Simon Willison’s Weblog

22nd April 2025 - Link Blog

Abusing DuckDB-WASM by making SQL draw 3D graphics (Sort Of) (via) Brilliant hack by Patrick Trainer who got an ASCII-art Doom clone running in the browser using convoluted SQL queries running against the WebAssembly build of DuckDB. Here’s the live demo, and the code on GitHub.

The SQL is so much fun. Here’s a snippet that implements ray tracing as part of a SQL view:

CREATE OR REPLACE VIEW render_3d_frame AS
WITH RECURSIVE
    -- ...
    rays AS (
        SELECT 
            c.col, 
            (p.dir - s.fov/2.0 + s.fov * (c.col*1.0 / (s.view_w - 1))) AS angle 
        FROM cols c, s, p
    ),
    raytrace(col, step_count, fx, fy, angle) AS (
        SELECT 
            r.col, 
            1, 
            p.x + COS(r.angle)*s.step, 
            p.y + SIN(r.angle)*s.step, 
            r.angle 
        FROM rays r, p, s 
        UNION ALL 
        SELECT 
            rt.col, 
            rt.step_count + 1, 
            rt.fx + COS(rt.angle)*s.step, 
            rt.fy + SIN(rt.angle)*s.step, 
            rt.angle 
        FROM raytrace rt, s 
        WHERE rt.step_count < s.max_steps 
          AND NOT EXISTS (
              SELECT 1 
              FROM map m 
              WHERE m.x = CAST(rt.fx AS INT) 
                AND m.y = CAST(rt.fy AS INT) 
                AND m.tile = '#'
          )
    ),
    -- ...