# LANE B — NOTES (measured)

## Round 6 (Fable's ROUND6 → Lane B) — place the orphaned street props

Placed the two published-but-unconsumed street GLBs (`procity_street_bin_01`, `procity_street_bus_shelter_01`)
via the existing use-if-ready furniture GLB path (fail-soft to primitives; `?noassets` → primitives,
**0 network** verified). All in `furniture.js` (+ a 3-line collider merge in `chunks.js`).

- **Bins** — genuinely sparse now (one loop, ~1 per block: `s += 78 m`, seeded side per edge), a country
  town not a mall. Decoupled from benches. GLB (3.0k tris) on its 0.57×0.68 footprint, primitive fallback.
- **Bus shelters — on the street graph, and this is the future tram/bus-stop contract.** Deterministic
  rule: **the midpoint of every MAIN edge whose `hashEdge(id) % 3 === 0`, on the road-side footpath by the
  kerb, long axis along the edge, open front to the road** — yields **1–3 per town** (2 in seed 20261990).
  The GLB (2.33×2.4×1.41, 8.0k tris) gets a **solid oriented-rect collider** so the player rounds it
  (furniture now returns `colliders`; `chunks.js` merges them into `getColliders`). Collision-verified: a
  straight walk into it is blocked.
  - **→ whoever builds the V2 tram/bus loop:** call **`busShelterStops(plan)`** (exported from
    `furniture.js`) → `[{ edgeId, x, z, yaw }]`. It re-derives the stops from the exact same rule the
    shelters are placed by — pure function of the plan, zero side effects. That is the stop list; don't
    re-invent it. To move/space stops, change the one rule + `busShelterStops` together.
- **Perf (measured, worst view WITH the rig-fleet citizens, midday):** **94k tris · 148 draws** — both
  well under the ≤200k / ≤300 gates (~100k tri and ~150 draw margin). Determinism holds (seed → same
  props). All-flags-on (`?winmap=1&dig=1&roster=stream`) composes clean, 0 console errors. Shot:
  `docs/shots/laneB/bus_shelter.png`. `qa.sh --strict` GREEN.
  - **→ Lane E (decimation candidate, not blocking):** the `street_bin` GLB is **3.0k tris** — heavy for
    a prop placed ~15×; I bounded it with the sparse cadence, but a decimate to ~500 tris would give back
    tri headroom if the combined-lane budget tightens. (Same class as the deferred `novelty_record`.)

---

## Round 5 (Fable's ROUND5 → Lane B) — v2: the Vuntra window trick, behind `?winmap=1`

- **Parallax interior-mapping glass** (V2_IDEAS "window trick"). Behind **`?winmap=1`, default-off.**
  Single-cube interior mapping in one shared `ShaderMaterial` on the existing window geometry: each
  glass fragment casts the view ray into a virtual room box and shades the surface it hits (back wall
  + seeded shelf silhouettes with product blocks, side walls, floor/ceiling) — a plausible room with
  real parallax, **zero extra geometry, still 1 window draw/chunk**. Per-shop variation rides
  attributes (`aTangent` = window right vector, `aTint` = seeded room colour, `aSeed` = shelf
  variation), **not per-shop materials**. Verified live: rooms are visible through the glass with
  parallax day + night.
- **§3.5 respected** via the same `uHour/uNight` + `aHours` the closed-facade system uses: at night an
  **open shop's room glows warm** ("Video Regal" lit), a **closed shop's room is dark** ("Second Time"
  dark) — screenshots in `docs/shots/laneB/winmap_*.png`.
- **v2 prime law held.** `WINMAP` is read straight from the URL in **buildings.js** — **no shell seam,
  so F only needs a flags-table row, no `index.html` wiring.** Flag-OFF path is byte-identical to v1:
  `windowQuad` collapses to the v1 `hoursQuad` (no extra attributes) and the finalize uses the v1
  `windowMaterial()` — verified: flag-off windows are `MeshStandardMaterial` with no `aTangent`;
  flag-on are the interior `ShaderMaterial` with `aTangent`. Seeded from `shop.seed` (deterministic).
- **Budget + fetches:** flag-on worst continuous-walk view with citizens **122–168 draws** (≤300);
  the shader is **100% procedural** — measured **0 fetch delta** vs the `?noassets` baseline (both 22
  = the pre-existing facade/ground skin JPEGs). `?noassets=1&winmap=1` adds no network. **0 console
  errors** in all modes. `qa.sh --strict` GREEN (4/4); `GOLDEN.hash` untouched (no plan change).

