Guerilla Games: SPUs secret to PS3's performance

Guerilla Games' development director reveals that those who ignore the PlayStation 3's SPUs won't be able to achieve Killzone 2 quality graphics.

Guerilla Games' goal was to develop a cinematic development engine that wasn't pixel-perfect, but used post-processing to create noise, Hollywood quality motion blur and over-bloom.

In a highly recommended video interview over at Gamekings.tv Guerilla Games reveal that the secret to their deferred rendering engine was their ability to exploit the Cell processor's six SPUs (high speed mini-processors). Arjan Brussee, Development Director and a Guerilla Games founder explains:

"The trick of PlayStation 3 performance really is the use of the SPUs. You have to see it! There are six co-processors running on 3.2GHz. They are really fast. Normally we can't achieve [these graphics] in a game because it's too slow...[so] we throw it all on the SPUs."

Brussee reveals that they don't always use all of the SPUs:

"Normally we use about two of the six SPUs, but if we're going full force, then we simply use all six. If you get in crowded fire fights online, then these things really max out."

He continues to list how the Dutch team used the SPUs for tasks usually taken up by graphics chips:

"We use SPUs for all kings of things. We use them for physics, for particles, we use it to decode and mix a lot of MP3 streams simultaneously. We've got 7.1 audio mixing. It's really cool. If you have a 7.1 set it's totally amazing! If you do not have one, you really want to have one! Believe me! And we use it for things like lighting.

"One of the first things we do with the PlayStation 3 is we use the SPUs, not only the graphics chip, but the SPUs, in order to really help with rendering. You normally use only the GPU, but the SPUs are so fast; they really help to post-process all those particles and work with each other. So we gain about 20-40% extra speed."

Brussee waxes lyrical on how GG use the SPUs to mix Killzone 2's 7.1 audio:

"We push the PS3 perhaps further than other games. We achieved things I haven't seen in other games. For example, the audio, which is really special. We've got ambient streams. Those are MP3s with 4 or 5.1 channels. We rotate them according to the way you look. So you hear the sound quadraphonic around you. There's also a stereo soundtrack. There are 3D sound effects. There are voices of people who are positioned. We filter sounds with the SPUs. So if a character is talking behind a wall, you hear him very full, than if he is in front of you. We mix it all together and throw it out in 7.1 uncompressed."

To watch the full interview, with subtitles, please make your way over to Gamekings.tv You'll be able to observe how Guerilla Games built their deferred rendering engine, and a live demonstration of a level featuring 230 different light sources.