Tech Interview: Split/Second

Digital Foundry gets technical with tech director David Jefferies.

Next week Eurogamer runs its review of Disney's Split/Second: Velocity, a brand new racing game from Brighton's Black Rock studio, the developer responsible for the superb Pure.

Digital Foundry has already got to grips with the playable demo available on PlayStation Network and Xbox Live, we're big fans of Pure, and it's been a while since we've run one of our extensive tech interviews.

So, when Split/Second technical director David Jefferies offered us the chance to talk candidly about the developmental process behind the new game, we leapt at the chance.

Responding to our numerous, nosey enquiries about the Black Rock engine, Jefferies did us proud in discussing Split/Second's innovative approach to lighting, his take on cross-format console development, the ages-old 30FPS vs. 60FPS debate, the always-controversial subject of anti-aliasing, and lots, lots more.

It's in-depth technical discussion from start to finish, and we hope to be doing more of these a lot more frequently. Look out for the next one soon...

Digital Foundry: Pure was a really impressive breakthrough product and a substantial technical leap over what we'd seen previously from what was at that point Climax Studios. Can you talk us through the genesis of the engine? What were your objectives for the tech? Does it have a name?

David Jefferies: Pure's engine is based on a core set of libraries called Blimey that have been in development at our studio for the past 10 years. They provide all the basic building blocks for making a game, such as maths functions, serialisation, memory and file management and so on.

The original Blimey libraries had a PS2 and Xbox renderer and then in 2003 our Core Technology Group (CTG) started work on a next generation renderer on the PC. That renderer is still in use today in our in-house modeling tool called Tomcat. In January 2005 we began the work of porting the renderer to the Xbox 360 ready for our first next-gen title MotoGP '06. It was a good renderer, if a little feature-light by today's standards, and it had a solid lighting model at its core.

When the Pure team started up the following year they took the renderer used by MotoGP '06 and extended it greatly, particularly making advances in post-processing such as motion blur, colour grading, vignetting and bloom. For Split/Second we took the Pure renderer and used that as the starting point for the Split/Second renderer.

Digital Foundry: There's a very close parity between Xbox 360 and PS3 performance in both Pure and what we've seen thus far of Split/Second. What is your overall philosophy in dealing with the different multi-core structures and varying GPU abilities of the two console platforms?

David Jefferies: I think the key in dealing with the differences between Xbox360 and PS3 is having a deep understanding of the hardware for both. If you really want to push both consoles to their limits then you need specialised code paths for each platform.

On the Xbox 360 it's all about leveraging the powerful GPU and on the PS3 it's all about SPU utilisation - these are fundamentally different technologies that require very specific code paths. On Split/Second, the final image for each platform is nearly identical but how the pixels get into the image is very different indeed.

Digital Foundry: Regarding Pure, rendering all those trees was surely a headache... Could you describe how you were able to the render vast landscapes with such alpha-heavy scenes for gameplay?

David Jefferies: Pure had to render a massive amount of alpha-heavy foliage which just wouldn't have been possible using traditional techniques. We came up with some innovative new ways of rendering alpha - for more information check out our technology page.

Digital Foundry: We're big Pure fans, but there's a sense that it was overlooked by the audience. That's somewhat surprising considering the superb look and feel of the game, plus of course the favourable reviews. What is your view on that?

David Jefferies: Pure is our biggest-selling title to date and thanks to a Microsoft bundle deal has reached millions of users. It was the title that established us as a AAA games studio and whenever we speak to people about Split/Second they recognise Black Rock from Pure - it was a great expression of intent for the studio.

Digital Foundry: Post-Pure, looking forward to the next game, which would end up being Split/Second, what were the technological challenges you set yourself? Was there anything fundamental to the Pure engine that needed a complete overhaul?

David Jefferies: The Pure engine was very well suited to the requirements of Pure and so the overhaul required was due to the differing requirements of Split/Second rather than any deficiencies in the engine. We rewrote the render engine to be a gamma correct deferred shading renderer rather than a more traditional forward renderer.

We placed a lot of emphasis on further improvements to the post-processing pipeline with per-pixel motion blur and anamorphic lens flare. We also introduced a colour grading system whereby the artists could take a screenshot and bring it into Photoshop and then treat the image however they liked. We have some software that analyses the colour mappings that the artists had performed and recreated them in the game. This system is used at all times during gameplay to give the exact look we want.

We also invested a lot in a new VFX pipeline for the huge volumes of dust, smoke and fire in the game. There's a lot of processor power that goes into the VFX and a lot of clever tricks to be able to render huge amounts of them without exceeding the fill-rate. The particles are all correctly lit from the light sources and the smoke even moves out of the way as the vehicles travel through it.

Digital Foundry: The use of different routes and track-changing hazards was something that Criterion initially looked into during development of Burnout Revenge before returning to its more traditional setup for the shipping game. Bearing in mind that you have some Burnout alumni working at Black Rock, was there a sense of unfinished business there for your new recruits?

David Jefferies: I don't think so - the Burnout boys all love arcade racers and what attracted them to Split/Second was the opportunity to put a new twist on the genre they love. Right from the beginning Split/Second was its own game and the similarities with Burnout are fairly superficial.

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