Box2D for Flash Games

Don't let some bodies collide – filtering collisions

Don't be fooled by the heading: we are going to build the siege machine, it's just that it does not introduce anything new, and I want you to learn something new at every step. The main purpose of this section is to learn collision filtering.

1. First things first, let's build the siege machine. The morning star projectile will be bound to the trailer with a distance joint that we need to be able to destroy to fire the projectile, so we need it as a class level variable:

   private var world:b2World;
   private var worldScale:Number=30;
   private var left:Boolean=false;
   private var right:Boolean=false;
   private var frj:b2RevoluteJoint;
   private var rrj:b2RevoluteJoint;
   private var motorSpeed:Number=0;
   private ...