I think the issue is that the licensing of GameWorks, which HairWorks is part of, prevents the game developer from sharing it's source code with anyone other th

I think the issue is that the licensing of GameWorks, which HairWorks is part of, prevents the game developer from sharing it's source code with anyone other than other licensees. That means AMD has to reverse engineer it if they want to optimize their drivers for it. That isn't the case for TressFX, which is freely available to anyone and allowed Nvidia to quickly add support for it after Tomb Raider released.