To determine if some point P is visible, we shoot a ray from the
cyclopean origin O (on 
and near the fish's mouth) to P (see
Fig. 
). First, if 
and the angle
between the ray and the fish's x-axis is less than 150 degrees then
P is within the view volume. Second, to examine if P is occluded, we
test if the ray intersects other objects (fishes or static obstacles)
in the fish's view volume.
| Xiaoyuan Tu | January 1996 |
