Function ReverseTrainDirection

src/train_cmd.cpp:1985–2067

* Turn a train around. * @param v %Train to turn around. */

 * @param v %Train to turn around.
 */
void ReverseTrainDirection(Train *v)
{
	if (IsRailDepotTile(v->tile)) {
		if (IsWholeTrainInsideDepot(v)) return;
		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
	}

	/* Clear path reservation in front if train is not stuck. */
	if (!v->flags.Test(VehicleRailFlag::Stuck)) FreeTrainTrackReservation(v);

	/* Check if we were approaching a rail/road-crossing */
	TileIndex crossing = TrainApproachingCrossingTile(v);

	/* count number of vehicles */
	int r = CountVehiclesInChain(v) - 1;  // number of vehicles - 1

	AdvanceWagonsBeforeSwap(v);

	/* swap start<>end, start+1<>end-1, ... */
	int l = 0;
	do {
		ReverseTrainSwapVeh(v, l++, r--);
	} while (l <= r);

	AdvanceWagonsAfterSwap(v);

	if (IsRailDepotTile(v->tile)) {
		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
	}

	v->flags.Flip(VehicleRailFlag::Reversed);
	v->flags.Reset(VehicleRailFlag::Reversing);

	/* recalculate cached data */
	v->ConsistChanged(CCF_TRACK);

	/* update all images */
	for (Train *u = v; u != nullptr; u = u->Next()) u->UpdateViewport(false, false);

	/* update crossing we were approaching */
	if (crossing != INVALID_TILE) UpdateLevelCrossing(crossing);

	/* maybe we are approaching crossing now, after reversal */
	crossing = TrainApproachingCrossingTile(v);
	if (crossing != INVALID_TILE) MaybeBarCrossingWithSound(crossing);

	/* If we are inside a depot after reversing, don't bother with path reserving. */
	if (v->track == TRACK_BIT_DEPOT) {
		/* Can't be stuck here as inside a depot is always a safe tile. */
		if (v->flags.Test(VehicleRailFlag::Stuck)) SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
		v->flags.Reset(VehicleRailFlag::Stuck);
		return;
	}

	/* VehicleExitDir does not always produce the desired dir for depots and
	 * tunnels/bridges that is needed for UpdateSignalsOnSegment. */
	DiagDirection dir = VehicleExitDir(v->direction, v->track);
	if (IsRailDepotTile(v->tile) || IsTileType(v->tile, MP_TUNNELBRIDGE)) dir = INVALID_DIAGDIR;