forked from sent/waves
283 lines
12 KiB
JavaScript
283 lines
12 KiB
JavaScript
/**
|
|
* Module that takes care of audio playback
|
|
*/
|
|
var AudioEngine = {
|
|
FADE_TIME: 1,
|
|
AUDIO_BUFFER_CACHE: {},
|
|
_audioContext: null,
|
|
_master: null,
|
|
_currentBackgroundMusic: null,
|
|
_currentEventAudio: null,
|
|
_currentSoundEffectAudio: null,
|
|
_initialized: false,
|
|
init: function () {
|
|
AudioEngine._initAudioContext();
|
|
// AudioEngine._preloadAudio(); // removed to save bandwidth
|
|
AudioEngine._initialized = true;
|
|
},
|
|
_preloadAudio: function () {
|
|
// start loading music and events early
|
|
// ** could be used later if we specify a better set of
|
|
// audio files to preload -- i.e. we probably don't need to load
|
|
// the later villages or events audio, and esp. not the ending
|
|
for (var key in AudioLibrary) {
|
|
if (
|
|
key.toString().indexOf('MUSIC_') > -1 ||
|
|
key.toString().indexOf('EVENT_') > -1) {
|
|
AudioEngine.loadAudioFile(AudioLibrary[key]);
|
|
}
|
|
}
|
|
},
|
|
_initAudioContext: function () {
|
|
AudioEngine._audioContext = new (window.AudioContext || window.webkitAudioContext);
|
|
AudioEngine._createMasterChannel();
|
|
},
|
|
_createMasterChannel: function () {
|
|
// create master
|
|
AudioEngine._master = AudioEngine._audioContext.createGain();
|
|
AudioEngine._master.gain.setValueAtTime(1.0, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._master.connect(AudioEngine._audioContext.destination);
|
|
},
|
|
_getMissingAudioBuffer: function () {
|
|
// plays beeping sound to indicate missing audio
|
|
var buffer = AudioEngine._audioContext.createBuffer(
|
|
1,
|
|
AudioEngine._audioContext.sampleRate,
|
|
AudioEngine._audioContext.sampleRate
|
|
);
|
|
// Fill the buffer
|
|
var bufferData = buffer.getChannelData(0);
|
|
for (var i = 0; i < buffer.length / 2; i++) {
|
|
bufferData[i] = Math.sin(i * 0.05) / 4; // max .25 gain value
|
|
}
|
|
return buffer;
|
|
},
|
|
_playSound: function (buffer) {
|
|
if (AudioEngine._currentSoundEffectAudio &&
|
|
AudioEngine._currentSoundEffectAudio.source.buffer == buffer) {
|
|
return;
|
|
}
|
|
|
|
var source = AudioEngine._audioContext.createBufferSource();
|
|
source.buffer = buffer;
|
|
source.onended = function(event) {
|
|
// dereference current sound effect when finished
|
|
if (AudioEngine._currentSoundEffectAudio &&
|
|
AudioEngine._currentSoundEffectAudio.source.buffer == buffer) {
|
|
AudioEngine._currentSoundEffectAudio = null;
|
|
}
|
|
};
|
|
|
|
source.connect(AudioEngine._master);
|
|
source.start();
|
|
|
|
AudioEngine._currentSoundEffectAudio = {
|
|
source: source
|
|
};
|
|
},
|
|
_playBackgroundMusic: function (buffer) {
|
|
var source = AudioEngine._audioContext.createBufferSource();
|
|
source.buffer = buffer;
|
|
source.loop = true;
|
|
|
|
var envelope = AudioEngine._audioContext.createGain();
|
|
envelope.gain.setValueAtTime(0.0, AudioEngine._audioContext.currentTime);
|
|
|
|
var fadeTime = AudioEngine._audioContext.currentTime + AudioEngine.FADE_TIME;
|
|
|
|
// fade out current background music
|
|
if (AudioEngine._currentBackgroundMusic &&
|
|
AudioEngine._currentBackgroundMusic.source &&
|
|
AudioEngine._currentBackgroundMusic.source.playbackState !== 0) {
|
|
var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(0.0, fadeTime);
|
|
AudioEngine._currentBackgroundMusic.source.stop(fadeTime + 0.3); // make sure fade has completed
|
|
}
|
|
|
|
// fade in new backgorund music
|
|
source.connect(envelope);
|
|
envelope.connect(AudioEngine._master);
|
|
source.start();
|
|
envelope.gain.linearRampToValueAtTime(1.0, fadeTime);
|
|
|
|
// update current background music
|
|
AudioEngine._currentBackgroundMusic = {
|
|
source: source,
|
|
envelope: envelope
|
|
};
|
|
},
|
|
_playEventMusic: function (buffer) {
|
|
var source = AudioEngine._audioContext.createBufferSource();
|
|
source.buffer = buffer;
|
|
source.loop = true;
|
|
|
|
var envelope = AudioEngine._audioContext.createGain();
|
|
envelope.gain.setValueAtTime(0.0, AudioEngine._audioContext.currentTime);
|
|
|
|
var fadeTime = AudioEngine._audioContext.currentTime + AudioEngine.FADE_TIME * 2;
|
|
|
|
// turn down current background music
|
|
if (AudioEngine._currentBackgroundMusic != null) {
|
|
var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(0.2, fadeTime);
|
|
}
|
|
|
|
// fade in event music
|
|
source.connect(envelope);
|
|
envelope.connect(AudioEngine._master);
|
|
source.start();
|
|
envelope.gain.linearRampToValueAtTime(1.0, fadeTime);
|
|
|
|
