title: Intersection Between 2 lines in COCOS2D
body: <p>I am developing a game using COCOS2D.
  In my game, there are 4 points, each point is connected with each other by one line.
  When user moves the point, the lines move with the point.
  At the time of moving, if a line intersects with another line, line color should become red.
  How can I do this, i.e. line to colored red?
  And how to detect the intersection of two lines?
  Can anyone help me to solve this intersection problem in COCOS2D?</p>