Under the Bonnet: SHIFT 2 Unleashed - 1

It was important to us that we achieve an equivalent game experience across all three platforms. While we do use a lot of platform-specific code to maintain a high frame-rate on the consoles, our dedication to cross-platform equivalence means that a feature we'd only be able to implement on one of the platforms couldn't be included. The only major exception to this was anti-aliasing, where we used the SPU-based MLAA approach on PS3, and more traditional MSAA on 360 and PC.

We basically looked at what the required output was - be it damage, motion blur, HDR etc, and then at the initial source data for that stage. How we then got from one to the other was left to the platform-specific teams since (due to using completely different techniques on each platform) certain things took longer to process on one than the other; damage for example is a breeze on an SPU but takes longer on a 360 core. On the other hand, the 360 has a much quicker GPU in general so some graphical items had to be processed on SPU on PS3.

We didn't really impose any restrictions on the techniques that could be used, be it SPUs on PS3 or threads on 360 - just use what you have available.

For modern cars the manufacturers provide us with CAD data, images from official photoshoots, car specs, technical details, and a whole other bunch of information; anything we can get our hands on, basically. The car is then completely remodelled to reasonable game specs using the CAD data as reference for accuracy.

For older cars however there is far less information available and usually no CAD data at all. These cars are created purely from blueprints and photos, and therefore need highly talented modellers and deep research in order to recreate a complete car with the same attention to detail as a modern one.

Car production starts with modelling the high detail LOD (level of detail) exterior of the car, followed by the first-person cockpit. After this, the textures for both are then created and the fine details are added: realistic windscreen reflections in the cockpit, interior animations (vibrating mirrors and hoods for example), animated parts (rear wings, popup lights etc..), individual drivers, realistic multi-function dashboard displays and gauges, gearstick and shift animations, individual HUD gauges, authentic racing liveries, full crash damage setup for the car body and a pretty complicated setup for all the available upgrades and customisation options. Obviously, these features all take a lot of time to get them to perfection.

Last, but not least, the individual car physics are added...

The physics model is a full 3D scope engine capable of creating the car dynamics based on parameters taken from the specs of the real-life car - those provided by manufacturers directly and those provided from extensive research. Chassis, suspension, aerodynamics and tyres all generate their forces in 3D in real time. We run these models and recalculate the car state at 400 times per second which makes for a very convincing experience as nothing is left to guesswork.

The chassis model in itself is pretty extensive (approximately 150 parameters). Basics include weight and CG heights and positions and we model the weight and inertia of the sprung and un-sprung masses separately along with spin inertias of the un-sprung items (wheels, brake discs etc). There are 3D suspension geometry parameters for all inner/outer points of a double wishbone along with the tie-rod and damper placements.

The dampers themselves have slow and fast parameters (n/mm/sec) with adjustable switchover points and bump stops with their own stiffness settings. Differentials are the standard 'Salisbury' type with accel/deccel lock settings and visco electronic diffs are also modelled along with inputs for spring rate. Brake torque and brake heating are monitored on a per wheel basis in order to get the heating right for brake pad fade and disc glows.

The tyre model is based on the 'brush model' slip curve generation. Core parameters here include: cornering/braking/self-aligning stiffness, load and camber sensitivities, heating parameters, rolling resistance and base grip of the rubber in longitudinal/lateral directions. The tyre model therefore is class leading (if not the best) in the sim industry.

Finally, the engine model uses a standard rpm/torque curve lookup in 250rpm increments. Some parameters are: rotating inertia, accel friction drag, deccel drag, heating. Turbos are modelled as separate components with their own separate physics and can be bolted on to directly effect it as in the real world.

Once the physics are input, intensive testing takes place and the upgrades and final audio are balanced. All in all the complete production of one car takes two months (dependent on the number of visual upgrades and complexity) with usually two artists working on it from start to finish. The tools used are Autodesk 3DS Max for the 3D work, Photoshop for textures and our own proprietary toolchain for exporting, physics input, and functionality tweaking.