npf.cpp

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00001 /* $Id: npf.cpp 15299 2009-01-31 20:16:06Z smatz $ */
00002 
00005 #include "stdafx.h"
00006 #include "npf.h"
00007 #include "debug.h"
00008 #include "landscape.h"
00009 #include "depot_base.h"
00010 #include "depot_map.h"
00011 #include "network/network.h"
00012 #include "tunnelbridge_map.h"
00013 #include "functions.h"
00014 #include "vehicle_base.h"
00015 #include "tunnelbridge.h"
00016 #include "pbs.h"
00017 #include "settings_type.h"
00018 
00019 static AyStar _npf_aystar;
00020 
00021 /* The cost of each trackdir. A diagonal piece is the full NPF_TILE_LENGTH,
00022  * the shorter piece is sqrt(2)/2*NPF_TILE_LENGTH =~ 0.7071
00023  */
00024 #define NPF_STRAIGHT_LENGTH (uint)(NPF_TILE_LENGTH * STRAIGHT_TRACK_LENGTH)
00025 static const uint _trackdir_length[TRACKDIR_END] = {
00026   NPF_TILE_LENGTH, NPF_TILE_LENGTH, NPF_STRAIGHT_LENGTH, NPF_STRAIGHT_LENGTH, NPF_STRAIGHT_LENGTH, NPF_STRAIGHT_LENGTH,
00027   0, 0,
00028   NPF_TILE_LENGTH, NPF_TILE_LENGTH, NPF_STRAIGHT_LENGTH, NPF_STRAIGHT_LENGTH, NPF_STRAIGHT_LENGTH, NPF_STRAIGHT_LENGTH
00029 };
00030 
00037 static uint NPFDistanceTrack(TileIndex t0, TileIndex t1)
00038 {
00039   const uint dx = Delta(TileX(t0), TileX(t1));
00040   const uint dy = Delta(TileY(t0), TileY(t1));
00041 
00042   const uint straightTracks = 2 * min(dx, dy); /* The number of straight (not full length) tracks */
00043   /* OPTIMISATION:
00044    * Original: diagTracks = max(dx, dy) - min(dx,dy);
00045    * Proof:
00046    * (dx+dy) - straightTracks  == (min + max) - straightTracks = min + max - 2 * min = max - min */
00047   const uint diagTracks = dx + dy - straightTracks; /* The number of diagonal (full tile length) tracks. */
00048 
00049   /* Don't factor out NPF_TILE_LENGTH below, this will round values and lose
00050    * precision */
00051   return diagTracks * NPF_TILE_LENGTH + straightTracks * NPF_TILE_LENGTH * STRAIGHT_TRACK_LENGTH;
00052 }
00053 
00054 
00055 #if 0
00056 static uint NTPHash(uint key1, uint key2)
00057 {
00058   /* This function uses the old hash, which is fixed on 10 bits (1024 buckets) */
00059   return PATHFIND_HASH_TILE(key1);
00060 }
00061 #endif
00062 
00070 static uint NPFHash(uint key1, uint key2)
00071 {
00072   /* TODO: think of a better hash? */
00073   uint part1 = TileX(key1) & NPF_HASH_HALFMASK;
00074   uint part2 = TileY(key1) & NPF_HASH_HALFMASK;
00075 
00076   assert(IsValidTrackdir((Trackdir)key2));
00077   assert(IsValidTile(key1));
00078   return ((part1 << NPF_HASH_HALFBITS | part2) + (NPF_HASH_SIZE * key2 / TRACKDIR_END)) % NPF_HASH_SIZE;
00079 }
00080 
00081 static int32 NPFCalcZero(AyStar *as, AyStarNode *current, OpenListNode *parent)
00082 {
00083   return 0;
00084 }
00085 
00086 /* Calcs the tile of given station that is closest to a given tile
00087  * for this we assume the station is a rectangle,
00088  * as defined by its top tile (st->train_tile) and its width/height (st->trainst_w, st->trainst_h)
00089  */
00090 static TileIndex CalcClosestStationTile(StationID station, TileIndex tile)
00091 {
00092   const Station *st = GetStation(station);
00093 
00094   /* If the rail station is (temporarily) not present, use the station sign to drive near the station */
00095   if (!IsValidTile(st->train_tile)) return st->xy;
00096 
00097   uint minx = TileX(st->train_tile);  // topmost corner of station
00098   uint miny = TileY(st->train_tile);
00099   uint maxx = minx + st->trainst_w - 1; // lowermost corner of station
00100   uint maxy = miny + st->trainst_h - 1;
00101   uint x;
00102   uint y;
00103 
00104   /* we are going the aim for the x coordinate of the closest corner
00105    * but if we are between those coordinates, we will aim for our own x coordinate */
00106   x = Clamp(TileX(tile), minx, maxx);
00107 
00108   /* same for y coordinate, see above comment */
00109   y = Clamp(TileY(tile), miny, maxy);
00110 
00111   /* return the tile of our target coordinates */
00112   return TileXY(x, y);
00113 }
00114 
00115 /* Calcs the heuristic to the target station or tile. For train stations, it
00116  * takes into account the direction of approach.
