An issue surrounding a patent for a specific shading technique has held up a promised open source release for the code behind Doom 3
, as programmer John Carmack goes back to make modifications.
Carmack promised at an August QuakeCon keynote speech
that the open source release for Doom 3
would come after the company's October release of Rage
But Carmack explained in a tweet yesterday
that the "lawyers are still skittish about the patent issue," referring to a Creative Labs patent on a 3D shading technique known as "depth fail
Creative Labs filed for a patent on the technique in 1999
, though the process became widely known as "Carmack's Reverse" after the Doom 3
programmer independently discovered and publicized it during the game's development.
Id used the technique under a license from Creative for Doom 3
's 2004 release, but Carmack will have to "write some new code" to get around the legal issues for the open source release, he tweeted.
In a 2004 forum discussion
, Carmack suggested he had devised a separate shading method that got around the patent issues but that resulted in a "speed hit" on performance.