lowlevelmetal · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026
diff --git a/README.md b/README.md
@@ -12,8 +12,11 @@ of that, OpenMM2 adds:
 - online multiplayer over UDP with automatic port forwarding (UPnP)
 - a Windows installer, and native Linux builds
 
-> **Status:** early development. OpenMM2 reads the original game data and its
-> subsystems are being built up; it is not playable yet.
+> **Status:** early but playable. London and San Francisco, cruise, Blitz,
+> checkpoint and circuit races, the crash courses, Cops and Robbers and online
+> multiplayer all run from the original game data. Behaviour is checked
+> against the original game function by function; the results, and the gaps
+> still open (mostly in network play), are in [docs/parity/](docs/parity/README.md).
 
 ## You need the original game
 

diff --git a/docs/ai.md b/docs/ai.md
@@ -58,10 +58,18 @@ Poles (`aiTrafficLightInstance::Init`, `World::signals()`): at
 `trafficLightAxis` (which points away from the road on retail data), Z =
 (-x.z, 0, x.x), so the glows on +Z face the arriving traffic and the SF
 models' arms (-X) reach over the road. The dual model for approaches with
-two or more lanes. `DrawGlow` draws the light's glow together with the
-pedestrian signal (WALK in state 4, NOWALK otherwise) and only when the
-model has both; NIGHT glows from the evening on (time of day > 1). Stop
-signs are static instances in `city/<map>_ai.inst`, drawn with the city.
+two or more lanes. Each pole is an unhit Y banger of its model's banger
+data (`aiTrafficLightInstance` derives from `dgUnhitYBangerInstance`): its
+frame (GetMatrix) is the base + R * CG, at which the CG-centred body is
+drawn; `SetFourWay` puts it in the room of its CG (GetPosition). Cars
+collide with it as with any prop and knock it over into its BREAKnn parts
+(`BangerSet`; the parts are ordinary hit bangers), after which neither its
+body nor its glows are drawn; the lights keep cycling. `DrawGlow` draws
+the light's glow together with the pedestrian signal (WALK in state 4,
+NOWALK otherwise), modelled from the base (GetMatrix less R * CG), and
+only when the model has both; NIGHT glows from the evening on (time of
+day > 1). Stop signs are static instances in `city/<map>_ai.inst`, drawn
+with the city.
 
 ## Ambient traffic (`Traffic`, `AmbientRoute`)
 

diff --git a/docs/audio.md b/docs/audio.md
@@ -198,7 +198,7 @@ a time. Ported from MM2 `Aud3DObject` and `Aud3DObjectManager`:
 | Pre-race: r = RandomizeNumber(11.5); ≤ 7.5 a random row of the mode's pre-race range, ≤ 8.5 time of day, ≤ 9.5 weather (nothing if that table was not loaded), else the car's line (else the mode's); it starts 1.5 s later | MM2 (`mmRaceSpeech::PlayPreRace`) |
 | Results: 1st win; a place above half the field mid; else poor. Win/mid use the car's line when r > 5 of 10, poor when r > 8; without a "mid" table (blitz) nothing is said | MM2 (`PlayResults`, `PlayResultsWin` / `Mid` / `Poor`) |
 | Final checkpoint, final lap, damage penalty, race progress, texture unlock and results stop the line playing and empty the queue; unlock-race and unlock-vehicle lines wait 0.1 s in the queue. The queue starts with one slot and gains one for every unlock-vehicle line loaded (and every unlock header after the first in a table); a play that finds no free slot is dropped; the first due play starts once nothing is playing | MM2 (`AudSpeech::Play`, `PutInQueue`, `Update`, `Stop`, `AllocateQueuePlayData`) |
-| The queue is updated twice a frame while the game runs (GameLoop's `AudManager::Update`, then `mmGame::Update`), so its delays pass at twice the clock's speed: the pre-race line starts 0.75 s after it is queued, not 1.5 s. While the game is paused only `mmGame::Update`'s update is left: the queue counts at the clock's speed and a due line starts during the pause (after the pause has stopped every sound, below) | MM2 (`AudManager::Update`, `mmGame::Update`, `mmSpeechContainer::Update`); `AudioManager` |
+| The queue is updated three times a frame while the game runs (`AudManager::Update` twice, by GameLoop and again as asRoot's first node, then `mmGame::Update`), so its delays pass at three times the clock's speed: the pre-race line starts 0.5 s after it is queued, not 1.5 s. While the game is paused only `mmGame::Update`'s update is left: the queue counts at the clock's speed and a due line starts during the pause (after the pause has stopped every sound, below) | MM2 (`AudManager::Update`, `mmGame::Update`, `mmSpeechContainer::Update`); `AudioManager` |
 | What calls them: the pre-race line at the start (`mmGame::Reset`), the final checkpoint when a checkpoint race has only the finish left and when a circuit's final lap reaches its last checkpoint (`mmWaypoints::Update`, the race's FinalCheckpoint event), the damage penalty and blitz results (`mmSingleBlitz::UpdateGame`), the results and unlock lines (`mmGameSingle::UpdateRewards`). Nothing in build 3393 calls the final lap, race progress or unlock-race lines (`mmRaceSpeech::PlayFinalLap`, `PlayRaceProgress`, `PlayUnlockRace`), the crash course's unlock line or the Cops & Robbers commentary (`mmCNRSpeech::Play`): their tables load but are never heard, and OpenMM2 does not play them either | MM2 (callers of the Play methods) |
 | File names `<announcer><prefix>NN` | verified against the sample names |
 | Cops & Robbers: `bullshit.csv` in SF, `cnrlondon.csv` elsewhere; an event draws one of its rows, cuts the line playing and starts after 0.01 s; a fourth "num used" column smaller than the row's range picks a random window of that many lines. The London rows' names end in a space ("AL1\AL1ROBROB "), which MM2 keeps, so those files are never found and London's Cops & Robbers commentary is silent | MM2 (`mmSpeechContainer::InitCNR`, `mmCNRSpeech::LoadGroup`, `SetReadState`, `Play`); the missing files **inferred** from `AudStream::PlayOnce`'s path |
@@ -236,7 +236,7 @@ a time. Ported from MM2 `Aud3DObject` and `Aud3DObjectManager`:
 
