public void CollideWith(GameObject obj) { if (obj is Plane) { Plane plane = (Plane)obj; plane.Damage(Power); plane.AffectImpulse(Velocity * Mass, Position); } else if (obj is Bullet) { Bullet bullet = (Bullet)obj; bullet.IsGarbage = true; } else if (obj is Bonus) { ((Bonus)obj).Damage(Power); } IsGarbage = true; }