The developers of upcoming sci-fi survival horror game Dead Space are more than happy to show you the schematics they've worked up for protagonist Isaac Clarke's ore cutter, or how a handheld graviton accelerator might work in the far future, but it was the practicalities of the game's dynamic lighting system that blinded us with science. Under the jump, concepts that boggled the minds of people (me, mainly) used to getting their science served up with generous portions of fiction, such as the mysteries of ambient occlusion and how many milliseconds of the GPU Dead Space can allocate to bringing the awesome.
Not every person in the video game industry is going to compare the work they do to Gaudi's Sagrada Familia, but lighting designer David Blizard did exactly that at the opening of his presentation at the community event at Electronic Arts Redwood Shores on Wednesday. "Construction of the Sagrada Familia began in 1882 and its current scheduled completion development is 2026," Blizard explained. "Similarly, there's never a scheduled completion date for how things look in video games, as the tech is always constantly evolving." According to Blizard, Dead Space uses a deferred lighting mesh, completely different from anything that's been done in traditional video games: "[Deferred lighting] has had very limited use in the marketplace until now." (There was a brief back-and-forth between Blizard and producer Rich Briggs on this point-Briggs thought Dead Space, when it hits the market, will be the only game to use a deferred lighting system, Blizard believed GTA4 had used dynamic lighting although he didn't know if it was used throughout, or relegated to special sections.)
"With static lighting, we have set light sources. We may only have four light sources available to us, and we usually can't set those sources in any way to take advantage of shadows or darkness," Blizard said. "Or we can create the look of light in an environment by 'baking' it into the textures. But a shadow that's baked into the environment won't move." "With dynamic lighting," said Blizard, "we're not limited to how many lights we can put in the world, we're only limited by rendering speed. We can have point lights, cone lights, directional lights, and the lighting and shadow situations that come with them. But in order to have a game run smoothly at 30 or 60 frames per second, we have to keep the resources of the GPU [graphics processing unit] tightly allocated... Very roughly, each frame of an animated movie requires about six hours of rendering time. By contrast, the processing resources allocated for the lighting for a video game graphics running at 30 frames per second is typically 33 milliseconds." Explaining the importance of this math, Blizard said that one pass over one frame may only allow 7.5 milliseconds of processing power dedicated to the deferred lighting buffer, 4 milliseconds for the shadow buffer, and two milliseconds of cycle time for the 'post' effects (such as "bloom"-the way bright things might glow under light-and anti-aliasing). To put that in perspective, the GPU calculates the proper application of the shadows and the post effects in approximately two beats of a housefly's wings.
Blizard also broke our brains by boiling the principle of ambient occlusion down to an easily graspable sentence: essentially, objects that are closer together get darker. With that principle in mind, he showed how the dynamic lighting mesh could generate ambient occlusion throughout the Dead Space environment, and how he and the lighting crew could do passes of each stage to check the ambient occlusion was correct for massed objects. For the player, this means Dead Space is not just a game that contrasts just light and darkness, but-appropriately enough for a survival horror game-layers of darkness, so the application of light upon the environment is more convincing to the eye. Interestingly, Dead Space's dynamic lighting not only aids the player's enjoyment of the game, it greatly aided the actual creation. In an interview after the presentation, Blizard spoke briefly about the advantages of dynamic lighting on the building of the game. "From a sense of the production pipeline, we knew we couldn't use static lighting again. Static lighting requires all the models to be done before the lighting can be rigged. If one new object is added, everything has to be rigged all over again and it's a very time-consuming process. In this model, even if the level is very blocky, we can still begin lighting it. Creating a video game is like setting sail on a ship while you're still building it and while you still may not be entirely sure where you're going. In a situation like that, yeah, let's try to build tools that don't completely flail about if things aren't done in a particular order. By keeping as much as we could dynamic, we were just able to crank every day on the lighting-in tandem with the people building art and the people putting new items in the game."
Although one might infer frustration from the presentation's opening comparison of using video game technology to the Sisyphean task of constructing Gaudi's Sagrada Familia, it's actually the opposite for Blizard. Blizard came from movies (he was the lighting supervisor for Minority Report) to games because of the challenges: "Games to me were just a more interesting medium than films in a lot of ways, because there are still many horizons to be crossed in games." While the dynamic lighting system utilized for Dead Space allowed it to cross just such an (event) horizon, the expanding field of technology for both creators and players of video games ensure that Blizard and crew will be again setting sail before too long.