title: MouseJointDef libgdx - draw a trajectory line like Angry Birds
body: <p>in libgdx game </p>
  
  <p>I want to touchDown and then drag somewhere and then on the release (touchUp) apply a directional force based on the distance and direction from the target body. When you touchdown the target body stays still and then on touchup the force is applied along the desired trajectory.</p>
  
  <p>(very similar to Angry birds - where you get to see the trajectory in dotted lines for the target body when you hold hack the slingshot - I want to do the same)</p>
  
  <p>So I guess that this might not be the hardest thing to do but given a few options Im leaning towards using a MouseJointDef but its an immediate force applied (i.e. the target moves immediately - I want it to stay still and then once the touchup event happens then apply the force)</p>
  
  <p>Whats the easiest way to draw the trajectory also? Im using Box2D also.</p>