/* $Id$ */ /** @file pathfind.cpp Implementation of the oldest supported pathfinder. */ #include "stdafx.h" #include "station_map.h" #include "settings_type.h" #include "pathfind.h" #include "debug.h" #include "tunnelbridge_map.h" #include "core/random_func.hpp" #include "core/alloc_type.hpp" #include "tunnelbridge.h" /* remember which tiles we have already visited so we don't visit them again. */ static bool TPFSetTileBit(TrackPathFinder *tpf, TileIndex tile, int dir) { uint hash, val, offs; TrackPathFinderLink *link, *new_link; uint bits = 1 << dir; if (tpf->disable_tile_hash) return true; hash = PATHFIND_HASH_TILE(tile); val = tpf->hash_head[hash]; if (val == 0) { /* unused hash entry, set the appropriate bit in it and return true * to indicate that a bit was set. */ tpf->hash_head[hash] = bits; tpf->hash_tile[hash] = tile; return true; } else if (!(val & 0x8000)) { /* single tile */ if (tile == tpf->hash_tile[hash]) { /* found another bit for the same tile, * check if this bit is already set, if so, return false */ if (val & bits) return false; /* otherwise set the bit and return true to indicate that the bit * was set */ tpf->hash_head[hash] = val | bits; return true; } else { /* two tiles with the same hash, need to make a link */ /* allocate a link. if out of links, handle this by returning * that a tile was already visisted. */ if (tpf->num_links_left == 0) { return false; } tpf->num_links_left--; link = tpf->new_link++; /* move the data that was previously in the hash_??? variables * to the link struct, and let the hash variables point to the link */ link->tile = tpf->hash_tile[hash]; tpf->hash_tile[hash] = PATHFIND_GET_LINK_OFFS(tpf, link); link->flags = tpf->hash_head[hash]; tpf->hash_head[hash] = 0xFFFF; // multi link link->next = 0xFFFF; } } else { /* a linked list of many tiles, * find the one corresponding to the tile, if it exists. * otherwise make a new link */ offs = tpf->hash_tile[hash]; do { link = PATHFIND_GET_LINK_PTR(tpf, offs); if (tile == link->tile) { /* found the tile in the link list, * check if the bit was alrady set, if so return false to indicate that the * bit was already set */ if (link->flags & bits) return false; link->flags |= bits; return true; } } while ((offs=link->next) != 0xFFFF); } /* get here if we need to add a new link to link, * first, allocate a new link, in the same way as before */ if (tpf->num_links_left == 0) { return false; } tpf->num_links_left--; new_link = tpf->new_link++; /* then fill the link with the new info, and establish a ptr from the old * link to the new one */ new_link->tile = tile; new_link->flags = bits; new_link->next = 0xFFFF; link->next = PATHFIND_GET_LINK_OFFS(tpf, new_link); return true; } static void TPFModeShip(TrackPathFinder *tpf, TileIndex tile, DiagDirection direction) { assert(tpf->tracktype == TRANSPORT_WATER); if (IsTileType(tile, MP_TUNNELBRIDGE)) { /* wrong track type */ if (GetTunnelBridgeTransportType(tile) != tpf->tracktype) return; DiagDirection dir = GetTunnelBridgeDirection(tile); /* entering tunnel / bridge? */ if (dir == direction) { TileIndex endtile = GetOtherTunnelBridgeEnd(tile); tpf->rd.cur_length += GetTunnelBridgeLength(tile, endtile) + 1; TPFSetTileBit(tpf, tile, 14); TPFSetTileBit(tpf, endtile, 14); tile = endtile; } else { /* leaving tunnel / bridge? */ if (ReverseDiagDir(dir) != direction) return; } } /* This addition will sometimes overflow by a single tile. * The use of TILE_MASK here makes sure that we still point at a valid * tile, and then this tile will be in the sentinel row/col, so GetTileTrackStatus will fail. */ tile = TILE_MASK(tile + TileOffsByDiagDir(direction)); if (++tpf->rd.cur_length > 50) return; TrackBits bits = TrackStatusToTrackBits(GetTileTrackStatus(tile, tpf->tracktype, tpf->sub_type)) & DiagdirReachesTracks(direction); if (bits == TRACK_BIT_NONE) return; assert(TileX(tile) != MapMaxX() && TileY(tile) != MapMaxY()); bool only_one_track = true; do { Track track = RemoveFirstTrack(&bits); if (bits != TRACK_BIT_NONE) only_one_track = false; RememberData rd = tpf->rd; /* Change direction 4 times only */ if (!only_one_track && track != tpf->rd.last_choosen_track) { if (++tpf->rd.depth > 4) { tpf->rd = rd; return; } tpf->rd.last_choosen_track = track; } tpf->the_dir = TrackEnterdirToTrackdir(track, direction); if (!