A>
</H1>

<P>

<H2><A NAME="SECTION03051000000000000000">
Viewing</A>
</H2>
A viewing object manages viewing coordinate system
whose origin is located at the position of a virtual camera,
<EM>-z</EM> axis is oriented to the objects observed, and xy-plane is the
projection screen.
Since viewing inherits class cascaded-coords,
it accepts coordinates transformation message
such as <B>:translate, :rotate</B> and <B>:transform</B>.
Also, it can be attached to another object derived from cascaded-coords,
allowing