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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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126
network/entities.cpp
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@@ -44,10 +44,11 @@ bool is_drivable(TDynamicObject const *Vehicle)
if (Vehicle == nullptr || Vehicle->MoverParameters == nullptr)
return false;
// anything with its own drive, plus anything the scenario already put a driver in
// (this covers driving trailers of multiple units, which carry no engine of their own)
// TODO: a cab count exposed by TMoverParameters would be a more precise test
return Vehicle->MoverParameters->EngineType != TEngineType::None || Vehicle->Mechanik != nullptr;
auto const &mover = *Vehicle->MoverParameters;
// a driving position is what counts, not an engine: the driving trailer of a multiple
// unit has a full desk and no traction of its own, and the scenario puts nobody in it
return mover.EngineType != TEngineType::None || Vehicle->Mechanik != nullptr || mover.MainCtrlPosNo > 0 || mover.BrakeCtrlPosNo > 0;
}
void entity_registry::clear()
@@ -61,10 +62,12 @@ void entity_registry::build()
{
clear();
// every vehicle gets an id, not only the ones worth driving. commands are addressed by
// it, and a player working a train may walk into any of its cars
std::vector<std::string> names;
for (TDynamicObject *vehicle : simulation::Vehicles.sequence())
{
if (!is_drivable(vehicle))
if (vehicle == nullptr)
continue;
names.emplace_back(vehicle->name());
}
@@ -88,10 +91,22 @@ void entity_registry::build()
m_byname.emplace(name, entry.id);
}
if (m_entries.size() > 0xffff)
{
// the command channel packs the recipient into sixteen bits
ErrorLog("net: scenario holds more vehicles than the command channel can address", logtype::net);
}
reindex();
refresh();
WriteLog("net: assigned network ids to " + std::to_string(m_entries.size()) + " drivable vehicles", logtype::net);
uint32_t drivable{0};
for (auto const &entry : m_entries)
if (entry.drivable)
++drivable;
WriteLog("net: assigned network ids to " + std::to_string(m_entries.size()) + " vehicles, " + std::to_string(drivable) + " of them with a driving position",
logtype::net);
}
void entity_registry::adopt(std::vector<vehicle_entry> const &Entries)
@@ -112,15 +127,110 @@ void entity_registry::reindex()
void entity_registry::refresh()
{
// only there so that a malformed consist cannot spin us forever
int const CONSIST_LIMIT{256};
for (auto &entry : m_entries)
{
TDynamicObject const *vehicle = resolve(entry.id);
entry.consist_id = entry.id;
entry.consist_size = 1;
entry.consist_lead = false;
entry.drivable = is_drivable(vehicle);
entry.ai_active = (vehicle != nullptr && vehicle->Mechanik != nullptr && vehicle->Mechanik->AIControllFlag);
entry.crew_count = Crews.count(entry.id);
entry.crew_capacity = CREW_CAPACITY;
entry.claimable = (vehicle != nullptr && entry.crew_count < entry.crew_capacity);
}
// group the vehicles into the trains they are currently coupled into. this is redone
// every time, so a train that comes apart turns into two trains here, and the crews
// follow whichever half each player happens to be sitting in
std::unordered_set<TDynamicObject const *> visited;
for (auto const &entry : m_entries)
{
TDynamicObject *vehicle = resolve(entry.id);
if (vehicle == nullptr || visited.count(vehicle) > 0)
continue;
TDynamicObject *front = vehicle;
for (int step = 0; step < CONSIST_LIMIT; ++step)
{
TDynamicObject *previous = front->Prev();
if (previous == nullptr || previous == vehicle || visited.count(previous) > 0)
break;
front = previous;
}
std::vector<NetworkEntityId> members;
TDynamicObject *member = front;
for (int step = 0; step < CONSIST_LIMIT && member != nullptr; ++step, member = member->Next())
{
if (visited.count(member) > 0)
break;
visited.emplace(member);
auto const id = id_of(member->name());
if (id != ENTITY_NONE)
members.emplace_back(id);
}
if (members.empty())
continue;
// the lowest id in the set names the train, and the lowest one that can actually
// be driven stands for it in the lobby
NetworkEntityId consist{members.front()};
NetworkEntityId lead{ENTITY_NONE};
uint8_t crew{0};
for (auto const id : members)
{
consist = std::min(consist, id);
crew = (uint8_t)std::min<int>(255, crew + Crews.count(id));
auto const *candidate = find(id);
if (candidate != nullptr && candidate->drivable && (lead == ENTITY_NONE || id < lead))
lead = id;
}
if (lead == ENTITY_NONE)
lead = consist;
for (auto const id : members)
{
auto const lookup = m_byid.find(id);
if (lookup == m_byid.end())
continue;
auto &target = m_entries[lookup->second];
target.consist_id = consist;
target.consist_size = (uint8_t)std::min<size_t>(255, members.size());
target.consist_lead = (id == lead);
target.crew_count = crew;
target.claimable = (crew < target.crew_capacity);
}
}
}
NetworkEntityId entity_registry::consist_of(NetworkEntityId Id) const
{
auto const *entry = find(Id);
return entry != nullptr ? entry->consist_id : ENTITY_NONE;
}
std::vector<NetworkEntityId> entity_registry::consist_members(NetworkEntityId Consist) const
{
std::vector<NetworkEntityId> members;
if (Consist == ENTITY_NONE)
return members;
for (auto const &entry : m_entries)
{
if (entry.consist_id == Consist)
members.emplace_back(entry.id);
}
return members;
}
NetworkEntityId entity_registry::id_of(std::string const &Name) const