TTF-DOOM – A raycaster running inside TrueType font hinting

In plain words

TTF-DOOM is a raycasting engine built entirely within TrueType font hinting bytecode, a Turing-complete virtual machine designed to adjust glyph shapes. The glyph "A" contains 16 vertical bars that are repositioned to render a Wolfenstein-style first-person view by ray marching against a tile map stored in the font's memory. Player coordinates are passed through CSS font-variation-settings while JavaScript handles movement and game logic, using the font as an unconventional rendering layer. The implementation totals approximately 6.5 KB of bytecode.

written from the facts on this page · September 2026

From the sources

A 3D raycasting engine running inside a TrueType font's hinting virtual machine - 4RH1T3CT0R7/ttf-doom

A DOOM-style raycaster that runs inside a TrueType font's hinting program. TrueType fonts have a built-in virtual machine for grid-fitting glyphs. It's got a stack, storage slots, arithmetic, conditionals, function calls - and it turns out it's Turing-complete. I wanted to see if I could get it to render 3D graphics. The font file contains a DDA raycasting engine written in TrueType bytecode. The glyph "A" has 16 vertical bar contours, and the hinting program raycasts against a 16x16 tile map and repositions those bars using SCFS instructions to form a 3D perspective view. The whole thing is 6.5 KB. JS handles movement, enemies, and shooting, then passes coordinates to the font through…from github.com

In the maker’s words, at launch

TrueType fonts have a hinting VM that grid-fits glyphs. It has a stack, storage area, conditionals, function calls, and it turns out it's Turing-complete. So I built a raycasting engine in the hinting bytecode. The glyph "A" in the font has 16 vertical bar contours. The hinting program reads player coordinates from…

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