00117  */
00118 static int32 NPFCalcStationOrTileHeuristic(AyStar *as, AyStarNode *current, OpenListNode *parent)
00119 {
00120   NPFFindStationOrTileData *fstd = (NPFFindStationOrTileData*)as->user_target;
00121   NPFFoundTargetData *ftd = (NPFFoundTargetData*)as->user_path;
00122   TileIndex from = current->tile;
00123   TileIndex to = fstd->dest_coords;
00124   uint dist;
00125 
00126   /* for train-stations, we are going to aim for the closest station tile */
00127   if (as->user_data[NPF_TYPE] == TRANSPORT_RAIL && fstd->station_index != INVALID_STATION)
00128     to = CalcClosestStationTile(fstd->station_index, from);
00129 
00130   if (as->user_data[NPF_TYPE] == TRANSPORT_ROAD) {
00131     /* Since roads only have diagonal pieces, we use manhattan distance here */
00132     dist = DistanceManhattan(from, to) * NPF_TILE_LENGTH;
00133   } else {
00134     /* Ships and trains can also go diagonal, so the minimum distance is shorter */
00135     dist = NPFDistanceTrack(from, to);
00136   }
00137 
00138   DEBUG(npf, 4, "Calculating H for: (%d, %d). Result: %d", TileX(current->tile), TileY(current->tile), dist);
00139 
00140   if (dist < ftd->best_bird_dist) {
00141     ftd->best_bird_dist = dist;
00142     ftd->best_trackdir = (Trackdir)current->user_data[NPF_TRACKDIR_CHOICE];
00143   }
00144   return dist;
00145 }
00146 
00147 
00148 /* Fills AyStarNode.user_data[NPF_TRACKDIRCHOICE] with the chosen direction to
00149  * get here, either getting it from the current choice or from the parent's
00150  * choice */
00151 static void NPFFillTrackdirChoice(AyStarNode *current, OpenListNode *parent)
00152 {
00153   if (parent->path.parent == NULL) {
00154     Trackdir trackdir = current->direction;
00155     /* This is a first order decision, so we'd better save the
00156      * direction we chose */
00157     current->user_data[NPF_TRACKDIR_CHOICE] = trackdir;
00158     DEBUG(npf, 6, "Saving trackdir: 0x%X", trackdir);
00159   } else {
00160     /* We've already made the decision, so just save our parent's decision */
00161     current->user_data[NPF_TRACKDIR_CHOICE] = parent->path.node.user_data[NPF_TRACKDIR_CHOICE];
00162   }
00163 }
00164 
00165 /* Will return the cost of the tunnel. If it is an entry, it will return the
00166  * cost of that tile. If the tile is an exit, it will return the tunnel length
00167  * including the exit tile. Requires that this is a Tunnel tile */
00168 static uint NPFTunnelCost(AyStarNode *current)
00169 {
00170   DiagDirection exitdir = TrackdirToExitdir(current->direction);
00171   TileIndex tile = current->tile;
00172   if (GetTunnelBridgeDirection(tile) == ReverseDiagDir(exitdir)) {
00173     /* We just popped out if this tunnel, since were
00174      * facing the tunnel exit */
00175     return NPF_TILE_LENGTH * (GetTunnelBridgeLength(current->tile, GetOtherTunnelEnd(current->tile)) + 1);
00176     /* @todo: Penalty for tunnels? */
00177   } else {
00178     /* We are entering the tunnel, the enter tile is just a
00179      * straight track */
00180     return NPF_TILE_LENGTH;
00181   }
00182 }
00183 
00184 static inline uint NPFBridgeCost(AyStarNode *current)
00185 {
00186   return NPF_TILE_LENGTH * GetTunnelBridgeLength(current->tile, GetOtherBridgeEnd(current->tile));
00187 }
00188 
00189 static uint NPFSlopeCost(AyStarNode *current)
00190 {
00191   TileIndex next = current->tile + TileOffsByDiagDir(TrackdirToExitdir(current->direction));
00192 
00193   /* Get center of tiles */
00194   int x1 = TileX(current->tile) * TILE_SIZE + TILE_SIZE / 2;
00195   int y1 = TileY(current->tile) * TILE_SIZE + TILE_SIZE / 2;
00196   int x2 = TileX(next) * TILE_SIZE + TILE_SIZE / 2;
00197   int y2 = TileY(next) * TILE_SIZE + TILE_SIZE / 2;
00198 
00199   int dx4 = (x2 - x1) / 4;
00200   int dy4 = (y2 - y1) / 4;
00201 
00202   /* Get the height on both sides of the tile edge.
00203    * Avoid testing the height on the tile-center. This will fail for halftile-foundations.
00204    */
00205   int z1 = GetSlopeZ(x1 + dx4, y1 + dy4);
00206   int z2 = GetSlopeZ(x2 - dx4, y2 - dy4);
00207 
00208   if (z2 - z1 > 1) {
00209     /* Slope up */
00210     return _settings_game.pf.npf.npf_rail_slope_penalty;
00211   }
00212   return 0;
00213   /* Should we give a bonus for slope down? Probably not, we
00214    * could just substract that bonus from the penalty, because
00215    * there is only one level of steepness... */
00216 }
00217 
00218 static uint NPFReservedTrackCost(AyStarNode *current)
00219 {
00220   TileIndex tile = current->tile;
00221   TrackBits track = TrackToTrackBits(TrackdirToTrack(current->direction));
00222   TrackBits res = GetReservedTrackbits(tile);
00223 
00224   if (NPFGetFlag(current, NPF_FLAG_3RD_SIGNAL) || ((res & track) == TRACK_BIT_NONE && !TracksOverlap(res | track))) return 0;
00225 
00226   if (IsTileType(tile, MP_TUNNELBRIDGE)) {
00227     DiagDirection exitdir = TrackdirToExitdir(current->direction);
00228     if (GetTunnelBridgeDirection(tile) == ReverseDiagDir(exitdir)) {
00229       return  _settings_game.pf.npf.npf_rail_pbs_cross_penalty * (GetTunnelBridgeLength(tile, GetOtherTunnelBridgeEnd(tile)) + 1);
00230     }
00231   }
00232   return  _settings_game.pf.npf.npf_rail_pbs_cross_penalty;
00233 }
00234 
00239 static void NPFMarkTile(TileIndex tile)
00240 {
00241 #ifndef NO_DEBUG_MESSAGES
00242   if (_debug_npf_level < 1 || _networking) return;
00243   switch (GetTileType(tile)) {
00244     case MP_RAILWAY:
00245       /* DEBUG: mark visited tiles by mowing the grass under them ;-) */
00246       if (!IsRailDepot(tile)) {
00247         SetRailGroundType(tile, RAIL_GROUND_BARREN);
00248         MarkTileDirtyByTile(tile);
00249       }
00250       break;
00251 
00252     case MP_ROAD:
00253       if (!IsRoadDepot(tile)) {
00254         SetRoadside(tile, ROADSIDE_BARREN);
00255         MarkTileDirtyByTile(tile);
00256       }
00257       break;
00258 
00259     default:
00260       break;
00261   }
00262 #endif
00263 }
00264 
00265 static int32 NPFWaterPathCost(AyStar *as, AyStarNode *current, OpenListNode *parent)
00266 {
00267   /* TileIndex tile = current->tile; */
00268   int32 cost = 0;
00269   Trackdir trackdir = current->direction;
00270 
00271   cost = _trackdir_length[trackdir]; // Should be different for diagonal tracks
00272 
00273   if (IsBuoyTile(current->tile) && IsDiagonalTrackdir(trackdir))
00274     cost += _settings_game.pf.npf.npf_buoy_penalty; // A small penalty for going over buoys
00275 
00276   if (current->direction != NextTrackdir((Trackdir)parent->path.node.direction))
00277     cost += _settings_game.pf.npf.npf_water_curve_penalty;
00278 
00279   /* @todo More penalties? */
00280 
00281   return cost;
00282 }
00283 
00284 /* Determine the cost of this node, for road tracks */
00285 static int32 NPFRoadPathCost(AyStar *as, AyStarNode *current, OpenListNode *parent)
