tunnelbridge_cmd.cpp

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00001 /* $Id: tunnelbridge_cmd.cpp 19665 2010-04-17 22:27:49Z rubidium $ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
00006  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
00007  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
00008  */
00009 
00015 #include "stdafx.h"
00016 #include "rail_map.h"
00017 #include "landscape.h"
00018 #include "unmovable_map.h"
00019 #include "viewport_func.h"
00020 #include "cmd_helper.h"
00021 #include "command_func.h"
00022 #include "town.h"
00023 #include "variables.h"
00024 #include "train.h"
00025 #include "ship.h"
00026 #include "roadveh.h"
00027 #include "water_map.h"
00028 #include "pathfinder/yapf/yapf_cache.h"
00029 #include "newgrf_sound.h"
00030 #include "autoslope.h"
00031 #include "tunnelbridge_map.h"
00032 #include "strings_func.h"
00033 #include "date_func.h"
00034 #include "functions.h"
00035 #include "vehicle_func.h"
00036 #include "sound_func.h"
00037 #include "tunnelbridge.h"
00038 #include "cheat_type.h"
00039 #include "elrail_func.h"
00040 #include "landscape_type.h"
00041 #include "pbs.h"
00042 #include "company_base.h"
00043 #include "engine_base.h"
00044 #include "newgrf_railtype.h"
00045 
00046 #include "table/sprites.h"
00047 #include "table/strings.h"
00048 #include "table/bridge_land.h"
00049 
00050 BridgeSpec _bridge[MAX_BRIDGES];
00051 TileIndex _build_tunnel_endtile;
00052 
00054 void ResetBridges()
00055 {
00056   /* First, free sprite table data */
00057   for (BridgeType i = 0; i < MAX_BRIDGES; i++) {
00058     if (_bridge[i].sprite_table != NULL) {
00059       for (BridgePieces j = BRIDGE_PIECE_NORTH; j < BRIDGE_PIECE_INVALID; j++) free(_bridge[i].sprite_table[j]);
00060       free(_bridge[i].sprite_table);
00061     }
00062   }
00063 
00064   /* Then, wipe out current bidges */
00065   memset(&_bridge, 0, sizeof(_bridge));
00066   /* And finally, reinstall default data */
00067   memcpy(&_bridge, &_orig_bridge, sizeof(_orig_bridge));
00068 }
00069 
00073 int CalcBridgeLenCostFactor(int x)
00074 {
00075   int n;
00076   int r;
00077 
00078   if (x < 2) return x;
00079   x -= 2;
00080   for (n = 0, r = 2;; n++) {
00081     if (x <= n) return r + x * n;
00082     r += n * n;
00083     x -= n;
00084   }
00085 }
00086 
00087 Foundation GetBridgeFoundation(Slope tileh, Axis axis)
00088 {
00089   if ((tileh == SLOPE_FLAT) ||
00090       (((tileh == SLOPE_NE) || (tileh == SLOPE_SW)) && (axis == AXIS_X)) ||
00091       (((tileh == SLOPE_NW) || (tileh == SLOPE_SE)) && (axis == AXIS_Y))) return FOUNDATION_NONE;
00092 
00093   return (HasSlopeHighestCorner(tileh) ? InclinedFoundation(axis) : FlatteningFoundation(tileh));
00094 }
00095 
00103 bool HasBridgeFlatRamp(Slope tileh, Axis axis)
00104 {
00105   ApplyFoundationToSlope(GetBridgeFoundation(tileh, axis), &tileh);
00106   /* If the foundation slope is flat the bridge has a non-flat ramp and vice versa. */
00107   return (tileh != SLOPE_FLAT);
00108 }
00109 
00110 static inline const PalSpriteID *GetBridgeSpriteTable(int index, BridgePieces table)
00111 {
00112   const BridgeSpec *bridge = GetBridgeSpec(index);
00113   assert(table < BRIDGE_PIECE_INVALID);
00114   if (bridge->sprite_table == NULL || bridge->sprite_table[table] == NULL) {
00115     return _bridge_sprite_table[index][table];
00116   } else {
00117     return bridge->sprite_table[table];
00118   }
00119 }
00120 
00121 
00130 static CommandCost CheckBridgeSlopeNorth(Axis axis, Slope *tileh, uint *z)
00131 {
00132   Foundation f = GetBridgeFoundation(*tileh, axis);
00133   *z += ApplyFoundationToSlope(f, tileh);
00134 
00135   Slope valid_inclined = (axis == AXIS_X ? SLOPE_NE : SLOPE_NW);
00136   if ((*tileh != SLOPE_FLAT) && (*tileh != valid_inclined)) return CMD_ERROR;
00137 
00138   if (f == FOUNDATION_NONE) return CommandCost();
00139 
00140   return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
00141 }
00142 
00151 static CommandCost CheckBridgeSlopeSouth(Axis axis, Slope *tileh, uint *z)
00152 {
00153   Foundation f = GetBridgeFoundation(*tileh, axis);
00154   *z += ApplyFoundationToSlope(f, tileh);
00155 
00156   Slope valid_inclined = (axis == AXIS_X ? SLOPE_SW : SLOPE_SE);
00157   if ((*tileh != SLOPE_FLAT) && (*tileh != valid_inclined)) return CMD_ERROR;
00158 
00159   if (f == FOUNDATION_NONE) return CommandCost();
00160 
00161   return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
00162 }
00163 
00169 CommandCost CheckBridgeAvailability(BridgeType bridge_type, uint bridge_len, DoCommandFlag flags)
00170 {
00171   if (flags & DC_QUERY_COST) {
00172     if (bridge_len <= (_settings_game.construction.longbridges ? 100U : 16U)) return CommandCost();
00173     return_cmd_error(STR_ERROR_BRIDGE_TOO_LONG);
00174   }
00175 
00176   if (bridge_type >= MAX_BRIDGES) return CMD_ERROR;
00177 
00178   const BridgeSpec *b = GetBridgeSpec(bridge_type);
00179   if (b->avail_year > _cur_year) return CMD_ERROR;
00180 
00181   uint max = b->max_length;
00182   if (max >= 16 && _settings_game.construction.longbridges) max = 100;
00183 
00184   if (b->min_length > bridge_len) return CMD_ERROR;
00185   if (bridge_len <= max) return CommandCost();
00186   return_cmd_error(STR_ERROR_BRIDGE_TOO_LONG);
00187 }
00188 
00200 CommandCost CmdBuildBridge(TileIndex end_tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
00201 {
00202   RailType railtype = INVALID_RAILTYPE;
00203   RoadTypes roadtypes = ROADTYPES_NONE;
00204   CommandCost cost(EXPENSES_CONSTRUCTION);
00205   Owner owner;
00206 
00207   /* unpack parameters */
00208   BridgeType bridge_type = GB(p2, 0, 8);
00209 
00210   if (p1 >= MapSize()) return CMD_ERROR;
00211 
00212   TransportType transport_type = Extract<TransportType, 15, 2>(p2);
00213 
00214   /* type of bridge */
00215   switch (transport_type) {
00216     case TRANSPORT_ROAD:
00217       roadtypes = Extract<RoadTypes, 8, 2>(p2);
00218       if (!HasExactlyOneBit(roadtypes) || !HasRoadTypesAvail(_current_company, roadtypes)) return CMD_ERROR;
00219       break;
00220 
00221     case TRANSPORT_RAIL:
00222       railtype = Extract<RailType, 8, 4>(p2);
00223       if (!ValParamRailtype(railtype)) return CMD_ERROR;
00224       break;
00225 
00226     case TRANSPORT_WATER:
00227       break;
00228 
00229     default:
00230       /* Airports don't have bridges. */
00231       return CMD_ERROR;
00232   }
00233   TileIndex tile_start = p1;
00234   TileIndex tile_end = end_tile;
00235 
00236   if (tile_start == tile_end) {
00237     return_cmd_error(STR_ERROR_CAN_T_START_AND_END_ON);
00238   }
00239 
00240   Axis direction;
00241   if (TileX(tile_start) == TileX(tile_end)) {
00242     direction = AXIS_Y;
00243   } else if (TileY(tile_start) == TileY(tile_end)) {
00244     direction = AXIS_X;
00245   } else {
00246     return_cmd_error(STR_ERROR_START_AND_END_MUST_BE_IN);
00247   }
00248 
00249   if (tile_end < tile_start) Swap(tile_start, tile_end);