 | Behaviour | Evidence |
 |---|---|
-| While the game is paused (the popup menu in single player, the full-screen map) every wave sound stops, on the first two paused frames: engines, skids, sirens, ambience, rain, voices and the announcer's line. Loops start again from the beginning once the game runs on, as their owners find them stopped; one-shots are cut. The music (DirectMusic) plays on; the popup switches it to its pause segment (`mmPopup::PlayPauseMusic`) | MM2 (`AudManager::Update`, `AudManagerBase::UpdatePaused` with its counter limit of 1, `StopAllSounds`); `audio/game/AudioManager.h`, the race's hook at the start of its frame |
+| While the game is paused (the popup menu in single player, the full-screen map) every wave sound stops, on the first two paused updates (both in the first paused frame, `AudManager::Update` running twice a frame): engines, skids, sirens, ambience, rain, voices and the announcer's line. Loops start again from the beginning once the game runs on, as their owners find them stopped; one-shots are cut. The music (DirectMusic) plays on; the popup switches it to its pause segment (`mmPopup::PlayPauseMusic`) | MM2 (`AudManager::Update`, `AudManagerBase::UpdatePaused` with its counter limit of 1, `StopAllSounds`); `audio/game/AudioManager.h`, the race's hook at the start of its frame |
 
 ## Not implemented
 

diff --git a/docs/bangers.md b/docs/bangers.md
@@ -81,9 +81,12 @@ name. A mass of 0 or less becomes 1 in OpenMM2 (no retail file has one).
    xrefs place (lvlLevel::LoadInstances, the "xrefs" chunk read by
    lvlInstance::EndGeom): each xref's matrix times the record's, dropped
    when a row is zero or two rows have a dot product above 0.01, rows
-   outside 0.97..1.03 squared length normalised, kept as a full matrix with
-   the record's variant, in the room FindRoomId finds from the record's
-   room. An xref whose model has no banger data is not placed at all (MM2
+   outside 0.97..1.03 squared length normalised, then requested as Y
+   bangers (RequestBanger(name, 0), dgUnhitYBangerInstance: only the turn
+   about Y is kept, the CG offset is turned by the whole matrix) with the
+   record's variant, in the room FindRoomId finds from the record's room.
+   68 retail xrefs were exported Z up (awnings, the Chinatown sign, the
+   bridge and tower lights): MM2 stands them upright. An xref whose model has no banger data is not placed at all (MM2
    reports it as not exported): cl10's trees. 33 retail models have xrefs
    (tower and bridge lights, awnings, doors, windows): 65 bangers in London,
    368 in San Francisco. They are not drawn with their parent model.

