src/pathfinder/yapf/yapf_costrail.hpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file yapf_costrail.hpp Cost determination for rails. */
   9
  10 #ifndef YAPF_COSTRAIL_HPP
  11 #define YAPF_COSTRAIL_HPP
  12
  13
  14 #include "../../pbs.h"
  15
  16 template <class Types>
  17 class CYapfCostRailT : public CYapfCostBase {
  18 public:
  19         typedef typename Types::Tpf Tpf;              ///< the pathfinder class (derived from THIS class)
  20         typedef typename Types::TrackFollower TrackFollower;
  21         typedef typename Types::NodeList::Titem Node; ///< this will be our node type
  22         typedef typename Node::Key Key;               ///< key to hash tables
  23         typedef typename Node::CachedData CachedData;
  24
  25 protected:
  26
  27         /* Structure used inside PfCalcCost() to keep basic tile information. */
  28         struct TILE {
  29                 TileIndex   tile;
  30                 Trackdir    td;
  31                 TileType    tile_type;
  32                 RailType    rail_type;
  33
  34                 TILE()
  35                 {
  36                         tile = INVALID_TILE;
  37                         td = INVALID_TRACKDIR;
  38                         tile_type = MP_VOID;
  39                         rail_type = INVALID_RAILTYPE;
  40                 }
  41
  42                 TILE(TileIndex tile, Trackdir td)
  43                 {
  44                         this->tile = tile;
  45                         this->td = td;
  46                         this->tile_type = GetTileType(tile);
  47                         this->rail_type = GetTileRailType(tile);
  48                 }
  49         };
  50
  51 protected:
  52         /**
  53          * @note maximum cost doesn't work with caching enabled
  54          * @todo fix maximum cost failing with caching (e.g. FS#2900)
  55          */
  56         int m_max_cost;
  57         bool m_disable_cache;
  58         std::vector<int> m_sig_look_ahead_costs;
  59
  60 public:
  61         bool          m_stopped_on_first_two_way_signal;
  62 protected:
  63
  64         static const int s_max_segment_cost = 10000;
  65
  66         CYapfCostRailT() : m_max_cost(0), m_disable_cache(false), m_stopped_on_first_two_way_signal(false)
  67         {
  68                 /* pre-compute look-ahead penalties into array */
  69                 int p0 = Yapf().PfGetSettings().rail_look_ahead_signal_p0;
  70                 int p1 = Yapf().PfGetSettings().rail_look_ahead_signal_p1;
  71                 int p2 = Yapf().PfGetSettings().rail_look_ahead_signal_p2;
  72                 m_sig_look_ahead_costs.clear();
  73                 m_sig_look_ahead_costs.reserve(Yapf().PfGetSettings().rail_look_ahead_max_signals);
  74                 for (uint i = 0; i < Yapf().PfGetSettings().rail_look_ahead_max_signals; i++) {
  75                         m_sig_look_ahead_costs.push_back(p0 + i * (p1 + i * p2));
  76                 }
  77         }
  78
  79         /** to access inherited path finder */
  80         Tpf &Yapf()
  81         {
  82                 return *static_cast<Tpf *>(this);
  83         }
  84
  85 public:
  86         inline int SlopeCost(TileIndex tile, Trackdir td)
  87         {
  88                 if (!stSlopeCost(tile, td)) return 0;
  89                 return Yapf().PfGetSettings().rail_slope_penalty;
  90         }
  91
  92         inline int CurveCost(Trackdir td1, Trackdir td2)
  93         {
  94                 assert(IsValidTrackdir(td1));
  95                 assert(IsValidTrackdir(td2));
  96                 int cost = 0;
  97                 if (TrackFollower::Allow90degTurns()
  98                                 && HasTrackdir(TrackdirCrossesTrackdirs(td1), td2)) {
  99                         /* 90-deg curve penalty */
 100                         cost += Yapf().PfGetSettings().rail_curve90_penalty;
 101                 } else if (td2 != NextTrackdir(td1)) {
 102                         /* 45-deg curve penalty */
 103                         cost += Yapf().PfGetSettings().rail_curve45_penalty;
 104                 }
 105                 return cost;
 106         }
 107
 108         inline int SwitchCost(TileIndex tile1, TileIndex tile2, DiagDirection exitdir)
 109         {
 110                 if (IsPlainRailTile(tile1) && IsPlainRailTile(tile2)) {
 111                         bool t1 = KillFirstBit(GetTrackBits(tile1) & DiagdirReachesTracks(ReverseDiagDir(exitdir))) != TRACK_BIT_NONE;
 112                         bool t2 = KillFirstBit(GetTrackBits(tile2) & DiagdirReachesTracks(exitdir)) != TRACK_BIT_NONE;
 113                         if (t1 && t2) return Yapf().PfGetSettings().rail_doubleslip_penalty;
 114                 }
 115                 return 0;
 116         }
 117
 118         /** Return one tile cost (base cost + level crossing penalty). */
