Grand Theft Auto III - Game Engine

Game Engine

Grand Theft Auto III's new RenderWare game engine created by another British games company Criterion Games was a significant departure from its predecessors, most notably because it uses a forward-viewing perspective as the default view, similar to a majority of third-person shooters and driving games, and has much-improved street-level graphics. The game also offers several additional camera modes, including a cinematic view, and the top-down perspective prevalent in GTA III's predecessors (this last was omitted in following titles, making GTA III the last major console title in the series to include the top-down view). In console versions, the game runs in the display resolution dictated by the console, while the Microsoft Windows version permits resolutions of up to 1600 by 1200 pixels.

The in-game environment is displayed through extensive use of level of detail (LOD), allowing areas directly surrounding the player to display objects in higher polygon counts (including vehicles, buildings and terrain) or minor props (e.g. street furniture), while areas far from the player are displayed with fewer polygons and less detail. As such, LODs aid GTA III in displaying a large environment with a further draw distance, while ensuring that the game's performance remains optimum. When traveling within the city, the game constantly swaps models of varied detail as the player moves from one area to another. However, when the player travels to another island, the game is required to load detailed models of the entire destination island, while also loading low-detail models for the island the player is leaving, requiring substantially more processing time; in the process, the game displays a "Welcome to..." screen for a short amount of time, before play resumes.

Like the environment, vehicles and pedestrians are depicted by full three-dimensional models, compared to flat top-down sprites used in previous games. Both vehicles and pedestrians are constructed from individual polygons with a central "core" (the engine, chassis and body of vehicles, and the torso of pedestrians). The damage system of vehicles represents the minor vehicle parts (doors, frontal quarter panels, bumpers and wheels) as undamaged, damaged or missing, based on collisions detected on the vehicle; the core of each vehicle remains visually unchanged despite heavy damage. As pedestrians in GTA III are made out of separate polygon parts (limbs, a head and a torso), it is possible to detach the limbs or head of a pedestrian (by using heavy firearms or explosives).

As the game runs a simulated 24-hour cycle, including changing weather, the game engine is also required to simulate day and night periods, as well as weather effects. This is done by adjusting surrounding visual effects and details in accordance to the weather and time of day. Other minor details are also present, like a rainbow and shiny streets after rain, and the sun moving from the northeast in the morning to the northwest in the evening.