While the format itself is proprietary it was successfully reverse-engineered in 2001, and the actual RoQ decoder is present in the Quake 3 source code release. Internally RoQ uses vector quantization to encode video and DPCM to encode audio. In-game videos all use a proprietary format called 'RoQ', which was originally created by Graeme Devine, the co-designer of Quake 3, for the game The 11th Hour. In order to assist calculation of these shaders, id Tech 3 implements a specific fast inverse square root function, which attracted a significant amount of attention in the game development community for its clever use of integer operations. a water volume is defined by applying a water shader to its surfaces), light emission and which sound to play when a volume is trodden upon. The shader system goes beyond visual appearance, defining the contents of volumes (e.g. These features can readily be seen within the game with many bright and active surfaces in each map and even on character models. The graphical technology of the game is based tightly around a ' shader' system where the appearance of many surfaces can be defined in text files referred to as 'shader scripts.' Shaders are described and rendered as several layers, each layer contains a texture, a 'blend mode' which determines how to superimpose it over the previous layer and texture orientation modes such as environment mapping, scrolling, and rotation. Id Tech 3 introduced spline-based curved surfaces in addition to planar volumes, which are responsible for many of the surfaces present within the game. The engine does not include a software renderer. Unlike most other game engines released at the time - including its primary competitor, the Unreal Engine, id Tech 3 requires an OpenGL-compliant graphics accelerator to run.

Quake 3 arena mod