 119         inline int OneTileCost(TileIndex &tile, Trackdir trackdir)
 120         {
 121                 int cost = 0;
 122                 /* set base cost */
 123                 if (IsDiagonalTrackdir(trackdir)) {
 124                         cost += YAPF_TILE_LENGTH;
 125                         switch (GetTileType(tile)) {
 126                                 case MP_ROAD:
 127                                         /* Increase the cost for level crossings */
 128                                         if (IsLevelCrossing(tile)) {
 129                                                 cost += Yapf().PfGetSettings().rail_crossing_penalty;
 130                                         }
 131                                         break;
 132
 133                                 default:
 134                                         break;
 135                         }
 136                 } else {
 137                         /* non-diagonal trackdir */
 138                         cost = YAPF_TILE_CORNER_LENGTH;
 139                 }
 140                 return cost;
 141         }
 142
 143         /** Check for a reserved station platform. */
 144         inline bool IsAnyStationTileReserved(TileIndex tile, Trackdir trackdir, int skipped)
 145         {
 146                 TileIndexDiff diff = TileOffsByDiagDir(TrackdirToExitdir(ReverseTrackdir(trackdir)));
 147                 for (; skipped >= 0; skipped--, tile += diff) {
 148                         if (HasStationReservation(tile)) return true;
 149                 }
 150                 return false;
 151         }
 152
 153         /** The cost for reserved tiles, including skipped ones. */
 154         inline int ReservationCost(Node &n, TileIndex tile, Trackdir trackdir, int skipped)
 155         {
 156                 if (n.m_num_signals_passed >= m_sig_look_ahead_costs.size() / 2) return 0;
 157                 if (!IsPbsSignal(n.m_last_signal_type)) return 0;
 158
 159                 if (IsRailStationTile(tile) && IsAnyStationTileReserved(tile, trackdir, skipped)) {
 160                         return Yapf().PfGetSettings().rail_pbs_station_penalty * (skipped + 1);
 161                 } else if (TrackOverlapsTracks(GetReservedTrackbits(tile), TrackdirToTrack(trackdir))) {
 162                         int cost = Yapf().PfGetSettings().rail_pbs_cross_penalty;
 163                         if (!IsDiagonalTrackdir(trackdir)) cost = (cost * YAPF_TILE_CORNER_LENGTH) / YAPF_TILE_LENGTH;
 164                         return cost * (skipped + 1);
 165                 }
 166                 return 0;
 167         }
 168
 169         int SignalCost(Node &n, TileIndex tile, Trackdir trackdir)
 170         {
 171                 int cost = 0;
 172                 /* if there is one-way signal in the opposite direction, then it is not our way */
 173                 if (IsTileType(tile, MP_RAILWAY)) {
 174                         bool has_signal_against = HasSignalOnTrackdir(tile, ReverseTrackdir(trackdir));
 175                         bool has_signal_along = HasSignalOnTrackdir(tile, trackdir);
 176                         if (has_signal_against && !has_signal_along && IsOnewaySignal(tile, TrackdirToTrack(trackdir))) {
 177                                 /* one-way signal in opposite direction */
 178                                 n.m_segment->m_end_segment_reason |= ESRB_DEAD_END;
 179                         } else {
 180                                 if (has_signal_along) {
 181                                         SignalState sig_state = GetSignalStateByTrackdir(tile, trackdir);
 182                                         SignalType sig_type = GetSignalType(tile, TrackdirToTrack(trackdir));
 183
 184                                         n.m_last_signal_type = sig_type;
 185
 186                                         /* cache the look-ahead polynomial constant only if we didn't pass more signals than the look-ahead limit is */
 187                                         int look_ahead_cost = (n.m_num_signals_passed < m_sig_look_ahead_costs.size()) ? m_sig_look_ahead_costs[n.m_num_signals_passed] : 0;
 188                                         if (sig_state != SIGNAL_STATE_RED) {
 189                                                 /* green signal */
 190                                                 n.flags_u.flags_s.m_last_signal_was_red = false;
 191                                                 /* negative look-ahead red-signal penalties would cause problems later, so use them as positive penalties for green signal */
 192                                                 if (look_ahead_cost < 0) {
 193                                                         /* add its negation to the cost */
 194                                                         cost -= look_ahead_cost;
 195                                                 }