**→ Fable (F2 flags table):** `?winmap=1` — owner Lane B — state landed, default-off — needs **no
index.html wiring** (self-read in buildings.js). Smoke: boot `?winmap=1`, walk a block, glass shows
rooms; night open=warm / closed=dark.

---

## Round 4 (Fable's ROUND4 → Lane B) — done

- **B1 — closed-facade visuals (§3.5, the headline).** Closed shops now render **dark windows + a
  red CLOSED plate**; open shops (esp. the one `openLate` **video rental** at night) render **lit
  windows**; the door tooltip reads `🔒 <name> — CLOSED · opens HH:00` on aim. **Batched — the facade
  atlas is untouched:** per-shop open/closed rides on a per-vertex `aHours` (vec2 = the shop's
  `[open,close]`) feeding TWO shared shaders (window emissive gated by *open AND night*; plate alpha
  gated by *closed*), driven by ONE pair of shared uniforms (`uHour/uNight`) updated **once per
  day-segment change** — no per-shop materials, no per-frame poll. lighting.js dispatches a
  `procity:segment` event (numeric hour matching Lane F's `currentHour()`); buildings.js listens and
  calls `setFacadeHours`. Verified live: **22:00 → only "Video Regal" lit, every other facade CLOSED**;
  midday → all open, no plates; tooltip correct. **Worst view with citizens: 200 total draws** (≤300).
- **B2 — shot harness (gate-6).** (a) **Letterbox "fixed":** the bars were **not** a composer bug (I
  proved the composer/renderer/camera are correctly 1280×720 in headless at every stage) — they were
  `street_noon`/`arcade`/`warehouse_fringe` poses **jamming the camera against a big building wall**.
  Reframed those bookmarks to look *down a street* (`streetViewPose`), so all 10 tour shots now fill
  the frame. Also added a defensive `composer.setSize` sync in `DBG.render` per F's request. (b) Added
  the **3 missing poses** F listed (`crossroads_busy`, `residential_collar`, `warehouse_fringe`) —
  resolved from the live plan (busiest node / house-or-backstreets lot / outer-ring street), always a
  valid full-frame pose. `night_neon` now frames the open video shop glowing amid its CLOSED
  neighbours (the §3.5 money shot). `tools/shots.py` → 10 un-letterboxed shots, **0 console errors**.
- **B3 — street-furniture GLB upgrade + `novelty_record`.** furniture.js now upgrades primitives to
  depot GLBs via a **synchronous use-if-ready** check at chunk-build (no async write into a live
  chunk; `?noassets` → primitives, **0 network** verified). Placed the **novelty_record** landmark on
  the footpath in front of every record store (and a food_cart by market stalls / milk bars).
  **⚠ measured GLB tris:** bench **1.9k** ✓, food_cart **5.0k** ✓, streetlight **5.0k** ✓, but
  **novelty_record is 26.5k** (5× the ≤5k `glb_law`) — × many instances it spiked the busiest view to
  **574k tris**. So novelty_record stays on its **low-poly primitive** (giant vinyl disc, budget-safe)
  until Lane E decimates the GLB — **same treatment the ped rigs need (→ Lane E)**. With that, the
  bench GLB verified sitting on its exact footprint (0.44×1.21), tris back to ~25k.

