358 Chapter 6 Spatial Sorting
the plane into two half planes. The half plane to the side that the line normal points
to is gray. The other half plane is white. The view frustum overlaps both half planes.
The eye point is in the white half plane. The region that the view frustum encloses is
the only relevant region for drawing purposes. If you draw a ray from the eye point to
any point inside the gray subregion of the frustum (a line of sight, so to speak), that
ray will intersect any objects in the white subregion before it intersects any objects
in the gray subregion. Consequently, no object in the gr ay subregion can occlude an
object in the white subregion. If the objects in the gray subregion are drawn so that
the depth buffer is correctly written ...