 196                                         } else {
 197                                                 /* we have a red signal in our direction
 198                                                  * was it first signal which is two-way? */
 199                                                 if (!IsPbsSignal(sig_type) && Yapf().TreatFirstRedTwoWaySignalAsEOL() && n.flags_u.flags_s.m_choice_seen && has_signal_against && n.m_num_signals_passed == 0) {
 200                                                         /* yes, the first signal is two-way red signal => DEAD END. Prune this branch... */
 201                                                         Yapf().PruneIntermediateNodeBranch(&n);
 202                                                         n.m_segment->m_end_segment_reason |= ESRB_DEAD_END;
 203                                                         Yapf().m_stopped_on_first_two_way_signal = true;
 204                                                         return -1;
 205                                                 }
 206                                                 n.m_last_red_signal_type = sig_type;
 207                                                 n.flags_u.flags_s.m_last_signal_was_red = true;
 208
 209                                                 /* look-ahead signal penalty */
 210                                                 if (!IsPbsSignal(sig_type) && look_ahead_cost > 0) {
 211                                                         /* add the look ahead penalty only if it is positive */
 212                                                         cost += look_ahead_cost;
 213                                                 }
 214
 215                                                 /* special signal penalties */
 216                                                 if (n.m_num_signals_passed == 0) {
 217                                                         switch (sig_type) {
 218                                                                 case SIGTYPE_COMBO:
 219                                                                 case SIGTYPE_EXIT:   cost += Yapf().PfGetSettings().rail_firstred_exit_penalty; break; // first signal is red pre-signal-exit
 220                                                                 case SIGTYPE_BLOCK:
 221                                                                 case SIGTYPE_ENTRY:  cost += Yapf().PfGetSettings().rail_firstred_penalty; break;
 222                                                                 default: break;
 223                                                         }
 224                                                 }
 225                                         }
 226
 227                                         n.m_num_signals_passed++;
 228                                         n.m_segment->m_last_signal_tile = tile;
 229                                         n.m_segment->m_last_signal_td = trackdir;
 230                                 }
 231
 232                                 if (has_signal_against && IsPbsSignal(GetSignalType(tile, TrackdirToTrack(trackdir)))) {
 233                                         cost += n.m_num_signals_passed < Yapf().PfGetSettings().rail_look_ahead_max_signals ? Yapf().PfGetSettings().rail_pbs_signal_back_penalty : 0;
 234                                 }
 235                         }
 236                 }
 237                 return cost;
 238         }
 239
 240         inline int PlatformLengthPenalty(int platform_length)
 241         {
 242                 int cost = 0;
 243                 const Train *v = Yapf().GetVehicle();
 244                 assert(v != nullptr);
 245                 assert(v->type == VEH_TRAIN);
 246                 assert(v->gcache.cached_total_length != 0);
 247                 int missing_platform_length = CeilDiv(v->gcache.cached_total_length, TILE_SIZE) - platform_length;
 248                 if (missing_platform_length < 0) {
 249                         /* apply penalty for longer platform than needed */
 250                         cost += Yapf().PfGetSettings().rail_longer_platform_penalty + Yapf().PfGetSettings().rail_longer_platform_per_tile_penalty * -missing_platform_length;
 251                 } else if (missing_platform_length > 0) {
 252                         /* apply penalty for shorter platform than needed */
 253                         cost += Yapf().PfGetSettings().rail_shorter_platform_penalty + Yapf().PfGetSettings().rail_shorter_platform_per_tile_penalty * missing_platform_length;
 254                 }
 255                 return cost;
 256         }
 257
 258 public:
 259         inline void SetMaxCost(int max_cost)
 260         {
 261                 m_max_cost = max_cost;
 262         }
 263
 264         /**
 265          * Called by YAPF to calculate the cost from the origin to the given node.
