Since a full visibility check for a cylinder would be computationally
expensive, we perform the following simple test: Let *P* be the point
on the axis of cylinder *C* that is closest in height to the
cyclopean origin *O*. Then we say that *C* is visible if , where *r* is the radius of *C*. Since the cylinders in a
typical virtual marine world in our animation are fairly scattered,
the occlusion test is neglected.

Xiaoyuan Tu | January 1996 |