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Code Issues 151 Wiki Activity

multiplayer: a player works a train, not a car - and put the corrections right

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Second live test. Four things, three of them the same mistake seen from
different angles: the session was reasoning about single vehicles where it
should have been reasoning about trains.

- a peer may now operate anything coupled into the set it is sitting in. This
  is what "cabchangebackward rejected: not a member of the crew of that
  vehicle" was: the crew was recorded against one car of a four-car unit, and
  the cab switch addressed another
- every vehicle gets a network id, not only the ones worth driving. Commands
  are addressed by that id, and a player has to be able to walk into any car
  of their train. "peer 3 cannot take en71-017rb_4: no such vehicle in this
  session" was the driving trailer of an EN71 - a full desk, no engine, and
  nobody assigned to it, so the old test missed it. Having a driving position
  is what counts now, engine or not
- the roster groups vehicles into the trains they are coupled into and the
  lobby lists one row per train. Coupling is worked out afresh every time, so
  a train that comes apart becomes two, and because a crew entry sits on the
  car its player occupies, each half keeps the people who were riding in it
- walking to another car of your own train is not a new claim and asks nothing
  of the crew capacity, which counts people per train

Positional correction never actually did anything: it identified a track by
name, and most track in a scenery has none, so the lookup returned nothing and
place_on_track() was never reached. The client sat 178 m out of place for
minutes, reporting four vehicles "put back on the rails" every time while
moving none of them. Tracks now travel as their index in the path table, which
comes from the scenery file and is therefore the same on every peer.

Also from the test:

