@mcmartin@mastodon.gamedev.place The Thief Dark Project renderer used octagonal bounding box pairs to keep track of what was visible through portals (the primary sorting/display mechanism of the terrain/world renderer) to reduce overdraw and to cull non-visible objects. (Quake, a similar-era renderer, used front-to-back span lists to reduce overaw perfectly, but only for terrain polygons, and could not cull objects as effectively.)