x,
i.e., the transformation is taken in the three dimensional homogeneous
coordinates.
Class <B>projection</B> is an abstract class for both of these.
Since these projection classes inherit the viewing class,
two coordinates transformation, world-to-viewing and projection
can be performed at the same time.
By sending the <TT>:project3</TT> message with a 3D vector to a projection object,
a float-vector of four elements is returned.
<B>Homo2normal</B> function is used to convert this homogeneous vector
to th