Game Development Reference
In-Depth Information
soundtracks. Instead of managing all of this, functionality to simply play one soundtrack at a time
starts looking very useful.
To facilitate this soundtrack functionality, we have created a single
SoundChannel
object named
soundTrackChannel
. If that
soundTrackChannel
is not null (which means a soundtrack is playing),
we call the
stop()
function of
soundTrackChannel
. If it is null, we set
soundTrackChannel
equal to
the value returned when we start playing the sound. However, this code begs the question, “What
is a
SoundChannel
?”
SoundChannel
objects in AS3 are used to differentiate sounds that are played, so you can set the
volume
and
pan
attributes separately for each sound. I know this might not sound like much, but
this is a revelation after AS2. In AS2, you were forced to create separate sound objects attached
to separate
MovieClip
objects to make this work correctly, and the code was still buggy in places.
There were times when, no matter how hard we tried, every sound in a game would be set to the
same volume or worse, no volume at all. With
SoundChannel
objects, all these limitations go away.
However, the price you pay is slightly more complicated code than in previous versions of Flash.
The good news is this: a
SoundChannel
is provided for you every time you play a sound. All you
need to do is set its properties once you have a reference to one. In our code, that reference is
stored in the
soundChannels
array, keyed by the
soundName
parameter. We store these
SoundChannel
objects because, if we don't we will have no way to stop the sound from playing on
request. We will cover this when we discuss the
stopSound()
function.
if (isSoundTrack) {
if (soundTrackChannel != null) {
soundTrackChannel.stop();
}
soundTrackChannel = tempSound.play(offset,loops);
soundTrackChannel.soundTransform=tempSoundTransform;
}else {
soundChannels[soundName] = tempSound.play(offset, loops);
soundChannels[soundName].soundTransform=tempSoundTransform;
}
}
The
stopSound()
function is called by
Main
when it receives a
CustomSoundEvent
with the
type
parameter set to
CustomEventSound.STOP_SOUND
. The function looks to see if we should treat the
stop as a soundtrack or not and then stops the sound accordingly. If it is a soundtrack, we ignore
the
soundName
and just call the
stop()
function of
soundTrackChannel
. If not, we use
soundName
as
the index into the
soundChannels
array to find the correct
SoundChannel
to stop.
public function stopSound(soundName:String, isSoundTrack:Boolean=false):void {
if (isSoundTrack) {
soundTrackChannel.stop();
}else {
soundChannels[soundName].stop;
}
}
The
muteSound()
function is used to turn off all the sounds playing in a game. Just like with a
sound channel, we need
SoundTransform
object to set the volume to mute all sounds. First, we
check the
soundMute
Boolean. If it is
true
, we have already muted the sounds, and we will make
them audible again. If it is
false
, it is time to mute everything. To mute, we set the
muteSoundTransform.volume
property to
0
. To unmute, we set the
muteSoundTransform.volume
property to
1
. Then, we set the
flash.media.SoundMixer.soundTransform
static property to the