00286 {
00287   TileIndex tile = current->tile;
00288   int32 cost = 0;
00289 
00290   /* Determine base length */
00291   switch (GetTileType(tile)) {
00292     case MP_TUNNELBRIDGE:
00293       cost = IsTunnel(tile) ? NPFTunnelCost(current) : NPFBridgeCost(current);
00294       break;
00295 
00296     case MP_ROAD:
00297       cost = NPF_TILE_LENGTH;
00298       /* Increase the cost for level crossings */
00299       if (IsLevelCrossing(tile)) cost += _settings_game.pf.npf.npf_crossing_penalty;
00300       break;
00301 
00302     case MP_STATION:
00303       cost = NPF_TILE_LENGTH;
00304       /* Increase the cost for drive-through road stops */
00305       if (IsDriveThroughStopTile(tile)) cost += _settings_game.pf.npf.npf_road_drive_through_penalty;
00306       break;
00307 
00308     default:
00309       break;
00310   }
00311 
00312   /* Determine extra costs */
00313 
00314   /* Check for slope */
00315   cost += NPFSlopeCost(current);
00316 
00317   /* Check for turns. Road vehicles only really drive diagonal, turns are
00318    * represented by non-diagonal tracks */
00319   if (!IsDiagonalTrackdir(current->direction))
00320     cost += _settings_game.pf.npf.npf_road_curve_penalty;
00321 
00322   NPFMarkTile(tile);
00323   DEBUG(npf, 4, "Calculating G for: (%d, %d). Result: %d", TileX(current->tile), TileY(current->tile), cost);
00324   return cost;
00325 }
00326 
00327 
00328 /* Determine the cost of this node, for railway tracks */
00329 static int32 NPFRailPathCost(AyStar *as, AyStarNode *current, OpenListNode *parent)
00330 {
00331   TileIndex tile = current->tile;
00332   Trackdir trackdir = current->direction;
00333   int32 cost = 0;
00334   /* HACK: We create a OpenListNode manually, so we can call EndNodeCheck */
00335   OpenListNode new_node;
00336 
00337   /* Determine base length */
00338   switch (GetTileType(tile)) {
00339     case MP_TUNNELBRIDGE:
00340       cost = IsTunnel(tile) ? NPFTunnelCost(current) : NPFBridgeCost(current);
00341       break;
00342 
00343     case MP_RAILWAY:
00344       cost = _trackdir_length[trackdir]; /* Should be different for diagonal tracks */
00345       break;
00346 
00347     case MP_ROAD: /* Railway crossing */
00348       cost = NPF_TILE_LENGTH;
00349       break;
00350 
00351     case MP_STATION:
00352       /* We give a station tile a penalty. Logically we would only want to give
00353        * station tiles that are not our destination this penalty. This would
00354        * discourage trains to drive through busy stations. But, we can just
00355        * give any station tile a penalty, because every possible route will get
00356        * this penalty exactly once, on its end tile (if it's a station) and it
00357        * will therefore not make a difference. */
00358       cost = NPF_TILE_LENGTH + _settings_game.pf.npf.npf_rail_station_penalty;
00359       break;
00360 
00361     default:
00362       break;
00363   }
00364 
00365   /* Determine extra costs */
00366 
00367   /* Check for signals */
00368   if (IsTileType(tile, MP_RAILWAY)) {
00369     if (HasSignalOnTrackdir(tile, trackdir)) {
00370       /* Ordinary track with signals */
00371       if (GetSignalStateByTrackdir(tile, trackdir) == SIGNAL_STATE_RED) {
00372         /* Signal facing us is red */
00373         if (!NPFGetFlag(current, NPF_FLAG_SEEN_SIGNAL)) {
00374           /* Penalize the first signal we
00375            * encounter, if it is red */
00376 
00377           /* Is this a presignal exit or combo? */
00378           SignalType sigtype = GetSignalType(tile, TrackdirToTrack(trackdir));
00379           if (!IsPbsSignal(sigtype)) {
00380             if (sigtype == SIGTYPE_EXIT || sigtype == SIGTYPE_COMBO) {
00381               /* Penalise exit and combo signals differently (heavier) */
00382               cost += _settings_game.pf.npf.npf_rail_firstred_exit_penalty;
00383             } else {
00384               cost += _settings_game.pf.npf.npf_rail_firstred_penalty;
00385             }
00386           }
00387         }
00388         /* Record the state of this signal */
00389         NPFSetFlag(current, NPF_FLAG_LAST_SIGNAL_RED, true);
00390       } else {
00391         /* Record the state of this signal */
00392         NPFSetFlag(current, NPF_FLAG_LAST_SIGNAL_RED, false);
00393       }
00394       if (NPFGetFlag(current, NPF_FLAG_SEEN_SIGNAL)) {
00395         if (NPFGetFlag(current, NPF_FLAG_2ND_SIGNAL)) {
00396           NPFSetFlag(current, NPF_FLAG_3RD_SIGNAL, true);
00397         } else {
00398           NPFSetFlag(current, NPF_FLAG_2ND_SIGNAL, true);
00399         }
00400       } else {
00401         NPFSetFlag(current, NPF_FLAG_SEEN_SIGNAL, true);
00402       }
00403     }
00404 
00405     if (HasPbsSignalOnTrackdir(tile, ReverseTrackdir(trackdir)) && !NPFGetFlag(current, NPF_FLAG_3RD_SIGNAL)) {
00406       cost += _settings_game.pf.npf.npf_rail_pbs_signal_back_penalty;
00407     }
00408   }
00409 
00410   /* Penalise the tile if it is a target tile and the last signal was
00411    * red */
00412   /* HACK: We create a new_node here so we can call EndNodeCheck. Ugly as hell
00413    * of course... */
00414   new_node.path.node = *current;
00415   if (as->EndNodeCheck(as, &new_node) == AYSTAR_FOUND_END_NODE && NPFGetFlag(current, NPF_FLAG_LAST_SIGNAL_RED))
00416     cost += _settings_game.pf.npf.npf_rail_lastred_penalty;
00417 
00418   /* Check for slope */
00419   cost += NPFSlopeCost(current);
00420 
00421   /* Check for turns */
00422   if (current->direction != NextTrackdir((Trackdir)parent->path.node.direction))
00423     cost += _settings_game.pf.npf.npf_rail_curve_penalty;
00424   /*TODO, with realistic acceleration, also the amount of straight track between
00425    *      curves should be taken into account, as this affects the speed limit. */
00426 
00427   /* Check for reverse in depot */
00428   if (IsRailDepotTile(tile) && as->EndNodeCheck(as, &new_node) != AYSTAR_FOUND_END_NODE) {
00429     /* Penalise any depot tile that is not the last tile in the path. This
00430      * _should_ penalise every occurence of reversing in a depot (and only
00431      * that) */
00432     cost += _settings_game.pf.npf.npf_rail_depot_reverse_penalty;
00433   }
00434 
00435   /* Check for occupied track */
00436   cost += NPFReservedTrackCost(current);
00437 
00438   NPFMarkTile(tile);
00439   DEBUG(npf, 4, "Calculating G for: (%d, %d). Result: %d", TileX(current->tile), TileY(current->tile), cost);
00440   return cost;
00441 }
00442 
00443 /* Will find any depot */
00444 static int32 NPFFindDepot(AyStar *as, OpenListNode *current)
00445 {
00446   /* It's not worth caching the result with NPF_FLAG_IS_TARGET here as below,
00447    * since checking the cache not that much faster than the actual check */
00448   return IsDepotTypeTile(current->path.node.tile, (TransportType)as->user_data[NPF_TYPE]) ?