`bash tools/qa.sh --strict` **GREEN** (4/4) after these changes. Round-4 files: `dbg.js`, `buildings.js`,
`lighting.js`, `hud.js`, `furniture.js` (+ these docs, + `docs/shots/laneB_r4/`).

---


Streetscape + game shell. Files: `web/index.html`, `web/js/world/*`, `web/js/world/fixture_plan.js`.
All numbers measured in-browser (Chromium, M-series) via `renderer.info`, 1280×720-ish viewport.
`renderer.info.autoReset` is off and reset once/frame, so **draws/tris are the true per-frame
totals across all passes** (scene + bloom + output). "scene draws" below excludes the ~11
post-processing passes; "total" adds them.

## Perf — fixture (`fixture_plan.js`, "Yarraville Junction", 26 shops, radius 3, shadows on)

| metric | measured | gate | status |
|---|---|---|---|
| draw calls | **148 scene (~159 total)** | ≤ 300 | ✅ |
| triangles | **~5.8k** | ≤ 200k | ✅ |
| skin materials (city-wide, shared) | **21** | ≤ 25 | ✅ |
| live chunks (radius 3) | 12 | — | — |
| chunk build | ~1–8 ms | 4 ms/frame budget | drained 1/frame |

Walked the fixture end-to-end (~310 m of main street + the backstreets): contiguous, no seams,
chunks stream in/out silently (live count 8↔12 as you move; build queue never starved), day/night
cycles through 6 segments, signs legible, door tooltips + `procity:enterShop` fire, collision
stops the player at wall−radius (measured 10.62 m against an 11 m frontage, radius 0.38). Runs with
`web/assets/` renamed away — no crashes, flat-colour fallback town, canvas signs still legible.

## Perf — Lane A integration (`generatePlan`, "Boolarra Heads", ~493 shops, 1 km², radius 2 auto, shadows off)

Lane A's `generatePlan` landed mid-build; `index.html` prefers it over the fixture (guarded import),
so this is the shipped default now. It is a full city with content in nearly every chunk — far
denser than the fixture the ≤300 gate was sized against.

Streetscape numbers below are **buildings + ground + furniture only** (what Lane B owns), measured by
a scripted continuous walk (real streaming + disposal, so ≤25 live chunks — no orphan-chunk inflation).

**Round-3 re-measure WITH Lane D citizens (pop 140, the shipped default).** Driving the real loop
(`chunks.update` + `citizens.update`) along the dense corridors via `window.DBG`, up to **125 active
peds** at midday: worst continuous-walk view **263 scene / 275 total** at **MIDDAY** and **275 total
at NIGHT** — **≤300 everywhere**, ~25 draw margin. Peds are a batched impostor layer (~1–2 draws for
the whole near tier), so they cost far less than their count. Radius-2 auto is already the spawn
default for a big city; no config change was needed. (Fable's independent integrated read is ~191 on a
typical main-street view.)

| metric | measured | gate | status |
|---|---|---|---|
| draw calls (worst gameplay view, continuous walk) | **~261 total (249 scene)** | ≤ 300 | ✅ ~40 draw margin |
| draw calls (typical street view) | **~130–210 total** | ≤ 300 | ✅ |
| triangles | 12k–25k | ≤ 200k | ✅ (huge headroom) |
| skin materials (shared, city-wide) | **5** | ≤ 25 | ✅ (facade atlas collapsed ~22 facade mats → 1) |
| live chunks (radius 2, walking) | ≤ 25 | — | — |
| chunk build | min ~1 / median ~8 / max ~22 ms | 4 ms/frame | ~1 heavy chunk/frame |

Integration verified: Lane B streams and renders Lane A's 493-shop city correctly — facades, signs,
doors, ground, furniture, day/night all work. Collision holds for the arbitrary lot orientations
`generatePlan` emits (e.g. `ry = −1.32 rad`); see the collision fix below.