00250 
00251   uint bridge_len = GetTunnelBridgeLength(tile_start, tile_end);
00252   if (transport_type != TRANSPORT_WATER) {
00253     /* set and test bridge length, availability */
00254     CommandCost ret = CheckBridgeAvailability(bridge_type, bridge_len, flags);
00255     if (ret.Failed()) return ret;
00256   } else {
00257     if (bridge_len > (_settings_game.construction.longbridges ? 100U : 16U)) return_cmd_error(STR_ERROR_BRIDGE_TOO_LONG);
00258   }
00259 
00260   /* retrieve landscape height and ensure it's on land */
00261   if (IsWaterTile(tile_start) || IsWaterTile(tile_end)) {
00262     return_cmd_error(STR_ERROR_ENDS_OF_BRIDGE_MUST_BOTH);
00263   }
00264 
00265   uint z_start;
00266   uint z_end;
00267   Slope tileh_start = GetTileSlope(tile_start, &z_start);
00268   Slope tileh_end = GetTileSlope(tile_end, &z_end);
00269   bool pbs_reservation = false;
00270 
00271   CommandCost terraform_cost_north = CheckBridgeSlopeNorth(direction, &tileh_start, &z_start);
00272   CommandCost terraform_cost_south = CheckBridgeSlopeSouth(direction, &tileh_end,   &z_end);
00273 
00274   if (z_start != z_end) return_cmd_error(STR_ERROR_BRIDGEHEADS_NOT_SAME_HEIGHT);
00275 
00276   if (IsBridgeTile(tile_start) && IsBridgeTile(tile_end) &&
00277       GetOtherBridgeEnd(tile_start) == tile_end &&
00278       GetTunnelBridgeTransportType(tile_start) == transport_type) {
00279     /* Replace a current bridge. */
00280 
00281     /* If this is a railway bridge, make sure the railtypes match. */
00282     if (transport_type == TRANSPORT_RAIL && GetRailType(tile_start) != railtype) {
00283       return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
00284     }
00285 
00286     /* Do not replace town bridges with lower speed bridges. */
00287     if (!(flags & DC_QUERY_COST) && IsTileOwner(tile_start, OWNER_TOWN) &&
00288         GetBridgeSpec(bridge_type)->speed < GetBridgeSpec(GetBridgeType(tile_start))->speed) {
00289       Town *t = ClosestTownFromTile(tile_start, UINT_MAX);
00290 
00291       if (t == NULL) {
00292         return CMD_ERROR;
00293       } else {
00294         SetDParam(0, t->index);
00295         return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
00296       }
00297     }
00298 
00299     /* Do not replace the bridge with the same bridge type. */
00300     if (!(flags & DC_QUERY_COST) && bridge_type == GetBridgeType(tile_start)) {
00301       return_cmd_error(STR_ERROR_ALREADY_BUILT);
00302     }
00303 
00304     /* Do not allow replacing another company's bridges. */
00305     if (!IsTileOwner(tile_start, _current_company) && !IsTileOwner(tile_start, OWNER_TOWN)) {
00306       return_cmd_error(STR_ERROR_AREA_IS_OWNED_BY_ANOTHER);
00307     }
00308 
00309     cost.AddCost((bridge_len + 1) * _price[PR_CLEAR_BRIDGE]); // The cost of clearing the current bridge.
00310     owner = GetTileOwner(tile_start);
00311 
00312     switch (transport_type) {
00313       case TRANSPORT_RAIL:
00314         /* Keep the reservation, the path stays valid. */
00315         pbs_reservation = HasTunnelBridgeReservation(tile_start);
00316         break;
00317 
00318       case TRANSPORT_ROAD:
00319         /* Do not remove road types when upgrading a bridge */
00320         roadtypes |= GetRoadTypes(tile_start);
00321         break;
00322 
00323       default: break;
00324     }
00325   } else {
00326     /* Build a new bridge. */
00327 
00328     bool allow_on_slopes = (_settings_game.construction.build_on_slopes && transport_type != TRANSPORT_WATER);
00329 
00330     /* Try and clear the start landscape */
00331     CommandCost ret = DoCommand(tile_start, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
00332     if (ret.Failed()) return ret;
00333     cost = ret;
00334 
00335     if (terraform_cost_north.Failed() || (terraform_cost_north.GetCost() != 0 && !allow_on_slopes))
00336       return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
00337     cost.AddCost(terraform_cost_north);
00338 
00339     /* Try and clear the end landscape */
00340     ret = DoCommand(tile_end, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
00341     if (ret.Failed()) return ret;
00342     cost.AddCost(ret);
00343 
00344     /* false - end tile slope check */
00345     if (terraform_cost_south.Failed() || (terraform_cost_south.GetCost() != 0 && !allow_on_slopes))
00346       return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
00347     cost.AddCost(terraform_cost_south);
00348 
00349     if (transport_type == TRANSPORT_WATER && (tileh_start == SLOPE_FLAT || tileh_end == SLOPE_FLAT)) return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
00350 
00351     const TileIndex heads[] = {tile_start, tile_end};
00352     for (int i = 0; i < 2; i++) {
00353       if (MayHaveBridgeAbove(heads[i])) {
00354         if (IsBridgeAbove(heads[i])) {
00355           TileIndex north_head = GetNorthernBridgeEnd(heads[i]);
00356 
00357           if (direction == GetBridgeAxis(heads[i])) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
00358 
00359           if (z_start + TILE_HEIGHT == GetBridgeHeight(north_head)) {
00360             return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
00361           }
00362         }
00363       }
00364     }
00365 
00366     TileIndexDiff delta = (direction == AXIS_X ? TileDiffXY(1, 0) : TileDiffXY(0, 1));
00367     for (TileIndex tile = tile_start + delta; tile != tile_end; tile += delta) {
00368       if (GetTileMaxZ(tile) > z_start) return_cmd_error(STR_ERROR_BRIDGE_TOO_LOW_FOR_TERRAIN);
00369 
00370       if (MayHaveBridgeAbove(tile) && IsBridgeAbove(tile)) {
00371         /* Disallow crossing bridges for the time being */
00372         return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
00373       }
00374 
00375       switch (GetTileType(tile)) {
00376         case MP_WATER:
00377           if (!IsWater(tile) && !IsCoast(tile)) goto not_valid_below;
00378           break;
00379 
00380         case MP_RAILWAY:
00381           if (!IsPlainRail(tile)) goto not_valid_below;
00382           break;
00383 
00384         case MP_ROAD:
00385           if (IsRoadDepot(tile)) goto not_valid_below;
00386           break;
00387 
00388         case MP_TUNNELBRIDGE:
00389           if (IsTunnel(tile)) break;
00390           if (direction == DiagDirToAxis(GetTunnelBridgeDirection(tile))) goto not_valid_below;
00391           if (z_start < GetBridgeHeight(tile)) goto not_valid_below;
00392           break;
00393 
00394         case MP_UNMOVABLE:
00395           if (!IsOwnedLand(tile)) goto not_valid_below;
00396           break;
00397 
00398         case MP_CLEAR:
00399           break;
00400 
00401         default:
00402   not_valid_below:;
00403           /* try and clear the middle landscape */
00404           ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
00405           if (ret.Failed()) return ret;
00406           cost.AddCost(ret);
00407           break;
00408       }
