From 70942925bc200da48196b5955d86156f12513d29 Mon Sep 17 00:00:00 2001
From: Philip Rosedale <philip@highfidelity.io>
Date: Mon, 19 Dec 2016 10:32:17 -0800
Subject: [PATCH] Entity script for ambisonic sound emitter

---
 .../tutorials/entity_scripts/ambientSound.js  | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 scripts/tutorials/entity_scripts/ambientSound.js

diff --git a/scripts/tutorials/entity_scripts/ambientSound.js b/scripts/tutorials/entity_scripts/ambientSound.js
new file mode 100644
index 0000000000..a387f00c10
--- /dev/null
+++ b/scripts/tutorials/entity_scripts/ambientSound.js
@@ -0,0 +1,101 @@
+//  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();
+        }
+    }; 
+
+})