 266          *  Calculates only the cost of given node, adds it to the parent node cost
 267          *  and stores the result into Node::m_cost member
 268          */
 269         inline bool PfCalcCost(Node &n, const TrackFollower *tf)
 270         {
 271                 assert(!n.flags_u.flags_s.m_targed_seen);
 272                 assert(tf->m_new_tile == n.m_key.m_tile);
 273                 assert((HasTrackdir(tf->m_new_td_bits, n.m_key.m_td)));
 274
 275                 /* Does the node have some parent node? */
 276                 bool has_parent = (n.m_parent != nullptr);
 277
 278                 /* Do we already have a cached segment? */
 279                 CachedData &segment = *n.m_segment;
 280                 bool is_cached_segment = (segment.m_cost >= 0);
 281
 282                 int parent_cost = has_parent ? n.m_parent->m_cost : 0;
 283
 284                 /* Each node cost contains 2 or 3 main components:
 285                  *  1. Transition cost - cost of the move from previous node (tile):
 286                  *    - curve cost (or zero for straight move)
 287                  *  2. Tile cost:
 288                  *    - base tile cost
 289                  *      - YAPF_TILE_LENGTH for diagonal tiles
 290                  *      - YAPF_TILE_CORNER_LENGTH for non-diagonal tiles
 291                  *    - tile penalties
 292                  *      - tile slope penalty (upward slopes)
 293                  *      - red signal penalty
 294                  *      - level crossing penalty
 295                  *      - speed-limit penalty (bridges)
 296                  *      - station platform penalty
 297                  *      - penalty for reversing in the depot
 298                  *      - etc.
 299                  *  3. Extra cost (applies to the last node only)
 300                  *    - last red signal penalty
 301                  *    - penalty for too long or too short platform on the destination station
 302                  */
 303                 int transition_cost = 0;
 304                 int extra_cost = 0;
 305
 306                 /* Segment: one or more tiles connected by contiguous tracks of the same type.
 307                  * Each segment cost includes 'Tile cost' for all its tiles (including the first
 308                  * and last), and the 'Transition cost' between its tiles. The first transition
 309                  * cost of segment entry (move from the 'parent' node) is not included!