00409 
00410       if (flags & DC_EXEC) {
00411         /* We do this here because when replacing a bridge with another
00412          * type calling SetBridgeMiddle isn't needed. After all, the
00413          * tile alread has the has_bridge_above bits set. */
00414         SetBridgeMiddle(tile, direction);
00415       }
00416     }
00417 
00418     owner = _current_company;
00419   }
00420 
00421   /* do the drill? */
00422   if (flags & DC_EXEC) {
00423     DiagDirection dir = AxisToDiagDir(direction);
00424 
00425     switch (transport_type) {
00426       case TRANSPORT_RAIL:
00427         MakeRailBridgeRamp(tile_start, owner, bridge_type, dir,                 railtype);
00428         MakeRailBridgeRamp(tile_end,   owner, bridge_type, ReverseDiagDir(dir), railtype);
00429         SetTunnelBridgeReservation(tile_start, pbs_reservation);
00430         SetTunnelBridgeReservation(tile_end,   pbs_reservation);
00431         break;
00432 
00433       case TRANSPORT_ROAD:
00434         MakeRoadBridgeRamp(tile_start, owner, bridge_type, dir,                 roadtypes);
00435         MakeRoadBridgeRamp(tile_end,   owner, bridge_type, ReverseDiagDir(dir), roadtypes);
00436         break;
00437 
00438       case TRANSPORT_WATER:
00439         MakeAqueductBridgeRamp(tile_start, owner, dir);
00440         MakeAqueductBridgeRamp(tile_end,   owner, ReverseDiagDir(dir));
00441         break;
00442 
00443       default:
00444         NOT_REACHED();
00445     }
00446 
00447     /* Mark all tiles dirty */
00448     TileIndexDiff delta = (direction == AXIS_X ? TileDiffXY(1, 0) : TileDiffXY(0, 1));
00449     for (TileIndex tile = tile_start; tile <= tile_end; tile += delta) {
00450       MarkTileDirtyByTile(tile);
00451     }
00452   }
00453 
00454   if ((flags & DC_EXEC) && transport_type == TRANSPORT_RAIL) {
00455     Track track = AxisToTrack(direction);
00456     AddSideToSignalBuffer(tile_start, INVALID_DIAGDIR, _current_company);
00457     YapfNotifyTrackLayoutChange(tile_start, track);
00458   }
00459 
00460   /* for human player that builds the bridge he gets a selection to choose from bridges (DC_QUERY_COST)
00461    * It's unnecessary to execute this command every time for every bridge. So it is done only
00462    * and cost is computed in "bridge_gui.c". For AI, Towns this has to be of course calculated
00463    */
00464   Company *c = Company::GetIfValid(_current_company);
00465   if (!(flags & DC_QUERY_COST) || (c != NULL && c->is_ai)) {
00466     bridge_len += 2; // begin and end tiles/ramps
00467 
00468     if (c != NULL) bridge_len = CalcBridgeLenCostFactor(bridge_len);
00469 
00470     cost.AddCost((int64)bridge_len * _price[PR_BUILD_BRIDGE] * GetBridgeSpec(bridge_type)->price >> 8);
00471 
00472     /* Aqueducts are a little more expensive. */
00473     if (transport_type == TRANSPORT_WATER) cost.AddCost((int64)bridge_len * _price[PR_CLEAR_WATER]);
00474   }
00475 
00476   return cost;
00477 }
00478 
00479 
00489 CommandCost CmdBuildTunnel(TileIndex start_tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
00490 {
00491   TransportType transport_type = Extract<TransportType, 8, 2>(p1);
00492   CommandCost cost(EXPENSES_CONSTRUCTION);
00493 
00494   RailType railtype = INVALID_RAILTYPE;
00495   RoadTypes rts = ROADTYPES_NONE;
00496   _build_tunnel_endtile = 0;
00497   switch (transport_type) {
00498     case TRANSPORT_RAIL:
00499       railtype = Extract<RailType, 0, 4>(p1);
00500       if (!ValParamRailtype(railtype)) return CMD_ERROR;
00501       break;
00502 
00503     case TRANSPORT_ROAD:
00504       rts = Extract<RoadTypes, 0, 2>(p1);
00505       if (!HasExactlyOneBit(rts) || !HasRoadTypesAvail(_current_company, rts)) return CMD_ERROR;
00506       break;
00507 
00508     default: return CMD_ERROR;
00509   }
00510 
00511   uint start_z;
00512   uint end_z;
00513   Slope start_tileh = GetTileSlope(start_tile, &start_z);
00514   DiagDirection direction = GetInclinedSlopeDirection(start_tileh);
00515   if (direction == INVALID_DIAGDIR) return_cmd_error(STR_ERROR_SITE_UNSUITABLE_FOR_TUNNEL);
00516 
00517   if (IsWaterTile(start_tile)) return_cmd_error(STR_ERROR_CAN_T_BUILD_ON_WATER);
00518 
00519   CommandCost ret = DoCommand(start_tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
00520   if (ret.Failed()) return ret;
00521 
00522   /* XXX - do NOT change 'ret' in the loop, as it is used as the price
00523    * for the clearing of the entrance of the tunnel. Assigning it to
00524    * cost before the loop will yield different costs depending on start-
00525    * position, because of increased-cost-by-length: 'cost += cost >> 3' */
00526 
00527   TileIndexDiff delta = TileOffsByDiagDir(direction);
00528   DiagDirection tunnel_in_way_dir;
00529   if (DiagDirToAxis(direction) == AXIS_Y) {
00530     tunnel_in_way_dir = (TileX(start_tile) < (MapMaxX() / 2)) ? DIAGDIR_SW : DIAGDIR_NE;
00531   } else {
00532     tunnel_in_way_dir = (TileY(start_tile) < (MapMaxX() / 2)) ? DIAGDIR_SE : DIAGDIR_NW;
00533   }
00534 
00535   TileIndex end_tile = start_tile;
00536 
00537   /* Tile shift coeficient. Will decrease for very long tunnels to avoid exponential growth of price*/
00538   int tiles_coef = 3;
00539   /* Number of tiles from start of tunnel */
00540   int tiles = 0;
00541   /* Number of tiles at which the cost increase coefficient per tile is halved */
00542   int tiles_bump = 25;
00543 
00544   Slope end_tileh;
00545   for (;;) {
00546     end_tile += delta;
00547     if (!IsValidTile(end_tile)) return_cmd_error(STR_ERROR_TUNNEL_THROUGH_MAP_BORDER);
00548     end_tileh = GetTileSlope(end_tile, &end_z);
00549 
00550     if (start_z == end_z) break;
00551 
00552     if (!_cheats.crossing_tunnels.value && IsTunnelInWayDir(end_tile, start_z, tunnel_in_way_dir)) {
00553       return_cmd_error(STR_ERROR_ANOTHER_TUNNEL_IN_THE_WAY);
00554     }
00555 
00556     tiles++;
00557     if (tiles == tiles_bump) {
00558       tiles_coef++;
00559       tiles_bump *= 2;
00560     }
00561 
00562     cost.AddCost(_price[PR_BUILD_TUNNEL]);
00563     cost.AddCost(cost.GetCost() >> tiles_coef); // add a multiplier for longer tunnels
00564   }
00565 
00566   /* Add the cost of the entrance */
00567   cost.AddCost(_price[PR_BUILD_TUNNEL]);
00568   cost.AddCost(ret);
00569 
00570   /* if the command fails from here on we want the end tile to be highlighted */
00571   _build_tunnel_endtile = end_tile;
00572 
00573   if (IsWaterTile(end_tile)) return_cmd_error(STR_ERROR_CAN_T_BUILD_ON_WATER);
00574 
00575   /* slope of end tile must be complementary to the slope of the start tile */
00576   if (end_tileh != ComplementSlope(start_tileh)) {
00577     /* Check if there is a structure on the terraformed tile. Do not add the cost, that will be done by the terraforming
00578      * Note: Currently the town rating is also affected by this clearing-test. So effectivly the player is punished twice for clearing
00579      *       the tree on end_tile.