00449     AYSTAR_FOUND_END_NODE : AYSTAR_DONE;
00450 }
00451 
00453 static int32 NPFFindSafeTile(AyStar *as, OpenListNode *current)
00454 {
00455   const Vehicle *v = ((NPFFindStationOrTileData*)as->user_target)->v;
00456 
00457   return
00458     IsSafeWaitingPosition(v, current->path.node.tile, current->path.node.direction, true, _settings_game.pf.forbid_90_deg) &&
00459     IsWaitingPositionFree(v, current->path.node.tile, current->path.node.direction, _settings_game.pf.forbid_90_deg) ?
00460       AYSTAR_FOUND_END_NODE : AYSTAR_DONE;
00461 }
00462 
00463 /* Will find a station identified using the NPFFindStationOrTileData */
00464 static int32 NPFFindStationOrTile(AyStar *as, OpenListNode *current)
00465 {
00466   NPFFindStationOrTileData *fstd = (NPFFindStationOrTileData*)as->user_target;
00467   AyStarNode *node = &current->path.node;
00468   TileIndex tile = node->tile;
00469 
00470   /* If GetNeighbours said we could get here, we assume the station type
00471    * is correct */
00472   if (
00473     (fstd->station_index == INVALID_STATION && tile == fstd->dest_coords) || /* We've found the tile, or */
00474     (IsTileType(tile, MP_STATION) && GetStationIndex(tile) == fstd->station_index) /* the station */
00475   ) {
00476     return AYSTAR_FOUND_END_NODE;
00477   } else {
00478     return AYSTAR_DONE;
00479   }
00480 }
00481 
00489 static const PathNode *FindSafePosition(PathNode *path, const Vehicle *v)
00490 {
00491   /* If there is no signal, reserve the whole path. */
00492   PathNode *sig = path;
00493 
00494   for(; path->parent != NULL; path = path->parent) {
00495     if (IsSafeWaitingPosition(v, path->node.tile, path->node.direction, true, _settings_game.pf.forbid_90_deg)) {
00496       sig = path;
00497     }
00498   }
00499 
00500   return sig;
00501 }
00502 
00506 static void ClearPathReservation(const PathNode *start, const PathNode *end)
00507 {
00508   bool first_run = true;
00509   for (; start != end; start = start->parent) {
00510     if (IsRailwayStationTile(start->node.tile) && first_run) {
00511       SetRailwayStationPlatformReservation(start->node.tile, TrackdirToExitdir(start->node.direction), false);
00512     } else {
00513       UnreserveRailTrack(start->node.tile, TrackdirToTrack(start->node.direction));
00514     }
00515     first_run = false;
00516   }
00517 }
00518 
00525 static void NPFSaveTargetData(AyStar *as, OpenListNode *current)
00526 {
00527   NPFFoundTargetData *ftd = (NPFFoundTargetData*)as->user_path;
00528   ftd->best_trackdir = (Trackdir)current->path.node.user_data[NPF_TRACKDIR_CHOICE];
00529   ftd->best_path_dist = current->g;
00530   ftd->best_bird_dist = 0;
00531   ftd->node = current->path.node;
00532   ftd->res_okay = false;
00533 
00534   if (as->user_target != NULL && ((NPFFindStationOrTileData*)as->user_target)->reserve_path && as->user_data[NPF_TYPE] == TRANSPORT_RAIL) {
00535     /* Path reservation is requested. */
00536     const Vehicle  *v = ((NPFFindStationOrTileData*)as->user_target)->v;
00537 
00538     const PathNode *target = FindSafePosition(&current->path, v);
00539     ftd->node = target->node;
00540 
00541     /* If the target is a station skip to platform end. */
00542     if (IsRailwayStationTile(target->node.tile)) {
00543       DiagDirection dir = TrackdirToExitdir(target->node.direction);
00544       uint len = GetStationByTile(target->node.tile)->GetPlatformLength(target->node.tile, dir);
00545       TileIndex end_tile = TILE_ADD(target->node.tile, (len - 1) * TileOffsByDiagDir(dir));
00546 
00547       /* Update only end tile, trackdir of a station stays the same. */
00548       ftd->node.tile = end_tile;
00549       if (!IsWaitingPositionFree(v, end_tile, target->node.direction, _settings_game.pf.forbid_90_deg)) return;
00550       SetRailwayStationPlatformReservation(target->node.tile, dir, true);
00551       SetRailwayStationReservation(target->node.tile, false);
00552     } else {
00553       if (!IsWaitingPositionFree(v, target->node.tile, target->node.direction, _settings_game.pf.forbid_90_deg)) return;
00554     }
00555 
00556     for (const PathNode *cur = target; cur->parent != NULL; cur = cur->parent) {
00557       if (!TryReserveRailTrack(cur->node.tile, TrackdirToTrack(cur->node.direction))) {
00558         /* Reservation failed, undo. */
00559         ClearPathReservation(target, cur);
00560         return;
00561       }
00562     }
00563 
00564     ftd->res_okay = true;
00565   }
00566 }
00567 
00577 static bool CanEnterTileOwnerCheck(Owner owner, TileIndex tile, DiagDirection enterdir)
00578 {
00579   if (IsTileType(tile, MP_RAILWAY) ||             /* Rail tile (also rail depot) */
00580       IsRailwayStationTile(tile) ||   /* Rail station tile */
00581       IsRoadDepotTile(tile) ||        /* Road depot tile */
00582       IsStandardRoadStopTile(tile)) { /* Road station tile (but not drive-through stops) */
00583     return IsTileOwner(tile, owner); /* You need to own these tiles entirely to use them */
00584   }
00585 
00586   switch (GetTileType(tile)) {
00587     case MP_ROAD:
00588       /* rail-road crossing : are we looking at the railway part? */
00589       if (IsLevelCrossing(tile) &&
00590           DiagDirToAxis(enterdir) != GetCrossingRoadAxis(tile)) {
00591         return IsTileOwner(tile, owner); /* Railway needs owner check, while the street is public */
00592       }
00593       break;
00594 
00595     case MP_TUNNELBRIDGE:
