高级声音功能

配置

移动设备上的游戏会遇到一些特殊的情景，比如游戏应用被切换至后台又切换回前台，正在玩游戏的时候电话来了，电话打完继续玩游戏，这些你在进行声音控制的时候都得考虑。

幸运的是，游戏引擎在设计的时候已经考虑到这些情景了，注意在 AppDelegate.cpp 中，有这样几个方法：

C++

  1. // This function will be called when the app is inactive. When comes a phone call,
  2. // it's be invoked too
  3. void AppDelegate::applicationDidEnterBackground() {
  4.     Director::getInstance()->stopAnimation();
  6.     // if you use SimpleAudioEngine, it must be pause
  7.     // SimpleAudioEngine::getInstance()->pauseBackgroundMusic();
  8. }
  10. // this function will be called when the app is active again
  11. void AppDelegate::applicationWillEnterForeground() {
  12.     Director::getInstance()->startAnimation();
  14.     // if you use SimpleAudioEngine, it must resume here
  15.     // SimpleAudioEngine::getInstance()->resumeBackgroundMusic();
  16. }

看到了那些被注释的行吗？如果你有使用 SimpleAudioEngine 在游戏中播放声音，记得取消这些注释。当这些被注释的代码生效，你的游戏就能应对刚才提到的场景。

预加载

加载音乐和音效通常是个耗时间的过程，为了防止由加载产生的延时导致实际播放与游戏播放不协调的现象，在播放音乐和音效前，可以预加载音乐文件。

C++

  1. #include "SimpleAudioEngine.h"
  2. using namespace CocosDenshion;
  4. auto audio = SimpleAudioEngine::getInstance();
  6. // pre-loading background music and effects. You could pre-load
  7. // effects, perhaps on app startup so they are already loaded
  8. // when you want to use them.
  9. audio->preloadBackgroundMusic("myMusic1.mp3");
  10. audio->preloadBackgroundMusic("myMusic2.mp3");
  12. audio->preloadEffect("myEffect1.mp3");
  13. audio->preloadEffect("myEffect2.mp3");
  15. // unload a sound from cache. If you are finished with a sound and
  16. // you wont use it anymore in your game. unload it to free up
  17. // resources.
  18. audio->unloadEffect("myEffect1.mp3");

音量控制

可以像下面这样，通过代码控制音乐和音效的音量：

C++

  1. #include "SimpleAudioEngine.h"
  2. using namespace CocosDenshion;
  4. auto audio = SimpleAudioEngine::getInstance();
  6. // setting the volume specifying value as a float
  7. audio->setEffectsVolume(5.0f);

原文: http://docs.cocos.com/cocos2d-x/manual/zh/audio/advanced.html