00580      */
00581     ret = DoCommand(end_tile, 0, 0, DC_AUTO, CMD_LANDSCAPE_CLEAR);
00582     if (ret.Failed()) return_cmd_error(STR_ERROR_UNABLE_TO_EXCAVATE_LAND);
00583 
00584     ret = DoCommand(end_tile, end_tileh & start_tileh, 0, flags, CMD_TERRAFORM_LAND);
00585     if (ret.Failed()) return_cmd_error(STR_ERROR_UNABLE_TO_EXCAVATE_LAND);
00586   } else {
00587     ret = DoCommand(end_tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
00588     if (ret.Failed()) return ret;
00589   }
00590   cost.AddCost(_price[PR_BUILD_TUNNEL]);
00591   cost.AddCost(ret);
00592 
00593   if (flags & DC_EXEC) {
00594     if (transport_type == TRANSPORT_RAIL) {
00595       MakeRailTunnel(start_tile, _current_company, direction,                 railtype);
00596       MakeRailTunnel(end_tile,   _current_company, ReverseDiagDir(direction), railtype);
00597       AddSideToSignalBuffer(start_tile, INVALID_DIAGDIR, _current_company);
00598       YapfNotifyTrackLayoutChange(start_tile, DiagDirToDiagTrack(direction));
00599     } else {
00600       MakeRoadTunnel(start_tile, _current_company, direction,                 rts);
00601       MakeRoadTunnel(end_tile,   _current_company, ReverseDiagDir(direction), rts);
00602     }
00603   }
00604 
00605   return cost;
00606 }
00607 
00608 
00609 static inline bool CheckAllowRemoveTunnelBridge(TileIndex tile)
00610 {
00611   /* Floods can remove anything as well as the scenario editor */
00612   if (_current_company == OWNER_WATER || _game_mode == GM_EDITOR) return true;
00613 
00614   switch (GetTunnelBridgeTransportType(tile)) {
00615     case TRANSPORT_ROAD: {
00616       RoadTypes rts = GetRoadTypes(tile);
00617       Owner road_owner = _current_company;
00618       Owner tram_owner = _current_company;
00619 
00620       if (HasBit(rts, ROADTYPE_ROAD)) road_owner = GetRoadOwner(tile, ROADTYPE_ROAD);
00621       if (HasBit(rts, ROADTYPE_TRAM)) tram_owner = GetRoadOwner(tile, ROADTYPE_TRAM);
00622 
00623       /* We can remove unowned road and if the town allows it */
00624       if (road_owner == OWNER_TOWN && !(_settings_game.construction.extra_dynamite || _cheats.magic_bulldozer.value)) return CheckTileOwnership(tile);
00625       if (road_owner == OWNER_NONE || road_owner == OWNER_TOWN) road_owner = _current_company;
00626       if (tram_owner == OWNER_NONE) tram_owner = _current_company;
00627 
00628       return CheckOwnership(road_owner, tile) && CheckOwnership(tram_owner, tile);
00629     }
00630 
00631     case TRANSPORT_RAIL:
00632     case TRANSPORT_WATER:
00633       return CheckOwnership(GetTileOwner(tile));
00634 
00635     default: NOT_REACHED();
00636   }
00637 }
00638 
00639 static CommandCost DoClearTunnel(TileIndex tile, DoCommandFlag flags)
00640 {
00641   Town *t = NULL;
00642   TileIndex endtile;
00643 
00644   if (!CheckAllowRemoveTunnelBridge(tile)) return CMD_ERROR;
00645 
00646   endtile = GetOtherTunnelEnd(tile);
00647 
00648   if (HasVehicleOnTunnelBridge(tile, endtile)) return CMD_ERROR;
00649 
00650   _build_tunnel_endtile = endtile;
00651 
00652   if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
00653     t = ClosestTownFromTile(tile, UINT_MAX); // town penalty rating
00654 
00655     /* Check if you are allowed to remove the tunnel owned by a town
00656      * Removal depends on difficulty settings */
00657     if (!CheckforTownRating(flags, t, TUNNELBRIDGE_REMOVE)) {
00658       SetDParam(0, t->index);
00659       return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
00660     }
00661   }
00662 
00663   /* checks if the owner is town then decrease town rating by RATING_TUNNEL_BRIDGE_DOWN_STEP until
00664    * you have a "Poor" (0) town rating */
00665   if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
00666     ChangeTownRating(t, RATING_TUNNEL_BRIDGE_DOWN_STEP, RATING_TUNNEL_BRIDGE_MINIMUM, flags);
00667   }
00668 
00669   if (flags & DC_EXEC) {
00670     if (GetTunnelBridgeTransportType(tile) == TRANSPORT_RAIL) {
00671       /* We first need to request values before calling DoClearSquare */
00672       DiagDirection dir = GetTunnelBridgeDirection(tile);
00673       Track track = DiagDirToDiagTrack(dir);
00674       Owner owner = GetTileOwner(tile);
00675 
00676       Train *v = NULL;
00677       if (HasTunnelBridgeReservation(tile)) {
00678         v = GetTrainForReservation(tile, track);
00679         if (v != NULL) FreeTrainTrackReservation(v);
00680       }
00681 
00682       DoClearSquare(tile);
00683       DoClearSquare(endtile);
00684 
00685       /* cannot use INVALID_DIAGDIR for signal update because the tunnel doesn't exist anymore */
00686       AddSideToSignalBuffer(tile,    ReverseDiagDir(dir), owner);
00687       AddSideToSignalBuffer(endtile, dir,                 owner);
00688 
00689       YapfNotifyTrackLayoutChange(tile,    track);
00690       YapfNotifyTrackLayoutChange(endtile, track);
00691 
00692       if (v != NULL) TryPathReserve(v);
00693     } else {
00694       DoClearSquare(tile);
00695       DoClearSquare(endtile);
00696     }
00697   }
00698   return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_CLEAR_TUNNEL] * (GetTunnelBridgeLength(tile, endtile) + 2));
00699 }
00700 
00701 
00702 static CommandCost DoClearBridge(TileIndex tile, DoCommandFlag flags)
00703 {
00704   DiagDirection direction;
00705   TileIndexDiff delta;
00706   TileIndex endtile;
00707   Town *t = NULL;
00708 
00709   if (!CheckAllowRemoveTunnelBridge(tile)) return CMD_ERROR;
00710 
00711   endtile = GetOtherBridgeEnd(tile);
00712 
00713   if (HasVehicleOnTunnelBridge(tile, endtile)) return CMD_ERROR;
00714 
00715   direction = GetTunnelBridgeDirection(tile);
00716   delta = TileOffsByDiagDir(direction);
00717 
00718   if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
00719     t = ClosestTownFromTile(tile, UINT_MAX); // town penalty rating
00720 
00721     /* Check if you are allowed to remove the bridge owned by a town
00722      * Removal depends on difficulty settings */
00723     if (!CheckforTownRating(flags, t, TUNNELBRIDGE_REMOVE)) {
00724       SetDParam(0, t->index);
00725       return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
00726     }
00727   }
00728 
00729   /* checks if the owner is town then decrease town rating by RATING_TUNNEL_BRIDGE_DOWN_STEP until
00730    * you have a "Poor" (0) town rating */
00731   if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
00732     ChangeTownRating(t, RATING_TUNNEL_BRIDGE_DOWN_STEP, RATING_TUNNEL_BRIDGE_MINIMUM, flags);
00733   }
00734 
00735   if (flags & DC_EXEC) {
00736     /* read this value before actual removal of bridge */
00737     bool rail = GetTunnelBridgeTransportType(tile) == TRANSPORT_RAIL;
00738     Owner owner = GetTileOwner(tile);
00739     uint height = GetBridgeHeight(tile);
00740     Train *v = NULL;
00741 
00742     if (rail && HasTunnelBridgeReservation(tile)) {
00743       v = GetTrainForReservation(tile, DiagDirToDiagTrack(direction));
00744       if (v != NULL) FreeTrainTrackReservation(v);
00745     }
00746 
00747     DoClearSquare(tile);
00748     DoClearSquare(endtile);
00749     for (TileIndex c = tile + delta; c != endtile; c += delta) {
00750       /* do not let trees appear from 'nowhere' after removing bridge */
00751       if (IsNormalRoadTile(c) && GetRoadside(c) == ROADSIDE_TREES) {
00752         uint minz = GetTileMaxZ(c) + 3 * TILE_HEIGHT;
00753         if (height < minz) SetRoadside(c, ROADSIDE_PAVED);
00754       }
00755       ClearBridgeMiddle(c);
00756       MarkTileDirtyByTile(c);
00757     }
00758 
00759     if (rail) {
00760       /* cannot use INVALID_DIAGDIR for signal update because the bridge doesn't exist anymore */
00761       AddSideToSignalBuffer(tile,    ReverseDiagDir(direction), owner);
00762       AddSideToSignalBuffer(endtile, direction,                 owner);
00763 
00764       Track track = DiagDirToDiagTrack(direction);
00765       YapfNotifyTrackLayoutChange(tile,    track);
00766       YapfNotifyTrackLayoutChange(endtile, track);
00767 
00768       if (v != NULL) TryPathReserve(v, true);
00769     }
00770   }
00771 
00772   return CommandCost(EXPENSES_CONSTRUCTION, (GetTunnelBridgeLength(tile, endtile) + 2) * _price[PR_CLEAR_BRIDGE]);
00773 }
00774 
00775 static CommandCost ClearTile_TunnelBridge(TileIndex tile, DoCommandFlag flags)
00776 {
00777   if (IsTunnel(tile)) {
00778     if (flags & DC_AUTO) return_cmd_error(STR_ERROR_MUST_DEMOLISH_TUNNEL_FIRST);
00779     return DoClearTunnel(tile, flags);
00780   } else { // IsBridge(tile)
00781     if (flags & DC_AUTO) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
00782     return DoClearBridge(tile, flags);
00783   }
00784 
00785   return CMD_ERROR;
00786 }
00787 
00799 static void DrawBridgePillars(const PalSpriteID *psid, const TileInfo *ti, Axis axis, bool drawfarpillar, int x, int y, int z_bridge)
00800 {
00801   /* Do not draw bridge pillars if they are invisible */
00802   if (IsInvisibilitySet(TO_BRIDGES)) return;
00803 
00804   SpriteID image = psid->sprite;
00805 
00806   if (image != 0) {
00807     /* "side" specifies the side the pillars stand on.