 310                  */
 311                 int segment_entry_cost = 0;
 312                 int segment_cost = 0;
 313
 314                 const Train *v = Yapf().GetVehicle();
 315
 316                 /* start at n.m_key.m_tile / n.m_key.m_td and walk to the end of segment */
 317                 TILE cur(n.m_key.m_tile, n.m_key.m_td);
 318
 319                 /* the previous tile will be needed for transition cost calculations */
 320                 TILE prev = !has_parent ? TILE() : TILE(n.m_parent->GetLastTile(), n.m_parent->GetLastTrackdir());
 321
 322                 EndSegmentReasonBits end_segment_reason = ESRB_NONE;
 323
 324                 TrackFollower tf_local(v, Yapf().GetCompatibleRailTypes());
 325
 326                 if (!has_parent) {
 327                         /* We will jump to the middle of the cost calculator assuming that segment cache is not used. */
 328                         assert(!is_cached_segment);
 329                         /* Skip the first transition cost calculation. */
 330                         goto no_entry_cost;
 331                 }
 332
 333                 for (;;) {
 334                         /* Transition cost (cost of the move from previous tile) */
 335                         transition_cost = Yapf().CurveCost(prev.td, cur.td);
 336                         transition_cost += Yapf().SwitchCost(prev.tile, cur.tile, TrackdirToExitdir(prev.td));
 337
 338                         /* First transition cost counts against segment entry cost, other transitions
 339                          * inside segment will come to segment cost (and will be cached) */
 340                         if (segment_cost == 0) {
 341                                 /* We just entered the loop. First transition cost goes to segment entry cost)*/
 342                                 segment_entry_cost = transition_cost;
 343                                 transition_cost = 0;
 344
 345                                 /* It is the right time now to look if we can reuse the cached segment cost. */
 346                                 if (is_cached_segment) {
 347                                         /* Yes, we already know the segment cost. */
 348                                         segment_cost = segment.m_cost;
 349                                         /* We know also the reason why the segment ends. */
 350                                         end_segment_reason = segment.m_end_segment_reason;
 351                                         /* We will need also some information about the last signal (if it was red). */
 352                                         if (segment.m_last_signal_tile != INVALID_TILE) {
 353                                                 assert(HasSignalOnTrackdir(segment.m_last_signal_tile, segment.m_last_signal_td));
 354                                                 SignalState sig_state = GetSignalStateByTrackdir(segment.m_last_signal_tile, segment.m_last_signal_td);
 355                                                 bool is_red = (sig_state == SIGNAL_STATE_RED);
 356                                                 n.flags_u.flags_s.m_last_signal_was_red = is_red;
 357                                                 if (is_red) {
 358                                                         n.m_last_red_signal_type = GetSignalType(segment.m_last_signal_tile, TrackdirToTrack(segment.m_last_signal_td));
 359                                                 }
 360                                         }
 361                                         /* No further calculation needed. */
 362                                         cur = TILE(n.GetLastTile(), n.GetLastTrackdir());
 363                                         break;
 364                                 }
 365                         } else {
 366                                 /* Other than first transition cost count as the regular segment cost. */
 367                                 segment_cost += transition_cost;
 368                         }
 369
 370 no_entry_cost: // jump here at the beginning if the node has no parent (it is the first node)
 371
 372                         /* All other tile costs will be calculated here. */
 373                         segment_cost += Yapf().OneTileCost(cur.tile, cur.td);
 374
 375                         /* If we skipped some tunnel/bridge/station tiles, add their base cost */
 376                         segment_cost += YAPF_TILE_LENGTH * tf->m_tiles_skipped;
 377
 378                         /* Slope cost. */
 379                         segment_cost += Yapf().SlopeCost(cur.tile, cur.td);
 380
 381                         /* Signal cost (routine can modify segment data). */
 382                         segment_cost += Yapf().SignalCost(n, cur.tile, cur.td);
 383
 384                         /* Reserved tiles. */
 385                         segment_cost += Yapf().ReservationCost(n, cur.tile, cur.td, tf->m_tiles_skipped);
 386
 387                         end_segment_reason = segment.m_end_segment_reason;
 388
 389                         /* Tests for 'potential target' reasons to close the segment. */
 390                         if (cur.tile == prev.tile) {
 391                                 /* Penalty for reversing in a depot. */
