Thanks lisa for all the infos and the video (the anim is really cool and your capture is ok).
Painting over the 2D wireframe ... I should have guess
BTW : I just saw on your website that you had been involved into a game that I have in my PS2 games collection (Splashdown).
This game was a great fun even if it was already too hard for me in the middle (I'm not what we can call an "hardcore gamer" as you can see ;o))