00808      * The length of the pillars is then set to the height of the bridge over the corners of this edge.
00809      *
00810      *                axis==AXIS_X  axis==AXIS_Y
00811      *   side==false      SW            NW
00812      *   side==true       NE            SE
00813      *
00814      * I have no clue, why this was done this way.
00815      */
00816     bool side = HasBit(image, 0);
00817 
00818     /* "dir" means the edge the pillars stand on */
00819     DiagDirection dir = AxisToDiagDir(axis);
00820     if (side != (axis == AXIS_Y)) dir = ReverseDiagDir(dir);
00821 
00822     /* Determine ground height under pillars */
00823     int front_height = ti->z;
00824     int back_height = ti->z;
00825     GetSlopeZOnEdge(ti->tileh, dir, &front_height, &back_height);
00826 
00827     /* x and y size of bounding-box of pillars */
00828     int w = (axis == AXIS_X ? 16 : 2);
00829     int h = (axis == AXIS_X ? 2 : 16);
00830     /* sprite position of back facing pillar */
00831     int x_back = x - (axis == AXIS_X ? 0 : 9);
00832     int y_back = y - (axis == AXIS_X ? 9 : 0);
00833 
00834     for (int cur_z = z_bridge; cur_z >= front_height || cur_z >= back_height; cur_z -= TILE_HEIGHT) {
00835       /* Draw front facing pillar */
00836       if (cur_z >= front_height) {
00837         AddSortableSpriteToDraw(image, psid->pal, x, y, w, h, BB_HEIGHT_UNDER_BRIDGE - 5, cur_z, IsTransparencySet(TO_BRIDGES), 0, 0, -5);
00838       }
00839 
00840       /* Draw back facing pillar, but not the highest part directly under the bridge-floor */
00841       if (drawfarpillar && cur_z >= back_height && cur_z < z_bridge - TILE_HEIGHT) {
00842         AddSortableSpriteToDraw(image, psid->pal, x_back, y_back, w, h, BB_HEIGHT_UNDER_BRIDGE - 5, cur_z, IsTransparencySet(TO_BRIDGES), 0, 0, -5);
00843       }
00844     }
00845   }
00846 }
00847 
00857 static void DrawBridgeTramBits(int x, int y, byte z, int offset, bool overlay, bool head)
00858 {
00859   static const SpriteID tram_offsets[2][6] = { { 107, 108, 109, 110, 111, 112 }, { 4, 5, 15, 16, 17, 18 } };
00860   static const SpriteID back_offsets[6]    =   {  95,  96,  99, 102, 100, 101 };
00861   static const SpriteID front_offsets[6]   =   {  97,  98, 103, 106, 104, 105 };
00862 
00863   static const uint size_x[6] = {  1, 16, 16,  1, 16,  1 };
00864   static const uint size_y[6] = { 16,  1,  1, 16,  1, 16 };
00865   static const uint front_bb_offset_x[6] = { 15,  0,  0, 15,  0, 15 };
00866   static const uint front_bb_offset_y[6] = {  0, 15, 15,  0, 15,  0 };
00867 
00868   /* The sprites under the vehicles are drawn as SpriteCombine. StartSpriteCombine() has already been called
00869    * The bounding boxes here are the same as for bridge front/roof */
00870   if (head || !IsInvisibilitySet(TO_BRIDGES)) {
00871     AddSortableSpriteToDraw(SPR_TRAMWAY_BASE + tram_offsets[overlay][offset], PAL_NONE,
00872       x, y, size_x[offset], size_y[offset], 0x28, z,
00873       !head && IsTransparencySet(TO_BRIDGES));
00874   }
00875 
00876   /* Do not draw catenary if it is set invisible */
00877   if (!IsInvisibilitySet(TO_CATENARY)) {
00878     AddSortableSpriteToDraw(SPR_TRAMWAY_BASE + back_offsets[offset], PAL_NONE,
00879       x, y, size_x[offset], size_y[offset], 0x28, z,
00880       IsTransparencySet(TO_CATENARY));
00881   }
00882 
00883   /* Start a new SpriteCombine for the front part */
00884   EndSpriteCombine();
00885   StartSpriteCombine();
00886 
00887   /* For sloped sprites the bounding box needs to be higher, as the pylons stop on a higher point */
00888   if (!IsInvisibilitySet(TO_CATENARY)) {
00889     AddSortableSpriteToDraw(SPR_TRAMWAY_BASE + front_offsets[offset], PAL_NONE,
00890       x, y, size_x[offset] + front_bb_offset_x[offset], size_y[offset] + front_bb_offset_y[offset], 0x28, z,
00891       IsTransparencySet(TO_CATENARY), front_bb_offset_x[offset], front_bb_offset_y[offset]);
00892   }
00893 }
00894 
00908 static void DrawTile_TunnelBridge(TileInfo *ti)
00909 {
00910   SpriteID image;
00911   TransportType transport_type = GetTunnelBridgeTransportType(ti->tile);
00912   DiagDirection tunnelbridge_direction = GetTunnelBridgeDirection(ti->tile);
00913 
00914   if (IsTunnel(ti->tile)) {
00915     /* Front view of tunnel bounding boxes:
00916      *
00917      *   122223  <- BB_Z_SEPARATOR
00918      *   1    3
00919      *   1    3                1,3 = empty helper BB
00920      *   1    3                  2 = SpriteCombine of tunnel-roof and catenary (tram & elrail)
00921      *
00922      */
00923 
00924     static const int _tunnel_BB[4][12] = {
00925       /*  tunnnel-roof  |  Z-separator  | tram-catenary
00926        * w  h  bb_x bb_y| x   y   w   h |bb_x bb_y w h */
00927       {  1,  0, -15, -14,  0, 15, 16,  1, 0, 1, 16, 15 }, // NE
00928       {  0,  1, -14, -15, 15,  0,  1, 16, 1, 0, 15, 16 }, // SE
00929       {  1,  0, -15, -14,  0, 15, 16,  1, 0, 1, 16, 15 }, // SW
00930       {  0,  1, -14, -15, 15,  0,  1, 16, 1, 0, 15, 16 }, // NW
00931     };
00932     const int *BB_data = _tunnel_BB[tunnelbridge_direction];
00933 
00934     bool catenary = false;
00935 
00936     if (transport_type == TRANSPORT_RAIL) {
00937       image = GetRailTypeInfo(GetRailType(ti->tile))->base_sprites.tunnel;
00938     } else {
00939       image = SPR_TUNNEL_ENTRY_REAR_ROAD;
00940     }
00941 
00942     if (HasTunnelBridgeSnowOrDesert(ti->tile)) image += 32;
00943 
00944     image += tunnelbridge_direction * 2;
00945     DrawGroundSprite(image, PAL_NONE);
00946 
00947     /* PBS debugging, draw reserved tracks darker */
00948     if (_game_mode != GM_MENU && _settings_client.gui.show_track_reservation && (transport_type == TRANSPORT_RAIL && HasTunnelBridgeReservation(ti->tile))) {
00949       const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
00950       DrawGroundSprite(DiagDirToAxis(tunnelbridge_direction) == AXIS_X ? rti->base_sprites.single_x : rti->base_sprites.single_y, PALETTE_CRASH);
00951     }
00952 
00953     if (transport_type == TRANSPORT_ROAD) {
00954       RoadTypes rts = GetRoadTypes(ti->tile);
00955 
00956       if (HasBit(rts, ROADTYPE_TRAM)) {
00957         static const SpriteID tunnel_sprites[2][4] = { { 28, 78, 79, 27 }, {  5, 76, 77,  4 } };
00958 
00959         DrawGroundSprite(SPR_TRAMWAY_BASE + tunnel_sprites[rts - ROADTYPES_TRAM][tunnelbridge_direction], PAL_NONE);
00960 
00961         /* Do not draw wires if they are invisible */
00962         if (!IsInvisibilitySet(TO_CATENARY)) {
00963           catenary = true;
00964           StartSpriteCombine();
00965           AddSortableSpriteToDraw(SPR_TRAMWAY_TUNNEL_WIRES + tunnelbridge_direction, PAL_NONE, ti->x, ti->y, BB_data[10], BB_data[11], TILE_HEIGHT, ti->z, IsTransparencySet(TO_CATENARY), BB_data[8], BB_data[9], BB_Z_SEPARATOR);
