lowlevelmetal · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.25...4.0)
 
 project(OpenMM2
-    VERSION 0.2.0
+    VERSION 0.3.0
     DESCRIPTION "Open source reimplementation of Midtown Madness 2"
     HOMEPAGE_URL "https://github.com/lowlevelmetal/OpenMM2"
     LANGUAGES C CXX)

diff --git a/docs/architecture.md b/docs/architecture.md
@@ -44,8 +44,9 @@ which is parsed as data.
 ## Timing
 
 The simulation runs on a fixed time step; rendering interpolates between the
-last two simulation states so any refresh rate works. Multiplayer exchanges
-simulation state at a fixed rate independent of the frame rate.
+last two simulation states so any refresh rate works (rendering.md, "Drawing
+between simulation steps"). Multiplayer exchanges simulation state at a fixed
+rate independent of the frame rate.
 
 Each frame's time step is the real time since the previous frame, held to
 0.0001–0.1 s as MM2's `datTimeManager::Update` does, so a long hitch slows

diff --git a/docs/effects.md b/docs/effects.md
@@ -193,6 +193,12 @@ unless the other party is a vehicle. Then:
   engine), above 75 mph two random wheel/hub pairs and a fender, above
   50 mph one pair, thrown at 1.3 times the car's speed.
 
+In a network race the other players' cars and a client's shared police show
+their owner's damage: the smoke from the replicated level, and the texel
+damage, broken parts, sparks and shards replayed from the owner's events
+(multiplayer.md, "Damage"); they lay no tyre tracks and throw no wheel
+particles.
+
 Ejected parts take their physics from `tune/banger/<car>_<part>.dgBangerData`
 (`vehBreakableMgr::Create`). Retail data has these for every car's wheels and
 for some cars' BREAK parts, sirens and fenders, but none for hubs. MM2 still

diff --git a/docs/gamemodes.md b/docs/gamemodes.md
@@ -91,8 +91,10 @@ penalties (below).
 
 Circuits and checkpoint races start the countdown only once the pre-race
 camera has finished (`UpdateGame` state 0 waits for mmPlayer +0xE5A; Blitz
-does not), and the multiplayer races only after the host's start message
-(OpenMM2: 2.5 s before the shared start time). Each countdown line plays
+does not), and the multiplayer races only after the host's start message,
+which comes once every player has reported its race loaded (OpenMM2: a
+shared start time, the countdown's lines following the time left to it; see
+docs/multiplayer.md, "Race start"). Each countdown line plays
 "Startracelow", "Go!" plays "Startracehigh".
 
 ### Checkpoints
@@ -366,14 +368,18 @@ by the game. Falling into the water fails the event 0.5 s later.
 HUD, car):
 
 * **Start**: no countdown; "Go!" (113) for 2 s at the top with
-  "Startracehigh". Players start at random intersections drawn from a
-  stream seeded with their id (`mmGame::RespawnXYZ`).
+  "Startracehigh". MM2's host starts at once and each joiner when the host's
+  game state reaches it; OpenMM2's machines wait for everyone and go together
+  at the shared start (docs/multiplayer.md, "Race start"). Players start at
+  random intersections drawn from a stream seeded with their id
+  (`mmGame::RespawnXYZ`).
 * **Machines**: each machine runs the rules for its own car and tells the
   others (`CopsAndRobbers::updateNetwork` / `receive`): a client that
   reaches free gold asks the host (0x25e) and the gold waits; the host
   grants it (0x25a); the carrier's machine reports a drop (0x259) and a
   delivery (600); the host draws the next set and sends its places (0x261).
-  OpenMM2 seeds the first set with the shared start time.
+  OpenMM2 seeds the first set with the time the host ordered the race,
+  which every machine knows when it loads.
 
 * **Places**: `race/<city>/multicopwaypoints.csv` is a pool of places (at
   least 3; the last row is never picked). Each set, at the start and after

