Obbe Vermeij: A completely new level of detail system was implemented whereby a number of models (buildings) can share a single low detail model. This way the low detail models could be loaded as the player moves around the map as opposed to in one go as the player moves between islands (like it was in Vice)

John Whyte: There are always limits! There are limits to the number of objects which can be in any section of the map and this determines more than anything the density of objects in the game. Some of the city sections have effectively max’ed out the game in it’s current form. If we wanted to increase the density of objects then we would have to go back to the code and re-write it to handle much larger numbers. (Technically speaking there are a lot of structures in code which rely on 8-bit indexing to save space.)

John Whyte: That’s a good idea! But I’m afraid there isn’t any way of the scripts identifying the date and creating events which are scheduled like this.

John Whyte: The map is 6x6 kilometres or 36,000,000 square metres. That’s just the outside map and doesn’t include the interior locations in the game (of which there are many…). On top of that the player is not restricted to the populated area of the map. The player can take a boat or plane and travel in any direction as far as she want.

John Whyte: Definitely. The PC version has a further clip distance so more of the map is always visible and the map has a lot of the detail that had to be removed from the PS2 version to get it to fit in the small memory footprint. The clip distances for cars and peds are increased too – because the PC will be running at a higher resolution we have to draw these things further out. In total this means that the PC is pushing around a lot more than the PS2.

Chris Rothwell: Our dedicated team of programmers are always continually striving to improve feature sets, efficiency and usability of the scripting engine throughout the development of the GTA series. Although fundamentally the scripting language and engine hasn’t changed much since it was used to make GTA3 five years ago.

Since Vice City numerous improvements have been made to make scripting more powerful; such as the addition of arrays, switch statements, sequence tasks for character AI and uncountable game specific commands. A favourite tool that was added during SA was the ability to record cars positions while driving them around the city in game, then replay these car recordings in real time during a mission. This enabled us to really polish and improve our on-rails missions and scripted cut scenes.

A lot of the new gameplay features in SA were only made possible by these advancements in the scripting language. For example the 2D based casino and console games weren’t viable in VC until a host of HUD sprite commands were added during the development of SA. Also in VC there were very few custom animations used during missions, but for SA we had a brand new animation scripting interface. This system allowed the designers to implement animation heavy gameplay coded entirely within the scripting language such the pool game, basketball odd job, the parachute and in numerous other areas.

Chris Rothwell: The GTA scripting engine is incredibly powerful and flexible; within the game there is very little that cannot be affected, altered or modified by script. In theory, nearly any genre of game could be made using the GTA engine without a single change to the executable just by adding new scripts and art assets.

We have an overall governing script we call the ‘main script’. Among other things this main script keeps track of the players’ progress in the game then loads and launches a mission script when the player steps on a mission trigger or starts one of the odd jobs. Only one ‘mission’ script is in memory and running at one time. In addition to the missions we have ambient scripts resident in memory throughout the duration of the game that keep track of a wide variety of in-game systems. Examples of these are the mobile phone, stunt jumps and shop interface scripts. Another type of ambient scripts streams in and out of memory as the player moves around the map; these would be used for location specific encounters or attached to the various usable objects around the map like the crane or vending machines.

John Whyte: Re-skinning is a much more complicated task in SA. This is because the model for CJ has 3 variations (normal, buff and fat depending on gameplay) and the clothes for the model have to be put together item by item because you have full control over CJ’s wardrobe. It can still be done, but will probably require some custom tools to be useable.

John Whyte: By trial and error!

Obbe Vermeij: The rendering code generally has been given a big overhaul. Improvements have been made in the culling techniques that stop things from being rendered when they are not visible on screen. The resulting higher frame rate in combination with tons of new effects gives the game a smashing new look.

John Whyte: The textures were all originally created at their highest resolution and then cut back for those platforms that didn’t have the memory or performance to handle it.

John Whyte: Shadows are a mixture of shadow buffers and shadow volumes to get the results we wanted. Unfortunately it is difficult to get a consistent look with them when mixed. Reflections on cars was being done at one point by environment mapping the contents of the screen buffer onto the car with a low alpha, but it didn’t look right in some cases so we took it out.

John Whyte: A lot of the code in SA is done in a particular way to keep it closely in sync with the console versions, otherwise it would have taken a lot longer to finish! On the consoles we have to rely a lot more heavily on the graphics hardware to do things rather than being able to process through the CPU.