Per review: +48 (whois_name | whois_load, mode_alt clear) was an
unused combination of the existing mode bits - use that instead of
claiming a new bit 6. +56 (same, with mode_alt set) stays free for a
future mode. No new flags::* entry needed; mtable.h/.cpp unchanged.
Dispatcher scripts that route trains at a station based on where they
go afterwards (e.g. a big terminal throat with several outbound
directions) have no way to read that: whois +40 only exposes the
current/next timetable entry (NextStop()/IsStop()), which while the
train is at that very station is that station itself.
Adds flags::whois_ahead (bit 6, previously unused) plus
TTrainParameters::StationNameAhead(Offset)/StationIsStopAhead(Offset),
returning the raw TimeTable[] entry Offset positions past StationIndex
(name and whether it's a booked stop, "none"/false past the end of the
timetable). The new whois branch calls both with Offset=1, mirroring
the existing +40 branch's UpdateValues()/WriteLog() shape.
Logic-verified with an isolated harness mirroring the touched types
(TTrainParameters/TController/TMemCell shapes and the exact function
bodies); not yet build-tested against the full engine locally - relying
on CI for that.
In TSegment there were two different formulas for a derivative. Most places called GetFirstDerivative() that used the direct formula from the curve points. However RaPositionGet() had its own calculation based on pre-computed cubic polynomial coefficients. This latter method is faster and simpler, so change GetFirstDerivative() to use it and change RaPositionGet() to just call GetFirstDerivative().
TSegment::GetTFromS() is a significant hotspot in the non-rendering part of the state_manager update (about 13%). This change introduces a FastGetTFromS() version that interpolates from precomputed values instead of doing the whole calculation on every call. Computing position from track distance is now done in constant time. This reduces the contribution to about 0.3%.
- Lua bindings are no longer using FFI in favor of the "classic" Lua C API.
- This makes it work properly on native Linux builds.
- Changed the Lua API slightly:
- Removed the `api.event_preparefunc()` function because it is no longer necessary. Instead, you can pass any function you want without preparing it first.
- Added an `api.event_exists()` function. Takes a single `name` argument.
- Any `api.find_*()` functions return `nil` instead of an userdata representing a null pointer when the requested object is not found.
