Adding Bodies to the World - Box2D for Flash Games - page 12

Creating a fixture
A fixture. is used to bind the shape on a body, and to define its material setting
density, friction, and restitution. Don't worry about materials at the moment,
and let's focus on the fixture.

1. The first step is to create the fixture:
var fixtureDef:b2FixtureDef = new b2FixtureDef();
fixtureDef.shape=circleShape;

Once we have created the fixture with the constructor, we assign the
previously created shape using the shape property.

2. Finally we are ready to add the ball to the world:

var theBall:b2Body=world.CreateBody(bodyDef);
theBall.CreateFixture(fixtureDef);

b2Body is the body itself: the physical, concrete body that has been
created using the bodyDef attribute.

3. To recap, use the following steps when you want to place a body in

the world:
i. Create a body definition, which will hold body information
such as its position.
ii. Create a shape, which is how the body will look.
iii. Create a fixture to attach the shape to the body definition.
iv. Create the body itself in the world using the fixture.

Once you know the importance of each step, adding bodies to your
Box2D World will be easy and fun.

4. Back to our project. The following is how the class should look now:

package {
import flash.display.Sprite;
import flash.events.Event;
import Box2D.Dynamics.*;
import Box2D.Collision.*;
import Box2D.Collision.Shapes.*;
import Box2D.Common.Math.*;
public class Main extends Sprite {
private var world:b2World;
private var worldScale:Number=30;
public function Main() {