If a sprites' DECAL flag is set, the sprite
will be oriented in world space according to its PAN, TILT,
and ROLL angles,
rather than facing the player, and it's back side won't be visible. This is
useful for placing images, inscriptions, or bullet holes at walls, or for
placing a shadow sprite flat onto the ground.
The sprite will also be oriented in world space when
one of its PAN or TILT angles
are nonzero, but without DECAL it is then visible from
both sides - useful for fences or transparent windows.
my.DECAL = ON;