 392                                 assert(IsRailDepot(cur.tile));
 393                                 segment_cost += Yapf().PfGetSettings().rail_depot_reverse_penalty;
 394
 395                         } else if (IsRailDepotTile(cur.tile)) {
 396                                 /* We will end in this pass (depot is possible target) */
 397                                 end_segment_reason |= ESRB_DEPOT;
 398
 399                         } else if (cur.tile_type == MP_STATION && IsRailWaypoint(cur.tile)) {
 400                                 if (v->current_order.IsType(OT_GOTO_WAYPOINT) &&
 401                                                 GetStationIndex(cur.tile) == v->current_order.GetDestination() &&
 402                                                 !Waypoint::Get(v->current_order.GetDestination())->IsSingleTile()) {
 403                                         /* This waypoint is our destination; maybe this isn't an unreserved
 404                                          * one, so check that and if so see that as the last signal being
 405                                          * red. This way waypoints near stations should work better. */
 406                                         CFollowTrackRail ft(v);
 407                                         TileIndex t = cur.tile;
 408                                         Trackdir td = cur.td;
 409                                         /* Arbitrary maximum tiles to follow to avoid infinite loops. */
 410                                         uint max_tiles = 20;
 411                                         while (ft.Follow(t, td)) {
 412                                                 assert(t != ft.m_new_tile);
 413                                                 t = ft.m_new_tile;
 414                                                 if (t == cur.tile || --max_tiles == 0) {
 415                                                         /* We looped back on ourself or found another loop, bail out. */
 416                                                         td = INVALID_TRACKDIR;
 417                                                         break;
 418                                                 }
 419                                                 if (KillFirstBit(ft.m_new_td_bits) != TRACKDIR_BIT_NONE) {
 420                                                         /* We encountered a junction; it's going to be too complex to
 421                                                          * handle this perfectly, so just bail out. There is no simple
 422                                                          * free path, so try the other possibilities. */
 423                                                         td = INVALID_TRACKDIR;
 424                                                         break;
 425                                                 }
 426                                                 td = RemoveFirstTrackdir(&ft.m_new_td_bits);
 427                                                 /* If this is a safe waiting position we're done searching for it */
 428                                                 if (IsSafeWaitingPosition(v, t, td, true, _settings_game.pf.forbid_90_deg)) break;
 429                                         }
 430
 431                                         /* In the case this platform is (possibly) occupied we add penalty so the
 432                                          * other platforms of this waypoint are evaluated as well, i.e. we assume
 433                                          * that there is a red signal in the waypoint when it's occupied. */
 434                                         if (td == INVALID_TRACKDIR ||
 435                                                         !IsSafeWaitingPosition(v, t, td, true, _settings_game.pf.forbid_90_deg) ||
 436                                                         !IsWaitingPositionFree(v, t, td, _settings_game.pf.forbid_90_deg)) {
 437                                                 extra_cost += Yapf().PfGetSettings().rail_lastred_penalty;
 438                                         }
 439                                 }
 440                                 /* Waypoint is also a good reason to finish. */
 441                                 end_segment_reason |= ESRB_WAYPOINT;
 442
 443                         } else if (tf->m_is_station) {
 444                                 /* Station penalties. */
 445                                 uint platform_length = tf->m_tiles_skipped + 1;
 446                                 /* We don't know yet if the station is our target or not. Act like
 447                                  * if it is pass-through station (not our destination). */
 448                                 segment_cost += Yapf().PfGetSettings().rail_station_penalty * platform_length;
 449                                 /* We will end in this pass (station is possible target) */
 450                                 end_segment_reason |= ESRB_STATION;
 451
 452                         } else if (TrackFollower::DoTrackMasking() && cur.tile_type == MP_RAILWAY) {
 453                                 /* Searching for a safe tile? */
 454                                 if (HasSignalOnTrackdir(cur.tile, cur.td) && !IsPbsSignal(GetSignalType(cur.tile, TrackdirToTrack(cur.td)))) {
