/* $Id$ */ /** @file pathfind.cpp */ #include "stdafx.h" #include "openttd.h" #include "bridge_map.h" #include "station_map.h" #include "depot.h" #include "tile_cmd.h" #include "landscape.h" #include "pathfind.h" #include "rail_type.h" #include "debug.h" #include "tunnel_map.h" #include "settings_type.h" #include "depot.h" #include "tunnelbridge_map.h" #include "core/random_func.hpp" /* 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 const byte _bits_mask[4] = { 0x19, 0x16, 0x25, 0x2A, }; static const DiagDirection _tpf_new_direction[14] = { DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SW, DIAGDIR_SE, INVALID_DIAGDIR, INVALID_DIAGDIR, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NE, }; static const DiagDirection _tpf_prev_direction[14] = { DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SE, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SW, INVALID_DIAGDIR, INVALID_DIAGDIR, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NE, DIAGDIR_NW, }; static const byte _otherdir_mask[4] = { 0x10, 0, 0x5, 0x2A, }; static void TPFMode2(TrackPathFinder* tpf, TileIndex tile, DiagDirection direction) { uint bits; RememberData rd; assert(tpf->tracktype == TRANSPORT_WATER); /* 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; bits = GetTileTrackStatus(tile, tpf->tracktype, tpf->sub_type); bits = (byte)((bits | (bits >> 8)) & _bits_mask[direction]); if (bits == 0) return; assert(TileX(tile) != MapMaxX() && TileY(tile) != MapMaxY()); uint i = 0; /* only one direction */ if (KillFirstBit(bits) == 0) { i = FindFirstBit(bits); rd = tpf->rd; goto continue_here; } /* several directions */ do { i = FindFirstBit(bits); rd = tpf->rd; /* Change direction 4 times only */ if ((byte)i != tpf->rd.pft_var6) { if (++tpf->rd.depth > 4) { tpf->rd = rd; return; } tpf->rd.pft_var6 = (byte)i; } continue_here: tpf->the_dir = (Trackdir)(i + (HasBit(_otherdir_mask[direction], i) ? 8 : 0)); if (!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, NULL)) { TPFMode2(tpf, tile, _tpf_new_direction[tpf->the_dir]); } tpf->rd = rd; } while (ClrBit(bits, i) != 0); } /* Returns the end tile and the length of a tunnel. The length does not * include the starting tile (entry), it does include the end tile (exit). */ FindLengthOfTunnelResult FindLengthOfTunnel(TileIndex tile, DiagDirection dir) { TileIndexDiff delta = TileOffsByDiagDir(dir); uint z = GetTileZ(tile); FindLengthOfTunnelResult flotr; flotr.length = 0; dir = ReverseDiagDir(dir); do { flotr.length++; tile += delta; } while( !IsTunnelTile(tile) || GetTunnelBridgeDirection(tile) != dir || GetTileZ(tile) != z ); flotr.tile = tile; return flotr; } static const uint16 _tpfmode1_and[4] = { 0x1009, 0x16, 0x520, 0x2A00 }; static uint SkipToEndOfTunnel(TrackPathFinder* tpf, TileIndex tile, DiagDirection direction) { FindLengthOfTunnelResult flotr; TPFSetTileBit(tpf, tile, 14); flotr = FindLengthOfTunnel(tile, direction); tpf->rd.cur_length += flotr.length; TPFSetTileBit(tpf, flotr.tile, 14); return flotr.tile; } static void TPFMode1(TrackPathFinder* tpf, TileIndex tile, DiagDirection direction) { TileIndex tile_org = tile; if (IsTileType(tile, MP_TUNNELBRIDGE)) { if (IsTunnel(tile)) { if (GetTunnelBridgeTransportType(tile) != tpf->tracktype) { return; } /* Only skip through the tunnel if heading inwards. We can * be headed