00966         }
00967       }
00968     } else {
00969       const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
00970       if (rti->UsesOverlay()) {
00971         SpriteID surface = GetCustomRailSprite(rti, ti->tile, RTSG_TUNNEL);
00972         if (surface != 0) DrawGroundSprite(surface + tunnelbridge_direction, PAL_NONE);
00973       }
00974 
00975       if (HasCatenaryDrawn(GetRailType(ti->tile))) {
00976         /* Maybe draw pylons on the entry side */
00977         DrawCatenary(ti);
00978 
00979         catenary = true;
00980         StartSpriteCombine();
00981         /* Draw wire above the ramp */
00982         DrawCatenaryOnTunnel(ti);
00983       }
00984     }
00985 
00986     AddSortableSpriteToDraw(image + 1, PAL_NONE, ti->x + TILE_SIZE - 1, ti->y + TILE_SIZE - 1, BB_data[0], BB_data[1], TILE_HEIGHT, ti->z, false, BB_data[2], BB_data[3], BB_Z_SEPARATOR);
00987 
00988     if (catenary) EndSpriteCombine();
00989 
00990     /* Add helper BB for sprite sorting, that separate the tunnel from things beside of it */
00991     AddSortableSpriteToDraw(SPR_EMPTY_BOUNDING_BOX, PAL_NONE, ti->x,              ti->y,              BB_data[6], BB_data[7], TILE_HEIGHT, ti->z);
00992     AddSortableSpriteToDraw(SPR_EMPTY_BOUNDING_BOX, PAL_NONE, ti->x + BB_data[4], ti->y + BB_data[5], BB_data[6], BB_data[7], TILE_HEIGHT, ti->z);
00993 
00994     DrawBridgeMiddle(ti);
00995   } else { // IsBridge(ti->tile)
00996     const PalSpriteID *psid;
00997     int base_offset;
00998     bool ice = HasTunnelBridgeSnowOrDesert(ti->tile);
00999 
01000     if (transport_type == TRANSPORT_RAIL) {
01001       base_offset = GetRailTypeInfo(GetRailType(ti->tile))->bridge_offset;
01002       assert(base_offset != 8); // This one is used for roads
01003     } else {
01004       base_offset = 8;
01005     }
01006 
01007     /* as the lower 3 bits are used for other stuff, make sure they are clear */
01008     assert( (base_offset & 0x07) == 0x00);
01009 
01010     DrawFoundation(ti, GetBridgeFoundation(ti->tileh, DiagDirToAxis(tunnelbridge_direction)));
01011 
01012     /* HACK Wizardry to convert the bridge ramp direction into a sprite offset */
01013     base_offset += (6 - tunnelbridge_direction) % 4;
01014 
01015     if (ti->tileh == SLOPE_FLAT) base_offset += 4; // sloped bridge head
01016 
01017     /* Table number BRIDGE_PIECE_HEAD always refers to the bridge heads for any bridge type */
01018     if (transport_type != TRANSPORT_WATER) {
01019       psid = &GetBridgeSpriteTable(GetBridgeType(ti->tile), BRIDGE_PIECE_HEAD)[base_offset];
01020     } else {
01021       psid = _aqueduct_sprites + base_offset;
01022     }
01023 
01024     if (!ice) {
01025       DrawClearLandTile(ti, 3);
01026     } else {
01027       DrawGroundSprite(SPR_FLAT_SNOW_DESERT_TILE + _tileh_to_sprite[ti->tileh], PAL_NONE);
01028     }
01029 
01030     /* draw ramp */
01031 
01032     /* Draw Trambits and PBS Reservation as SpriteCombine */
01033     if (transport_type == TRANSPORT_ROAD || transport_type == TRANSPORT_RAIL) StartSpriteCombine();
01034 
01035     /* HACK set the height of the BB of a sloped ramp to 1 so a vehicle on
01036      * it doesn't disappear behind it
01037      */
01038     /* Bridge heads are drawn solid no matter how invisibility/transparency is set */
01039     AddSortableSpriteToDraw(psid->sprite, psid->pal, ti->x, ti->y, 16, 16, ti->tileh == SLOPE_FLAT ? 0 : 8, ti->z);
01040 
01041     if (transport_type == TRANSPORT_ROAD) {
01042       RoadTypes rts = GetRoadTypes(ti->tile);
01043 
01044       if (HasBit(rts, ROADTYPE_TRAM)) {
01045         uint offset = tunnelbridge_direction;
01046         uint z = ti->z;
01047         if (ti->tileh != SLOPE_FLAT) {
01048           offset = (offset + 1) & 1;
01049           z += TILE_HEIGHT;
01050         } else {
01051           offset += 2;
01052         }
01053         /* DrawBridgeTramBits() calls EndSpriteCombine() and StartSpriteCombine() */
01054         DrawBridgeTramBits(ti->x, ti->y, z, offset, HasBit(rts, ROADTYPE_ROAD), true);
01055       }
01056       EndSpriteCombine();
01057     } else if (transport_type == TRANSPORT_RAIL) {
01058       const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
01059       if (rti->UsesOverlay()) {
01060         SpriteID surface = GetCustomRailSprite(rti, ti->tile, RTSG_BRIDGE);
01061         if (surface != 0) {
01062           if (HasBridgeFlatRamp(ti->tileh, DiagDirToAxis(tunnelbridge_direction))) {
01063             AddSortableSpriteToDraw(surface + ((DiagDirToAxis(tunnelbridge_direction) == AXIS_X) ? RTBO_X : RTBO_Y), PAL_NONE, ti->x, ti->y, 16, 16, 0, ti->z + 8);
01064           } else {
01065             AddSortableSpriteToDraw(surface + RTBO_SLOPE + tunnelbridge_direction, PAL_NONE, ti->x, ti->y, 16, 16, 8, ti->z);
01066           }
01067         }
01068         /* Don't fallback to non-overlay sprite -- the spec states that
01069          * if an overlay is present then the bridge surface must be
01070          * present. */
01071       } else if (_game_mode != GM_MENU &&_settings_client.gui.show_track_reservation && HasTunnelBridgeReservation(ti->tile)) {
01072         if (HasBridgeFlatRamp(ti->tileh, DiagDirToAxis(tunnelbridge_direction))) {
01073           AddSortableSpriteToDraw(DiagDirToAxis(tunnelbridge_direction) == AXIS_X ? rti->base_sprites.single_x : rti->base_sprites.single_y, PALETTE_CRASH, ti->x, ti->y, 16, 16, 0, ti->z + 8);
01074         } else {
01075           AddSortableSpriteToDraw(rti->base_sprites.single_sloped + tunnelbridge_direction, PALETTE_CRASH, ti->x, ti->y, 16, 16, 8, ti->z);
01076         }
01077       }
01078       EndSpriteCombine();
01079       if (HasCatenaryDrawn(GetRailType(ti->tile))) {
01080         DrawCatenary(ti);
01081       }
01082     }
01083 
01084     DrawBridgeMiddle(ti);
01085   }
01086 }
01087 
01088 
01106 static BridgePieces CalcBridgePiece(uint north, uint south)
01107 {
01108   if (north == 1) {
01109     return BRIDGE_PIECE_NORTH;
01110   } else if (south == 1) {
01111     return BRIDGE_PIECE_SOUTH;
01112   } else if (north < south) {
01113     return north & 1 ? BRIDGE_PIECE_INNER_SOUTH : BRIDGE_PIECE_INNER_NORTH;
01114   } else if (north > south) {
01115     return south & 1 ? BRIDGE_PIECE_INNER_NORTH : BRIDGE_PIECE_INNER_SOUTH;
01116   } else {
01117     return north & 1 ? BRIDGE_PIECE_MIDDLE_EVEN : BRIDGE_PIECE_MIDDLE_ODD;
01118   }
01119 }
01120 
01121 
01122 void DrawBridgeMiddle(const TileInfo *ti)
01123 {
01124   /* Sectional view of bridge bounding boxes:
01125    *