00596       if (GetTunnelBridgeTransportType(tile) == TRANSPORT_RAIL) {
00597         return IsTileOwner(tile, owner);
00598       }
00599       break;
00600 
00601     default:
00602       break;
00603   }
00604 
00605   return true; // no need to check
00606 }
00607 
00608 
00612 static DiagDirection GetDepotDirection(TileIndex tile, TransportType type)
00613 {
00614   assert(IsDepotTypeTile(tile, type));
00615 
00616   switch (type) {
00617     case TRANSPORT_RAIL:  return GetRailDepotDirection(tile);
00618     case TRANSPORT_ROAD:  return GetRoadDepotDirection(tile);
00619     case TRANSPORT_WATER: return GetShipDepotDirection(tile);
00620     default: return INVALID_DIAGDIR; /* Not reached */
00621   }
00622 }
00623 
00625 static DiagDirection GetSingleTramBit(TileIndex tile)
00626 {
00627   if (IsNormalRoadTile(tile)) {
00628     RoadBits rb = GetRoadBits(tile, ROADTYPE_TRAM);
00629     switch (rb) {
00630       case ROAD_NW: return DIAGDIR_NW;
00631       case ROAD_SW: return DIAGDIR_SW;
00632       case ROAD_SE: return DIAGDIR_SE;
00633       case ROAD_NE: return DIAGDIR_NE;
00634       default: break;
00635     }
00636   }
00637   return INVALID_DIAGDIR;
00638 }
00639 
00650 static DiagDirection GetTileSingleEntry(TileIndex tile, TransportType type, uint subtype)
00651 {
00652   if (type != TRANSPORT_WATER && IsDepotTypeTile(tile, type)) return GetDepotDirection(tile, type);
00653 
00654   if (type == TRANSPORT_ROAD) {
00655     if (IsStandardRoadStopTile(tile)) return GetRoadStopDir(tile);
00656     if (HasBit(subtype, ROADTYPE_TRAM)) return GetSingleTramBit(tile);
00657   }
00658 
00659   return INVALID_DIAGDIR;
00660 }
00661 
00671 static inline bool ForceReverse(TileIndex tile, DiagDirection dir, TransportType type, uint subtype)
00672 {
00673   DiagDirection single_entry = GetTileSingleEntry(tile, type, subtype);
00674   return single_entry != INVALID_DIAGDIR && single_entry != dir;
00675 }
00676 
00688 static bool CanEnterTile(TileIndex tile, DiagDirection dir, TransportType type, uint subtype, RailTypes railtypes, Owner owner)
00689 {
00690   /* Check tunnel entries and bridge ramps */
00691   if (IsTileType(tile, MP_TUNNELBRIDGE) && GetTunnelBridgeDirection(tile) != dir) return false;
00692 
00693   /* Test ownership */
00694   if (!CanEnterTileOwnerCheck(owner, tile, dir)) return false;
00695 
00696   /* check correct rail type (mono, maglev, etc) */
00697   if (type == TRANSPORT_RAIL) {
00698     RailType rail_type = GetTileRailType(tile);
00699     if (!HasBit(railtypes, rail_type)) return false;
00700   }
00701 
00702   /* Depots, standard roadstops and single tram bits can only be entered from one direction */
00703   DiagDirection single_entry = GetTileSingleEntry(tile, type, subtype);
00704   if (single_entry != INVALID_DIAGDIR && single_entry != ReverseDiagDir(dir)) return false;
00705 
00706   return true;
00707 }
00708 
00720 static TrackdirBits GetDriveableTrackdirBits(TileIndex dst_tile, Trackdir src_trackdir, TransportType type, uint subtype)
00721 {
00722   TrackdirBits trackdirbits = TrackStatusToTrackdirBits(GetTileTrackStatus(dst_tile, type, subtype));
00723 
00724   if (trackdirbits == 0 && type == TRANSPORT_ROAD && HasBit(subtype, ROADTYPE_TRAM)) {
00725     /* GetTileTrackStatus() returns 0 for single tram bits.
00726      * As we cannot change it there (easily) without breaking something, change it here */
00727     switch (GetSingleTramBit(dst_tile)) {
00728       case DIAGDIR_NE:
00729       case DIAGDIR_SW:
00730         trackdirbits = TRACKDIR_BIT_X_NE | TRACKDIR_BIT_X_SW;
00731         break;
00732 
00733       case DIAGDIR_NW:
00734       case DIAGDIR_SE:
00735         trackdirbits = TRACKDIR_BIT_Y_NW | TRACKDIR_BIT_Y_SE;
00736         break;
00737 
00738       default: break;
00739     }
00740   }
00741 
00742   DEBUG(npf, 4, "Next node: (%d, %d) [%d], possible trackdirs: 0x%X", TileX(dst_tile), TileY(dst_tile), dst_tile, trackdirbits);
00743 
00744   /* Select only trackdirs we can reach from our current trackdir */
00745   trackdirbits &= TrackdirReachesTrackdirs(src_trackdir);
00746 
00747   /* Filter out trackdirs that would make 90 deg turns for trains */
00748   if (_settings_game.pf.forbid_90_deg && (type == TRANSPORT_RAIL || type == TRANSPORT_WATER)) trackdirbits &= ~TrackdirCrossesTrackdirs(src_trackdir);
00749 
00750   DEBUG(npf, 6, "After filtering: (%d, %d), possible trackdirs: 0x%X", TileX(dst_tile), TileY(dst_tile), trackdirbits);
00751 
00752   return trackdirbits;
00753 }
00754 
00755 
00756 /* Will just follow the results of GetTileTrackStatus concerning where we can
00757  * go and where not. Uses AyStar.user_data[NPF_TYPE] as the transport type and
00758  * an argument to GetTileTrackStatus. Will skip tunnels, meaning that the
00759  * entry and exit are neighbours. Will fill
00760  * AyStarNode.user_data[NPF_TRACKDIR_CHOICE] with an appropriate value, and
00761  * copy AyStarNode.user_data[NPF_NODE_FLAGS] from the parent */
00762 static void NPFFollowTrack(AyStar *aystar, OpenListNode *current)
00763 {
00764   /* We leave src_tile on track src_trackdir in direction src_exitdir */
00765   Trackdir src_trackdir = current->path.node.direction;
00766   TileIndex src_tile = current->path.node.tile;
00767   DiagDirection src_exitdir = TrackdirToExitdir(src_trackdir);
00768 
00769   /* Is src_tile valid, and can be used?
00770    * When choosing track on a junction src_tile is the tile neighboured to the junction wrt. exitdir.
