title: Getting contact points on bodies in Cocos2d & Box2d
body: <blockquote>
    <p>I'm very <em>new</em> to Cocos2d and Box2d, I
    have been following <a href="http://www.raywenderlich.com/" rel="nofollow">tutorials</a> and
    generally hacking. However, I have one
    problem I cannot solve.</p>
  </blockquote>
  
  <p>I create 2 bodies and fixtures (in the Box2d world) and create a "Contact Listener" object. This object stores a list of contacts along with the "contact point". </p>
  
  <p>When the two bodies collide a contact point is reported but this (I think) is in the world co-ordinate system.</p>
  
  <p>My problem is I can't seem to convert the contact point to a usable co-ordinate on <strong>both</strong> of the bodies.</p>
  
  <blockquote>
    <p>I want to add a crack graphic to the
    sprite (connected to the body) at the
    point of contact on both
    bodies/fixtures.</p>
  </blockquote>
  
  <p>Has anyone solved this? I may be storing the "contact point" relative to the "world" is completely the wrong way to go.</p>