fix space music fading in when ending game by adding separate backgro…

…und volume function

script/audio.js

@@ -191,7 +191,25 @@ var AudioEngine = {
             });
         }
     },
-    setVolume: function (volume, s) {
+    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;

script/space.js

@@ -400,8 +400,8 @@ var Space = {
 		}
 		delete Outside._popTimeout;
 
-		AudioEngine.setVolume(1.0);
 		AudioEngine.playBackgroundMusic(AudioLibrary.MUSIC_ENDING);
+
 		$('#hullRemaining', Space.panel).animate({opacity: 0}, 500, 'linear');
 		Space.ship.animate({
 			top: '350px',
@@ -558,8 +558,10 @@ var Space = {
 
 	lowerVolume: function () {
 		if (Space.done) return;
+
 		// lower audio as ship gets further into space
-		var newVolume = 1.0 - (Space.altitude / 60);
-		AudioEngine.setVolume(newVolume, .3);
+		var progress = Space.altitude / 60;
+		var newVolume = 1.0 - progress;
+		AudioEngine.setBackgroundMusicVolume(newVolume, .3);
 	}
 };