title: How to Create joint in Box2d
body: <p>i am developing a game, in this game i have Chain. chains One side is Static and another is dynamic. and chain is moving in ccTouchMove.as chain move,dynamic part get exten and looks like a curve. chain length  is Fix. So how can i set fix Length and curve in it.  </p>
  
  <p>Refer me Which Joint i have to Use. i am trying RopeJoint but i get error in 
                  b2RopeJointDef  jd;</p>
  
  <p>can some one send me sample code.</p>