 455                                         end_segment_reason |= ESRB_SAFE_TILE;
 456                                 }
 457                         }
 458
 459                         /* Apply min/max speed penalties only when inside the look-ahead radius. Otherwise
 460                          * it would cause desync in MP. */
 461                         if (n.m_num_signals_passed < m_sig_look_ahead_costs.size())
 462                         {
 463                                 int min_speed = 0;
 464                                 int max_speed = tf->GetSpeedLimit(&min_speed);
 465                                 int max_veh_speed = std::min<int>(v->GetDisplayMaxSpeed(), v->current_order.GetMaxSpeed());
 466                                 if (max_speed < max_veh_speed) {
 467                                         extra_cost += YAPF_TILE_LENGTH * (max_veh_speed - max_speed) * (4 + tf->m_tiles_skipped) / max_veh_speed;
 468                                 }
 469                                 if (min_speed > max_veh_speed) {
 470                                         extra_cost += YAPF_TILE_LENGTH * (min_speed - max_veh_speed);
 471                                 }
 472                         }
 473
 474                         /* Finish if we already exceeded the maximum path cost (i.e. when
 475                          * searching for the nearest depot). */
 476                         if (m_max_cost > 0 && (parent_cost + segment_entry_cost + segment_cost) > m_max_cost) {
 477                                 end_segment_reason |= ESRB_PATH_TOO_LONG;
 478                         }
 479
 480                         /* Move to the next tile/trackdir. */
 481                         tf = &tf_local;
 482                         tf_local.Init(v, Yapf().GetCompatibleRailTypes());
 483
 484                         if (!tf_local.Follow(cur.tile, cur.td)) {
 485                                 assert(tf_local.m_err != TrackFollower::EC_NONE);
 486                                 /* Can't move to the next tile (EOL?). */
 487                                 if (tf_local.m_err == TrackFollower::EC_RAIL_ROAD_TYPE) {
 488                                         end_segment_reason |= ESRB_RAIL_TYPE;
 489                                 } else {
 490                                         end_segment_reason |= ESRB_DEAD_END;
 491                                 }
 492
 493                                 if (TrackFollower::DoTrackMasking() && !HasOnewaySignalBlockingTrackdir(cur.tile, cur.td)) {
 494                                         end_segment_reason |= ESRB_SAFE_TILE;
 495                                 }
 496                                 break;
 497                         }
 498
 499                         /* Check if the next tile is not a choice. */
 500                         if (KillFirstBit(tf_local.m_new_td_bits) != TRACKDIR_BIT_NONE) {
 501                                 /* More than one segment will follow. Close this one. */
 502                                 end_segment_reason |= ESRB_CHOICE_FOLLOWS;
 503                                 break;
 504                         }
 505
 506                         /* Gather the next tile/trackdir/tile_type/rail_type. */
 507                         TILE next(tf_local.m_new_tile, (Trackdir)FindFirstBit(tf_local.m_new_td_bits));
 508
 509                         if (TrackFollower::DoTrackMasking() && IsTileType(next.tile, MP_RAILWAY)) {
 510                                 if (HasSignalOnTrackdir(next.tile, next.td) && IsPbsSignal(GetSignalType(next.tile, TrackdirToTrack(next.td)))) {
 511                                         /* Possible safe tile. */
 512                                         end_segment_reason |= ESRB_SAFE_TILE;
 513                                 } else if (HasSignalOnTrackdir(next.tile, ReverseTrackdir(next.td)) && GetSignalType(next.tile, TrackdirToTrack(next.td)) == SIGTYPE_PBS_ONEWAY) {
 514                                         /* Possible safe tile, but not so good as it's the back of a signal... */
 515                                         end_segment_reason |= ESRB_SAFE_TILE | ESRB_DEAD_END;
 516                                         extra_cost += Yapf().PfGetSettings().rail_lastred_exit_penalty;
 517                                 }
 518                         }
 519
 520                         /* Check the next tile for the rail type. */
 521                         if (next.rail_type != cur.rail_type) {
 522                                 /* Segment must consist from the same rail_type tiles. */
 523                                 end_segment_reason |= ESRB_RAIL_TYPE;
 524                                 break;
 525                         }
 526
 527                         /* Avoid infinite looping. */
 528                         if (next.tile == n.m_key.m_tile && next.td == n.m_key.m_td) {
 529                                 end_segment_reason |= ESRB_INFINITE_LOOP;
 530                                 break;
 531                         }
 532
 533                         if (segment_cost > s_max_segment_cost) {
 534                                 /* Potentially in the infinite loop (or only very long segment?). We should
