For the past couple of days, I've been scratching my head over how to modify the tokaspt source code (gl_scene_cc to be more specific) in order to cram in some 2D gameplay physics (circle/circle collision detection) and direct user interaction with the paddles. Unfortunately without much success. I've come to the disheartening conclusion that I know too little about C++ to be able to write useful working code for the game (I know how to program very basic routine-like stuff with loops, hoping that would suffice, but alas). If anyone is interested to help out with this project, I would be eternally grateful! You can contact me at the address on this page http://i55.tinypic.com/2ppfqma.jpg
UPDATE: for the game physics of Cornell Box Pong, I've decided to use Box2D, an excellent easy-to-learn and open source 2D physics engine used by many iPhone games, which uses an advanced continuous collision detection model. You can also specify parameters such as gravity, friction, physics simulation rate and accuracy of the physics.
If I'm done with this project, I plan to integrate Bullet, the open source 3D physics engine, into tokaspt so real-time path traced physics driven animations like in this awesome video will be possible in real-time.