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length)) { TPFModeShip(tpf, tile, TrackdirToExitdir(tpf->the_dir)); } tpf->rd = rd; } while (bits != TRACK_BIT_NONE); } /** * Checks if any vehicle can enter/leave tile in given diagdir * Checks only for rail/road depots and road non-drivethrough stations * @param tile tile to check * @param side side of tile we are trying to leave/enter * @param tracktype type of transport * @pre tile has trackbit at that diagdir * @return true iff vehicle can enter/leve the tile in given side */ static inline bool CanAccessTileInDir(TileIndex tile, DiagDirection side, TransportType tracktype) { if (tracktype == TRANSPORT_RAIL) { /* depot from wrong side */ if (IsRailDepotTile(tile) && GetRailDepotDirection(tile) != side) return false; } else if (tracktype == TRANSPORT_ROAD) { /* depot from wrong side */ if (IsRoadDepotTile(tile) && GetRoadDepotDirection(tile) != side) return false; /* non-driverthrough road station from wrong side */ if (IsStandardRoadStopTile(tile) && GetRoadStopDir(tile) != side) return false; } return true; } static void TPFModeNormal(TrackPathFinder *tpf, TileIndex tile, DiagDirection direction) { const TileIndex tile_org = tile; if (IsTileType(tile, MP_TUNNELBRIDGE)) { /* wrong track type */ if (GetTunnelBridgeTransportType(tile) != tpf->tracktype) return; DiagDirection dir = GetTunnelBridgeDirection(tile); /* entering tunnel / bridge? */ if (dir == direction) { TileIndex endtile = GetOtherTunnelBridgeEnd(tile); tpf->rd.cur_length += GetTunnelBridgeLength(tile, endtile) + 1; TPFSetTileBit(tpf, tile, 14); TPFSetTileBit(tpf, endtile, 14); tile = endtile; } else { /* leaving tunnel / bridge? */ if (ReverseDiagDir(dir) != direction) return; } } else { /* can we leave tile in this dir? */ if (!CanAccessTileInDir(tile, direction, tpf->tracktype)) return; } tile += TileOffsByDiagDir(direction); /* can we enter tile in this dir? */ if (!CanAccessTileInDir(tile, ReverseDiagDir(direction), tpf->tracktype)) return; /* Check if the new tile is a tunnel or bridge head and that the direction * and transport type match */ if (IsTileType(tile, MP_TUNNELBRIDGE)) { if (GetTunnelBridgeDirection(tile) != direction || GetTunnelBridgeTransportType(tile) != tpf->tracktype) { return; } } TrackdirBits trackdirbits = TrackStatusToTrackdirBits(GetTileTrackStatus(tile, tpf->tracktype, tpf->sub_type)); /* Check in case of rail if the owner is the same */ if (tpf->tracktype == TRANSPORT_RAIL) { if (trackdirbits != TRACKDIR_BIT_NONE && TrackStatusToTrackdirBits(GetTileTrackStatus(tile_org, TRANSPORT_RAIL, 0)) != TRACKDIR_BIT_NONE) { if (GetTileOwner(tile_org) != GetTileOwner(tile)) return; } } tpf->rd.cur_length++; trackdirbits &= DiagdirReachesTrackdirs(direction); TrackBits bits = TrackdirBitsToTrackBits(trackdirbits); if (bits != TRACK_BIT_NONE) { if (!tpf->disable_tile_hash || (tpf->rd.cur_length <= 64 && (KillFirstBit(bits) == 0 || ++tpf->rd.depth <= 7))) { do { Track track = RemoveFirstTrack(&bits); tpf->the_dir = TrackEnterdirToTrackdir(track, direction); RememberData rd = tpf->rd; /* make sure we are not leaving from invalid side */ if (TPFSetTileBit(tpf, tile, tpf->the_dir) && CanAccessTileInDir(tile, TrackdirToExitdir(tpf->the_dir), tpf->tracktype) && !tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length) ) { TPFModeNormal(tpf, tile, TrackdirToExitdir(tpf->the_dir)); } tpf->rd = rd; } while (bits != TRACK_BIT_NONE); } } } void FollowTrack(TileIndex