diff --git a/docs/formats/bai.md b/docs/formats/bai.md
@@ -125,10 +125,12 @@ for its end-1 and its end-0 intersection, in that order):
 * each end intersection lists it last, then sorts its list by
   `atan2(dx, dz)` from its centre to each road's far end (the road's last
   centre vertex when its end 0 is the intersection, else its first),
-  smallest first, and rewrites every listed road's index there. MM2 first
-  moves the centre to the bound-sphere centre of the intersection's room;
-  OpenMM2 keeps the file's centre (**inferred**: every main-file list is
-  already sorted round it);
+  smallest first, and rewrites every listed road's index there. First the
+  intersection's centre moves to the bound-sphere centre of its room
+  (`cityLevel::GetBoundSphere`: the room perimeter's area centroid at the
+  mean height of its corners); the file's centres of these intersections are
+  already within 0.21 m of it (66 in San Francisco), and `mmGame::RespawnXYZ`
+  starts a cruise at the moved centre;
 * `aiMap::MapRoadToRooms(road, 2)` lists it, as component type 2, for the
   rooms of its centre vertices 1 to n - 2 and for every room its two curbs
   cross, sampled trunc(section length) times per section (the second

diff --git a/docs/formats/environment.md b/docs/formats/environment.md
@@ -6,11 +6,11 @@ Parsers: `src/city/Environment.{h,cpp}`; loaded by `loadCity`.
 |------|--------|---------|
 | `<map>.lt00`..`.lt15` | Angel "type: a" | Lighting per time of day and weather. Index = timeOfDay × 4 + weather (time: morning, noon, evening, night; weather: clear, cloudy, foggy, rainy; verified from the block names). Fields `KeyHeading/KeyPitch/KeyColor`, `Fill1*`, `Fill2*` (radians, 0..1 colours), `Ambient` (signed int, ARGB). |
 | `<map>_fog.csv` | CSV | 16 rows in the same order: fog colour (0..255), start, end. The description column is ignored per its header. |
-| `<map>.sky` | text | `model a b c` (`sky_dome_l 0 0.95 0.005`). Parameter meanings unknown. |
+| `<map>.sky` | text | `model a b c` (`sky_dome_l 0 0.95 0.005`), read by `lvlSky::AutoInit` (`%s %f %f %f`): the dome sits at the camera with its height = camera height x b + a (`lvlSky::DrawHat`) and turns about +Y at c radians per second (`lvlSky::Update`). |
 | `<map>.water` | text | water plane height, then room ids (inferred: rooms that use it). |
-| `<map>.ext` | text | `minX minZ maxX maxZ`, a world rectangle inside the PSDL bounds (inferred: HUD map extent). |
-| `<map>.reset` | text | `x y z  # comment` recovery points ("GG fallthru" = Golden Gate fall-through). |
-| `<map>.lmap` | binary | `"LMP0"`, `u32 n`, `u32 argb[n]`. London: n = rooms - 1, entry 0 = 0xCDCDCDCD. SF: n = 1,125 for 1,171 rooms. Likely per-room ambient colours (mm2hook `lvlRoomInfo::Color`). Indexing is unconfirmed and SF's count does not match its PSDL. |
+| `<map>.ext` | text | `minX minZ maxX maxZ`, a world rectangle inside the PSDL bounds. midtown2.exe has no reader for it (an editor file). |
+| `<map>.reset` | text | `x y z  # comment` recovery points ("GG fallthru" = Golden Gate fall-through). midtown2.exe has no reader for it: the game respawns at checkpoints or intersections instead. |
+| `<map>.lmap` | binary | `"LMP0"`, `u32 n`, `u32 argb[n]`: one colour per room id (entry 0, the dummy room, is 0xCDCDCDCD). `cityLevel::Load` takes it only when n equals the PSDL's room count (dummy room 0 included); then room i gets argb[i] (`lvlRoomInfo` +0x1c, the street colour and the instance light tint), else every room is white. Neither retail file matches (London 1,341 for 1,342, SF 1,125 for 1,172), so the retail game draws every room white. |
 | `materials.mtl` | text | Physics materials: `mtl name { elasticity: f friction: f effect: s sound: n drag: f width: f height: f depth: f ptxindex: a b ptxthreshold: a b }`. |
 | `materials.csv` | CSV | `texture,physics`: texture name → material name (`none`, `cobblestone`, `grass`, `water`, `deepwater`, `sand`, `mud`, `ash`). |
 

