[dmbaggett]

An early inspiration for our precomputation approach was Seth Teller's 1992 Ph.D. thesis (bio at http://www.csail.mit.edu/user/1544).

Seth worked out the (5D) math to trace the propagation of light through portals and precompute the set of visible polygons from any point in a so-called "architectural walkthrough" -- i.e., traversal of a space with lots of walls.

We knew that would never work for something as low-power as the PS1, but we were intrigued enough by Teller's work to try a very watered-down brute force variant.

As Andy describes in the article, this is what led to our precomputing the visible set of polygons (and their relative sort order) for every frame of the game. This was actually hard for three reasons:

- we had to distribute the precomputation work across all the artists' SGI workstations to get it done in under an hour per level - we had to store a sorted list of polygons per frame in a compact enough way that it would fit - we had to weave the foreground elements, which were not precomputed, into the background, which was

It was a really fun, but very challenging, project to get this all to work.