Computing Visibility with BSP trees
Starting from the root of the tree.
- Classify viewpoint as being in the positive
or negative halfspace of our plane
- Call this routine with the negative child
(if it exists)
- Draw the current partitioning plane
- Call this routine with the positive child
(if it exists)
Intuitively, at each partition, we first draw the stuff further away than the current plane,
then we draw the current plane, and then we draw the closer stuff.
BSP traversal is called a "hidden surface elimination" algorithm, but it doesn't
really "eliminate" anything; it simply orders the drawing of primitive in a back-to-front order
like the Painter's algorithm.
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