 535                                  * not force it to finish prematurely unless we are on a regular tile. */
 536                                 if (IsTileType(tf->m_new_tile, MP_RAILWAY)) {
 537                                         end_segment_reason |= ESRB_SEGMENT_TOO_LONG;
 538                                         break;
 539                                 }
 540                         }
 541
 542                         /* Any other reason bit set? */
 543                         if (end_segment_reason != ESRB_NONE) {
 544                                 break;
 545                         }
 546
 547                         /* For the next loop set new prev and cur tile info. */
 548                         prev = cur;
 549                         cur = next;
 550
 551                 } // for (;;)
 552
 553                 /* Don't consider path any further it if exceeded max_cost. */
 554                 if (end_segment_reason & ESRB_PATH_TOO_LONG) return false;
 555
 556                 bool target_seen = false;
 557                 if ((end_segment_reason & ESRB_POSSIBLE_TARGET) != ESRB_NONE) {
 558                         /* Depot, station or waypoint. */
 559                         if (Yapf().PfDetectDestination(cur.tile, cur.td)) {
 560                                 /* Destination found. */
 561                                 target_seen = true;
 562                         }
 563                 }
 564
 565                 /* Update the segment if needed. */
 566                 if (!is_cached_segment) {
 567                         /* Write back the segment information so it can be reused the next time. */
 568                         segment.m_cost = segment_cost;
 569                         segment.m_end_segment_reason = end_segment_reason & ESRB_CACHED_MASK;
 570                         /* Save end of segment back to the node. */
 571                         n.SetLastTileTrackdir(cur.tile, cur.td);
 572                 }
 573
 574                 /* Do we have an excuse why not to continue pathfinding in this direction? */
 575                 if (!target_seen && (end_segment_reason & ESRB_ABORT_PF_MASK) != ESRB_NONE) {
 576                         /* Reason to not continue. Stop this PF branch. */
 577                         return false;
 578                 }
 579
 580                 /* Special costs for the case we have reached our target. */
 581                 if (target_seen) {
 582                         n.flags_u.flags_s.m_targed_seen = true;
 583                         /* Last-red and last-red-exit penalties. */
 584                         if (n.flags_u.flags_s.m_last_signal_was_red) {
 585                                 if (n.m_last_red_signal_type == SIGTYPE_EXIT) {
 586                                         /* last signal was red pre-signal-exit */
 587                                         extra_cost += Yapf().PfGetSettings().rail_lastred_exit_penalty;
 588                                 } else if (!IsPbsSignal(n.m_last_red_signal_type)) {
 589                                         /* Last signal was red, but not exit or path signal. */
 590                                         extra_cost += Yapf().PfGetSettings().rail_lastred_penalty;
 591                                 }
 592                         }
 593
 594                         /* Station platform-length penalty. */
 595                         if ((end_segment_reason & ESRB_STATION) != ESRB_NONE) {
 596                                 const BaseStation *st = BaseStation::GetByTile(n.GetLastTile());
 597                                 assert(st != nullptr);
 598                                 uint platform_length = st->GetPlatformLength(n.GetLastTile(), ReverseDiagDir(TrackdirToExitdir(n.GetLastTrackdir())));
 599                                 /* Reduce the extra cost caused by passing-station penalty (each station receives it in the segment cost). */
 600                                 extra_cost -= Yapf().PfGetSettings().rail_station_penalty * platform_length;
 601                                 /* Add penalty for the inappropriate platform length. */
 602                                 extra_cost += PlatformLengthPenalty(platform_length);
 603                         }
 604                 }
 605
 606                 /* total node cost */
 607                 n.m_cost = parent_cost + segment_entry_cost + segment_cost + extra_cost;
 608
 609                 return true;
 610         }
 611
 612         inline bool CanUseGlobalCache(Node &n) const
 613         {
 614                 return !m_disable_cache
 615                         && (n.m_parent != nullptr)
 616                         && (n.m_parent->m_num_signals_passed >= m_sig_look_ahead_costs.size());
 617         }
 618
 619         inline void ConnectNodeToCachedData(Node &n, CachedData &ci)
 620         {
 621                 n.m_segment = &ci;
 622                 if (n.m_segment->m_cost < 0) {
 623                         n.m_segment->m_last_tile = n.m_key.m_tile;
 624                         n.m_segment->m_last_td = n.m_key.m_td;
 625                 }
 626         }
 627
 628         void DisableCache(bool disable)
 629         {
 630                 m_disable_cache = disable;
 631         }
 632 };
 633
 634 #endif /* YAPF_COSTRAIL_HPP */