Another flat, finite object available with POV-Ray is the
disc. The disc is infinitely thin, it has
no thickness. If you want a disc with true thickness you should use a very short cylinder. A disc shape may be defined
<Center>, <Normal>, Radius [, Hole_Radius]
Disc default values:
HOLE RADIUS : 0.0
<Center> defines the x, y, z coordinates of the center of the disc. The
<Normal> vector describes its orientation by describing its surface normal vector. This is followed
by a float specifying the
Radius. This may be optionally followed by another float specifying
the radius of a hole to be cut from the center of the disc.
Note: The inside of a disc is the inside of the plane that contains the disc. Also
note that it is not constrained by the radius of the disc.