CG on the Fly

SIGGRAPH spotlights real-time animation

People who work with real-time animation don’t often see their work projected at SIGGRAPH. Whenever real-time projects have appeared in the conference’s premier show, the Electronic Theater, they’re usually pre-rendered game cinematics scattered amongst vfx-driven movie sequences’an arrangement that Microsoft’s Evan Hirsch calls ‘a two-game sorbet.’

But things are different at SIGGRAPH ’09. For the first time, the E.T. will spotlight real-time projects running on their actual platforms, with output projected on the big screen. Electronic Arts will demo its A.I. and physics-driven boxing game Fight Night Round 4 on the Xbox 360; That Game Company will explore the pastoral worlds of Flower on the Playstation 3; Soka University researchers will unveil the abstract animations of DT4 Identity on the Macintosh; and AMD will demo the hordes of characters and globally illuminated worlds of Froblins, which runs on ATI’s Radeon HD 4800 GPU series.

‘Each is a five-minute live demo,’ explains Hirsch, SIGGRAPH’s Real Time Rendering Chair. ‘We’ll have consoles and a preview monitor on stage, and spike images to the projectors so that the people doing the demos don’t have latency issues. From a logistical perspective it will be wild. Of course we’ll have redundant machines in case anybody has a crash.’

Hirsch, who is director of Microsoft Live Labs, initially proposed this idea several years ago. ‘E.T. is presented as the best of computer graphics, and every year people say to the games guys, ‘You didn’t contribute anything.’ And the games guys say, ‘What could we contribute that would compete with a 2K film render?’ Now that games run natively in HD, I felt we should find a way to show live demos on the big screen.’

Like everything shown at SIGGRAPH, the real-time selections were chosen by a jury that considered submissions from academia as well as game companies.

‘Our jury had the experience to know what’s impressive in real time,’ notes Hirsch. It included Microsoft’s Ian Shaw, EA’s Bob Nicoll, veteran CG author Andrew Glassner, MGM Interactive’s Dave Davis, Alligator Planet’s Ralph Guggenheim and Sony’s Joshua Grow. In addition to the E.T. demos, SIGGRAPH will include several behind-the-scenes sessions from Disney Interactive, nVidia and Epic Games/Microsoft.

But presenting real-time animation on SIGGRAPH’s main stage is an opportunity that Fight Night 4 CG supervisor Frank Vitz calls ‘a coup for games.’ Vitz, who’ll be playing EA’s boxing game live with art director Jenny Freeman, notes, ‘This version allows us to decrease the duration of the rounds and increase the amount of damage that each punch does, so the audience will get to see a lot of cool stuff in this quick demo. And because we’re playing live, it will be clear it’s being rendered in real time.’

Fight Night 4 represents the latest in EA’s approach to artificial intelligence, explains Vitz, whose many credits before joining EA include supervising visual effects in the X-Men franchise. ‘This game is ‘trainable.’ You fight in a particular style and the A.I. tracks everything you do and mimics it. If you keep throwing uppercuts, your opponent will ‘learn’ that’s what you’re doing and evade them. The role of the game animator starts becoming more of a ‘trainer’ who creates a character, gives it behavior, trains it how to act in different scenarios, and then turns it loose. Animators still agonize over creating the perfect kick, but it’s a different paradigm to create a character who draws upon animated behaviors.’

‘This animation system is fundamentally a hybrid,’ Vitz elaborates. ‘Mocap clip-driven animations are interpreted by a physics animation system. I like to think of the animation as the character’s ‘goal’ or his memorized behavior’the way that we know how to walk or throw a punch. The physics system comes in to play when a punch gets interrupted, absorbs the energy and causes your body to react. A chain of circumstantial reactions modify that original clip, so no two punches are ever the same. If your opponent has his arm up it will affect how accurately your punch lands or how much force it hits with. So we score the damage you do based on real physics.’ Vitz isn’t counting on winning his E.T bout with his colleague, however. ‘Jenny usually kicks my ass.’

The hope is that SIGGRAPH audiences will see the refinements in the look of game graphics that are possible today. Vitz notes, ‘We’ve spent our rendering horsepower on the boxers, not their surroundings, so their skin has dynamic sweat that runs properly down their bodies. And there’s ambient occlusion that causes them to shadow each other, which is something you wouldn’t expect in real time.’

With images rendered at 720p resolution and presented in 5.1 Dolby sound, Vitz thinks these demos could be a vindication for game graphics at SIGGRAPH. Hirsch agrees, noting, ‘When they’re projected, good things happen because the pixels bleed and the images soften a bit. We don’t often get to see games projected this big, so we’re gonna find out!’