def __init__(self):
     PhysicsManager.__init__(self)
     self.time_step = 1.0/CONST.framerate
     self.vel_iters = 10
     self.pos_iters = 10
 def loop(self):
     PhysicsManager.loop(self)
     for world in self.worlds:
         world.Step(self.time_step,self.vel_iters,self.pos_iters)
         world.ClearForces()