?: Vec2[] If the object is about to collide and the collision normal direction is
in here (i.e. the object is moving roughly in this direction), the object won't collide.
Should be a list of unit vectors LEFT, RIGHT, UP, or DOWN.
Defaults to [UP], i.e. the object will only be able to pass through when it
is jumping upwards, but will collide when it is moving downwards or sideways.