diff --git a/docs/formats/images.md b/docs/formats/images.md
@@ -40,7 +40,7 @@ rectangle.
 MM2 stores these images the other way round: its TGA, BMP and JPEG readers
 all put the picture's top row first (only `.tex` files are copied in file
 order). Its 2D drawing blits them upright, as OpenMM2's UI does. On a 3D mesh
-MM2's v = 0 is the top of a TGA picture, while OpenMM2 uploads row 0 (the
-bottom) as v = 0, so a TGA on a mesh is upside down relative to MM2 unless
-the renderer flips it. The only retail case is the HUD map dots, which are
-symmetric.
+MM2's v = 0 is the first stored row, so the top of a TGA, BMP or JPEG picture
+and the bottom of a `.tex` one: `game::TextureLibrary::readImage` flips
+TGA, BMP and JPEG images to the top row first before it uploads them, so
+meshes sample every format as MM2 does.
diff --git a/docs/formats/race.md b/docs/formats/race.md
@@ -39,14 +39,21 @@ editor files or crash-course event lists.
 Header plus one row per race: `Description`, then two blocks of 10 columns:
 amateur then professional. Each block is `CarType, TimeofDay (0..3),
 Weather (0..3), Opponents, Cops, Ambient (density 0..1), Peds (density),
-NumLaps, TimeLimit (seconds), Difficulty`.
+NumLaps, TimeLimit (seconds), Difficulty`. `Cops` is a count (0 to 8 in
+the retail tables) that the race menu keeps as the cop density unchanged;
+the police placement clamps it to 0..1 (all posts from 1 up).
 
 ### Waypoints: `<race>Nwaypoints.csv`
 
 `x,y,z,a,radius,...`: checkpoint position, heading in degrees, checkpoint
 radius. Some files label column 5 `poly count`. The remaining columns
 (`frame rate`, `state changes`, `texture changes`, `msg`) are editor profiling
-fields and are kept verbatim. Crash-course event lists, `copchase.csv` and
+fields and are kept verbatim, except that column 6 is the waypoint's hit
+flag. Heading h faces (sin h, 0, -cos h): 0 is -Z and 90 is +X. The game
+turns the car at the start by h x -0.017453292 about +Y
+(`mmWaypoints::GetStartAngle`); a heading of exactly 0 on a waypoint after
+the first means "towards the next waypoint" (`mmWaypoints::LoadCSV`). A
+radius of 0 means 15. Crash-course event lists, `copchase.csv` and
 `multicopwaypoints.csv` use the same layout.
 
 ### Opponent lines: `*.opp`
@@ -55,6 +62,14 @@ CSV `x,y,z,brake,forward offset,side offset,target speed,speed start,side start`
 Named `<race>-a-<n>.opp` (amateur) and `<race>-p-<n>.opp` (professional) and
 referenced from the `[Opponent]` section of the `.aimap`.
 
+MM2's `aiRouteRacer::Init` reads only the first four numbers of a row
+(`atof`). The first row is the racer's grid place: its fourth column (headed
+`brake`) is the start angle in degrees, stored as the car's reset rotation
+times 0.017444445 (MM2's own degree factor) and, unlike a waypoint heading,
+not negated: 90 faces -X. The rows in between become route waypoints (the
+first intersection of the room each point lies in) and the last row is the
+destination. The other columns are not read.
+
 ### AI setup: `*.aimap`, `*.aimap_p`
 
 `[Section]` headers, `#` comments. A section is a *list* when its first line is
@@ -71,7 +86,7 @@ reproduces it for every retail file.
 | Ambients Drive On The Left | value | 0/1 |
 | Traffic Lights | value | two model names |
 | Exceptions | list | `road density speedLimit` per AI path id |
-| Police | list | `car x y z heading mode lane ? ?` (the file's comment header is stale) |
+| Police | list | `car x y z heading mode behaviours chance range` (the file's comment header is stale): heading in degrees, stored as the reset rotation heading x -0.017444445 (`aiRaceData::aiRaceData`); `mode` is read and never used; `behaviours` (default 15) are the apprehend bits; `chance` (default 0.5) and `range` (default 50 m) govern pursuing opponents |
 | Opponent | list | `car oppFile <numbers>` |
 | Ambient Types/Density | list | `model cumulativeProbability ?` |
 | GoodWeatherPedName / BadWeatherPedName | list | `goodModel badModel` |