diff --git a/docs/multiplayer.md b/docs/multiplayer.md
diff --git a/docs/parity/mm2/game-flow.md b/docs/parity/mm2/game-flow.md
@@ -317,7 +317,7 @@ movers, `aiMap::Update`), `Reset` (a restart).
 | --- | --- | --- | --- |
 | `mmGameMulti::mmGameMulti`, `~mmGameMulti`, `` `scalar_deleting_destructor' `` | not needed | — | |
 | `mmGameMulti::Init` | ported (new) | `RaceScreen::loadAi`, `loadRaceSetup` | traffic, cop and opponent densities 0 and no rail cars; the race modes clear mmGame's AI flag (no AI map at all) |
-| `mmGameMulti::InitGameStrings` | ported (new) | `RaceScreen::updateNetPlayers` | "has left the game" (38); the "Waiting for N players" lines belong to the ready gate (replaced) |
+| `mmGameMulti::InitGameStrings` | ported (new) | `RaceScreen::updateNetPlayers`, `NetRaceStart::waitingText` | "has left the game" (38); "Waiting for 1 player" ... "Waiting for 7 players" (31-37) while others load |
 | `mmGameMulti::InitOtherPlayers` | replaced | `RaceScreen::updateRemoteCars` | |
 | `mmGameMulti::InitRoster` | ported (new) | `Popup::Roster` | |
 | `mmGameMulti::StartXYZ` | ported | `multiplayerGridOffset`, `RaceScreen::startSlot` | slot = the place in the host's player list (new; was the player id); slots 8-15 have no place (OpenMM2 allows 16) |
@@ -339,7 +339,7 @@ movers, `aiMap::Update`), `Reset` (a restart).
 | `mmGameMulti::BootPlayerCB` | ported (new) | `Popup::Roster` -> `NetGame::kick` | |
 | `mmGameMulti::RegisterMapNetObjects`, `ActivateMapNetObject`, `DeactivateMapNetObject` | ported (new) | `RaceScreen` blips (HUD audit), places 0 / 10 | the other players on the map and their cards, by start slot |
 | `mmGameMulti::GetInactiveNetObjectIndex`, `GetNetObject`, `GetNetObjectIndex`, `ClearNetObjects` | replaced | `m_remotes` | |
-| `mmGameMulti::PlayerFinishedLoading`, `PlayerClearLoaded`, `SendRaceReady`, `SendGameSet`, `SendTimeMsg` | replaced | the shared start time, ClockSync | no ready gate (deviation, session record) |
+| `mmGameMulti::PlayerFinishedLoading`, `PlayerClearLoaded`, `SendRaceReady`, `SendGameSet`, `SendTimeMsg` | ported (new) | `NetGame::reportLoaded` (`RaceLoaded`), `net::Session` (the loaded flags, cleared at each race and return), `NetRaceStart`, ClockSync | the ready gate (docs/multiplayer.md, "Race start"); the start is a shared session time and the host stops waiting after 60 s (deviations); no car CRC; `SendTimeMsg` replaced by ClockSync |
 | `mmGameMulti::SendPosition`, `SendMsg` | replaced | snapshots, `sendEvent` | |
 | `mmGameMulti::GetCarCRC`, `SendCheater` | open | — | the tuning CRC check (low) |
 | `mmGameMulti::BroadCastCarTuning`, `SendCarTuning` | not needed | — | `SendCarTuning` is empty |
@@ -361,8 +361,8 @@ movers, `aiMap::Update`), `Reset` (a restart).
 | `mmMultiRoam::InitHUD`, `mmMultiRace::InitHUD`, `mmMultiCircuit::InitHUD`, `mmMultiBlitz::InitHUD` | ported | `Hud` | the place readout now counts the network players (new); Blitz's place readout and no checkpoint cards (HUD audit) |
 | `mmMultiRoam::Reset` | ported | `cruiseStart` | at the start (from mmGameMulti::InitOtherPlayers) its RespawnXYZ is the first of the two seeded picks; no in-race restart in a network game (round 3: [cruise-spawn](../round3/cruise-spawn.md)) |
 | `mmMultiRace::Reset`, `mmMultiCircuit::Reset`, `mmMultiBlitz::Reset` | replaced | the lobby | no in-race restart |
-| `mmMultiRoam::UpdateGame`, `SwitchState` | ported | `Session::start` / `updateRace` | "Go!" and the car released at once (new: no shared start in cruise) |
-| `mmMultiRace::UpdateGame`, `SwitchState`, `mmMultiCircuit::UpdateGame`, `SwitchState`, `mmMultiBlitz::UpdateGame`, `SwitchState` | ported | `Session::updateRace`, `updateNetRace` | countdown, wreck penalty (no warning, finish or clock check during it, new), finish line, the wait for all finishers and the timeout (new); the ready gate and the end taper are replaced (session record) |
+| `mmMultiRoam::UpdateGame`, `SwitchState` | ported | `Session::start` / `updateRace`, `NetRaceStart` | "Go!" and the car released at once (new: no shared start in cruise); "<name>" / "has joined" as each other machine reports (`GameMessageCB` 0x1fa) |
+| `mmMultiRace::UpdateGame`, `SwitchState`, `mmMultiCircuit::UpdateGame`, `SwitchState`, `mmMultiBlitz::UpdateGame`, `SwitchState` | ported | `Session::updateRace`, `updateNetRace` | countdown, wreck penalty (no warning, finish or clock check during it, new), finish line, the wait for all finishers and the timeout (new); the ready gate (state 0: 5 s, RaceReady, "Waiting for N players", the start; `NetRaceStart`, on a shared start time); the end taper is replaced (session record) |
 | `mmMultiRace::SetTimeoutOn`, `SetTimeoutOff` | ported (new) | `Session::addNetResult`, `updateNetRace` | 60 s from the first finish ("Race over", DNF) |
 | `mmMultiBlitz::PlayTimerWarning` | ported | `Session::timerWarning` | |
 | `mmMultiRoam::GameMessage`, `mmMultiRace::GameMessage`, `mmMultiCircuit::GameMessage`, `mmMultiBlitz::GameMessage` | ported (new) | `updateNetRace`, `Session::remoteFinished` | the finish lines (host 152 / 110 / 99, client 150 / 107 / 96) with Messagenote; the time-up / restart / host-quit messages are replaced |

