The Making of God of War III
"Camera is a crucial element to God of War, and the fact that the player isn't in control means that for some of the puzzling stages, it's important for the scripts to include an overall view of the surrounding area. In this case, an on-rails camera provides the goods, and is also used to good effect to get the best possible viewpoints on some of the game's most spectacular levels. The game sets out its stall in an enormously effective manner in the very first level, which pits Kratos up against the god of the oceans, Poseidon, while circumnavigating Gaia - a titanic figure as tall as the Sears Tower, over 1400 feet high."
"Perhaps part of the solution comes from the data streaming system running continuously in the background. Once you're in gameplay, God of War III has no pauses for loading whatsoever, and runs with no mandatory hard disk installation, in common with most Sony first-party games. Everything is being streamed from BD to system memory in the background."
"In terms of post-processing effects, the game is given an additional boost in realism thanks to an impressive implementation of motion blur. Superficially, it's a similar system to that seen in previous technological showcases like Uncharted 2: Among Thieves and Killzone 2, and helps to smooth some of the judder caused by a frame-rate that can vary between anything from 30 frames per second to 60.
Most games that implement motion blur do so just on a "camera" basis - that is, the whole scene is processed - an effect that of variable effectiveness in terms of achieving a realistic look.
According to Sony Santa Monica's Ken Feldman, motion blur is calculated not just on the camera, but on an individual object and inner object basis too."
"Another key effect in producing a filmic look to God of War III comes from development of new anti-aliasing technology. Removing the jaggies associated with videogaming obviously helps to create a more pleasing appearance.
Initially the game used the RSX chip to carry out a traditional 2x multisampling anti-aliasing effect. This, combined with the game's lack of high-contrast edges, produced an extremely clean look in last year's E3 demo. For the final game, the Sony Santa Monica team implemented a solution that goes way beyond that.
According to director of technology Tim Moss, God of War III worked with the Sony technology group in the UK to produce an edge-smoothing technique for the game that the developers call MLAA, or morphological anti-aliasing. Indeed, Moss's colleague Christer Ericson took us to task on the specifics of MLAA a few months back in this DF blog post, revealing that the team has put extensive research into this in search of their own solution.
The specifics of the implementation are still unknown at this time (though Ken Feldman suggests it "goes beyond" the papers Ericson spoke about in the DF piece) but the bottom line is that the final result in God of War III is simply phenomenal: aliasing is all but eliminated and the sub-pixel jitter typically associated with this technique has been massively reduced compared to other implementations we've seen."
"The custom anti-aliasing solution is also another example of how PlayStation 3 developers are using the Cell CPU as a parallel graphics chip working in tandem with the RSX. As Richard Lemarchand discussed in his Uncharted 2 post-mortem, the basic theory is all about moving tasks typically performed by the graphics chip over the Cell. Post-processing effects in particular work well being ported across.
The more flexible nature of the CPU means that while such tasks can be more computationally expensive, you get a higher-quality result. The increased latency incurred can be reduced by parallelising across multiple SPUs.
In the case of God of War III, any given frame typically takes between 16ms and 30ms to render, give or take a millisecond or two. The original 2x multisampling AA solution took a big chunk of rendering time, at 5ms. Now, the hugely more impressive MLAA algorithm takes a total of 20ms of CPU time. However, it's running on five SPUs, meaning that overall latency is a mere 4ms. So the final result is actually faster, and that previous 5ms of GPU time can be repurposed for other tasks."
"Where there is light, there is a shadow. Or at least there should be. On the majority of videogames, shadowing tech is fairly basic. Producing realistic shadows is computationally expensive, hence we get a range of ugly artifacts as a result: serrated edges that look ugly up close, or cascade shadowmaps that transition in quality in stages right before your eyes.
God of War III stands out in this regard simply because you don't tend to notice the shadows. They're realistic. The human eye is drawn to elements that stick out like a sore thumb, and that includes shadows.
The result is subtle and it works beautifully. Sony Santa Monica programmer Ben Diamand spent around three years working mostly on the deferred shadowing system employed in God of War III, that works beautifully in eliminating the artifacts and blending dynamically-generated shadows along with others that are pre-baked into the scenery."
"Sony Santa Monica's artistic and technical achievements are clearly considerable, but what is truly impressive is the team's commitment to continually refining and optimising code, right up until the very closing stages of development. It's an impressive juxtaposition of the team's passion in getting the very best product out there: Ben Diamand can spend over three years perfecting his shadowing tech, but at the same time, right up to the creation of the final gold master, the team was still optimising performance.
According to director of technology Tom Moss, in the last week of development, after the first review copies had been dispatched, programmer Cedric Perthuis continued refining code, achieving impressive performance gains to the tune of around eight per cent for the final game."
"It's games like this, along with Uncharted 2: Among Thieves and Killzone 2, that give the platform holder ownership of the bleeding edge of console gaming technology in the current generation.
It also makes a very convincing argument that there's plenty of life left in the system yet. God of War III is just the first PS3 title from Sony Santa Monica, and already director Stig Asmussen is hinting that we can expect "a lot more" from the current God of War III engine."
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