Cryect writes "Earlier today it was announced by Creative that they would be adding in EAX 3D sound support to Doom 3, and that they had come to an 'agreement relating to Creative's patented shadowing technique [also known as Carmack's Reverse in some coding circles] and id's cutting-edge 3D graphics DOOM 3 engine.' This seemed somewhat suspicious, almost as if id was being pressured, and a quick email to John Carmack from Reverend @ Beyond3d got this reply: 'The patent situation well and truly sucks... It was tempting to take a stand and say that our products were never going to use any advanced Creative/3DLabs products because of their position on patenting gaming software algorithms, but that would only have hurt the users...' There's also some possible prior art [PPT link] to Creative Labs' patent, from a 1999 talk by Nvidia's Sim Dietrich."
http://slashdot.org/article.pl?sid=04/07/28/1529222