00771    * But we must not check the validity of this move, as src_tile is totally unrelated to the move, if a roadvehicle reversed on a junction. */
00772   bool ignore_src_tile = (current->path.parent == NULL && NPFGetFlag(&current->path.node, NPF_FLAG_IGNORE_START_TILE));
00773 
00774   /* Information about the vehicle: TransportType (road/rail/water) and SubType (compatible rail/road types) */
00775   TransportType type = (TransportType)aystar->user_data[NPF_TYPE];
00776   uint subtype = aystar->user_data[NPF_SUB_TYPE];
00777 
00778   /* Initialize to 0, so we can jump out (return) somewhere an have no neighbours */
00779   aystar->num_neighbours = 0;
00780   DEBUG(npf, 4, "Expanding: (%d, %d, %d) [%d]", TileX(src_tile), TileY(src_tile), src_trackdir, src_tile);
00781 
00782   /* We want to determine the tile we arrive, and which choices we have there */
00783   TileIndex dst_tile;
00784   TrackdirBits trackdirbits;
00785 
00786   /* Find dest tile */
00787   if (ignore_src_tile) {
00788     /* Do not perform any checks that involve src_tile */
00789     dst_tile = src_tile + TileOffsByDiagDir(src_exitdir);
00790     trackdirbits = GetDriveableTrackdirBits(dst_tile, src_trackdir, type, subtype);
00791   } else if (IsTileType(src_tile, MP_TUNNELBRIDGE) && GetTunnelBridgeDirection(src_tile) == src_exitdir) {
00792     /* We drive through the wormhole and arrive on the other side */
00793     dst_tile = GetOtherTunnelBridgeEnd(src_tile);
00794     trackdirbits = TrackdirToTrackdirBits(src_trackdir);
00795   } else if (ForceReverse(src_tile, src_exitdir, type, subtype)) {
00796     /* We can only reverse on this tile */
00797     dst_tile = src_tile;
00798     src_trackdir = ReverseTrackdir(src_trackdir);
00799     trackdirbits = TrackdirToTrackdirBits(src_trackdir);
00800   } else {
00801     /* We leave src_tile in src_exitdir and reach dst_tile */
00802     dst_tile = AddTileIndexDiffCWrap(src_tile, TileIndexDiffCByDiagDir(src_exitdir));
00803 
00804     if (dst_tile != INVALID_TILE && !CanEnterTile(dst_tile, src_exitdir, type, subtype, (RailTypes)aystar->user_data[NPF_RAILTYPES], (Owner)aystar->user_data[NPF_OWNER])) dst_tile = INVALID_TILE;
00805 
00806     if (dst_tile == INVALID_TILE) {
00807       /* We cannot enter the next tile. Road vehicles can reverse, others reach dead end */
00808       if (type != TRANSPORT_ROAD || HasBit(subtype, ROADTYPE_TRAM)) return;
00809 
00810       dst_tile = src_tile;
00811       src_trackdir = ReverseTrackdir(src_trackdir);
00812     }
00813 
00814     trackdirbits = GetDriveableTrackdirBits(dst_tile, src_trackdir, type, subtype);
00815 
00816     if (trackdirbits == 0) {
00817       /* We cannot enter the next tile. Road vehicles can reverse, others reach dead end */
00818       if (type != TRANSPORT_ROAD || HasBit(subtype, ROADTYPE_TRAM)) return;
00819 
00820       dst_tile = src_tile;
00821       src_trackdir = ReverseTrackdir(src_trackdir);
00822 
00823       trackdirbits = GetDriveableTrackdirBits(dst_tile, src_trackdir, type, subtype);
00824     }
00825   }
00826 
00827   if (NPFGetFlag(&current->path.node, NPF_FLAG_IGNORE_RESERVED)) {
00828     /* Mask out any reserved tracks. */
00829     TrackBits reserved = GetReservedTrackbits(dst_tile);
00830     trackdirbits &= ~TrackBitsToTrackdirBits(reserved);
00831 
00832     uint bits = TrackdirBitsToTrackBits(trackdirbits);
00833     int i;
00834     FOR_EACH_SET_BIT(i, bits) {
00835       if (TracksOverlap(reserved | TrackToTrackBits((Track)i))) trackdirbits &= ~TrackToTrackdirBits((Track)i);
00836     }
00837   }
00838 
00839   /* Enumerate possible track */
00840   uint i = 0;
00841   while (trackdirbits != 0) {
00842     Trackdir dst_trackdir = RemoveFirstTrackdir(&trackdirbits);
00843     DEBUG(npf, 5, "Expanded into trackdir: %d, remaining trackdirs: 0x%X", dst_trackdir, trackdirbits);
00844 
00845     /* Tile with signals? */
00846     if (IsTileType(dst_tile, MP_RAILWAY) && GetRailTileType(dst_tile) == RAIL_TILE_SIGNALS) {
00847       if (HasSignalOnTrackdir(dst_tile, ReverseTrackdir(dst_trackdir)) && !HasSignalOnTrackdir(dst_tile, dst_trackdir) && IsOnewaySignal(dst_tile, TrackdirToTrack(dst_trackdir)))
00848         /* If there's a one-way signal not pointing towards us, stop going in this direction. */
00849         break;
00850     }
00851     {
00852       /* We've found ourselves a neighbour :-) */
00853       AyStarNode *neighbour = &aystar->neighbours[i];
00854       neighbour->tile = dst_tile;
00855       neighbour->direction = dst_trackdir;
00856       /* Save user data */
00857       neighbour->user_data[NPF_NODE_FLAGS] = current->path.node.user_data[NPF_NODE_FLAGS];
00858       NPFFillTrackdirChoice(neighbour, current);
00859     }
00860     i++;
00861   }
00862   aystar->num_neighbours = i;
00863 }
00864 
00865 /*
00866  * Plan a route to the specified target (which is checked by target_proc),
00867  * from start1 and if not NULL, from start2 as well. The type of transport we
00868  * are checking is in type. reverse_penalty is applied to all routes that
00869  * originate from the second start node.
00870  * When we are looking for one specific target (optionally multiple tiles), we
00871  * should use a good heuristic to perform aystar search. When we search for
00872  * multiple targets that are spread around, we should perform a breadth first
00873  * search by specifiying CalcZero as our heuristic.
