mirror of
https://github.com/doublespeakgames/adarkroom.git
synced 2026-05-28 00:01:54 +08:00
We have audio! Thanks @orsi!
This commit is contained in:
jorsi
+236
@@ -0,0 +1,236 @@
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/**
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* Module that takes care of audio playback
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*/
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var AudioEngine = {
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FADE_TIME: 1,
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AUDIO_BUFFER_CACHE: {},
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_audioContext: null,
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_master: null,
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_currentBackgroundMusic: null,
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_currentEventAudio: null,
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_currentSoundEffectAudio: null,
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init: function () {
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AudioEngine._initAudioContext();
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},
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_initAudioContext: function () {
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AudioEngine._audioContext = new (window.AudioContext || window.webkitAudioContext);
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AudioEngine._createMasterChannel();
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},
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_createMasterChannel: function () {
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// create master
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AudioEngine._master = AudioEngine._audioContext.createGain();
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AudioEngine._master.gain.setValueAtTime(1.0, AudioEngine._audioContext.currentTime);
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AudioEngine._master.connect(AudioEngine._audioContext.destination);
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},
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_getMissingAudioBuffer: function () {
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// plays beeping sound to indicate missing audio
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var buffer = AudioEngine._audioContext.createBuffer(
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1,
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AudioEngine._audioContext.sampleRate,
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AudioEngine._audioContext.sampleRate
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);
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// Fill the buffer
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var bufferData = buffer.getChannelData(0);
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for (var i = 0; i < buffer.length / 2; i++) {
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bufferData[i] = Math.sin(i * 0.05) / 4; // max .25 gain value
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}
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return buffer;
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},
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_playSound: function (buffer) {
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if (AudioEngine._currentSoundEffectAudio &&
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AudioEngine._currentSoundEffectAudio.source.buffer == buffer) {
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return;
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}
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var source = AudioEngine._audioContext.createBufferSource();
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source.buffer = buffer;
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source.onended = function(event) {
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// dereference current sound effect when finished
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if (AudioEngine._currentSoundEffectAudio &&
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AudioEngine._currentSoundEffectAudio.source.buffer == buffer) {
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AudioEngine._currentSoundEffectAudio = null;
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}
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};
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source.connect(AudioEngine._master);
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source.start();
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AudioEngine._currentSoundEffectAudio = {
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source: source
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};
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},
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_playBackgroundMusic: function (buffer) {
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var source = AudioEngine._audioContext.createBufferSource();
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source.buffer = buffer;
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source.loop = true;
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var envelope = AudioEngine._audioContext.createGain();
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envelope.gain.setValueAtTime(0.0, AudioEngine._audioContext.currentTime);
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var fadeTime = AudioEngine._audioContext.currentTime + AudioEngine.FADE_TIME;
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// fade out current background music
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if (AudioEngine._currentBackgroundMusic &&
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AudioEngine._currentBackgroundMusic.source &&
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AudioEngine._currentBackgroundMusic.source.playbackState !== 0) {
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var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
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AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(0.0, fadeTime);
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AudioEngine._currentBackgroundMusic.source.stop(fadeTime + 0.3); // make sure fade has completed
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}
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// fade in new backgorund music
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source.connect(envelope);
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envelope.connect(AudioEngine._master);
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source.start();
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envelope.gain.linearRampToValueAtTime(1.0, fadeTime);
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// update current background music
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AudioEngine._currentBackgroundMusic = {
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source: source,
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envelope: envelope
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};
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},
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_playEventMusic: function (buffer) {
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var source = AudioEngine._audioContext.createBufferSource();
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source.buffer = buffer;
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source.loop = true;
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var envelope = AudioEngine._audioContext.createGain();
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envelope.gain.setValueAtTime(0.0, AudioEngine._audioContext.currentTime);
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var fadeTime = AudioEngine._audioContext.currentTime + AudioEngine.FADE_TIME * 2;
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// turn down current background music
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if (AudioEngine._currentBackgroundMusic != null) {
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var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
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AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(0.2, fadeTime);
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}
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// fade in event music
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source.connect(envelope);
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envelope.connect(AudioEngine._master);
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source.start();
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envelope.gain.linearRampToValueAtTime(1.0, fadeTime);
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// update reference
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AudioEngine._currentEventAudio = {
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source: source,