- the camera jumped in and out of the cab on the client whenever the host
  reversed, because the correction was forcing the server's CabActive and
  CabOccupied onto it. Which cab somebody sits in is theirs alone - two people
  sharing a vehicle each have their own - so it is no longer replicated
- the correction no longer touches the control positions of the train the local
  player is working. Their crew's commands reach every peer on their own, and
  snapping a lever back a fraction of a second after it was moved is what made
  the reverser look dead
- the frame buffer was sized for the old lockstep, up to sixty frames deep.
  Every frame in it is input lag, so it is down to twelve with a target of one
- asking the AI of a vehicle to step aside is given five tries and then said
  once, instead of every thirty frames forever; and a resync request now has a
  real cooldown
This commit is contained in:
Hirek
2026-09-06 23:39:13 +00:00
parent a72c3292ad
commit 0b75e701fc
9 changed files with 357 additions and 52 deletions
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110
network/snapshot.cpp
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@@ -38,6 +38,45 @@ double const REPOSITION_TOLERANCE_CORRECTION{2.5};
// ---------------------------------------------------------------------------
// what the authority last sent, so that a routine correction only carries changes
// most tracks in a scenery carry no name at all, so a name is useless as an identity.
// their order in the path table comes straight from the scenery file and is therefore the
// same on every peer, which makes the index a usable one
std::vector<TTrack *> g_trackindex;
std::unordered_map<TTrack const *, uint32_t> g_trackids;
void refresh_track_index()
{
auto const &paths = simulation::Paths.sequence();
if (g_trackindex.size() == paths.size())
return;
g_trackindex.assign(paths.begin(), paths.end());
g_trackids.clear();
for (uint32_t i = 0; i < g_trackindex.size(); ++i)
{
if (g_trackindex[i] != nullptr)
g_trackids.emplace(g_trackindex[i], i);
}
}
uint32_t track_id_of(TTrack const *Track)
{
if (Track == nullptr)
return 0xffffffff;
refresh_track_index();
auto const lookup = g_trackids.find(Track);
return lookup != g_trackids.end() ? lookup->second : 0xffffffff;
}
TTrack *track_by_id(uint32_t const Id)
{
refresh_track_index();
return (Id < g_trackindex.size() ? g_trackindex[Id] : nullptr);
}
std::unordered_map<std::string, uint64_t> g_lastvehicles;
std::unordered_map<std::string, uint64_t> g_lastmemcells;
std::unordered_map<std::string, int> g_lastswitches;
@@ -137,7 +176,7 @@ void read_session(std::istream &Stream, network::snapshot_mode const Mode)
struct vehicle_state
{
std::string name;
std::string track;
uint32_t track{0xffffffff};
double translation{0.0};
uint8_t axlefirst{0};
uint8_t direction{0};
@@ -164,8 +203,6 @@ struct vehicle_state
bool battery{false};
bool converterallow{false};
bool compressorallow{false};
int32_t cabactive{0};
int32_t caboccupied{0};
std::array<bool, 2> pantenabled{{false, false}};
std::array<bool, 2> pantdisabled{{false, false}};
std::array<bool, 2> pantactive{{false, false}};
@@ -179,7 +216,7 @@ struct vehicle_state
void serialize_vehicle(std::ostream &Stream, vehicle_state const &State)
{
sn_utils::s_str(Stream, State.name);
sn_utils::s_str(Stream, State.track);
sn_utils::ls_uint32(Stream, State.track);
sn_utils::ls_float64(Stream, State.translation);
sn_utils::s_uint8(Stream, State.axlefirst);
sn_utils::s_uint8(Stream, State.direction);
@@ -204,8 +241,6 @@ void serialize_vehicle(std::ostream &Stream, vehicle_state const &State)
sn_utils::s_bool(Stream, State.battery);
sn_utils::s_bool(Stream, State.converterallow);
sn_utils::s_bool(Stream, State.compressorallow);
sn_utils::ls_int32(Stream, State.cabactive);
sn_utils::ls_int32(Stream, State.caboccupied);
for (int i = 0; i < 2; ++i)
{
sn_utils::s_bool(Stream, State.pantenabled[i]);
@@ -227,7 +262,7 @@ vehicle_state deserialize_vehicle(std::istream &Stream)
vehicle_state state;
state.name = sn_utils::d_str(Stream);
state.track = sn_utils::d_str(Stream);
state.track = sn_utils::ld_uint32(Stream);
state.translation = sn_utils::ld_float64(Stream);
state.axlefirst = sn_utils::d_uint8(Stream);
state.direction = sn_utils::d_uint8(Stream);
@@ -252,8 +287,6 @@ vehicle_state deserialize_vehicle(std::istream &Stream)
state.battery = sn_utils::d_bool(Stream);
state.converterallow = sn_utils::d_bool(Stream);
state.compressorallow = sn_utils::d_bool(Stream);
state.cabactive = sn_utils::ld_int32(Stream);
state.caboccupied = sn_utils::ld_int32(Stream);
for (int i = 0; i < 2; ++i)
{
state.pantenabled[i] = sn_utils::d_bool(Stream);
@@ -279,7 +312,7 @@ vehicle_state read_from(TDynamicObject const &Vehicle)
vehicle_state state;
state.name = Vehicle.name();
state.track = (track != nullptr ? track->name() : std::string());
state.track = track_id_of(track);
state.translation = Vehicle.RaTranslationGet();
state.axlefirst = (uint8_t)(Vehicle.iAxleFirst ? 1 : 0);
state.direction = (uint8_t)(Vehicle.iDirection ? 1 : 0);
@@ -304,8 +337,6 @@ vehicle_state read_from(TDynamicObject const &Vehicle)
state.battery = mover.Battery;
state.converterallow = mover.ConverterAllow;
state.compressorallow = mover.CompressorAllow;
state.cabactive = mover.CabActive;
state.caboccupied = mover.CabOccupied;
for (int i = 0; i < 2; ++i)
{
state.pantenabled[i] = mover.Pantographs[i].valve.is_enabled;
@@ -324,19 +355,41 @@ vehicle_state read_from(TDynamicObject const &Vehicle)
return state;
}
// true for the train the local player is working. its controls are driven by the commands
// its crew issue, which every peer already receives, so the correction must keep its hands
// off them - otherwise it keeps snapping a lever back a fraction of a second after the
// player moved it, and the control looks broken
bool is_own_train(std::string const &Name)
{
auto const seat = network::Crews.vehicle_of(Global.network_peer_id);
if (seat == network::ENTITY_NONE)
return false;
auto const train = network::Entities.consist_of(network::Entities.id_of(Name));
return (train != network::ENTITY_NONE) && (network::Entities.consist_of(seat) == train);
}
// applies everything except where the vehicle is; position is dealt with per consist,
// because moving one vehicle of a coupled set on its own tears the couplers apart
void apply_controls(TDynamicObject &Vehicle, vehicle_state const &State)
{
auto &mover = *Vehicle.MoverParameters;
// what the physics produced is always taken from the authority; what a person set is
// not, on the train that person is working
bool const ours = is_own_train(State.name);
mover.V = State.velocity;
mover.Vel = State.velocitykmh;
mover.DirActive = State.diractive;
mover.MainCtrlPos = State.mainctrl;
mover.ScndCtrlPos = State.scndctrl;
mover.BrakeCtrlPos = State.brakectrl;
mover.LocalBrakePosA = State.localbrake;
if (!ours)
{
mover.DirActive = State.diractive;
mover.MainCtrlPos = State.mainctrl;
mover.ScndCtrlPos = State.scndctrl;
mover.BrakeCtrlPos = State.brakectrl;
mover.LocalBrakePosA = State.localbrake;
}
mover.PipePress = State.pipepress;
mover.BrakePress = State.brakepress;
@@ -345,6 +398,14 @@ void apply_controls(TDynamicObject &Vehicle, vehicle_state const &State)
mover.Compressor = State.compressor;
mover.CompressedVolume = State.compressedvolume;
if (ours)
{
// the rest of it is what the crew set, and their commands reach us on their own
if (Vehicle.Mechanik != nullptr && Vehicle.Mechanik->AIControllFlag != State.aiactive)
Vehicle.Mechanik->TakeControl(State.aiactive);
return;
}
// the appliances go through the vehicle's own switches wherever it has them, so that
// whatever they drag along stays consistent. range local: every vehicle carries its
// own state in the update, there is no need to push it down the consist twice
@@ -357,8 +418,9 @@ void apply_controls(TDynamicObject &Vehicle, vehicle_state const &State)
if (mover.CompressorAllow != State.compressorallow)
mover.CompressorSwitch(State.compressorallow, range_t::local);
mover.CabActive = State.cabactive;
mover.CabOccupied = State.caboccupied;
// CabActive and CabOccupied are deliberately not replicated: which cab a player is
// sitting in is theirs alone, and two people sharing a vehicle each have their own.
// forcing the server's value on them is what made the camera jump in and out
for (int i = 0; i < 2; ++i)
{
@@ -388,9 +450,17 @@ void apply_controls(TDynamicObject &Vehicle, vehicle_state const &State)
// its leading bogie; this inverts the arithmetic that function itself does
void reposition(TDynamicObject &Vehicle, vehicle_state const &State)
{
TTrack *track = (State.track.empty() ? nullptr : simulation::Paths.find(State.track));
TTrack *track = track_by_id(State.track);
if (track == nullptr)
{
static bool reported{false};
if (!reported)
{
reported = true;
ErrorLog("net: cannot place " + Vehicle.name() + ", track " + std::to_string(State.track) + " is unknown here", logtype::net);
}
return;
}
double const half = Vehicle.fAxleDist * 0.5;
double const axleoffset = (State.axlefirst ? -half : half);