一款开发精良的游戏离不开精心制作的声音效果。Cocos2d-x中提供了一个叫做SimpleAudioEngine的音频引擎。SimpleAudioEngine能够在游戏中播放背景音效以及游戏音效。SimpleAudioEngine是一个共享的单例对象，因此你可以在程序的任意地方调用它。就算是一个 HelloWorld 工程也可以很方便地使用这个引擎。SimpleAudioEgnine 支持多种格式的音频，比如MP3和CAF(Core Audio Forma)

新手入门

     SimpleAudioEngine API的使用非常简单。

播放背景音乐

     选择一个音频文件作为背景音乐，这个文件会被单曲循环一直播放。

auto audio = SimpleAudioEngine::getInstance();

// set the background music and continuously play it.

audio->playBackgroundMusic("mymusic.mp3", true);

// set the background music and play it just once.

audio->playBackgroundMusic("mymusic.mp3", false);

播放音效

       播放音效的方法如下：

auto audio = SimpleAudioEngine::getInstance();

// play a sound effect, just once.

audio->playEffect("myEffect.mp3", false, 1.0f, 1.0f, 1.0f);

暂停、停止、恢复音乐和音效的播放

       当播放音乐和音效时，我们常常需要暂停、停止或者恢复它们。这些实现起来是比较简单的!

暂停

auto audio = SimpleAudioEngine::getInstance();

// pause background music.

audio->pauseBackgroundMusic();

// pause a sound effect.

audio->pauseEffect();

// pause all sound effects.

audio->pauseAllEffects();

停止

auto audio = SimpleAudioEngine::getInstance();

// stop background music.

audio->stopBackgroundMusic();

// stop a sound effect.

audio->stopEffect();

// stops all running sound effects.

audio->stopAllEffects();

Resume 恢复

auto audio = SimpleAudioEngine::getInstance();

// resume background music.

audio->resumeBackgroundMusic();

// resume a sound effect.

audio->resumeEffect();

// resume all sound effects.

audio->resumeAllEffects();

音频高级功能

Setup 设置

SimpleAudioEngine的API非常简单，但是在游戏中使用还是有一些注意事项，尤其是在手机和平板的等移动设备中使用时。比如在多个APP中切换时应如何处理，在或者当你玩着游戏时有电话打进来又该怎么办?这些异常在制作游戏时都必须提前想好处理方法，当然幸运的是，你能想到的异常引擎都帮我们做好了，你只需使用就好。

在AppDelegate.cpp中，注意以下几个方法：

// This function will be called when the app is inactive. When comes a phone call,

// it's be invoked too

void AppDelegate::applicationDidEnterBackground() {

Director::getInstance()->stopAnimation();

// if you use SimpleAudioEngine, it must be pause

// SimpleAudioEngine::getInstance()->pauseBackgroundMusic();

}

// this function will be called when the app is active again

void AppDelegate::applicationWillEnterForeground() {

Director::getInstance()->startAnimation();

// if you use SimpleAudioEngine, it must resume here

// SimpleAudioEngine::getInstance()->resumeBackgroundMusic();

}

       如果你要用SimpleAudioEngine实现背景音乐和音效，那么就需要注意别忘了去掉代码中有用代码的注释。

预加载音效

        当游戏开始时，你需要预加载一些音效到内存中，以便当你想使用它们时能随时播放出来。

auto audio = SimpleAudioEngine::getInstance();

// pre-loading background music and effects. You could pre-load

// effects, perhaps on app startup so they are already loaded

// when you want to use them.

audio->preloadBackgroundMusic("myMusic1.mp3");

audio->preloadBackgroundMusic("myMusic2.mp3");

audio->preloadEffect("myEffect1.mp3");

audio->preloadEffect("myEffect2.mp3");

// unload a sound from cache. If you are finished with a sound and

// you wont use it anymore in your game. unload it to free up

// resources.

audio->unloadEffect("myEffect1.mp3");

音量

      你可以通过程序的控制来增大减小音量。

auto audio = SimpleAudioEngine::getInstance();

// setting the volume specifying value as a float

audio->setEffectsVolume(5.0f);