(svn r15518) -Fix [FS#2631]: use distance to closest station tile as estimate for YAPF too (NPF already does so). This makes it behave 'better' with wide stations.

src/pathfind.h

@@ -77,4 +77,36 @@ DECLARE_ENUM_AS_BIT_SET(PathfindFlags)
 void FollowTrack(TileIndex tile, PathfindFlags flags, TransportType tt, uint sub_type, DiagDirection direction, TPFEnumProc *enum_proc, TPFAfterProc *after_proc, void *data);
 void NewTrainPathfind(TileIndex tile, TileIndex dest, RailTypes railtypes, DiagDirection direction, NTPEnumProc *enum_proc, void *data);
 
+
+/**
+ * Calculates the tile of given station that is closest to a given tile
+ * for this we assume the station is a rectangle,
+ * as defined by its top tile (st->train_tile) and its width/height (st->trainst_w, st->trainst_h)
+ * @param station The station to calculate the distance to
+ * @param tile The tile from where to calculate the distance
+ * @return The closest station tile to the given tile.
+ */
+static inline TileIndex CalcClosestStationTile(StationID station, TileIndex tile)
+{
+	const Station *st = GetStation(station);
+
+	/* If the rail station is (temporarily) not present, use the station sign to drive near the station */
+	if (st->train_tile == INVALID_TILE) return st->xy;
+
+	uint minx = TileX(st->train_tile);  // topmost corner of station
+	uint miny = TileY(st->train_tile);
+	uint maxx = minx + st->trainst_w - 1; // lowermost corner of station
+	uint maxy = miny + st->trainst_h - 1;
+
+	/* we are going the aim for the x coordinate of the closest corner
+	 * but if we are between those coordinates, we will aim for our own x coordinate */
+	uint x = ClampU(TileX(tile), minx, maxx);
+
+	/* same for y coordinate, see above comment */
+	uint y = ClampU(TileY(tile), miny, maxy);
+
+	/* return the tile of our target coordinates */
+	return TileXY(x, y);
+}
+
 #endif /* PATHFIND_H */