Joints and Motors - Box2D for Flash Games - page 102

9. At this time, two static carts will be created. Test the movie and check if

everything seems ok:

Remember, when you're building something new with Box2D,
always start with static bodies to what your level is going to look,
with no gravity, forces, and collisions.

Now that everything looks fine, let's make bodies dynamic and add
required joints.

10. Start making wheels and carts dynamic by adding the type property in
both addWheel and addCart functions. The addWheel function is shown
as follows:
private function addWheel(pX:Number,pY:Number):b2Body {
var bodyDef:b2BodyDef=new b2BodyDef();
bodyDef.position.Set(pX/worldScale,pY/worldScale);
bodyDef.type=b2Body.b2_dynamicBody;
var circleShape:b2CircleShape=new b2CircleShape(0.5);
var fixtureDef:b2FixtureDef=new b2FixtureDef();
fixtureDef.shape=circleShape;
fixtureDef.density=1;
fixtureDef.restitution=0.5;
fixtureDef.friction=0.5;
var body:b2Body=world.CreateBody(bodyDef);
body.CreateFixture(fixtureDef);
return body;
}

11. And the addCart function must be modified in the same way:
private function addCart(pX:Number,pY:Number):b2Body {
var bodyDef:b2BodyDef=new b2BodyDef();
bodyDef.position.Set(pX/worldScale,pY/worldScale);