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<H4> 7.6.6.3 Perspective Correction </H4>
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<P>
Objects in camera space are still 3D and thus not suited for immediate display
on a 2-dimensional screen. Therefore you still need to do perspective
correction as follows:
</P><P>
<BLOCKQUOTE>
<EM>x = (F * Vc.x) / Vc.z</EM><BR>
<EM>y = (F * Vc.y) / Vc.z</EM>
</BLOCKQUOTE>
<P>
<EM>x</EM> and <EM>y</EM> are then the 2-dimensional coordinates corresponding to
the 3D vertex. We will call this 2D vector <EM>Vs</EM>.
</P><P>
<EM>F</EM> is some factor needed to get a correct <EM>Field of Vision</EM>
(FOV). Crystal Space currently uses the height of the display (in
pixels) for this. You can experiment with other values in the `<TT>walktest</TT>'
application (see section <A HREF="cs_55.html#SEC136">4.2 Walktest</A>) using the `<SAMP>-fov</SAMP>' command-line option or
the <KBD>f</KBD> or <KBD><KBD>Shift</KBD>-f</KBD> keys while the program is running.
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