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|