// update reference
|
|
AudioEngine._currentEventAudio = {
|
|
source: source,
|
|
envelope: envelope
|
|
};
|
|
},
|
|
_stopEventMusic: function () {
|
|
var fadeTime = AudioEngine._audioContext.currentTime + AudioEngine.FADE_TIME * 2;
|
|
|
|
// fade out event music and stop
|
|
if (AudioEngine._currentEventAudio &&
|
|
AudioEngine._currentEventAudio.source &&
|
|
AudioEngine._currentEventAudio.source.buffer) {
|
|
var currentEventGainValue = AudioEngine._currentEventAudio.envelope.gain.value;
|
|
AudioEngine._currentEventAudio.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentEventAudio.envelope.gain.setValueAtTime(currentEventGainValue, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentEventAudio.envelope.gain.linearRampToValueAtTime(0.0, fadeTime);
|
|
AudioEngine._currentEventAudio.source.stop(fadeTime + 1); // make sure fade has completed
|
|
AudioEngine._currentEventAudio = null;
|
|
}
|
|
|
|
// turn up background music
|
|
if (AudioEngine._currentBackgroundMusic) {
|
|
var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(1.0, fadeTime);
|
|
}
|
|
},
|
|
isAudioContextRunning: function () {
|
|
return AudioEngine._audioContext.state !== 'suspended';
|
|
},
|
|
tryResumingAudioContext: function() {
|
|
if (AudioEngine._audioContext.state === 'suspended') {
|
|
AudioEngine._audioContext.resume();
|
|
}
|
|
},
|
|
playBackgroundMusic: function (src) {
|
|
if (!AudioEngine._initialized) {
|
|
return;
|
|
}
|
|
AudioEngine.loadAudioFile(src)
|
|
.then(function (buffer) {
|
|
AudioEngine._playBackgroundMusic(buffer);
|
|
});
|
|
},
|
|
playEventMusic: function (src) {
|
|
if (!AudioEngine._initialized) {
|
|
return;
|
|
}
|
|
AudioEngine.loadAudioFile(src)
|
|
.then(function (buffer) {
|
|
AudioEngine._playEventMusic(buffer);
|
|
});
|
|
},
|
|
stopEventMusic: function () {
|
|
if (!AudioEngine._initialized) {
|
|
return;
|
|
}
|
|
AudioEngine._stopEventMusic();
|
|
},
|
|
playSound: function (src) {
|
|
if (!AudioEngine._initialized) {
|
|
return;
|
|
}
|
|
AudioEngine.loadAudioFile(src)
|
|
.then(function (buffer) {
|
|
AudioEngine._playSound(buffer);
|
|
});
|
|
},
|
|
loadAudioFile: function (src) {
|
|
if (src.indexOf('http') === -1) {
|
|
src = window.location + src;
|
|
}
|
|
if (AudioEngine.AUDIO_BUFFER_CACHE[src]) {
|
|
return new Promise(function (resolve, reject) {
|
|
resolve(AudioEngine.AUDIO_BUFFER_CACHE[src]);
|
|
});
|
|
} else {
|
|
var request = new Request(src);
|
|
return fetch(request).then(function (response) {
|
|
return response.arrayBuffer();
|
|
}).then(function (buffer) {
|
|
if (buffer.byteLength === 0) {
|
|
console.error('cannot load audio from ' + src);
|
|
return AudioEngine._getMissingAudioBuffer();
|
|
}
|
|
|
|
var decodeAudioDataPromise = AudioEngine._audioContext.decodeAudioData(buffer, function (decodedData) {
|
|
AudioEngine.AUDIO_BUFFER_CACHE[src] = decodedData;
|
|
return AudioEngine.AUDIO_BUFFER_CACHE[src];
|
|
});
|
|
|
|
// Safari WebAudio does not return a promise based API for
|
|
// decodeAudioData, so we need to fake it if we want to play
|
|
// audio immediately on first fetch
|
|
if (decodeAudioDataPromise) {
|
|
return decodeAudioDataPromise;
|
|
} else {
|
|
return new Promise(function (resolve, reject) {
|
|
var fakePromiseId = setInterval(function() {
|
|
if (AudioEngine.AUDIO_BUFFER_CACHE[src]) {
|
|
resolve(AudioEngine.AUDIO_BUFFER_CACHE[src]);
|
|
clearInterval(fakePromiseId);
|
|
}
|
|
}, 20);
|
|
});
|
|
}
|
|
});
|
|
}
|
|
},
|
|
setBackgroundMusicVolume: function (volume, s) {
|
|
if (AudioEngine._master == null) return; // master may not be ready yet
|
|
if (volume === undefined) {
|
|
volume = 1.0;
|
|
}
|
|
if (s === undefined) {
|
|
s = 1.0;
|
|
}
|
|
|
|
// cancel any current schedules and then ramp
|
|
var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(
|
|
volume,
|
|
AudioEngine._audioContext.currentTime + s
|
|
);
|
|
},
|
|
setMasterVolume: function (volume, s) {
|
|
if (AudioEngine._master == null) return; // master may not be ready yet
|
|
if (volume === undefined) {
|
|
volume = 1.0;
|
|
}
|
|
if (s === undefined) {
|
|
s = 1.0;
|
|
}
|
|
|
|
// cancel any current schedules and then ramp
|
|
var currentGainValue = AudioEngine._master.gain.value;
|
|
AudioEngine._master.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
|
|
AudioEngine._master.gain.setValueAtTime(currentGainValue, AudioEngine._audioContext.currentTime);
|
|
AudioEngine._master.gain.linearRampToValueAtTime(
|
|
volume,
|
|
AudioEngine._audioContext.currentTime + s
|
|
);
|
|
}
|
|
};
|