public override void VisitAlienGrid(AlienGrid ag)
{
// AlienGrid vs Wall-Right
//Debug.WriteLine("\ncollide: {0} with {1}", this, ag);
//Debug.WriteLine(" --->DONE<----");
// Set a new direction : Positive means go right -->
ag.SetDelta(-1.0f);
ag.SetIsOnWall(true);
CollPair pCollPair = CollPairManager.GetActiveCollPair();
Debug.Assert(pCollPair != null);
// Register collisiton and notify the observers
pCollPair.SetCollision(ag, this);
pCollPair.NotifyListeners();
}