Old code may die, but it often sticks around to haunt you. John Carmack is rewriting the code for id Software's open-source version of the Doom 3 engine because of the chance for litigation due to the shadow rendering code.
According to Carmack's tweet, Bethesda's lawyer's have raised issues about the patent by Creative Labs for a stencil shadowing technique called “Carmack's Reverse” which was jointly created by Carmack and other coders. id Software used the technique under contract for Doom 3, but providing the source code using the technique might have caused a legal problem, hence the rewrite.
Fans are awaiting the release of the source code so they can make their own changes, but there's no word yet on when the release date might be.