01126    *  1           2                                1,2 = SpriteCombine of Bridge front/(back&floor) and TramCatenary
01127    *  1           2                                  3 = empty helper BB
01128    *  1     7     2                                4,5 = pillars under higher bridges
01129    *  1 6 88888 6 2                                  6 = elrail-pylons
01130    *  1 6 88888 6 2                                  7 = elrail-wire
01131    *  1 6 88888 6 2  <- TILE_HEIGHT                  8 = rail-vehicle on bridge
01132    *  3333333333333  <- BB_Z_SEPARATOR
01133    *                 <- unused
01134    *    4       5    <- BB_HEIGHT_UNDER_BRIDGE
01135    *    4       5
01136    *    4       5
01137    *
01138    */
01139 
01140   /* Z position of the bridge sprites relative to bridge height (downwards) */
01141   static const int BRIDGE_Z_START = 3;
01142 
01143   if (!IsBridgeAbove(ti->tile)) return;
01144 
01145   TileIndex rampnorth = GetNorthernBridgeEnd(ti->tile);
01146   TileIndex rampsouth = GetSouthernBridgeEnd(ti->tile);
01147   TransportType transport_type = GetTunnelBridgeTransportType(rampsouth);
01148 
01149   Axis axis = GetBridgeAxis(ti->tile);
01150   BridgePieces piece = CalcBridgePiece(
01151     GetTunnelBridgeLength(ti->tile, rampnorth) + 1,
01152     GetTunnelBridgeLength(ti->tile, rampsouth) + 1
01153   );
01154 
01155   const PalSpriteID *psid;
01156   bool drawfarpillar;
01157   if (transport_type != TRANSPORT_WATER) {
01158     BridgeType type =  GetBridgeType(rampsouth);
01159     drawfarpillar = !HasBit(GetBridgeSpec(type)->flags, 0);
01160 
01161     uint base_offset;
01162     if (transport_type == TRANSPORT_RAIL) {
01163       base_offset = GetRailTypeInfo(GetRailType(rampsouth))->bridge_offset;
01164     } else {
01165       base_offset = 8;
01166     }
01167 
01168     psid = base_offset + GetBridgeSpriteTable(type, piece);
01169   } else {
01170     drawfarpillar = true;
01171     psid = _aqueduct_sprites;
01172   }
01173 
01174   if (axis != AXIS_X) psid += 4;
01175 
01176   int x = ti->x;
01177   int y = ti->y;
01178   uint bridge_z = GetBridgeHeight(rampsouth);
01179   uint z = bridge_z - BRIDGE_Z_START;
01180 
01181   /* Add a bounding box, that separates the bridge from things below it. */
01182   AddSortableSpriteToDraw(SPR_EMPTY_BOUNDING_BOX, PAL_NONE, x, y, 16, 16, 1, bridge_z - TILE_HEIGHT + BB_Z_SEPARATOR);
01183 
01184   /* Draw Trambits as SpriteCombine */
01185   if (transport_type == TRANSPORT_ROAD || transport_type == TRANSPORT_RAIL) StartSpriteCombine();
01186 
01187   /* Draw floor and far part of bridge*/
01188   if (!IsInvisibilitySet(TO_BRIDGES)) {
01189     if (axis == AXIS_X) {
01190       AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 16, 1, 0x28, z, IsTransparencySet(TO_BRIDGES), 0, 0, BRIDGE_Z_START);
01191     } else {
01192       AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 1, 16, 0x28, z, IsTransparencySet(TO_BRIDGES), 0, 0, BRIDGE_Z_START);
01193     }
01194   }
01195 
01196   psid++;
01197 
01198   if (transport_type == TRANSPORT_ROAD) {
01199     RoadTypes rts = GetRoadTypes(rampsouth);
01200 
01201     if (HasBit(rts, ROADTYPE_TRAM)) {
01202       /* DrawBridgeTramBits() calls EndSpriteCombine() and StartSpriteCombine() */
01203       DrawBridgeTramBits(x, y, bridge_z, axis ^ 1, HasBit(rts, ROADTYPE_ROAD), false);
01204     } else {
01205       EndSpriteCombine();
01206       StartSpriteCombine();
01207     }
01208   } else if (transport_type == TRANSPORT_RAIL) {
01209     const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(rampsouth));
01210     if (rti->UsesOverlay()) {
01211       SpriteID surface = GetCustomRailSprite(rti, ti->tile, RTSG_BRIDGE);
01212       if (surface != 0) {
01213         AddSortableSpriteToDraw(surface + axis, PAL_NONE, x, y, 16, 16, 0, bridge_z, IsTransparencySet(TO_BRIDGES));
01214       }
01215     }
01216     EndSpriteCombine();
01217 
01218     if (HasCatenaryDrawn(GetRailType(rampsouth))) {
01219       DrawCatenaryOnBridge(ti);
01220     }
01221   }
01222 
01223   /* draw roof, the component of the bridge which is logically between the vehicle and the camera */
01224   if (!IsInvisibilitySet(TO_BRIDGES)) {
01225     if (axis == AXIS_X) {
01226       y += 12;
01227       if (psid->sprite & SPRITE_MASK) AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 16, 4, 0x28, z, IsTransparencySet(TO_BRIDGES), 0, 3, BRIDGE_Z_START);
01228     } else {
01229       x += 12;
01230       if (psid->sprite & SPRITE_MASK) AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 4, 16, 0x28, z, IsTransparencySet(TO_BRIDGES), 3, 0, BRIDGE_Z_START);
01231     }
01232   }
01233 
01234   /* Draw TramFront as SpriteCombine */
01235   if (transport_type == TRANSPORT_ROAD) EndSpriteCombine();
01236 
01237   /* Do not draw anything more if bridges are invisible */
01238   if (IsInvisibilitySet(TO_BRIDGES)) return;
01239 
01240   psid++;
01241   if (ti->z + 5 == z) {
01242     /* draw poles below for small bridges */
01243     if (psid->sprite != 0) {
01244       SpriteID image = psid->sprite;
01245       SpriteID pal   = psid->pal;
01246       if (IsTransparencySet(TO_BRIDGES)) {
01247         SetBit(image, PALETTE_MODIFIER_TRANSPARENT);
01248         pal = PALETTE_TO_TRANSPARENT;
01249       }
01250 
01251       DrawGroundSpriteAt(image, pal, x - ti->x, y - ti->y, z - ti->z);
01252     }
01253   } else if (_settings_client.gui.bridge_pillars) {
01254     /* draw pillars below for high bridges */
01255     DrawBridgePillars(psid, ti, axis, drawfarpillar, x, y, z);
01256   }
01257 }
01258 
01259 
01260 static uint GetSlopeZ_TunnelBridge(TileIndex tile, uint x, uint y)
01261 {
01262   uint z;
01263   Slope tileh = GetTileSlope(tile, &z);
01264 
01265   x &= 0xF;
01266   y &= 0xF;
01267 
01268   if (IsTunnel(tile)) {
01269     uint pos = (DiagDirToAxis(GetTunnelBridgeDirection(tile)) == AXIS_X ? y : x);
01270 
01271     /* In the tunnel entrance? */
01272     if (5 <= pos && pos <= 10) return z;
01273   } else { // IsBridge(tile)
01274     DiagDirection dir = GetTunnelBridgeDirection(tile);
01275     uint pos = (DiagDirToAxis(dir) == AXIS_X ? y : x);
01276 
01277     z += ApplyFoundationToSlope(GetBridgeFoundation(tileh, DiagDirToAxis(dir)), &tileh);
01278 
01279     /* On the bridge ramp? */
01280     if (5 <= pos && pos <= 10) {
01281       uint delta;
01282 
01283       if (tileh != SLOPE_FLAT) return z + TILE_HEIGHT;
01284 
01285       switch (dir) {
01286         default: NOT_REACHED();
01287         case DIAGDIR_NE: delta = (TILE_SIZE - 1 - x) / 2; break;
01288         case DIAGDIR_SE: delta = y / 2; break;
01289         case DIAGDIR_SW: delta = x / 2; break;
