Box2D for Flash Games

Placing the physics bird

This is when Box2D comes into play. As we are approximating the bird with a circle, we need to create a Box2D circle in the same point from where the player released the mouse.

Change the birdRelease function in the following way:

private function birdRelease(e:MouseEvent):void {
  var sphereX:Number=theBird.x/worldScale;
  var sphereY:Number=theBird.y/worldScale;
  var r:Number = 15/worldScale;
  var bodyDef:b2BodyDef=new b2BodyDef();
  bodyDef.position.Set(sphereX,sphereY);
  var circleShape:b2CircleShape=new b2CircleShape(r);
  var fixtureDef:b2FixtureDef=new b2FixtureDef();
  fixtureDef.shape=circleShape;
  fixtureDef.density=4;
  fixtureDef.restitution=0.4;
  fixtureDef.friction=0.5;
 var physicsBird:b2Body=world.CreateBody(bodyDef); ...