outwards if our starting position was in a * tunnel and we're pathfinding backwards */ if (GetTunnelBridgeDirection(tile) == direction) { tile = SkipToEndOfTunnel(tpf, tile, direction); } else if (GetTunnelBridgeDirection(tile) != ReverseDiagDir(direction)) { /* We don't support moving through the sides of a tunnel * entrance :-) */ return; } } else { // IsBridge(tile) TileIndex tile_end; if (GetTunnelBridgeDirection(tile) != direction || GetTunnelBridgeTransportType(tile) != tpf->tracktype) { return; } //fprintf(stderr, "%s: Planning over bridge\n", __func__); // TODO doesn't work - WHAT doesn't work? TPFSetTileBit(tpf, tile, 14); tile_end = GetOtherBridgeEnd(tile); tpf->rd.cur_length += DistanceManhattan(tile, tile_end); tile = tile_end; TPFSetTileBit(tpf, tile, 14); } } tile += TileOffsByDiagDir(direction); /* Check in case of rail if the owner is the same */ if (tpf->tracktype == TRANSPORT_RAIL) { /* don't enter train depot from the back */ if (IsTileDepotType(tile, TRANSPORT_RAIL) && GetRailDepotDirection(tile) == direction) return; if (IsTileType(tile_org, MP_RAILWAY) || IsTileType(tile_org, MP_STATION) || IsTileType(tile_org, MP_TUNNELBRIDGE)) if (IsTileType(tile, MP_RAILWAY) || IsTileType(tile, MP_STATION) || IsTileType(tile, MP_TUNNELBRIDGE)) if (GetTileOwner(tile_org) != GetTileOwner(tile)) return; } /* check if the new tile can be entered from that direction */ if (tpf->tracktype == TRANSPORT_ROAD) { /* road stops and depots now have a track (r4419) * don't enter road stop from the back */ if (IsStandardRoadStopTile(tile) && ReverseDiagDir(GetRoadStopDir(tile)) != direction) return; /* don't enter road depot from the back */ if (IsTileDepotType(tile, TRANSPORT_ROAD) && ReverseDiagDir(GetRoadDepotDirection(tile)) != direction) 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; } } tpf->rd.cur_length++; uint bits = GetTileTrackStatus(tile, tpf->tracktype, tpf->sub_type); if ((byte)bits != tpf->var2) { bits &= _tpfmode1_and[direction]; bits |= bits >> 8; } bits &= 0xBF; if (bits != 0) { if (!tpf->disable_tile_hash || (tpf->rd.cur_length <= 64 && (KillFirstBit(bits) == 0 || ++tpf->rd.depth <= 7))) { do { int i = FIND_FIRST_BIT(bits); bits = KillFirstBit(bits); tpf->the_dir = (Trackdir)((_otherdir_mask[direction] & (byte)(1 << i)) ? (i + 8) : i); RememberData rd = tpf->rd; if (TPFSetTileBit(tpf, tile, tpf->the_dir) && !tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, &tpf->rd.pft_var6) ) { TPFMode1(tpf, tile, _tpf_new_direction[tpf->the_dir]); } tpf->rd = rd; } while (bits != 0); } } } void FollowTrack(TileIndex tile, uint16 flags, uint sub_type, DiagDirection direction, TPFEnumProc *enum_proc, TPFAfterProc *after_proc, void *data) { TrackPathFinder tpf; assert(direction < 4); /* 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.pft_var6 = 0; tpf.var2 = HasBit(flags, 15) ? 