diff --git a/docs/parity/openmm2-only.md b/docs/parity/openmm2-only.md
@@ -130,6 +130,8 @@ counted in the summary above.
 | `phys::Instance::kinematicMotion`, `Body::kinematicMoves` | | openmm2 | A kinematic instance (network car) that reports its motion strikes as a car moving at it (MM2 has no kinematic instances); off by default, on for the network cars of a shared-traffic cruise and the received traffic and police. |
 | The host settings' SHARED TRAFFIC panel (`HostSettingsPage`) | `HostRaceMenu` (no traffic or cop settings) | deviation | On / off and the single-player cruise's traffic and cop density sliders (defaults 0.5 and 1, `RaceMenuBase::SetStateRace`), drawn by OpenMM2 in the upper right panel cruise leaves empty. |
 | A client's pedestrians and the received cars | `aiPedestrian::UpcomingAccident` / `Accident` (`aiObstacle::InAccident` in the road's section lists) | inferred | The host's section lists do not travel: a received car off its rail counts for its whole road or intersection (`MapView::mapComponent` of its place). |
+| A client's police cars' damage (`game::DamageReplica`, `VehicleEffects`, `AmbientEntity::damage`) | `vehCarDamage::Update`, `ApplyImpact`, `fxTexelDamage::ApplyDamage`, `vehBreakableMgr::Eject`, `vehCarModel::EjectOneshot` on the host's cars | openmm2 | Added 2026-10-09 (protocol 4): the host's police damage level (10 bits) drives the received car's smoke as `vehCarDamage::Update` does, and its dents, broken parts, sparks, shards and impact sounds are replayed from the host's records (docs/multiplayer.md, "Damage"); the wreck (out of action) as before, with its black smoke and the explosion sound. Before, a client saw the wreck flag and the explosion only. |
+| A client's knocked traffic cars' wheels (`AmbientEntity::wheels`, `game::trafficWheelMatrices`) | `aiVehicleInstance::Draw` with an `aiVehicleActive` (`vehWheelCheap`'s drawing matrices) | openmm2 | Added 2026-10-09 (protocol 4): a car with a body on the host sends its four wheels' drawing offsets; the client draws it on them and lays its shadow as a physical car's. Before, it was drawn on its rail wheels. |
 
 ## Files
 
@@ -160,6 +162,7 @@ counted in the summary above.
 | `src/core/StringUtil.h` | reclassified M | |
 | `src/net/AmbientState.cpp` | O | The shared cruise traffic's message (added 2026-10-09). |
 | `src/net/AmbientState.h` | O | |
+| `src/net/VehicleDamage.h` | O | A car's damage on the wire (added 2026-10-09); the rules it replays are MM2's (docs/multiplayer.md, "Damage"). |
 | `src/net/BitStream.cpp` | confirmed O | Wire encoding. |
 | `src/net/BitStream.h` | confirmed O | |
 | `src/net/ClockSync.cpp` | confirmed O | Host clock estimate. |

