Tech Focus: LucasArts moves to Unreal Engine

It's official: last week, LucasArts signed a long term, studio-wide deal that sees the developer licensing Epic's Unreal Engine 3 technology.

"Unreal Engine 3 is a forward-looking solution that shortens the path between inspiration and execution on a wide variety of gaming platforms," said Zak Phelps, director of technology at LucasArts. "We are thrilled to add another exceptional tool to our technology mix."

This is undoubtedly great business for Epic Games, facing increasing competition in the engine/middleware space, and we can assume that LucasArts is set to benefit from a more cost-effective means in bringing its games to market. On the other hand, implementing middleware company-wide may suggest that jobs may be affected. As Sony Santa Monica's director of technology Christer Ericson put it on his Twitter feed:

"LucasArts signs multi-year Unreal Engine 3 deal. In other news: LucasArts programmers, Sony Santa Monica is hiring!"

From a technological perspective, the studio's last big title - Star Wars: The Force Unleashed II - is a seriously impressive piece of work, and while the game is far from perfect, its issues are far more to do with design than they are with the core engine tech. In fact, we'd venture to suggest that it would take extensive re-development of Unreal Engine 3 to match the level of technical accomplishment LucasArts shipped with on its The Force Unleashed II Xbox 360 and PlayStation 3 SKUs.

Key to the visual look of The Force Unleashed II is the implementation of deferred rendering, allowing Lucas to employ far more light sources than traditional forward renderers. The standard technique for a multi-pass forward renderer like Unreal Engine 3 is to consider the scene several times dependent on the amount of lights, and how they affect each object on-screen. Essentially, the more lights that are in play, the costlier the impact on rendering time.

With a deferred lighting renderer, the composition of the frame is split up into a series of different render targets or frame buffers that cover off particular surface properties in the scene. These are then combined for the final image. There are processing and RAM implications, but hundreds of different light sources can be generated, transforming the look of the game.

Some of console gaming's most technologically advanced titles use a fully deferred approach, including hits such as the PS3 Killzone titles, Crysis 2, Need for Speed: Hot Pursuit and all the titles being developed on the Frostbite 2 platform (Battlefield 3 and more). Others, including SHIFT 2, Blur, GTA IV and MotorStorm Apocalypse employ a light pre-pass variant of the deferred technique.

Other elements of the technical make-up of the Force Unleashed II engine have yet to be seen in UE3. For example, object-based motion blur is beautifully handled in the existing LucasArts game, and its camera-based implementation utilises the strengths of the PlayStation 3 architecture in producing an effect smoother and more pleasing than the equivalent on Xbox 360. Conversely, in many UE3 titles, camera-based motion blur actually uses fewer samples on the PS3 compared to the 360 version and while object-based blur is in the engine, implementation has been restricted. In creating TFUII, LucasArts put extensive effort into SPU usage, following the example set by Sony first party developers in offloading traditionally GPU-driven effects onto Cell's powerful satellite processors.

Another interesting element to consider is overall performance. In Digital Foundry's continuing analyses over at Eurogamer, we consistently see the Xbox 360 version of Unreal Engine 3 titles operating with a notably more consistent frame-rate than PlayStation 3 equivalents. Indeed, in our latest analysis of Epic's own Bulletstorm, we see a slight performance deficit on PS3 and some pared back effects, including the studio's excellent god-ray tech: implemented nicely on Xbox 360 but absent on PS3.

In contrast, The Force Unleashed II demonstrated that LucasArts was getting seriously good at matching performance levels between the two consoles using its in-house tech - the leap over what was seen in the first game was remarkable. While there was still a 360 advantage in terms of absolute number of frames generated per second, the PS3 release compensated with higher precision effects.

Anti-aliasing is another issue where LucasArts did some fine work, employing a perceptual, directional approach (DLAA) that brought some exemplary edge-smoothing to the game. It's a post-process effect just like morphological anti-aliasing (MLAA) and while it does have some artifacting issues, it's effective and innovative nonetheless. In contrast, we've only seen limited anti-aliasing implementations within Xbox 360 versions of Unreal Engine 3 titles, and to the best of our knowledge, none at all of note on PlayStation 3 (we won't include blur filters, like those seen in Army of Two: 40th Day).