### Adaptive settings (index.html)
`BIG_CITY = plan.shops.length > 120`. Big city → **radius 2 + no sun-shadow pass**; fixture → radius
3 + shadows. Override with `?r=N` / `?shadows=0|1`. Dropping the shadow pass ≈ halves draw calls in
dense areas (the shadow map re-renders every caster) for little visual loss in a flat-lit low-poly
town — LANE_B doc explicitly allows "none".

### Draw-budget close-out (this session) — the gate now holds with margin
Fable's first integrated smoke test read **~334 draws at spawn** (that was radius 3, pre-adaptive) and
the deep districts appeared to peak ~445. Two things closed the gap:

1. **Facade texture atlas** (`skins.js` + `buildings.js`). Every facade skin packs into one 2048²
   atlas (6×6 slots, each pre-painted with the skin's flat fallback colour, then the JPEG drawn over
   it — house law preserved), so a chunk's facades merge into **one** mesh (was ~5–8 per-skin meshes)
   and ~22 facade materials collapse to **1** (this also fixes the "≤25 materials was at the cap /
   over for some seeds" concern — now **5** city-wide). UV convention mirrors the sign atlas.
2. **Instanced-mesh merges.** Awnings were one InstancedMesh *per skin* (red/green/blue) per chunk;
   now **one per chunk** with per-instance colour (the stripe JPEG lived on the awning's unseen top
   face, so flat colour reads the same under the verandah). Shells + parapets + posts merged into
   **one** InstancedMesh (per-instance colour) instead of two.

Measured effect (worst dense frustum): **393 → 265 scene draws**; worst *continuous-walk* gameplay
view **~261 total**. Note the earlier "445" figures were partly a **measurement artifact** — teleport-
jumping between distant spots left orphan chunks the real streamer disposes; a proper walk never
exceeds the radius-2 set. Verified day + night, facades still textured, awning colours still varied.

## Architecture decisions worth knowing (for Lane F)

- **Ground is built once, not streamed.** The street graph is a handful of edges; merged flat quads
  are a few draws total and can't seam. If Lane A ships a many-hundred-edge network, revisit.
- **Sky/lighting are global**, re-centred on the player each frame (dome radius 650, sun follows).
  Linear fog at `(radius+0.4)·64 m` doubles as the chunk pop-in mask.
- **Per-chunk streaming = buildings + furniture only.** `ChunkManager` keeps chunks within Chebyshev
  radius R, disposes past R+1, drains a nearest-first build queue under a 4 ms/frame budget. A single
  dense chunk can exceed 4 ms (median 8), so it builds ~1/frame → an occasional ~8–22 ms build frame
  entering a dense district (fog-masked). Splitting a chunk build across frames is the next step if
  that hitch matters.
- **Night lighting is faked** (Vuntra-style): window + streetlamp **emissive** toggled by a night
  flag, plus bloom — no per-streetlight real lights. `ChunkManager.setNight()` re-applies to chunks
  streamed in while already night.
- **`scene.environment` is set** (round 3, `lighting.attachRenderer`): a neutral PMREM'd sky→ground
  gradient (no asset). Lane D's rig-fleet peds bake their impostor atlas from `scene.environment`
  (`sim.js`) and go dark if it's null; set here *before* `CitizenSim` constructs. One env for all
  segments (the atlas bakes once; the mostly-non-metal streetscape is barely affected). Verified set
  in street/night/interior + after interior-return (`interior_mode` only swaps `scene.background`).
- **Shared materials, city-wide** (`skins.js`). Facades share **one atlas material** (all skins in a
  2048² atlas); shells + parapets + posts are **one** InstancedMesh/chunk (per-instance colour); all
  awning/canopy skins are **one** InstancedMesh/chunk (per-instance colour). Signs are a per-chunk
  canvas atlas sized to the chunk's actual sign count, mipmaps off. Net: ~1 draw per kind per chunk.
- **Orientation law** (obeyed by `buildings.toWorld`, the InstancedMesh shells, and `pushOutRect`):
  a lot at `ry=0` faces `+Z`; `local→world = RotY(ry)`. Collider and geometry share this convention.