diff --git a/docs/parity/round3/cruise-spawn.md b/docs/parity/round3/cruise-spawn.md
@@ -142,7 +142,7 @@ also changes every later single-player start of the run.
 | `Traffic::populate`, `Pedestrians::populate`, `Random::state` | `AdjustAmbients` / `AdjustPedestrians` from room 0 | fixed | the populations themselves were audited by the ai areas (draw for draw); with no ambient cars or pedestrians MM2 skips them and OpenMM2's draw nothing |
 | `city::addShortcuts`: centre | `aiIntersection::CreateRoadMap` | fixed | a shortcut road's end intersections move to their room's bound-sphere centre (`sdlRoomBoundSphere`; up to 0.21 m in San Francisco) before their road lists are sorted; RespawnXYZ starts there (ai-vehicles' open row, commit ef670f6) |
 | C&R picker (`RaceScreen::setupCopsAndRobbers` `randomIntersection`) | `GetRandomPoints`' helper: `RespawnXYZ(false, false, false)` less 2 m | fixed | the room by `FindRoomId`, only 0x24 rejected, no road rules, MSVC draws |
-| C&R picker: stream and draws | the host's global stream, (counter + 1) draws | deviation | every OpenMM2 machine draws the first set itself from the shared start time, one draw a pick (the counter is each machine's own, so using it could split the machines) |
+| C&R picker: stream and draws | the host's global stream, (counter + 1) draws | deviation | every OpenMM2 machine draws the first set itself from the race's order time, one draw a pick (the counter is each machine's own, so using it could split the machines) |
 | Cruise restart | `mmSingleRoam::Reset` -> `mmGameSingle::Reset` -> `mmGame::Reset` | verified | no new pick: `asNode::Reset` puts the car back at its reset place (`Session::restart`, RaceScreen's Restart); network games have no restart |
 | `CarSim::setResetPos` | `vehCarSim::SetResetPos` | verified | the CG added unrotated (+0x210) |
 | reset angle | +0x250 written from RespawnXYZ's angle | verified | 0: the body faces -Z (`SimVehicle::setResetPos(pos, 0)`) |

diff --git a/docs/parity/round3/random-streams.md b/docs/parity/round3/random-streams.md
@@ -170,7 +170,7 @@ this reason).
 | `vehWheel::GetBumpDisplacement` (via `vehDrivetrain::Update`) | the wheels' own stream (`phys/vehicle/Wheel`) | deviation | Physics; per sample. |
 | `vehCarModel::EjectOneshot`, `vehBreakableMgr::Eject` (also via `aiVehicleActive::Impact`) | RaceScreen and BangerSet eject streams | deviation | On impacts. |
 | `mmPlayer::UpdateFF`, `FFImpactCallback` | `ForceFeedback` stream | deviation | Already recorded as inferred own. |
-| `mmMultiCR::GetRandomIndex` (global), the Cops and Robbers point picker (secondary, clock-seeded) | `CopsAndRobbers` (its own LCG of the same form, seeded from the race start time) | deviation | Network; MM2's picker is seeded from the clock, so nothing to reproduce. The LCG constants differ from MSVC's (session record). |
+| `mmMultiCR::GetRandomIndex` (global), the Cops and Robbers point picker (secondary, clock-seeded) | `CopsAndRobbers` (its own LCG of the same form, seeded from the race's order time) | deviation | Network; MM2's picker is seeded from the clock, so nothing to reproduce. The LCG constants differ from MSVC's (session record). |
 | `ptxGlass::AddShards`, `ptxGlass::Update` | — | not needed | No retail banger is glass (BillFlags 0x100). |
 | `pedActive::FirstImpactCallback` | — | not needed | No ragdolls exist in MM2 (pedRagdollMgr is never built). |
 

