Function ChooseShipTrack

src/ship_cmd.cpp:465–496

* Runs the pathfinder to choose a track to continue along. * * @param v Ship to navigate * @param tile Tile, the ship is about to enter * @param tracks Available track choices on \a tile * @return Track to choose, or INVALID_TRACK when to reverse. */

 * @return Track to choose, or INVALID_TRACK when to reverse.
 */
static Track ChooseShipTrack(Ship *v, TileIndex tile, TrackBits tracks)
{
	bool path_found = true;
	Track track;

	if (v->dest_tile == 0) {
		/* No destination, don't invoke pathfinder. */
		track = TrackBitsToTrack(v->state);
		if (!IsDiagonalTrack(track)) track = TrackToOppositeTrack(track);
		if (!HasBit(tracks, track)) track = FindFirstTrack(tracks);
		path_found = false;
	} else {
		/* Attempt to follow cached path. */
		if (!v->path.empty()) {
			track = TrackdirToTrack(v->path.back().trackdir);

			if (HasBit(tracks, track)) {
				v->path.pop_back();
				/* HandlePathfindResult() is not called here because this is not a new pathfinder result. */
				return track;
			}

			/* Cached path is invalid so continue with pathfinder. */
			v->path.clear();
		}

		track = YapfShipChooseTrack(v, tile, path_found, v->path);
	}

	v->HandlePathfindingResult(path_found);
	return track;
}

/**
 * Get the available water tracks on a tile for a ship entering a tile.