Eurogamer: Living next to the sea myself, my very first impression of GTA IV was that you had captured the character of water under sun, metal and glass - the range of colours and their interaction with dynamic surroundings. Can you tell us a little bit about that process?
Aaron Garbut: A large part of this is down to programmers with a great eye. Most of what is going on with the water is very clever and creative code. The only influence we have as artists is obviously creating the world that's being reflected and then setting the lighting up to get this looking as nice as possible.
There are some lovely things going on in the water FX. From the way it reflects the surroundings and distorts that reflection, to the real-time physics on the surface (drop a car into the water and actual waves will distort the surface, which will affect nearby boats). There's even foam wherever the water gets shallower and simulations of viscosity around the edge. It's an insane level of detail, but you can see this when the water laps up and down a wooden post or jetties. All that is done in the FX code.
On top of that, we have global control for each time of day and each weather type to alter the way it fades with depth, which can help to make it look really murky. We can tint it subtly, but mainly it's the time of days, sunlight and sky colouring that has the biggest effect. But as artists we're just tweaking what is already at its base level a bloody nice effect.