TECH

Tech notes for version 0.9.


GRAPHICS
========

Rendering is straightforward enough. The picking code is a bit more interesting.

To find out on which object the player is clicking, the program shoots a ray
from the viewing position through the pixel where the player clicked. Finding
the intersection with the boards is easy, since they're just planes parallel
to xy. To find out if the ray intersects a piece, first the program checks if
the ray hits a sphere that encloses the piece. If it does, then the program
does a more expensive test against a BSP tree representation of the piece
volume. This is (theoretically) a O(log N) operation, which is better than a 
O(N) check against every polygon in the model. In practice, in the BSP tree
case N is a bit larger because of all the polygon splitting that happens when
building the tree. But it still wins.


A.I.
====

The artificial intelligence is "textbook" minimax with alpha-beta pruning.
Apart from trying to evaluate capture moves first, this version doesn't try
anything clever - there's no principal variation search, "killer heuristic", or
anything. The evaluation function is pretty simple, too - pretty much just
material imbalance. This should change in future releases.