So, this is interesting. At its GPU14 event in Hawaii last month, AMD said that Mantle, its new low-level graphics API, would be "cross-platform, but Windows first." We kind of figured the cross-platform part meant Mantle would work on the PlayStation 4 and Xbox One. After all, the graphics silicon in both systems is based on the same GCN architecture as the latest Radeons.
Well, we figured wrong. Microsoft has updated its Windows App Builder blog with some news about Direct3D, and the post says developers won't be able to use Mantle to write games for the Xbox One:
The Xbox One graphics API is “Direct3D 11.x” and the Xbox One hardware provides a superset of Direct3D 11.2 functionality. Other graphics APIs such as OpenGL and AMD’s Mantle are not available on Xbox One.
Despite shutting out AMD's API, Microsoft seems to have endeavored to simplify the process of porting Xbox One games to Windows PCs—and vice versa. The company says Xbox One developers will be able to use the "same programing constructs across Windows and Xbox, and benefit from all the improvements that have been introduced on Windows."
Microsoft also mentions that Direct3D on the Xbox has been enhanced to reduce runtime overhead. "The result is a very streamlined, 'close to metal' level of runtime performance," it says. Even better, some of these improvements will be making their way to Windows. "We're also working with our ISV and IHV partners on future efforts," Microsoft adds, "including bringing the lightweight runtime and tooling capabilities of the Xbox One Direct3D implementation to Windows."
Much of Mantle's appeal comes from its ability to reduce overhead. At GPU14, AMD said the API enables a nine-fold increase in draw calls per second, presumably over vanilla Direct3D. Reading today's blog post, it seems that Microsoft has made its own enhancement to Direct3D with an eye toward the same goal—and without stripping away the API's vendor-agnosticism. It's not yet clear how substantial Microsoft's optimizations are, though.
Update: AMD has addressed the Microsoft announcement in an extended Twitter post. The post says Mantle is "NOT in consoles" but goes on to note that the API "creates for the PC . . . a development environment that's *similar* to the consoles, which already offer low-level APIs, close-to-metal programming, easier development and more (vs. the complicated PC environment)."