def constrainQuat(self):
"""keep the object rotating in the correct plane"""
#FIXME is there a better way than fixing at every instant?
if not self.rot:
self.body.setQuaternion(Quat.identQuat())
return
q = self.body.getQuaternion()
q[1] = 0
q[2] = 0
q.normalize()
self.body.setQuaternion(Quat(q))
