Quake Engine

A computer game consists of two parts. One part is the content: landscapes, characters, sounds, rules. The other part is the program that turns this content into moving images on the screen. This program is called an engine. The Quake Engine is such an engine, written in 1996 by the American company id Software for their game Quake. It is considered one of the most influential pieces of programming work in the history of gaming.

The leap from fake 3D to true 3D

Before Quake, games looked spatial but technically were not. In its predecessor Doom, the world consisted of floor plans that were stretched upward. Rooms could therefore not lie on top of one another, and you could not really look up or down. The enemies were flat images that always turned to face the player. Nowadays this is sometimes mockingly called 2.5D.

The Quake Engine solved this. Every wall, every staircase, and every character consisted of triangles with true coordinates in space. This made bridges over chasms, winding towers, and views in every direction possible. This basic idea remains unchanged to this day: even current games assemble their worlds from triangles, just far more of them.

It was also important that all of this ran on ordinary home computers, without a special graphics card. This forced the developers to use tricks that later became standard knowledge in the industry. The programmer John Carmack even later released the engine’s source code freely, so that anyone could study it.

Precomputed visibility and painted-on light

The main problem was processing power. A processor from 1996 could not possibly recalculate the entire game world anew in every frame. The Quake Engine got around this with preparatory work. Before a level was playable, a tool broke the map down into many small areas and stored, for each area, which other areas were even visible from there.

In the game itself, the program then only had to look things up instead of calculating them. If the player is standing in an enclosed room, the rest of the level is ignored entirely. You can think of it like a cheat sheet written before an exam. The actual work happens beforehand; during play, only a quick glance at the list remains.

Light worked similarly. Shadows and brightness were also precalculated and laid onto the walls as an additional image layer, so-called lightmaps. The result seemed astonishingly atmospheric by the standards of the time. The price was inflexibility: anyone wanting to move a wall would have had to recalculate the lighting. This separation between precomputed and continuously computed light still occupies game development to this day.

Descendants in today’s games

The Quake Engine is not merely a museum piece. It directly gave rise to the technology behind Half-Life, and from that in turn came Valve’s Source Engine, on which Counter-Strike ran for a long time. Anyone starting a multiplayer game today is using ideas from this program, such as the way client and server constantly exchange position data and compensate for delays.

The term engine as a standalone product also dates back to this era. id Software sold the technology on to other studios instead of only releasing games. Today this is its own market: Unity and the Unreal Engine are licensed by thousands of companies, now also for films, architecture, and vehicle simulations.

In tech news, Quake also appears as a test case for artificial intelligence. Because the game runs fast, is freely available, and has clear rules, researchers pit programs against each other within it. An old first-person shooter thus serves as a training ground for systems meant to learn to find their way around in an environment.