diff --git a/docs/parity/session.md b/docs/parity/session.md
@@ -208,7 +208,7 @@ Behaviour is documented in `docs/gamemodes.md`. Tests:
 | `setRaceConfig`, `setPassword`, `kick`, `returnToLobby` | `NetArena` host | openmm2 | |
 | `setMaxPlayers`, `maxPlayers` | DirectPlay session (8 players) | deviation | OpenMM2 allows 2-16 |
 | `setGoldMass`, `goldMass` | `HostRaceMenu::GetGoldMassVal` (cnr_goldMass) | openmm2 | the setting's transport; the default is the host menu's (frontend-ui) |
-| `startRace`, `raceStartTime`, `secondsToStart`, `raceStarted` | `mmGameMulti` start message | deviation | a shared start time instead of the host's start message; the session starts the 2.5 s countdown 2.5 s before it |
+| `startRace`, `reportLoaded`, `playerLoaded`, `raceStartTime`, `secondsToStart`, `raceStarted` | `mmGameMulti::SendRaceReady`, `mmMultiRace` / `mmMultiCircuit` / `mmMultiBlitz::UpdateGame` state 0, `GameMessage` 0x1f6 / 0x213 / 0x20f, `SystemMessage` 0x2d | fixed | the ready gate (docs/multiplayer.md, "Race start"); deviations: the start is a shared session time, which the countdown follows, instead of the host's start message, and the host stops waiting after 60 s |
 | `startPortMapping`, `stopPortMapping`, `portMappingStatus` | — | openmm2 | UPnP / NAT-PMP |
 | `submitLocalState`, `remoteCars` | `mmNetObject` | openmm2 | snapshots with interpolation |
 | `sendEvent`, `sendCheckpoint`, `sendLap`, `sendFinish`, `sendGold`, `sendCollision`, `sendDamage`, `addSystemLine` | `mmGameMulti::SendMsg`, `mmMultiCR::Send*` | openmm2 | own messages |
@@ -281,7 +281,7 @@ Behaviour is documented in `docs/gamemodes.md`. Tests:
 | `updateRemoteCars`, `drawRemoteCars` | `mmNetObject::Init`, `Update` | fixed | network cars as kinematic bodies at their snapshots (deviation: MM2 simulates them with the remote inputs), the polygonal bound, a vpcop on the Mustang's tune, trailers except in multiplayer cruise and Cops and Robbers, type-3 movers |
 | `multiplayerGridOffset`, spawn | `mmGameMulti::StartXYZ`, `mmGame::RespawnXYZ` (seed), `mmGame::FindGroundPos` | fixed | the eight-slot grids (slot = player id, inferred), the cruise start seeded by the player id, spawns dropped with the wheels' probe |
 | `CopsAndRobbers::updateNetwork`, `receive` | `mmMultiCR::UpdateGame`, `UpdateGold`, `UpdateBank`, `UpdateHideout`, `ImpactCallback`, `GameMessage` (0x259, 0x25a, 0x25e, 600, 0x261) | fixed | new: each machine runs its own car, the host grants pickups and draws sets |
-| `setupCopsAndRobbers`, `updateCopsAndRobbers`, `fondleMass`, `crTeam` | `mmMultiCR::Init`, `InitMyPlayer`, `FondleCarMass`, `mmPlayer::UpdateRegen`, `mmGame::UpdateSteeringBrakes` | fixed | new: the mode is played (places, teams, messages, mass, throttle cap in every network game, regeneration, repair at delivery, HUD lines, limits, end after 3 s); the shared first set is seeded by the start time (OpenMM2) |
+| `setupCopsAndRobbers`, `updateCopsAndRobbers`, `fondleMass`, `crTeam` | `mmMultiCR::Init`, `InitMyPlayer`, `FondleCarMass`, `mmPlayer::UpdateRegen`, `mmGame::UpdateSteeringBrakes` | fixed | new: the mode is played (places, teams, messages, mass, throttle cap in every network game, regeneration, repair at delivery, HUD lines, limits, end after 3 s); the shared first set is seeded by the race's order time (OpenMM2) |
 | `Hud::drawCrObjects`, `drawCrReadouts`, arrow interest | `mmPowerupInstance::Draw`, `mmBillInstance::Draw`, `mmArrow::SetInterest`, `mmCRHUD::Init` | fixed | new: the spinning gold, the bases' billboards, the team totals ("COPS" / "ROBBERS" or "BLUE" / "RED"); the roster of names and the gold icon are not drawn, and the totals' corner is inferred |
 | Cops and Robbers speech | `mmSpeechContainer::InitCNR` | verified | loaded; nothing in build 3393 calls `mmCNRSpeech::Play` |
 

diff --git a/docs/physics.md b/docs/physics.md
@@ -51,6 +51,18 @@ scheme. (Several terms below scale with the sample length, e.g. the
 drivetrain's AngInertia * dt, so the original drove slightly differently at
 other frame rates.)
 
+The fixed step stays, for accuracy (the original at 60 fps) and determinism
+(network play, tests, the opponent sweep). A frame then runs no sample or
+several, and what is shown between two samples is OpenMM2's presentation:
+`World::step` calls a step observer before anything moves, the race screen
+keeps each body's state from before the sample (`game::StepHistory`), and
+the drawing blends it towards the current state by `interpolationAlpha()`
+(the unstepped remainder / the step; rendering.md, "Drawing between
+simulation steps"). The observer only reads; `CarSim::resets` (how many
+times `vehCar::Reset` put the car somewhere) tells the drawing not to blend
+across a reset, and nothing in the simulation reads it. The AI's fixed 1/30 s
+steps (`ai::World`) are drawn the same way.
+
 ## Rigid body (phInertialCS) — MM2
 
 * Every physics entity's update first adds its weight, Mass * -19.6 on y