In honor of the 30th anniversary of Quake, I made Slipgate, a map viewer and analysis tool. Link: https://dmjn.github.io/slipgate/ Project: https://github.com/dmjn/slipgate To use it, drop a **.bsp** file, or drop **pak0.pak** / **pak1.pak** and pick a map from the index. Nothing is uploaded; the file is parsed in its tab. Quake's paks sit in the **id1** folder of any Steam, GOG, or shareware install. Shareware pak0 carries the whole first episode. Here is a link to paks: https://archive.org/details/quake_pak_202306 ![[e1m2-iso-ui@4x (1).png]] **Slipgate** opens Quake's levels and lets you read them the way you would read a building: in plan, in section, in axonometric, with the ceilings lifted off and the walls turned to glass. It is not a level editor and it is not a game. It is an instrument for looking closely at thirty-year-old architecture that has been enormously influential and very rarely measured. Quake is worth this attention because it has almost no story. There is a military installation, a teleport experiment that went wrong, and then thirty-two levels and no further explanation. With nothing to follow, the level carries everything. Take the fiction away and nothing is lost, because the geometry was always the text. ## It reads your files, not ours Slipgate ships no game data. Drop your own `pak0.pak` and it is parsed inside the browser tab. Nothing is uploaded and nothing is sent anywhere. A pak you choose to keep is cached locally in IndexedDB and can be cleared from the opening screen. ## What it derives from the game's own data - **Geometry** from the BSP, split into floors, walls and ceilings at the same normal-z threshold the engine uses to decide whether you are standing on something, each independently dimmable or removable. - **Visibility** from the compiled PVS. Place a probe and see every surface the engine may draw from that leaf, or let it follow the cursor and sweep a room. - **Navigation** from hull 1, the collision geometry Quake pre-expanded to the player's 32 × 32 × 56 box, walked under the real movement rules: 18 units of step, a 45 unit jump apex, free falls, swimmable water, and lifts and teleporters as explicit edges. - **Progression** from the entity lump. Key doors, trigger chains and teleport destinations are resolved into the order a player must actually do things in, then drawn as a route with waypoints. - **Lighting** from the lightmap lump, giving a real brightness value per surface, so darkness can be measured rather than described. - **Text** from `progs.dat` in your own pak, which is where the game's own words live. ![[download (22).png]] ## What you can do with it Cut a section anywhere on any axis. Color surfaces by height, material, brush entity or baked light. Filter monsters by difficulty and watch placement change on identical geometry. Solve the critical path and read its length, detour ratio, backtracking, optional volume and the light profile beneath it. Run every map in a pak through the same solve and compare them in a sortable table with a scatter plot. Export true-scale SVG plans and sections with real cut lines, or PNG at up to four times the viewport. Any view can be linked. **COPY LINK TO THIS VIEW** writes the whole reading into the URL, so a footnote can point at a view rather than describe one. ## Honest limits The navigation grid samples on a lattice, so a ledge within one cell of the jump limit can read as reachable when it is marginal. The bias is deliberate, since an over-connection is a smaller error than a stranded exit, and when the solve cannot resolve every lock it says so rather than failing quietly. Brush entities such as `func_wall` are absent from the collision hull, so a handful of walls read as passable. The graph panel shows trigger and target logic rather than true room segmentation, which would need the `.prt` file the compiler discards. ## Licences three.js r128 and html2canvas 1.4.1 are vendored under `vendor/`, both MIT, with their licence files alongside. IBM Plex Mono is served from Google Fonts under the SIL Open Font License. Quake, its data formats and its level data are id Software's. Slipgate reads those formats and contains none of that content. ![[e1m6-iso-ui@1x (1).png]] ![[Screenshot 2026-08-10 123201.png]]