::getInstance()->getVisibleOrigin();
  _scoreNode->setPosition(origin.x + size.width * 3 / 4 + 4, origin.y + (size.height - _scoreNode->getContentSize().height) / 2 + 7);
  this->addChild(_scoreNode);
  ++_tmpScore;

  if (_tmpScore > _currentScore) {
    unschedule(schedule_selector(StatusLayer::refreshScoreUpdate));
  }
}

这是通过定时器来回调的，当刷新完成时，需要取消掉定时器。

点击重玩按钮时，进入到此函数：

void StatusLayer::menuRestartCallback(cocos2d::Ref *pSender) {
  CocosDenshion::SimpleAudioEngine::getInstance()->playEffect("sfx_swooshing.ogg");

  // We can't add TransitionScene object, otherwise it can't receive any touch event.
  // I don't know why.
  // We should remove all children and clean up resources, otherwise it will crash at
  // some time in the future. In fact, I don't know why, when Director replace a new
  // scene, does it remove and clean up?
  auto scene = Director::getInstance()->getRunningScene();
  scene->removeAllChildrenWithCleanup(true);
  Director::getInstance()->replaceScene(GameScene::createScene());
}

如果不加上这两行代码先释放资源，时不时就会崩溃，不知道是不是因为是自动释放的，但是事件循环并没有到，因此一直没有得到释放而导致的。

  auto scene = Director::getInstance()->getRunningScene();
  scene->removeAllChildrenWithCleanup(true);

这两行代码只是先把当前场景的所有资源先释放掉。

下一步，看一看我们设计的数字特效类