Constructors. The first uses a default sphere centered at the origin with radius 1.0; the sphere is supplied in the second. The
orientToEye parameter determines whether the sheet is perpendicular to the eye, or perpendicular
to the sphere's Z axis. Setting that parameter to TRUE (the default) specifies that the sheet be perpendicular to the eye, which is most often the desired behavior.
The default view volume is undefined,
and the working space is identity.