ambisonic.js

//  ambientSound.js
//
//  This entity script will allow you to create an ambient sound that loops when a person is within a given
//  range of this entity.  Great way to add one or more ambisonic soundfields to your environment.  
//
//  In the userData section for the entity, add two values:  
//      userData.SoundURL should be a string giving the URL to the sound file.  Defaults to 100 meters if not set.  
//      userData.range should be an integer for the max distance away from the entity where the sound will be audible.
//      userData.volume is the max volume at which the clip should play.
//
//  Note: When you update the above values, you need to reload the entity script for it to see the changes.  Also,
//  remember that the entity has to be visible to the user for the sound to play at all, so make sure the entity is
//  large enough to be loaded at the range you set, particularly for large ranges.  
//   
//  Copyright 2016 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//

(function(){ 
    //  This sample clip and range will be used if you don't add userData to the entity (see above)
    var DEFAULT_RANGE = 100;
    var DEFAULT_URL = "http://hifi-content.s3.amazonaws.com/ken/samples/forest_ambiX.wav";
    var DEFAULT_VOLUME = 1.0;

    var soundURL = DEFAULT_URL;
    var range = DEFAULT_RANGE;
    var maxVolume = DEFAULT_VOLUME;
    var UPDATE_INTERVAL_MSECS = 100;

    var entity;
    var ambientSound;
    var center;
    var soundPlaying = false;
    var updateTimer = false;

    var WANT_DEBUG = false;

    function debugPrint(string) {
        if (WANT_DEBUG) {
            print(string);
        }
    }

    this.preload = function(entityID) { 
        //  Load the sound and range from the entity userData fields, and note the position of the entity.
        debugPrint("Ambient sound preload");
        entity = entityID;
        var props = Entities.getEntityProperties(entityID, [ "userData" ]);
        var data = JSON.parse(props.userData);
        if (data.soundURL) {
            soundURL = data.soundURL;
            debugPrint("Read ambient sound URL: " + soundURL);    
        } 
        ambientSound = SoundCache.getSound(soundURL);
        if (data.range) {
            range = data.range;
            debugPrint("Read ambient sound range: " + range);
        }
        if (data.volume) {
            maxVolume = data.volume;
            debugPrint("Read ambient sound volume: " + maxVolume);
        }
        updateTimer = Script.setInterval(this.update, UPDATE_INTERVAL_MSECS);
    }; 

    this.update = function() {
        // Every UPDATE_INTERVAL_MSECS, update the volume of the ambient sound based on distance from my avatar
        var HYSTERESIS_FRACTION = 0.1;
        var props = Entities.getEntityProperties(entity, [ "position" ]);
        center = props.position;
        var distance = Vec3.length(Vec3.subtract(MyAvatar.position, center));
        if (distance <= range) {
            var volume = (1.0 - distance / range) * maxVolume;
            if (!soundPlaying && ambientSound.downloaded) {
                soundPlaying = Audio.playSound(ambientSound,  { loop: true, volume: volume });
                debugPrint("Starting ambient sound, volume: " + volume);
                Entities.editEntity(entity, { color: { red: 255, green: 0, blue: 0 }});
            } else if (soundPlaying && soundPlaying.playing) {
                soundPlaying.setOptions( { volume: volume } );
            }
        } else if (soundPlaying && soundPlaying.playing && (distance > range * HYSTERESIS_FRACTION)) {
            soundPlaying.stop();
            soundPlaying = false;
            Entities.editEntity(entity, { color: { red: 128, green: 128, blue: 128 }});
            debugPrint("Out of range, stopping ambient sound");
        }
    }

    this.unload = function(entityID) { 
        debugPrint("Ambient sound unload");
        if (updateTimer) {
            Script.clearInterval(updateTimer);
        }
        if (soundPlaying && soundPlaying.playing) {
            soundPlaying.stop();
        }
    }; 

})