## Fixes applied after an adversarial multi-agent review (this session)

- **Collision for arbitrary `ry`** (`planutil.pushOutRect`): world→local used the wrong rotation sign;
  correct only for axis-aligned `ry`. The fixture is axis-aligned so it passed, but Lane A's angled
  lots would let you walk through walls. Fixed to the true inverse of `toWorld`. **(Critical for Lane A.)**
- **House doors** were merged into the interactive door mesh with no `doorRects` → raycasting a house
  door mis-resolved to the nearest shop. Now a separate non-picked mesh.
- **Awning skin index** used a signed shift (`seed >> 3`) → negative index → undefined skin for ~⅓ of
  shops. Now `>>> 3`.
- **Sign atlas** was a fixed 2048² (~16 MB canvas + ~22 MB GPU each) per shop-chunk regardless of
  sign count. Now sized to the actual sign count, mipmaps off — critical at Lane A's density.
- **Furniture edge hashing** assumed string edge ids; `generatePlan` uses numeric ids → every edge
  got the same seed. Coerced with `String(id)`.
- **Furniture drop:** `chunkIndex` rasterised only the edge centreline, so furniture at a perpendicular
  offset could land in an unbuilt chunk and vanish. Rasterisation now covers the full road+verge band.
- **`takeShots()`** never restored the pre-shot mode (P in map mode dumped you into street).

Reviewers' non-issues (intentional): `getColliders` returns a shared scratch array (per-frame
alloc avoidance); per-frame `{clock,chunks}` HUD object (negligible).

## The `shot()` harness

Press **P** → renders 3 fixed cameras and downloads PNGs. Reference stills captured to
`docs/shots/laneB/` (main-street day, plaza overview, night strip). Note: at Lane A's city the fixed
camera poses are tuned for the fixture; re-aim if used against the generated city.

## `window.DBG` — the QA harness hook (this session, for Lane F's shots.py/soak.py)

Loaded only with **`?dbg=1`** (`js/world/dbg.js`, installed by the shell). Answers LANE_F_NOTES §4.
All poses are derived from the **live plan** so bookmarks work on any seed; the day cycle pauses on
the first scripted segment change for deterministic captures.

- `DBG.ready` — true once the first chunks are built + the queue is drained (textures may still decode).
- `DBG.shot(name)` — snaps to a named bookmark, sets its time-of-day, settles bloom, returns stats.
  Bookmarks: `street_noon`, `arcade` (dept anchor), `market_square` (stalls), `milkbar_dusk`, `night_neon`.
- `DBG.teleport(x, z, ry)` / `DBG.setSegment(seg 0–5)` — drive the soak walk + time of day.
- `DBG.enterShop(shopId)` / `DBG.exitShop()` — scripted interior visits (drives Lane F's bridge →
  Lane C `buildInterior`; verified end-to-end: `enterShop` → mode `interior`, `exitShop` → back to street).
- `DBG.info()` → `{ drawCalls, tris, fps, heapMB, geometries, textures, chunk, mode }` (budget/soak read this).

Every bookmark stays under budget (busiest, the dept anchor, ~269 draws). `fps` reads the HUD's
smoothed value (0 under a throttled/background tab; populates in a foreground Playwright run).

## `ChunkManager` lifecycle hooks (optional, LANE_F_NOTES §8)

`createChunkManager` now fires `ctx.onChunkBuilt(key, {cx, cz, buildings, furniture, data})` and
`ctx.onChunkDisposed(key, {cx, cz})` **if a consumer sets them on `ctx`** — a clean per-chunk seam
for spawning/ambient/LOD. Inert by default (the shell doesn't set them; **Lane D's citizens drive off
`plan.streets` instead of chunk lifecycle**, so this is a spare hook, not a dependency).

## Controls
WASD move · shift run · mouse look · click a door · `[` `]` step time-of-day · `T` pause clock ·
`M` map · `P` screenshot · Esc release pointer.