tile, PathfindFlags flags, TransportType tt, uint sub_type, DiagDirection direction, TPFEnumProc *enum_proc, TPFAfterProc *after_proc, void *data) { assert(IsValidDiagDirection(direction)); SmallStackSafeStackAlloc<TrackPathFinder, 1> tpf; /* initialize path finder variables */ tpf->userdata = data; tpf->enum_proc = enum_proc; tpf->new_link = tpf->links; tpf->num_links_left = lengthof(tpf->links); tpf->rd.cur_length = 0; tpf->rd.depth = 0; tpf->rd.last_choosen_track = INVALID_TRACK; tpf->disable_tile_hash = (flags & PATHFIND_FLAGS_DISABLE_TILE_HASH) != 0; tpf->tracktype = tt; tpf->sub_type = sub_type; if ((flags & PATHFIND_FLAGS_SHIP_MODE) != 0) { tpf->enum_proc(tile, data, INVALID_TRACKDIR, 0); TPFModeShip(tpf, tile, direction); } else { /* clear the hash_heads */ memset(tpf->hash_head, 0, sizeof(tpf->hash_head)); TPFModeNormal(tpf, tile, direction); } if (after_proc != NULL) after_proc(tpf); } struct StackedItem { TileIndex tile; uint16 cur_length; ///< This is the current length to this tile. uint16 priority; ///< This is the current length + estimated length to the goal. TrackdirByte track; byte depth; byte state; byte first_track; }; struct HashLink { TileIndex tile; uint16 typelength; uint16 next; }; struct NewTrackPathFinder { NTPEnumProc *enum_proc; void *userdata; TileIndex dest; TransportType tracktype; RailTypes railtypes; uint maxlength; HashLink *new_link; uint num_links_left; uint nstack; StackedItem stack[256]; ///< priority queue of stacked items uint16 hash_head[0x400]; ///< hash heads. 0 means unused. 0xFFFC = length, 0x3 = dir TileIndex hash_tile[0x400]; ///< tiles. or links. HashLink links[0x400]; ///< hash links }; #define NTP_GET_LINK_OFFS(tpf, link) ((byte*)(link) - (byte*)tpf->links) #define NTP_GET_LINK_PTR(tpf, link_offs) (HashLink*)((byte*)tpf->links + (link_offs)) #define ARR(i) tpf->stack[(i)-1] /** called after a new element was added in the queue at the last index. * move it down to the proper position */ static inline void HeapifyUp(NewTrackPathFinder *tpf) { StackedItem si; int i = ++tpf->nstack; while (i != 1 && ARR(i).priority < ARR(i>>1).priority) { /* the child element is larger than the parent item. * swap the child item and the parent item. */ si = ARR(i); ARR(i) = ARR(i >> 1); ARR(i >> 1) = si; i >>= 1; } } /** called after the element 0 was eaten. fill it with a new element */ static inline void HeapifyDown(NewTrackPathFinder *tpf) { StackedItem si; int i = 1, j; int n; assert(tpf->nstack > 0); n = --tpf->nstack; if (n == 0) return; // heap is empty so nothing to do? /* copy the last item to index 0. we use it as base for heapify. */ ARR(1) = ARR(n + 1); while ((j = i * 2) <= n) { /* figure out which is smaller of the children. */ if (j != n && ARR(j).priority > ARR(j + 1).priority) j++; // right item is smaller assert(i <= n && j <= n); if (ARR(i).priority <= ARR(j).priority) break; // base elem smaller than smallest, done! /* swap parent with the child */ si = ARR(i); ARR(i) = ARR(j); ARR(j) = si; i = j; } } /** mark a tile as visited and store the length of the path. * if we already had a better path to this tile, return false. * otherwise return true. */ static bool NtpVisit(NewTrackPathFinder *tpf, TileIndex tile, DiagDirection dir, uint length) { uint hash,head; HashLink *link, *new_link; assert(length < 16384-1); hash = PATHFIND_HASH_TILE(tile); /* never visited before? */ if ((head=tpf->hash_head[hash]) == 0) { tpf->hash_tile[hash] = tile; tpf->hash_head[hash] = dir | (length << 2); return true; } if (head != 0xffff) { if (tile == tpf->hash_tile[hash] && (head & 0x3) == (uint)dir) { /* longer length */ if (length >= (head >> 2)) return false; tpf->hash_head[hash] = dir | (length << 2); return true; } /* two tiles with the same hash, need to make a link * allocate a link. if out of links, handle this by returning * that a tile was already visisted. */ if (tpf->num_links_left == 0) { DEBUG(ntp, 1, "No links left"); return false; } tpf->num_links_left--; link = tpf->new_link++; /* move the data that was previously in the hash_??? variables * to the link struct, and let the hash variables point to the link */ link->tile = tpf->hash_tile[hash]; tpf->hash_tile[hash] = NTP_GET_LINK_OFFS(tpf, link); link->typelength = tpf->hash_head[hash]; tpf->hash_head[hash] = 0xFFFF; // multi link link->next = 0xFFFF; } else { /* a linked list of many tiles, * find the one corresponding to the tile, if it exists. * otherwise make a new link */ uint offs = tpf->hash_tile[hash]; do { link = NTP_GET_LINK_PTR(tpf, offs); if (tile == link->tile && (link->typelength & 0x3U) == (uint)dir) { if (length >= (uint)(link->typelength >> 2)) return false; link->typelength = dir | (length << 2); return true; } } while ((offs = link->next) != 0xFFFF); } /* get here if we need to add a new link to link, * first, allocate a new link, in the same way as before */ if (tpf->num_links_left == 0) { DEBUG(ntp, 1, "No links left"); return false; } tpf->num_links_left--; new_link = tpf->new_link++; /* then fill the link with the new info, and establish a ptr from the old * link to the new one */ new_link->tile = tile; new_link->typelength = dir | (length << 2); new_link->next = 0xFFFF; link->next = NTP_GET_LINK_OFFS(tpf, new_link); return true; } /** * Checks if the shortest path to the given tile/dir so far is still the given * length. * @return true if the length is still the same * @pre The given tile/dir combination should be present in the hash, by a * previous call to NtpVisit(). */ static bool NtpCheck(NewTrackPathFinder *tpf, TileIndex tile, uint dir, uint length) { uint hash,head,offs; HashLink *link; hash = PATHFIND_HASH_TILE(tile); head=tpf->hash_head[hash]; assert(head); if (head != 0xffff) { assert( tpf->hash_tile[hash] == tile && (head & 3) == dir); assert( (head >> 2) <= length); return length == (head >> 2); } /* else it's a linked list of many tiles */ offs = tpf->hash_tile[hash]; for (;;) { link = NTP_GET_LINK_PTR(tpf, offs); if (tile == link->tile && (link->typelength & 0x3U) == dir) { assert((uint)(link->typelength >> 2) <= length); return length == (uint)(link->typelength >> 2); } offs = link->next; assert(offs != 0xffff); } } static uint DistanceMoo(TileIndex t0, TileIndex t1) { const uint dx = Delta(TileX(t0), TileX(t1)); const uint dy = Delta(TileY(t0), TileY(t1)); const uint straightTracks = 2 * min(dx, dy); // The number of straight (not full length) tracks /* OPTIMISATION: * Original: diagTracks = max(dx, dy) - min(dx,dy); * Proof: * (dx-dy) - straightTracks == (min + max) - straightTracks = min + // max - 2 * min = max - min */ const uint diagTracks = dx + dy - straightTracks; // The number of diagonal (full tile length) tracks. return diagTracks*DIAG_FACTOR + straightTracks*STR_FACTOR; } /* These has to be small cause the max length of a track * is currently limited to 16384 */ static const byte _length_of_track[16] = { DIAG_FACTOR, DIAG_FACTOR, STR_FACTOR, STR_FACTOR, STR_FACTOR, STR_FACTOR, 0, 0, DIAG_FACTOR, DIAG_FACTOR, STR_FACTOR, STR_FACTOR, STR_FACTOR, STR_FACTOR, 0, 0 }; /* new more optimized pathfinder for trains... * Tile is the tile the train is at. * direction is the tile the train is moving towards. */ static void NTPEnum(NewTrackPathFinder *tpf, TileIndex tile, DiagDirection direction) { TrackBits bits, allbits; Trackdir track; TileIndex tile_org; StackedItem si; int estimation; /* Need to have a special case for the start. * We shouldn't call the callback for the current tile. */ si.cur_length = 1; // Need to start at 1 cause 0 is a reserved value. si.depth = 0; si.state = 0; si.first_track = 0xFF; goto start_at; for (;;) { /* Get the next item to search from from the priority queue */ do { if (tpf->nstack == 0) return; // nothing left? then we're done! si = tpf->stack[0]; tile = si.tile; HeapifyDown(tpf); /* Make sure we havn't already visited this tile. */ } while (!NtpCheck(tpf, tile, ReverseDiagDir(TrackdirToExitdir(ReverseTrackdir(si.track))), si.cur_length)); /* Add the length of this track. */ si.cur_length += _length_of_track[si.track]; callback_and_continue: if (tpf->enum_proc(tile, tpf->userdata, si.first_track, si.cur_length)) return; assert(si.track <= 13); direction = TrackdirToExitdir(si.track); start_at: /* If the tile is the entry tile of a tunnel, and we're not going out of the tunnel, * need to find the exit of the tunnel. */ if (IsTileType(tile, MP_TUNNELBRIDGE)) { if (GetTunnelBridgeDirection(tile) != ReverseDiagDir(direction)) { /* We are not just driving out of the tunnel/bridge */ if (GetTunnelBridgeDirection(tile) != direction || GetTunnelBridgeTransportType(tile) != tpf->tracktype) { /* We are not driving into the tunnel/bridge, or it is an invalid tunnel/bridge */ continue; } if (!HasBit(tpf->railtypes, GetRailType(tile))) { bits = TRACK_BIT_NONE; break; } TileIndex endtile = GetOtherTunnelBridgeEnd(tile); si.cur_length += DIAG_FACTOR * (GetTunnelBridgeLength(tile, endtile) + 1); tile = endtile; /* tile now points to the exit tile of the tunnel/bridge */ } } /* This is a special loop used to go through * a rail net and find the first intersection */ tile_org = tile; for (;;) { assert(direction <= 3); tile += TileOffsByDiagDir(direction); /* too long search length? bail out. */ if (si.cur_length >= tpf->maxlength) { DEBUG(ntp, 1, "Cur_length too big"); bits = TRACK_BIT_NONE; break; } /* Not a regular rail tile? * Then we can't use the code below, but revert to more general code. */ if (!IsTileType(tile, MP_RAILWAY) || !IsPlainRailTile(tile)) { /* We found a tile which is not a normal railway tile. * Determine which tracks that exist on this tile. */ bits = TrackdirBitsToTrackBits(TrackStatusToTrackdirBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)) & DiagdirReachesTrackdirs(direction)); /* Check that the tile contains exactly one track */ if (bits == 0 || KillFirstBit(bits) != 0) break; if (!HasBit(tpf->railtypes, GetRailType(tile))) { bits = TRACK_BIT_NONE; break; } /******************* * If we reach here, the tile has exactly one track. * tile - index to a tile that is not rail tile, but still straight (with optional signals) * bits - bitmask of which track that exist on the tile (exactly one bit is set) * direction - which direction are we moving in? *******************/ si.track = TrackEnterdirToTrackdir(FindFirstTrack(bits), direction); si.cur_length += _length_of_track[si.track]; goto callback_and_continue; } /* Regular rail tile, determine which tracks exist. */ allbits = GetTrackBits(tile); /* Which tracks are reachable? */ bits = allbits & DiagdirReachesTracks(direction); /* The tile has no reachable tracks => End of rail segment * or Intersection => End of rail segment. We check this agains all the * bits, not just reachable ones, to prevent infinite loops. */ if (bits == TRACK_BIT_NONE || TracksOverlap(allbits)) break; if (!HasBit(tpf->railtypes, GetRailType(tile))) { bits = TRACK_BIT_NONE; break; } /* If we reach here, the tile has exactly one track, and this track is reachable = > Rail segment continues */ track = TrackEnterdirToTrackdir(FindFirstTrack(bits), direction); assert(track != INVALID_TRACKDIR); si.cur_length += _length_of_track[track]; /* Check if this rail is an upwards slope. If it is, then add a penalty. */ if (IsDiagonalTrackdir(track) && IsUphillTrackdir(GetTileSlope(tile, NULL), track)) { /* upwards slope. add some penalty. */ si.cur_length += 4 * DIAG_FACTOR; } /* railway tile with signals..? */ if (HasSignals(tile)) { if (!HasSignalOnTrackdir(tile, track)) { /* if one way signal not pointing towards us, stop going in this direction => End of rail segment. */ if (HasSignalOnTrackdir(tile, ReverseTrackdir(track)) && IsOnewaySignal(tile, TrackdirToTrack(track))) { bits = TRACK_BIT_NONE; break; } } else if (GetSignalStateByTrackdir(tile, track) == SIGNAL_STATE_GREEN) { /* green signal in our direction. either one way or two way. */ si.state |= 3; } else { /* reached a red signal. */ if (HasSignalOnTrackdir(tile, ReverseTrackdir(track))) { /* two way red signal. unless we passed another green signal on the way, * stop going in this direction => End of rail segment. * this is to prevent us from going into a full platform. */ if (!