diff --git a/docs/parity/README.md b/docs/parity/README.md
@@ -72,15 +72,15 @@ record's summary counts them:
 | phys-bounds | 159 | 101 | 36 | 13 | 1 | 0 | 8 |
 | vehicle | 141 | 76 | 42 | 6 | 2 | 1 | 14 |
 | ai-vehicles | 170 | 71 | 67 | 3 | 2 | 1 | 26 |
-| ai-ambient-city | 236 | 116 | 61 | 13 | 22 | 4 | 20 |
-| session | 205 | 89 | 86 | 6 | 4 | 1 | 19 |
+| ai-ambient-city | 236 | 116 | 63 | 11 | 22 | 4 | 20 |
+| session | 205 | 87 | 89 | 5 | 4 | 1 | 19 |
 | camera-props | 195 | 107 | 57 | 11 | 2 | 0 | 18 |
 | rendering-fx | 197 | 67 | 95 | 8 | 3 | 4 | 20 |
 | audio | 265 | 69 | 155 | 11 | 10 | 0 | 20 |
 | frontend-ui | 151 | 80 | 39 | 11 | 3 | 2 | 16 |
 | formats | 119 | 23 | 44 | 11 | 7 | 0 | 34 |
 | OpenMM2-only | 34 | 6 | 8 | 5 | 4 | 1 | 10 |
-| **Total** | **2078** | **880** | **786** | **107** | **70** | **15** | **220** |
+| **Total** | **2078** | **878** | **791** | **104** | **70** | **15** | **220** |
 
 The open rows and each record's "Missing" table list what still differs
 from MM2 and what porting it needs. The larger missing features are the
@@ -105,7 +105,7 @@ placement.
 | Subsystem | Record | Reachable | Ported (new) | Replaced | Not needed | Open |
 | --- | --- | ---: | ---: | ---: | ---: | ---: |
 | world objects | [world-objects.md](mm2/world-objects.md) | 297 | 187 (124) | 30 | 75 | 5 |
-| game flow and spawns | [game-flow.md](mm2/game-flow.md) | 608 | 382 (62) | 66 | 151 | 9 |
+| game flow and spawns | [game-flow.md](mm2/game-flow.md) | 608 | 382 (62) | 65 | 152 | 9 |
 | AI | [ai.md](mm2/ai.md) | 507 | 409 (17) | 6 | 92 | 0 |
 | vehicle and physics | [vehicle-physics.md](mm2/vehicle-physics.md) | 736 | 574 (0) | 13 | 146 | 3 |
 | props and effects | [props-fx.md](mm2/props-fx.md) | 169 | 126 (1) | 0 | 43 | 0 |
@@ -127,6 +127,36 @@ record's Open section; the largest are late joins for network cruise and
 Cops and Robbers, the network tuning checksum, the water respawn sync and
 remote cars' sounds and damage.
 
+## Round 3: cross-cutting themes (2026-10-13)
+
+Two differences the maintainer saw after both audits (traffic lights out of
+line with their glows, and where cruise mode starts) were classes of bug
+that a function-by-function audit misses, because each function looked
+right on its own. Round 3 followed data across systems, one theme at a
+time, with records under [round3/](round3/):
+
+| Theme | Record | Cases | Verified | Fixed | Deviation | Inferred | Open | Other |
+| --- | --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
+| frames: where models, parts, glows and shadows are drawn | [frames.md](round3/frames.md) | 68 | 56 | 6 | 2 | 1 | 0 | 3 no retail data |
+| the cruise start (`mmGame::RespawnXYZ`) | [cruise-spawn.md](round3/cruise-spawn.md) | 22 | 5 | 11 | 4 | 1 | 0 | 1 openmm2 |
+| MM2's global random stream and its consumers | [random-streams.md](round3/random-streams.md) | 41 | 7 | 16 | 12 | 0 | 0 | 6 not needed |
+| init, reset, update and draw order | [order.md](round3/order.md) | 51 | 35 | 10 | 5 | 0 | 1 | |
+| units, signs, axes and conventions in data | [conventions.md](round3/conventions.md) | 104 | 83 | 8 | 6 | 3 | 0 | 4 openmm2 |
+| **Total** | | **286** | **186** | **51** | **29** | **5** | **1** | **14** |
+
+The fixes that show most: traffic lights stand on their CG as
+`aiTrafficLightInstance` does (the poles were 3.9 m in the ground under
+correctly placed glows) and are props cars knock over; cruise starts where
+MM2 does, from the one global stream right after `aiMap::Reset` (London
+intersection 19 at Marble Arch, San Francisco intersection 121 on the
+Embarcadero, with the cruise menu's default densities); a race is set up
+from that stream in `mmGame::Init`'s order; semi trailers, knocked traffic
+cars' wheels and shadows, and police headlight beams are drawn as MM2 draws
+them; a restart happens at the start of the next frame; a paused game keeps
+its camera, sky, rain and HUD message going; 68 PKG xref props stand
+upright; the player's steering tune comes from `tune/<car>.asnode`. The one
+open case is F2's pause (OpenMM2's F2 is the fly camera).
+
 ## Manifest
 
 Lines as of the start of the audit (files the audit added: as of when