Bake indirect light per area and hang troffer fixtures

[valuecodes]

What

• Part 2/2 of Toward a photorealistic Code Backrooms: light that behaves like the real place. Each area's walls, floor and ceiling now get a baked lightmap holding one bounce of the fixtures' light plus a fill that corners and junctions occlude, instead of the flat ambientLight.
• The bake runs in a worker (bake.worker.ts, three-mesh-bvh ray casts), one area at a time, keyed by the area object so a reseed or regeneration never receives a stale map. Unbaked areas use a flat 1×1 placeholder map. Placeholder and baked maps share channel, type and format, so a bake landing recompiles no shader (pinned by a test).
• Fixtures are now surface-mounted 2×4 troffers (an enamel housing with an inset diffuser). The fixtures over the player's room also get one of two always-mounted RectAreaLights, for the panel's real shape in the floor's sheen. These take 60 % of the fixture's light; the point light keeps the rest and still casts the shadow.
• Cost was measured on the repository's own world (168 areas, every one generated). It set the defaults: 0.5 m texels, 16 rays per texel plus a tent filter, at most 128k texels per area and 8M (64 MiB) per world. Median bake 1.3 s, largest area 7.3 s (in the worker, off the main thread). The full self world is 8.8M texels, so its last areas keep the placeholder.

How to test

pnpm install
pnpm typecheck
pnpm lint
pnpm knip
pnpm test
pnpm build
pnpm --filter web dev

Then open /?seed=7, walk through the first doorway, and press Q to compare low and high.

Screenshots

Same seed (7), before (main) / after, at low and high: start view and the walk through the first doorway. Taken headless (SwiftShader).

Security review

No security-impacting changes.

🤖 Generated with Claude Code

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-13T12:55:23.353161Z	2f12022	PR opened

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Reviewed commit: 2f12022153

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