Irrational Games Modify UE3 Engine for Bioshock Infinite

Hi folks! I'm the Technical Director here at Irrational, so I thought I'd just jump right in and give you a little more insight into the engine changes we've been making for BioShock Infinite.

Over the last few years we've been put together an world-class team of engineers with a single goal: do whatever it takes to bring the Columbia and the amazing world of BioShock Infinite to life. We're talking about a world where entire buildings are moving around in the sky, you're fighting AIs at 90mph on Sky-Lines as you dangle high above the earth, and racing through vicious weather to rescue Elizabeth while battling your way through hordes of enemies determined to stop you at any cost. Right from the outset we realized that this was going to be a monumental undertaking on the tech side, but decided it was a challenge that we simply had to take on in order to give gamers the kind of quality experience they've come to expect from Irrational Games and BioShock.

We started out by taking a look at the original BioShock engine, and very quickly realized that the tools in that engine were too underpowered and unwieldy for the depth and complexity of the gameplay and narrative we had planned -- our very patient but long-suffering designers and artists were due for a total toolset overhaul. That alone was one of the most compelling factors behind our decision to abandon that engine and start over with UE3 as a base.

But UE3 out of the box was not enough to meet the demands of this game, so we took out a knife and started doing some surgery:

• Given the intelligence and sheer number of AI we planned to throw at the player, we needed an entirely new AI system that was both more efficient and gave designers the ability to author their own behaviors. And because smooth and complex animation is the key to looking intelligent, we got down to business building a new animation system on top of Natural Motion's 'Morpheme' technology.

• All major FPS engines (CryEngine 3, UE3, id Tech 5) are designed and optimized for static environments that the player moves through, which is a reasonable choice because, even if there are trees moving in the wind, the ground under the player's feet isn't going anywhere. Unfortunately for our tech team (but good for you) everything in Columbia is capable of moving. The very ground beneath your feet could fall out of the sky at any moment, which makes for some awesome gameplay and visuals but required us to create a completely new technology that we're calling "Floating Worlds". You saw a little of this in the gameplay demo video (in the part right after Saltonstall jumps on the Sky-Line) and you'll be seeing a lot more of it in the future.

• To meet the aesthetic goals of our art team, our rendering gurus had to write a whole new renderer for BioShock Infinite based on Deferred Lighting (a technique used in Uncharted 2, CryEngine3, and Killzone 2), and on top of that they've developed a proprietary per-pixel dynamic relighting scheme that allows characters and dynamic objects to receive global illumination.

• BioShock 1's audio system was... umm... "sub-optimal". This time around our sound team demanded a new audio pipeline based on AudioKinetic's WWise technology that supported 5.1 with adjustable dynamic range and a fully dynamic mixing system. Not only did our engineers rise to that task, but they subsequently took it up a notch and implemented both a custom sound propagation system (so voices properly echo down corridors and around buildings) and a dynamic wind audio system that reinforces the dynamic weather in the world.

• Finally, we've built a whole new parallel processing framework (a "job architecture", in programmer lingo) that lets the engine take advantage of as many cores as you can throw at it. This will let us eke out all the power of the PS3 and 360, and also give hardcore PC gamers something to show off their rigs with.

That's just a sample of some of the major changes we've done so far on our way to building BioShock Infinite. Hopefully in the future we'll be talking some more about these and some others I haven't mentioned, so please subscribe to our podcast and keep your ears open!

-Chris

PS - We're always looking for world-class engineers of all experience levels. If that sounds like you, please check out the open positions at the bottom of our Careers page at http://irrationalgames.com/studio/careers-at-irrational