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envelope: envelope
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};
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},
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_stopEventMusic: function () {
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var fadeTime = AudioEngine._audioContext.currentTime + AudioEngine.FADE_TIME * 2;
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// fade out event music and stop
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if (AudioEngine._currentEventAudio) {
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var currentEventGainValue = AudioEngine._currentEventAudio.envelope.gain.value;
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AudioEngine._currentEventAudio.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
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AudioEngine._currentEventAudio.envelope.gain.setValueAtTime(currentEventGainValue, AudioEngine._audioContext.currentTime);
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AudioEngine._currentEventAudio.envelope.gain.linearRampToValueAtTime(0.0, fadeTime);
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AudioEngine._currentEventAudio.source.stop(fadeTime + 1); // make sure fade has completed
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AudioEngine._currentEventAudio = null;
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}
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// turn up background music
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if (AudioEngine._currentBackgroundMusic) {
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var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
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AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(1.0, fadeTime);
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}
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},
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isAudioContextRunning: function () {
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return AudioEngine._audioContext.state !== 'suspended';
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},
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tryResumingAudioContext: function() {
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if (AudioEngine._audioContext.state === 'suspended') {
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AudioEngine._audioContext.resume();
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}
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},
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playBackgroundMusic: function (src) {
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AudioEngine.loadAudioFile(src)
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.then(function (buffer) {
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AudioEngine._playBackgroundMusic(buffer);
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});
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},
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playEventMusic: function (src) {
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AudioEngine.loadAudioFile(src)
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.then(function (buffer) {
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AudioEngine._playEventMusic(buffer);
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});
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},
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stopEventMusic: function () {
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AudioEngine._stopEventMusic();
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},
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playSound: function (src) {
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AudioEngine.loadAudioFile(src)
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.then(function (buffer) {
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AudioEngine._playSound(buffer);
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});
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},
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loadAudioFile: function (src) {
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if (src.indexOf('http') === -1) {
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src = window.location + src;
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}
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if (AudioEngine.AUDIO_BUFFER_CACHE[src]) {
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return new Promise(function (resolve, reject) {
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resolve(AudioEngine.AUDIO_BUFFER_CACHE[src]);
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});
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} else {
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var request = new Request(src);
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return fetch(request).then(function (response) {
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return response.arrayBuffer();
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}).then(function (buffer) {
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if (buffer.byteLength === 0) {
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console.error('cannot load audio from ' + src);
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return AudioEngine._getMissingAudioBuffer();
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}
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return AudioEngine._audioContext.decodeAudioData(buffer, function (decodedData) {
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AudioEngine.AUDIO_BUFFER_CACHE[src] = decodedData;
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return AudioEngine.AUDIO_BUFFER_CACHE[src];
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});
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});
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}
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},
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setBackgroundMusicVolume: function (volume, s) {
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if (AudioEngine._master == null) return; // master may not be ready yet
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if (volume === undefined) {
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volume = 1.0;
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}
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if (s === undefined) {
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s = 1.0;
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}
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// cancel any current schedules and then ramp
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var currentBackgroundGainValue = AudioEngine._currentBackgroundMusic.envelope.gain.value;
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AudioEngine._currentBackgroundMusic.envelope.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.setValueAtTime(currentBackgroundGainValue, AudioEngine._audioContext.currentTime);
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AudioEngine._currentBackgroundMusic.envelope.gain.linearRampToValueAtTime(
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volume,
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AudioEngine._audioContext.currentTime + s
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);
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},
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setMasterVolume: function (volume, s) {
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if (AudioEngine._master == null) return; // master may not be ready yet
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if (volume === undefined) {
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volume = 1.0;
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}
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if (s === undefined) {
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s = 1.0;
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}
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// cancel any current schedules and then ramp
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var currentGainValue = AudioEngine._master.gain.value;
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AudioEngine._master.gain.cancelScheduledValues(AudioEngine._audioContext.currentTime);
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AudioEngine._master.gain.setValueAtTime(currentGainValue, AudioEngine._audioContext.currentTime);
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AudioEngine._master.gain.linearRampToValueAtTime(
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volume,
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AudioEngine._audioContext.currentTime + s
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);
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}
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};
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