00874  */
00875 static NPFFoundTargetData NPFRouteInternal(AyStarNode *start1, bool ignore_start_tile1, AyStarNode *start2, bool ignore_start_tile2, NPFFindStationOrTileData *target, AyStar_EndNodeCheck target_proc, AyStar_CalculateH heuristic_proc, TransportType type, uint sub_type, Owner owner, RailTypes railtypes, uint reverse_penalty)
00876 {
00877   int r;
00878   NPFFoundTargetData result;
00879 
00880   /* Initialize procs */
00881   _npf_aystar.CalculateH = heuristic_proc;
00882   _npf_aystar.EndNodeCheck = target_proc;
00883   _npf_aystar.FoundEndNode = NPFSaveTargetData;
00884   _npf_aystar.GetNeighbours = NPFFollowTrack;
00885   switch (type) {
00886     default: NOT_REACHED();
00887     case TRANSPORT_RAIL:  _npf_aystar.CalculateG = NPFRailPathCost;  break;
00888     case TRANSPORT_ROAD:  _npf_aystar.CalculateG = NPFRoadPathCost;  break;
00889     case TRANSPORT_WATER: _npf_aystar.CalculateG = NPFWaterPathCost; break;
00890   }
00891 
00892   /* Initialize Start Node(s) */
00893   start1->user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
00894   start1->user_data[NPF_NODE_FLAGS] = 0;
00895   NPFSetFlag(start1, NPF_FLAG_IGNORE_START_TILE, ignore_start_tile1);
00896   _npf_aystar.addstart(&_npf_aystar, start1, 0);
00897   if (start2) {
00898     start2->user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
00899     start2->user_data[NPF_NODE_FLAGS] = 0;
00900     NPFSetFlag(start2, NPF_FLAG_IGNORE_START_TILE, ignore_start_tile2);
00901     NPFSetFlag(start2, NPF_FLAG_REVERSE, true);
00902     _npf_aystar.addstart(&_npf_aystar, start2, reverse_penalty);
00903   }
00904 
00905   /* Initialize result */
00906   result.best_bird_dist = UINT_MAX;
00907   result.best_path_dist = UINT_MAX;
00908   result.best_trackdir  = INVALID_TRACKDIR;
00909   result.node.tile      = INVALID_TILE;
00910   result.res_okay       = false;
00911   _npf_aystar.user_path = &result;
00912 
00913   /* Initialize target */
00914   _npf_aystar.user_target = target;
00915 
00916   /* Initialize user_data */
00917   _npf_aystar.user_data[NPF_TYPE] = type;
00918   _npf_aystar.user_data[NPF_SUB_TYPE] = sub_type;
00919   _npf_aystar.user_data[NPF_OWNER] = owner;
00920   _npf_aystar.user_data[NPF_RAILTYPES] = railtypes;
00921 
00922   /* GO! */
00923   r = AyStarMain_Main(&_npf_aystar);
00924   assert(r != AYSTAR_STILL_BUSY);
00925 
00926   if (result.best_bird_dist != 0) {
00927     if (target != NULL) {
00928       DEBUG(npf, 1, "Could not find route to tile 0x%X from 0x%X.", target->dest_coords, start1->tile);
00929     } else {
00930       /* Assumption: target == NULL, so we are looking for a depot */
00931       DEBUG(npf, 1, "Could not find route to a depot from tile 0x%X.", start1->tile);
00932     }
00933 
00934   }
00935   return result;
00936 }
00937 
00938 NPFFoundTargetData NPFRouteToStationOrTileTwoWay(TileIndex tile1, Trackdir trackdir1, bool ignore_start_tile1, TileIndex tile2, Trackdir trackdir2, bool ignore_start_tile2, NPFFindStationOrTileData *target, TransportType type, uint sub_type, Owner owner, RailTypes railtypes)
00939 {
00940   AyStarNode start1;
00941   AyStarNode start2;
00942 
00943   start1.tile = tile1;
00944   start2.tile = tile2;
00945   /* We set this in case the target is also the start tile, we will just
00946    * return a not found then */
00947   start1.user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
00948   start1.direction = trackdir1;
00949   start2.direction = trackdir2;
00950   start2.user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
00951 
00952   return NPFRouteInternal(&start1, ignore_start_tile1, (IsValidTile(tile2) ? &start2 : NULL), ignore_start_tile2, target, NPFFindStationOrTile, NPFCalcStationOrTileHeuristic, type, sub_type, owner, railtypes, 0);
00953 }
00954 
00955 NPFFoundTargetData NPFRouteToStationOrTile(TileIndex tile, Trackdir trackdir, bool ignore_start_tile, NPFFindStationOrTileData *target, TransportType type, uint sub_type, Owner owner, RailTypes railtypes)
00956 {
00957   return NPFRouteToStationOrTileTwoWay(tile, trackdir, ignore_start_tile, INVALID_TILE, INVALID_TRACKDIR, false, target, type, sub_type, owner, railtypes);
00958 }
00959 
00960 NPFFoundTargetData NPFRouteToDepotBreadthFirstTwoWay(TileIndex tile1, Trackdir trackdir1, bool ignore_start_tile1, TileIndex tile2, Trackdir trackdir2, bool ignore_start_tile2, TransportType type, uint sub_type, Owner owner, RailTypes railtypes, uint reverse_penalty)
00961 {
00962   AyStarNode start1;
00963   AyStarNode start2;
00964 
00965   start1.tile = tile1;
00966   start2.tile = tile2;
00967   /* We set this in case the target is also the start tile, we will just
00968    * return a not found then */
00969   start1.user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
00970   start1.direction = trackdir1;
00971   start2.direction = trackdir2;
00972   start2.user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
00973 
00974   /* perform a breadth first search. Target is NULL,
00975    * since we are just looking for any depot...*/
00976   return NPFRouteInternal(&start1, ignore_start_tile1, (IsValidTile(tile2) ? &start2 : NULL), ignore_start_tile2, NULL, NPFFindDepot, NPFCalcZero, type, sub_type, owner, railtypes, reverse_penalty);
00977 }
00978 
00979 NPFFoundTargetData NPFRouteToDepotBreadthFirst(TileIndex tile, Trackdir trackdir, bool ignore_start_tile, TransportType type, uint sub_type, Owner owner, RailTypes railtypes)
00980 {
00981   return NPFRouteToDepotBreadthFirstTwoWay(tile, trackdir, ignore_start_tile, INVALID_TILE, INVALID_TRACKDIR, false, type, sub_type, owner, railtypes, 0);
00982 }
00983 
00984 NPFFoundTargetData NPFRouteToDepotTrialError(TileIndex tile, Trackdir trackdir, bool ignore_start_tile, TransportType type, uint sub_type, Owner owner, RailTypes railtypes)
00985 {
00986   /* Okay, what we're gonna do. First, we look at all depots, calculate
00987    * the manhatten distance to get to each depot. We then sort them by
00988    * distance. We start by trying to plan a route to the closest, then
00989    * the next closest, etc. We stop when the best route we have found so
00990    * far, is shorter than the manhattan distance. This will obviously
00991    * always find the closest depot. It will probably be most efficient
00992    * for ships, since the heuristic will not be to far off then. I hope.
