AMD's low-level Mantle graphics could mean big things for PC gaming

AMD’s next-gen R7 and R9 series Radeon graphics cards may have gotten all the attention at the company’s GPU 2014 event this week, but in the long run, a somewhat boring new technical addition may end up meaning more for AMD and PC gaming itself: the company’s newly announced “Mantle” application programming interface (API).

A low-level revolution

We have to get the technical details out of the way before I can describe Mantle’s potential bounties. I’ll keep it brief!

Mantle takes advantage of AMD’s unique position as the graphics provider for the Wii U, Xbox One, and PlayStation 4 consoles, and (some) PCs. Mantle’s low-level API, paired with Mantle graphics drivers, grants developers direct access to AMD’s Graphics Core Next (GCN) GPU hardware features, which allegedly allows developers to achieve a far higher level of hardware-optimized performance than is possible with OpenGL and DirectX. In fact, AMD claims Mantle can issue nine times as many draw calls per second as those “high-level,” non-hardware-specific APIs. That’s a major leap in performance.

Just as impressively, that programming language carries over across consoles and PCs alike—assuming said PCs are running GCN-based Radeon graphics. In short, Mantle is a clever (and aggressive) way for AMD to leverage its next-gen console wins.

(Click to enlarge.)

“The opportunity that we see is to get that [tight, low-level] fit and level of optimization, or something close to it, in PC games,” Radeon technical marketing manager David Nalasco told PCWorld when I asked him how the Radeon heart in next-gen consoles could improve PC gaming. “If you’re developing a game or a game engine and want to port it over to the PC, you don’t have to start over from scratch with your optimization. You’re starting from a base that has CPU cores that are much more similar, GPU cores that are much more similar, and other feature sets that are much more comparable.”

What that means for you is simple: better performance in games that utilize Mantle, assuming you have a Radeon graphics card or APU (accelerated processing unit). High-level APIs simply can’t match the chops of low-level ones. Check out the following tweet from Johan Andersson, the technical director for the Frostbite engine that powers Battlefield 4 and other games from Electronic Arts’ Digital Illusions CE (EA DICE):

"[With Mantle] there’s the potential to have a better experience on a smaller card because you’re not necessarily going through the size and girth of DirectX and OpenGL," says Patrick Moorhead, principal analyst at Moor Insights & Strategy and a former AMD VP. "But also, there’s the potential to give you a better experience on a bigger card, in that you can take special features to the max."

The API could also stimulate the fledgling, yet promising SteamOS operating system if—if—AMD tightens the tech’s ties to OpenGL. Valve is already touting SteamOS’s performance efficiencies compared to Windows, and Mantle could just be icing on the cake. Steam Machines, with its focus on a ten-foot interface and gamepad play, would also be a natural fit for console ports. Moorhead expects Mantle to be used mostly by console developers looking to bring their GCN-optimized titles over to the PC.

AMD rival Nvidia, however, has been working closely with Valve to optimize OpenGL support for SteamOS, so Valve might not embrace Mantle enthusiastically. That shouldn’t preclude AMD from offering Mantle support for the open-source SteamOS, though.

Roadblocks ahoy

While the promise of tight, nearly metal-level hardware optimization and easier cross-platform development carries a lot of appeal, it remains to be seen whether Mantle and its firm ties to AMD products will be adopted by developers that are used to ubiquitous high-level APIs such as DirectX and OpenGL.

Remember, the majority of discrete PC video cards out there today come from Nvidia, and Intel’s integrated CPU visuals are the most-used graphics around, so Mantle support would have to be in place alongside DirectX or OpenGL for PC games. (The next-gen consoles also support DirectX.) That won’t be cheap.

AMD told reporters that the Mantle API is open, however, so Nvidia could also theoretically embed the technology in their GPUs as well—though given the animosity between the two companies and the fact that Nvidia’s GPUs use a vastly different architecture than AMD’s GCN, the odds of that happening are virtually nil.

"I wouldn’t be surprised if Nvidia follows suit [with its own low-level API]," says Moorhead.

It’s certain that at least one major game maker will embrace AMD’s tech. EA DICE’s Frostbite 3 engine will default to Mantle—not DirectX—in Windows rigs running GCN-based graphics cards and APUs, with the blockbuster Battlefield 4 set to be the first title to support the technology after a December update.

That’s a huge win for AMD, and it could just be the tip of the iceberg. The company claims that developers have been asking for low-level GPU access, and AMD has been working hard to increase its profile with game makers.

The Never Settle promotional series bundles free, big-name games with Radeon graphics cards. (Click to enlarge.)

"I think a lot of this came out of the Never Settle bundles they’ve been doing," says Moorhead. "More than just bundling [games], it got them closer to developers. And when you combine getting closer to developers with Never Settle on the PC side, and then getting closer to developers on the game console side, it made sense to bring out Mantle today."

Questions abound

Time will tell whether Mantle proves successful. We’ve seen proprietary-ish low-level drivers like Voodoo’s Glide API before, and they’ve since gone the way of the dodo in favor of the high-level DirectX and OpenGL. Simply put, low-level APIs are highly dependent on specific hardware, and compatibility issues irked developers enough to drive them into the arms of device-spanning, high-level solutions. DirectX provided a standard playing field.

The API field is far less diverse than it was in the days of yore, however, and the pace of DirectX development seems to have slowed dramatically at Microsoft. Pair that with the fact that Mantle will already be a known entity with developers coding for the Xbox One and PS4, and the API’s strong-sounding performance benefits, and developers could be increasingly motivated to muddle with Mantle as the AMD user base grows along with the next-gen consoles.

Battlefield 4 will be the first game to utilize the Mantle API.

Potential abounds, but so do questions: How will Mantle’s claimed performance stack up in the real world? Will it be enough to convince developers to use Mantle even though they’d still need to do a proper DirectX port to satisfy Nvidia gamers? What happens as consoles grow long in the tooth and PC graphics grow ever more powerful and feature-rich? Do we need splintered, proprietary graphics technologies, even if individual solutions are more powerful?

We’ll know more in a couple of months. AMD says it will delve into Mantle in far greater detail at its 2013 Developer Summit in November. One thing’s for certain: Between Mantle and SteamOS, it’s an exciting time to be a PC gamer.

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