John Carmack is in the process of rewriting the code for id’s open-source version of the Doom 3 engine, due to legal issues surrounding the shadow rendering.

According to a tweet from the developer, Bethesda’s lawyers are “skittish about the patent issue” surrounding the code for “Carmack’s Reverse,” which is a stencil shadowing technique patented by Creative Labs and jointly created by the id legend and other coders.

id Software contracted the use of the tech for Doom 3, but providing a source code using the technique would have been a litigation issue.

No word yet on when the updated source code will be released.

Thanks, Shack.