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by
paviter singh (sonoport) and
kirupa | 20 October 2010
Have questions? Discuss this Flash / ActionScript tutorial
with others on the forums.
In the
previous page, you got your project up and running and
learned about what code you currently have to work with. In
this page, let's actually add the sound and look at ways at
making it sound different.
Now that
we've looked at the code responsible for moving our
spaceship around the screen, let's start adding sound! The
first thing we are going to do is add a import statement to
allow us to use the Sonoport library where a lot of the
functionality we will use lives.
Towards the top of the code file, you will see some
import statements:
- import
flash.display.*;
- import
flash.events.*;
Go ahead and add the import statement for the Sonoport
library to it:
- import
flash.display.*;
- import
flash.events.*;
- import
com.sonoport.*;
Adding an import statement won't really result in any
changes to your application right now, but you'll see
shortly that you can now use types that live inside this
library.
Ok, now let's actually get to adding the sound. First,
add a variable called snd
whose type is
SpaceShipSoundAmbience towards the top where your
other variables are declared:
-
private
const
wSWF:Number
=
750;
-
private
const
hSWF:Number
=
400;
-
-
private
var
targetX:Number
=
wSWF/2;
-
private
var
targetY:Number
=
hSWF/2;
-
-
private
var
ship:Sprite;
- private
var
snd:SpaceShipAmbience;
Once you have declared your snd variable, it is time to
initialize it. In your init function, copy and paste the two
non-grayed out lines that you see below:
-
private
function
init():void
- {
-
-
stage.scaleMode
=
StageScaleMode.NO_SCALE;
-
stage.align
=
StageAlign.TOP_LEFT;
-
-
- //
Creating a new Spacehip object
-
ship
=
new
Spaceship();
-
addChild(ship);
-
- snd
=
new SpaceShipAmbience();
- snd.play();
-
-
stage.addEventListener(Event.ENTER_FRAME,onEnter);
-
stage.addEventListener(MouseEvent.MOUSE_MOVE,
onMove);
-
- }
Once you have added the above two lines of code, test
your application by pressing Ctrl + Enter (Cmd + Return).
You will now see that a slight buzzing sound can be heard
through your speakers. In addition to the spaceship sound,
you might also hear a drip sound regularly. That’s our
watermark :-) To disable it, you will have to add the
following line of code:
- snd.setKey("[email protected]:SpaceShipAmbience:all:1:0:F6A6A1CE");
Insert that code in-between the two lines you just added
in the above section:
- snd
=
new
SpaceShipAmbience();
- snd.setKey("[email protected]:SpaceShipAmbience:all:1:0:F6A6A1CE");
- snd.play();
Once you have added this line, your sound should work.
While the sound works, it sounds pretty static - it just plays with
no real variation to it. Let's change that next.
What we want to do next is adjust the sound based on where
the spaceship actually is. For example, if the spaceship is
on the left side of your screen, you would probably want to
hear the sound coming from your left speakers. If the
spaceship is on the right side of your screen, it would be
good to hear the sound coming from your right speakers.
This will require a few more lines of code. Each sound model has a unique set of
dynamic parameters that can be changed using the setParam()
function. For what we want to do, we need to change the
panning of the sound, and it is based on the x-position of
our spaceship.
Inside the onEnter function, add the following two lines
towards the bottom of this function:
- var
pan:Number
= (ship.x-wSWF/2)
/ (wSWF/2);
- snd.setParam(BaseSound.PAN,
pan );
My onEnter function currently looks as follows:
- private
function
onEnter(event:Event):void
- {
- //calculation for
interpolating the ship's position
- ship.x
= (0.90*ship.x
+
0.1*targetX)-1;
- ship.y
= (0.90*ship.y
+
0.1*targetY)-1;
-
- var
dx:Number
=
Math.abs(targetX
-
ship.x);
- var
dy:Number
=
Math.abs(targetY
-
ship.y);
- //calculating the distance
that the ship has travelled
- var
distance:Number
=
Math.sqrt(dx
*
dx +
dy
* dy);
-
- if
(distance
>=
450)
- {
- distance
=
450;
- }
-
- //scaling the ship based
on its y-position
- ship.scaleX
=
ship.scaleY
=
ship.y
*
0.5 *
0.01;
-
- // Dynamic panning
- var
pan:Number
= (ship.x-wSWF/2)
/ (wSWF/2);
- snd.setParam(BaseSound.PAN,
pan
);
- }
If you run your application, you should now be able to
tell that the sound moves between your left and right
speakers depending on where on the screen your spaceship is.
This is done by first getting normalized values between
-1 and 1, and that is what the pan
variable determines and stores. The setParam function that
lives in your snd SpaceShipAmbience object takes the
BaseSound.PAN property and
the value of pan as determined one line earlier. When these
values hit the snd object, the currently playing sound is
altered to match the specified pan to give you the result
that you hear.
Ok, now that you are more familiar with dynamically
changing our sound model, let us do something more exciting...such
as changing the frequency!
To change the SpaceShipAmbience’s frequency, add the
following line of code towards the bottom of your onEnter
function:
- snd.setParam(SpaceShipAmbience.FREQ,
50+distance);
Test your application to see it at work. Now, notice that
I am using the setParam method again to specify the property
and the value that property needs to have. This time, the
property is SpaceShipAmbience.FREQ,
and the value is based on the total distance the spaceship
has traveled.
Since we are having so much fun, let's make some changes
to the Gain and Harmonics to make our spaceship sound even
more realistic. In the onEnter function, go ahead and tack
on the following lines of code:
- //calculating gain level based
on ship's y-position
- var
gainLevel:Number
= 1-((hSWF
- ship.y)
/ hSWF);
- snd.setParam(BaseSound.GAIN,
gainLevel);
-
- //changing the sound model's
harmonics value
- var
harVal:Number
= ship.y
/ 7
;
-
- //do check for harmonics max
level
- if(harVal
>= 50)
- {
- harVal
=
50;
- }
- snd.setParam(SpaceShipAmbience.HARMONICS,
harVal);
This code is also pretty straightforward. It just does
more things depending on where on the screen your spaceship
actually is. The BaseSound.GAIN
and SpaceShipAmbience.HARMONICS
properties are in the crosshairs this time.
You may be wondering how to know which property to use.
The
Sonoport API docs will help you out with that. For
example, the
SpaceShipAmbience page describes the harmonics and
frequency properties.
If anything,
hopefully this tutorial helped you to learn how easy it is
to enhance your applications by simply improving how you
work with sound. As you can see, the Sonoport library makes
it fairly easy to work with a variety of sounds and tweak
their respective parameters without having to break a sweat.
For any questions or comments, either visit
Sonoport's web site or post on the forums
here.
 |
Paviter Singh
(Sonoport) |
 |
Kirupa |
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