00993    */
00994   Queue depots;
00995   int r;
00996   NPFFoundTargetData best_result = {UINT_MAX, UINT_MAX, INVALID_TRACKDIR, {INVALID_TILE, INVALID_TRACKDIR, {0, 0}}, false};
00997   NPFFoundTargetData result;
00998   NPFFindStationOrTileData target;
00999   AyStarNode start;
01000   Depot *current;
01001   Depot *depot;
01002 
01003   init_InsSort(&depots);
01004   /* Okay, let's find all depots that we can use first */
01005   FOR_ALL_DEPOTS(depot) {
01006     /* Check if this is really a valid depot, it is of the needed type and
01007      * owner */
01008     if (IsDepotTypeTile(depot->xy, type) && IsTileOwner(depot->xy, owner))
01009       /* If so, let's add it to the queue, sorted by distance */
01010       depots.push(&depots, depot, DistanceManhattan(tile, depot->xy));
01011   }
01012 
01013   /* Now, let's initialise the aystar */
01014 
01015   /* Initialize procs */
01016   _npf_aystar.CalculateH = NPFCalcStationOrTileHeuristic;
01017   _npf_aystar.EndNodeCheck = NPFFindStationOrTile;
01018   _npf_aystar.FoundEndNode = NPFSaveTargetData;
01019   _npf_aystar.GetNeighbours = NPFFollowTrack;
01020   switch (type) {
01021     default: NOT_REACHED();
01022     case TRANSPORT_RAIL:  _npf_aystar.CalculateG = NPFRailPathCost;  break;
01023     case TRANSPORT_ROAD:  _npf_aystar.CalculateG = NPFRoadPathCost;  break;
01024     case TRANSPORT_WATER: _npf_aystar.CalculateG = NPFWaterPathCost; break;
01025   }
01026 
01027   /* Initialize target */
01028   target.station_index = INVALID_STATION; /* We will initialize dest_coords inside the loop below */
01029   _npf_aystar.user_target = &target;
01030 
01031   /* Initialize user_data */
01032   _npf_aystar.user_data[NPF_TYPE] = type;
01033   _npf_aystar.user_data[NPF_SUB_TYPE] = sub_type;
01034   _npf_aystar.user_data[NPF_OWNER] = owner;
01035 
01036   /* Initialize Start Node */
01037   start.tile = tile;
01038   start.direction = trackdir; /* We will initialize user_data inside the loop below */
01039 
01040   /* Initialize Result */
01041   _npf_aystar.user_path = &result;
01042   best_result.best_path_dist = UINT_MAX;
01043   best_result.best_bird_dist = UINT_MAX;
01044 
01045   /* Just iterate the depots in order of increasing distance */
01046   while ((current = (Depot*)depots.pop(&depots))) {
01047     /* Check to see if we already have a path shorter than this
01048      * depot's manhattan distance. HACK: We call DistanceManhattan
01049      * again, we should probably modify the queue to give us that
01050      * value... */
01051     if ( DistanceManhattan(tile, current->xy * NPF_TILE_LENGTH) > best_result.best_path_dist)
01052       break;
01053 
01054     /* Initialize Start Node */
01055     /* We set this in case the target is also the start tile, we will just
01056      * return a not found then */
01057     start.user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
01058     start.user_data[NPF_NODE_FLAGS] = 0;
01059     NPFSetFlag(&start, NPF_FLAG_IGNORE_START_TILE, ignore_start_tile);
01060     _npf_aystar.addstart(&_npf_aystar, &start, 0);
01061 
01062     /* Initialize result */
01063     result.best_bird_dist = UINT_MAX;
01064     result.best_path_dist = UINT_MAX;
01065     result.best_trackdir = INVALID_TRACKDIR;
01066 
01067     /* Initialize target */
01068     target.dest_coords = current->xy;
01069 
01070     /* GO! */
01071     r = AyStarMain_Main(&_npf_aystar);
01072     assert(r != AYSTAR_STILL_BUSY);
01073 
01074     /* This depot is closer */
01075     if (result.best_path_dist < best_result.best_path_dist)
01076       best_result = result;
01077   }
01078   if (result.best_bird_dist != 0) {
01079     DEBUG(npf, 1, "Could not find route to any depot from tile 0x%X.", tile);
01080   }
01081   return best_result;
01082 }
01083 
01084 NPFFoundTargetData NPFRouteToSafeTile(const Vehicle *v, TileIndex tile, Trackdir trackdir, bool override_railtype)
01085 {
01086   assert(v->type == VEH_TRAIN);
01087 
01088   NPFFindStationOrTileData fstd;
01089   fstd.v = v;
01090   fstd.reserve_path = true;
01091 
01092   AyStarNode start1;
01093   start1.tile = tile;
01094   /* We set this in case the target is also the start tile, we will just
01095    * return a not found then */
01096   start1.user_data[NPF_TRACKDIR_CHOICE] = INVALID_TRACKDIR;
01097   start1.direction = trackdir;
01098   NPFSetFlag(&start1, NPF_FLAG_IGNORE_RESERVED, true);
01099 
01100   RailTypes railtypes = v->u.rail.compatible_railtypes;
01101   if (override_railtype) railtypes |= GetRailTypeInfo(v->u.rail.railtype)->compatible_railtypes;
01102 
01103   /* perform a breadth first search. Target is NULL,
01104    * since we are just looking for any safe tile...*/
01105   return NPFRouteInternal(&start1, true, NULL, false, &fstd, NPFFindSafeTile, NPFCalcZero, TRANSPORT_RAIL, 0, v->owner, railtypes, 0);
01106 }
01107 
01108 void InitializeNPF()
01109 {
01110   static bool first_init = true;
01111   if (first_init) {
01112     first_init = false;
01113     init_AyStar(&_npf_aystar, NPFHash, NPF_HASH_SIZE);
01114   } else {
01115     AyStarMain_Clear(&_npf_aystar);
01116   }
01117   _npf_aystar.loops_per_tick = 0;
01118   _npf_aystar.max_path_cost = 0;
01119   //_npf_aystar.max_search_nodes = 0;
01120   /* We will limit the number of nodes for now, until we have a better
01121    * solution to really fix performance */
01122   _npf_aystar.max_search_nodes = _settings_game.pf.npf.npf_max_search_nodes;
01123 }
01124 
01125 void NPFFillWithOrderData(NPFFindStationOrTileData *fstd, Vehicle *v, bool reserve_path)
01126 {
01127   /* Ships don't really reach their stations, but the tile in front. So don't
01128    * save the station id for ships. For roadvehs we don't store it either,
01129    * because multistop depends on vehicles actually reaching the exact
01130    * dest_tile, not just any stop of that station.
01131    * So only for train orders to stations we fill fstd->station_index, for all
01132    * others only dest_coords */
01133   if (v->current_order.IsType(OT_GOTO_STATION) && v->type == VEH_TRAIN) {
01134     fstd->station_index = v->current_order.GetDestination();
01135     /* Let's take the closest tile of the station as our target for trains */
01136     fstd->dest_coords = CalcClosestStationTile(fstd->station_index, v->tile);
01137   } else {
01138     fstd->dest_coords = v->dest_tile;
01139     fstd->station_index = INVALID_STATION;
01140   }
01141   fstd->reserve_path = reserve_path;
01142   fstd->v = v;
01143 }

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