0x43 : 0xFF; // 0x8000 tpf.disable_tile_hash = HasBit(flags, 12); // 0x1000 tpf.tracktype = (TransportType)(flags & 0xFF); tpf.sub_type = sub_type; if (HasBit(flags, 11)) { tpf.rd.pft_var6 = 0xFF; tpf.enum_proc(tile, data, INVALID_TRACKDIR, 0, 0); TPFMode2(&tpf, tile, direction); } else { /* clear the hash_heads */ memset(tpf.hash_head, 0, sizeof(tpf.hash_head)); TPFMode1(&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; }; static const Trackdir _new_trackdir[6][4] = { {TRACKDIR_X_NE, INVALID_TRACKDIR, TRACKDIR_X_SW, INVALID_TRACKDIR,}, {INVALID_TRACKDIR, TRACKDIR_Y_SE, INVALID_TRACKDIR, TRACKDIR_Y_NW,}, {INVALID_TRACKDIR, TRACKDIR_UPPER_E, TRACKDIR_UPPER_W, INVALID_TRACKDIR,}, {TRACKDIR_LOWER_E, INVALID_TRACKDIR, INVALID_TRACKDIR, TRACKDIR_LOWER_W,}, {TRACKDIR_LEFT_N, TRACKDIR_LEFT_S, INVALID_TRACKDIR, INVALID_TRACKDIR,}, {INVALID_TRACKDIR, INVALID_TRACKDIR, TRACKDIR_RIGHT_S, TRACKDIR_RIGHT_N,}, }; 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 const uint16 _is_upwards_slope[15] = { 0, ///< no tileh (1 << TRACKDIR_X_SW) | (1 << TRACKDIR_Y_NW), ///< 1 (1 << TRACKDIR_X_SW) | (1 << TRACKDIR_Y_SE), ///< 2 (1 << TRACKDIR_X_SW), ///< 3 (1 << TRACKDIR_X_NE) | (1 << TRACKDIR_Y_SE), ///< 4 0, ///< 5 (1 << TRACKDIR_Y_SE), ///< 6 0, ///< 7 (1 << TRACKDIR_X_NE) | (1 << TRACKDIR_Y_NW), ///< 8, (1 << TRACKDIR_Y_NW), ///< 9 0, ///< 10 0, ///< 11, (1 << TRACKDIR_X_NE), ///< 12 0, ///< 13 0, ///< 14 }; 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, _tpf_prev_direction[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 = _tpf_new_direction[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 (IsTunnel(tile)) { if (GetTunnelBridgeDirection(tile) != ReverseDiagDir(direction)) { FindLengthOfTunnelResult flotr; /* We are not just driving out of the tunnel */ if (GetTunnelBridgeDirection(tile) != direction || GetTunnelBridgeTransportType(tile) != tpf->tracktype) { /* We are not driving into the tunnel, or it is an invalid tunnel */ continue; } if (!HasBit(tpf->railtypes, GetRailType(tile))) { bits = TRACK_BIT_NONE; break; } flotr = FindLengthOfTunnel(tile, direction); si.cur_length += flotr.length * DIAG_FACTOR; tile = flotr.tile; /* tile now points to the exit tile of the tunnel */ } } else { // IsBridge(tile) TileIndex tile_end; if (GetTunnelBridgeDirection(tile) != ReverseDiagDir(direction)) { /* We are not just leaving the bridge */ if (GetTunnelBridgeDirection(tile) != direction || GetTunnelBridgeTransportType(tile) != tpf->tracktype) { /* Not entering the bridge or not compatible */ continue; } } tile_end = GetOtherBridgeEnd(tile); si.cur_length += DistanceManhattan(tile, tile_end) * DIAG_FACTOR; tile = tile_end; } } /* 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. */ uint32 ts = GetTileTrackStatus(tile, TRANSPORT_RAIL, 0) & _tpfmode1_and[direction]; bits = TrackdirBitsToTrackBits((TrackdirBits)(ts & TRACKDIR_BIT_MASK)); /* 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 = _new_trackdir[FIND_FIRST_BIT(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 = _new_trackdir[FIND_FIRST_BIT(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. * Small optimization here.. if (track&7)>1 then it can't be a slope so we avoid calling GetTileSlope */ if ((track & 7) <= 1 && (_is_upwards_slope[GetTileSlope(tile, NULL)] & (1 << 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))) { 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 = _tpf_new_direction[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 = _new_trackdir[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) { NewTrackPathFinder tpf; tpf.dest = dest; tpf.userdata = data; tpf.enum_proc = enum_proc; tpf.tracktype = TRANSPORT_RAIL; tpf.railtypes = railtypes; tpf.maxlength = min(_patches.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); }