[wass08]

What does this PR do?

Replaces the daylight room-id map (viewer/src/lib/daylight) with a sparse tiled map, and fixes how the room light is built on large scenes.

The map. The old map was one texture with every level stacked along Y at 10 cm cells, levels found by height across the whole site and capped at 8. A 40-storey tower lit floors 8–39 with whichever room was rasterized last, a campus of buildings fell to ~80 cm cells and still mixed its buildings' floors, and a 300 × 200 m hall took 48 MB at 20 cm.

• Per level, tiled. Each level keeps its own 10 cm cells, cut into 1.6 m tiles. A tile inside one room (or outside every room) is one value; only tiles a room edge crosses keep their cells, in a shared two-byte atlas. A level's rooms are grouped into clusters with their own rects, so open ground between them costs nothing. Memory follows wall length, not site area, and nothing grows with the number of floors.
• Per building. A point finds candidate buildings in a coarse directory and its level by binary search over that building's live floor heights (sorted heights stay sorted when levels explode apart). Buildings side by side with different floor heights each keep their floors. No level cap.
• Built tile row by tile row, never a dense per-level grid; zone holes are rasterized; where zones overlap, the smallest room wins (an automatic floor-wide room or a unit no longer swallows the rooms in it).
• Presentation. "Open to the sky" and the meters read each level's real presentation (shown, not shadow-only; focused when every level over it in its building is hidden). Texture sizes come from the device. The lighting and the exterior mask share one lookup.

Building the room light.

• Doorway and cover rays test only the meshes near them (a 2 m grid of mesh bounds taken from current vertices) instead of every wall: room builds on a 2,560-wall scene drop from 37 s to 0.6 s.
• Rooms wait for the scene to settle and rebuild each time walls, slabs, openings or zones finish changing (they finish without a geometry revision). A scene still loading after 10 s builds anyway and again every 10 s while it progresses. Before, a large scene built its rooms from half-built walls and kept them: doorways read as whole walls and corner rooms got diagonal "openings" pouring outdoor light in.

Measured (CPU bench over every room of each scene, plus browser checks):

Scene	Before	After
40-storey tower	96/480 rooms right	480/480
Campus, 10 buildings × 5 floors	708/1770, ~80 cm cells, 35 MB	1770/1770, 10 cm, 17 MB
300 × 200 m, 8 floors	48 MB at 20 cm, 1.1 s build	14 MB at 10 cm, 0.3 s
Houses		same room at every point sampled at 5 cm (differences only within one cell of room edges); main-pass GPU time within run-to-run noise

Known limits, unchanged: double-height rooms read as outside above the next floor's line; stairs and atriums carry no light between floors.

How to test

1. bun test packages/viewer/src/lib/daylight: new tests for a 40-storey tower, buildings with different floor heights, courtyard holes, memory along walls for a 300 × 200 m hall, overlapping zones, a room off the tile grid, an index texture within a small device limit, and when a level opens from above.
2. Open a multi-storey building, select an upper floor at night: every room has its own lamp pool (on main, floors past the 8th share one map layer).
3. Open a large scene (thousands of walls) at night and let it load: rooms stay lit by their own windows and lamps, with no diagonal bright wedges in corner rooms.

Screenshots / screen recording

Not added yet.

Checklist

• I've tested this locally with bun dev
• My code follows the existing code style (run bun check to verify)
• I've updated relevant documentation (if applicable)
• This PR targets the main branch

Tested in the hosted app (headless WebGPU and a desktop browser at night and midday), not with this repo's bun dev. Viewer package: typecheck clean, 1359 tests pass, bun check has no new findings.

🤖 Generated with Claude Code

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Note

Medium Risk
Large refactor of viewer daylight shaders, GPU room lookup, and rebuild timing; behavior changes on multi-floor and large scenes, though coverage is broad in unit tests.

Overview
Replaces the daylight room-id map with a sparse tiled RoomMap (per level, per building, device-aware textures) so tall towers, multi-building sites, and huge floors resolve the correct room without blowing texture size or an 8-level cap. Zones can include holes (courtyards); overlapping zones prefer the smallest room.

RoomLighting now builds through that map, shares one probe between lighting and exterior mask, and tracks levels via setLevelPresentation (shown, shadow-only, focus / open-to-sky) instead of stacked levelY + offset uniforms. Doorway and cover rays use a spatial mesh grid so large wall counts build in sub-second time.

useDaylightRooms defers rebuilds until geometry settles (or after a 10s cap), skips builds while levels are exploding/moving, reapplies when loading still shrinks dirty nodes, and sets textureLimit from the renderer.

Scene input switches from height-stacked levels to MapLevel[] (floor Y + building index) in live and baked paths.

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