id Software · 1999 · 1990s · C
The first game engine to render curved surfaces in real time, and the one that turned the shader — a little script describing how a surface should look — into standard equipment.
id Tech 3, universally known at the time as the Quake III Arena engine, shipped in 1999 and immediately became one of the two engines the entire PC industry licensed, the other being Unreal. Its headline technical achievement was geometric: it was the first game engine to support spline-based curved surfaces, using Bézier patches, which meant that arches, pipes, domes and curved walls could be genuinely curved rather than approximated by a fan of flat polygons. After five years of first-person shooters made entirely of boxes, Quake III's levels looked organic in a way that was immediately legible even to players who could not have said why. The other significant contribution was the shader system. In id Tech 3 a surface is not a texture but a small script describing several layers, each with its own texture and a blend mode determining how it is composited over the layer beneath, plus orientation behaviours like scrolling, rotation and environment mapping. That is why Quake III's maps are full of surfaces that pulse, flow, shimmer and reflect — the artists were programming appearance rather than merely painting it. The engine also introduced higher-precision vertex animation via the MD3 model format, volumetric fog, decals, and precomputed portals. id released the source code under the GPL on 19 August 2005, and it went on to power a generation of licensed games and an enormous quantity of community work.