AMD recently announced their new Mantle API. This API has been said to give AMD a significant advantage over their competitor Nvidia in terms of in-game performance. Anandtech speculates that AMD might be confident of this because their Mantle API is a direct copy of Xbox One’s Graphics API allowing developers to directly port their games from Xbox One to PC. Since Mantle can use Direct3D high level shader language, Xbox One’s shader will be already coded in the first place so there is not much work involved in porting them to PC.
Article updated with Digital Foundry info. Digital Foundry thinks the Mantle API appears to have much in common with PS4′s GNM API.