The 3D Software Rendering Technology of 1998's Thief: The Dark Project

Summary

The 3D Software Rendering Technology of 1998's Thief: The Dark Project Sean Barrett 2011-09-19 In 1998 Looking Glass Studios released the stealth game Thief: The Dark Project. This was just as 3D hardware acceleration was taking off, so due to the development cycle it didn't use hardware acceleration; it was a purely software-rendered game. I was the primary author of the core rendering technology in Thief (although I didn't write the object or character renderers), as well as some related bits and pieces. The same rendering engine, modified by others to use 3D hardware acceleration, also did the rendering for System Shock 2 and Thief 2. The engine was written somewhat contemporaneously with Quake (despite the game being released much later), and the basic appearance strongly resembles Quake. Many of its technologies were copied from or inspired by Quake, but in many cases the way it works is slightly or significantly different. The Quake software rendering was thoroughly documented by Michael Abrash in a series of articles which were reprinted in his Graphics Programming Black Book. The techniques used in Thief were never written up and I thought it might be nice to write them down for once, even if they're now totally irrelevant. I'll try to describe them relative to the probably-more-familiar Quake approaches where possible. Important contemporaneous games with similar rendering technology: 1996-06-22 - Quake 1 (QTest in February 1996) 1998-05-22 - Unreal 1998-11-19 - Half-Life (derived from the Quake 1 engine) 1998-11-30 - Thief: The Dark Project Table of contents Visibility Looking Glass games previous to Thief had used grid-based worlds. System Shock 1 and the Ultima Underworlds computed visibility using a grid-based traversal. Thief, however, was totally free-form, so I had to start from scratch to design the Thief engine (which started long before Thief, and I imagine even before we shipped Terra Nova: Strike Force Centauri, which I worked on). Thief was bas...