(si.state & 1)) { bits = TRACK_BIT_NONE; break; } } if (!(si.state & 2)) { /* Is this the first signal we see? And it's red... add penalty */ si.cur_length += 10 * DIAG_FACTOR; si.state += 2; // remember that we added penalty. /* Because we added a penalty, we can't just continue as usual. * Need to get out and let A* do it's job with * possibly finding an even shorter path. */ break; } } if (tpf->enum_proc(tile, tpf->userdata, si.first_track, si.cur_length)) return; // Don't process this tile any further } /* continue with the next track */ direction = TrackdirToExitdir(track); /* safety check if we're running around chasing our tail... (infinite loop) */ if (tile == tile_org) { bits = TRACK_BIT_NONE; break; } } /* There are no tracks to choose between. * Stop searching in this direction */ if (bits == TRACK_BIT_NONE) continue; /**************** * We got multiple tracks to choose between (intersection). * Branch the search space into several branches. ****************/ /* Check if we've already visited this intersection. * If we've already visited it with a better length, then * there's no point in visiting it again. */ if (!NtpVisit(tpf, tile, direction, si.cur_length)) continue; /* Push all possible alternatives that we can reach from here * onto the priority heap. * 'bits' contains the tracks that we can choose between. */ /* First compute the estimated distance to the target. * This is used to implement A* */ estimation = 0; if (tpf->dest != 0) estimation = DistanceMoo(tile, tpf->dest); si.depth++; if (si.depth == 0) continue; // We overflowed our depth. No more searching in this direction. si.tile = tile; while (bits != TRACK_BIT_NONE) { Track track = RemoveFirstTrack(&bits); si.track = TrackEnterdirToTrackdir(track, direction); assert(si.track != 0xFF); si.priority = si.cur_length + estimation; /* out of stack items, bail out? */ if (tpf->nstack >= lengthof(tpf->stack)) { DEBUG(ntp, 1, "Out of stack"); break; } tpf->stack[tpf->nstack] = si; HeapifyUp(tpf); }; /* If this is the first intersection, we need to fill the first_track member. * so the code outside knows which path is better. * also randomize the order in which we search through them. */ if (si.depth == 1) { assert(tpf->nstack == 1 || tpf->nstack == 2 || tpf->nstack == 3); if (tpf->nstack != 1) { uint32 r = Random(); if (r & 1) Swap(tpf->stack[0].track, tpf->stack[1].track); if (tpf->nstack != 2) { TrackdirByte t = tpf->stack[2].track; if (r & 2) Swap(tpf->stack[0].track, t); if (r & 4) Swap(tpf->stack[1].track, t); tpf->stack[2].first_track = tpf->stack[2].track = t; } tpf->stack[0].first_track = tpf->stack[0].track; tpf->stack[1].first_track = tpf->stack[1].track; } } /* Continue with the next from the queue... */ } } /** new pathfinder for trains. better and faster. */ void NewTrainPathfind(TileIndex tile, TileIndex dest, RailTypes railtypes, DiagDirection direction, NTPEnumProc *enum_proc, void *data) { SmallStackSafeStackAlloc<NewTrackPathFinder, 1> tpf; tpf->dest = dest; tpf->userdata = data; tpf->enum_proc = enum_proc; tpf->tracktype = TRANSPORT_RAIL; tpf->railtypes = railtypes; tpf->maxlength = min(_settings_game.pf.opf.pf_maxlength * 3, 10000); tpf->nstack = 0; tpf->new_link = tpf->links; tpf->num_links_left = lengthof(tpf->links); memset(tpf->hash_head, 0, sizeof(tpf->hash_head)); NTPEnum(tpf, tile, direction); }