[H]ardOCP reports there has been much discussion on this whole issue of Creative?s patent and Carmack?s comments on the issue. Most people are upset at this move by Creative, some even suggesting that the patent held by Creative could be challenged on the ?prior art? basis. This post from September 2003 by NVIDIA?s Sim Dietrich lends a lot of credibility to the ?prior art? argument. Don't worry about it fellas. I described this technique publicly a few months before they filed the patent - hence Prior Art. Ironically, it was at a Creative Labs developer's forum. During my stencil buffer talk, I described doing shadow volumes the 'reverse' way. At the time, I didn't realize the major reason why the z fail method is better than the z pass method, although I did realize they were logically equivalent, which is why it's now known as 'Carmack's Reverse' and not 'Dietrich's Reverse'!