Function TrainController

src/train_cmd.cpp:3289–3612

* Move a vehicle chain one movement stop forwards. * @param v First vehicle to move. * @param nomove Stop moving this and all following vehicles. * @param reverse Set to false to not execute the vehicle reversing. This does not change any other logic. * @return True if the vehicle could be moved forward, false otherwise. */

 * @return True if the vehicle could be moved forward, false otherwise.
 */
bool TrainController(Train *v, Vehicle *nomove, bool reverse)
{
	Train *first = v->First();
	Train *prev;
	bool direction_changed = false; // has direction of any part changed?

	/* For every vehicle after and including the given vehicle */
	for (prev = v->Previous(); v != nomove; prev = v, v = v->Next()) {
		DiagDirection enterdir = DIAGDIR_BEGIN;
		bool update_signals_crossing = false; // will we update signals or crossing state?

		GetNewVehiclePosResult gp = GetNewVehiclePos(v);
		if (v->track != TRACK_BIT_WORMHOLE) {
			/* Not inside tunnel */
			if (gp.old_tile == gp.new_tile) {
				/* Staying in the old tile */
				if (v->track == TRACK_BIT_DEPOT) {
					/* Inside depot */
					gp.x = v->x_pos;
					gp.y = v->y_pos;
				} else {
					/* Not inside depot */

					/* Reverse when we are at the end of the track already, do not move to the new position */
					if (v->IsFrontEngine() && !TrainCheckIfLineEnds(v, reverse)) return false;

					auto vets = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
					if (vets.Test(VehicleEnterTileState::CannotEnter)) {
						goto invalid_rail;
					}
					if (vets.Test(VehicleEnterTileState::EnteredStation)) {
						/* The new position is the end of the platform */
						TrainEnterStation(v, GetStationIndex(gp.new_tile));
					}
				}
			} else {
				/* A new tile is about to be entered. */

				/* Determine what direction we're entering the new tile from */
				enterdir = DiagdirBetweenTiles(gp.old_tile, gp.new_tile);
				assert(IsValidDiagDirection(enterdir));

				/* Get the status of the tracks in the new tile and mask
				 * away the bits that aren't reachable. */
				TrackStatus ts = GetTileTrackStatus(gp.new_tile, TRANSPORT_RAIL, 0, ReverseDiagDir(enterdir));
				TrackdirBits reachable_trackdirs = DiagdirReachesTrackdirs(enterdir);

				TrackdirBits trackdirbits = TrackStatusToTrackdirBits(ts) & reachable_trackdirs;
				TrackBits red_signals = TrackdirBitsToTrackBits(TrackStatusToRedSignals(ts) & reachable_trackdirs);

				TrackBits bits = TrackdirBitsToTrackBits(trackdirbits);
				if (Rail90DegTurnDisallowed(GetTileRailType(gp.old_tile), GetTileRailType(gp.new_tile)) && prev == nullptr) {
					/* We allow wagons to make 90 deg turns, because forbid_90_deg
					 * can be switched on halfway a turn */
					bits &= ~TrackCrossesTracks(FindFirstTrack(v->track));
				}

				if (bits == TRACK_BIT_NONE) goto invalid_rail;