01290         case DIAGDIR_NW: delta = (TILE_SIZE - 1 - y) / 2; break;
01291       }
01292       return z + 1 + delta;
01293     }
01294   }
01295 
01296   return z + GetPartialZ(x, y, tileh);
01297 }
01298 
01299 static Foundation GetFoundation_TunnelBridge(TileIndex tile, Slope tileh)
01300 {
01301   return IsTunnel(tile) ? FOUNDATION_NONE : GetBridgeFoundation(tileh, DiagDirToAxis(GetTunnelBridgeDirection(tile)));
01302 }
01303 
01304 static void GetTileDesc_TunnelBridge(TileIndex tile, TileDesc *td)
01305 {
01306   TransportType tt = GetTunnelBridgeTransportType(tile);
01307 
01308   if (IsTunnel(tile)) {
01309     td->str = (tt == TRANSPORT_RAIL) ? STR_LAI_TUNNEL_DESCRIPTION_RAILROAD : STR_LAI_TUNNEL_DESCRIPTION_ROAD;
01310   } else { // IsBridge(tile)
01311     td->str = (tt == TRANSPORT_WATER) ? STR_LAI_BRIDGE_DESCRIPTION_AQUEDUCT : GetBridgeSpec(GetBridgeType(tile))->transport_name[tt];
01312   }
01313   td->owner[0] = GetTileOwner(tile);
01314 
01315   Owner road_owner = INVALID_OWNER;
01316   Owner tram_owner = INVALID_OWNER;
01317   RoadTypes rts = GetRoadTypes(tile);
01318   if (HasBit(rts, ROADTYPE_ROAD)) road_owner = GetRoadOwner(tile, ROADTYPE_ROAD);
01319   if (HasBit(rts, ROADTYPE_TRAM)) tram_owner = GetRoadOwner(tile, ROADTYPE_TRAM);
01320 
01321   /* Is there a mix of owners? */
01322   if ((tram_owner != INVALID_OWNER && tram_owner != td->owner[0]) ||
01323       (road_owner != INVALID_OWNER && road_owner != td->owner[0])) {
01324     uint i = 1;
01325     if (road_owner != INVALID_OWNER) {
01326       td->owner_type[i] = STR_LAND_AREA_INFORMATION_ROAD_OWNER;
01327       td->owner[i] = road_owner;
01328       i++;
01329     }
01330     if (tram_owner != INVALID_OWNER) {
01331       td->owner_type[i] = STR_LAND_AREA_INFORMATION_TRAM_OWNER;
01332       td->owner[i] = tram_owner;
01333     }
01334   }
01335 
01336   if (tt == TRANSPORT_RAIL) {
01337     const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
01338     td->rail_speed = rti->max_speed;
01339 
01340     if (!IsTunnel(tile)) {
01341       uint16 spd = GetBridgeSpec(GetBridgeType(tile))->speed;
01342       if (td->rail_speed == 0 || spd < td->rail_speed) {
01343         td->rail_speed = spd;
01344       }
01345     }
01346   }
01347 }
01348 
01349 
01350 static void TileLoop_TunnelBridge(TileIndex tile)
01351 {
01352   bool snow_or_desert = HasTunnelBridgeSnowOrDesert(tile);
01353   switch (_settings_game.game_creation.landscape) {
01354     case LT_ARCTIC:
01355       if (snow_or_desert != (GetTileZ(tile) > GetSnowLine())) {
01356         SetTunnelBridgeSnowOrDesert(tile, !snow_or_desert);
01357         MarkTileDirtyByTile(tile);
01358       }
01359       break;
01360 
01361     case LT_TROPIC:
01362       if (GetTropicZone(tile) == TROPICZONE_DESERT && !snow_or_desert) {
01363         SetTunnelBridgeSnowOrDesert(tile, true);
01364         MarkTileDirtyByTile(tile);
01365       }
01366       break;
01367 
01368     default:
01369       break;
01370   }
01371 }
01372 
01373 static TrackStatus GetTileTrackStatus_TunnelBridge(TileIndex tile, TransportType mode, uint sub_mode, DiagDirection side)
01374 {
01375   TransportType transport_type = GetTunnelBridgeTransportType(tile);
01376   if (transport_type != mode || (transport_type == TRANSPORT_ROAD && (GetRoadTypes(tile) & sub_mode) == 0)) return 0;
01377 
01378   DiagDirection dir = GetTunnelBridgeDirection(tile);
01379   if (side != INVALID_DIAGDIR && side != ReverseDiagDir(dir)) return 0;
01380   return CombineTrackStatus(TrackBitsToTrackdirBits(DiagDirToDiagTrackBits(dir)), TRACKDIR_BIT_NONE);
01381 }
01382 
01383 static void ChangeTileOwner_TunnelBridge(TileIndex tile, Owner old_owner, Owner new_owner)
01384 {
01385   for (RoadType rt = ROADTYPE_ROAD; rt < ROADTYPE_END; rt++) {
01386     /* Update all roadtypes, no matter if they are present */
01387     if (GetRoadOwner(tile, rt) == old_owner) {
01388       SetRoadOwner(tile, rt, new_owner == INVALID_OWNER ? OWNER_NONE : new_owner);
01389     }
01390   }
01391 
01392   if (!IsTileOwner(tile, old_owner)) return;
01393 
01394   if (new_owner != INVALID_OWNER) {
01395     SetTileOwner(tile, new_owner);
01396   } else {
01397     if (DoCommand(tile, 0, 0, DC_EXEC | DC_BANKRUPT, CMD_LANDSCAPE_CLEAR).Failed()) {
01398       /* When clearing the bridge/tunnel failed there are still vehicles on/in
01399        * the bridge/tunnel. As all *our* vehicles are already removed, they
01400        * must be of another owner. Therefore this can't be rail tunnel/bridge.
01401        * In that case we can safely reassign the ownership to OWNER_NONE. */
01402       assert(GetTunnelBridgeTransportType(tile) != TRANSPORT_RAIL);
01403       SetTileOwner(tile, OWNER_NONE);
01404     }
01405   }
01406 }
01407 
01408 
01409 static const byte _tunnel_fractcoord_1[4]    = {0x8E, 0x18, 0x81, 0xE8};
01410 static const byte _tunnel_fractcoord_2[4]    = {0x81, 0x98, 0x87, 0x38};
01411 static const byte _tunnel_fractcoord_3[4]    = {0x82, 0x88, 0x86, 0x48};
01412 static const byte _exit_tunnel_track[4]      = {1, 2, 1, 2};
01413 
01415 static const Trackdir _road_exit_tunnel_state[DIAGDIR_END] = {
01416   TRACKDIR_X_SW, TRACKDIR_Y_NW, TRACKDIR_X_NE, TRACKDIR_Y_SE
01417 };
01418 static const byte _road_exit_tunnel_frame[4] = {2, 7, 9, 4};
01419 
01420 static const byte _tunnel_fractcoord_4[4]    = {0x52, 0x85, 0x98, 0x29};
01421 static const byte _tunnel_fractcoord_5[4]    = {0x92, 0x89, 0x58, 0x25};
01422 static const byte _tunnel_fractcoord_6[4]    = {0x92, 0x89, 0x56, 0x45};
01423 static const byte _tunnel_fractcoord_7[4]    = {0x52, 0x85, 0x96, 0x49};
01424 
01425 static VehicleEnterTileStatus VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y)
01426 {
01427   int z = GetSlopeZ(x, y) - v->z_pos;
01428 
01429   if (abs(z) > 2) return VETSB_CANNOT_ENTER;
01430   const DiagDirection dir = GetTunnelBridgeDirection(tile);
01431 
01432   if (IsTunnel(tile)) {
01433     byte fc;
01434     DiagDirection vdir;
01435 
01436     if (v->type == VEH_TRAIN) {
01437       Train *t = Train::From(v);
01438       fc = (x & 0xF) + (y << 4);
01439 
01440       vdir = DirToDiagDir(t->direction);
01441 
01442       if (t->track != TRACK_BIT_WORMHOLE && dir == vdir) {
01443         if (t->IsFrontEngine() && fc == _tunnel_fractcoord_1[dir]) {
01444           if (!PlayVehicleSound(t, VSE_TUNNEL) && RailVehInfo(t->engine_type)->engclass == 0) {
01445             SndPlayVehicleFx(SND_05_TRAIN_THROUGH_TUNNEL, v);
01446           }
01447           return VETSB_CONTINUE;
01448         }
01449         if (fc == _tunnel_fractcoord_2[dir]) {
01450           t->tile = tile;
01451           t->track = TRACK_BIT_WORMHOLE;
01452           t->vehstatus |= VS_HIDDEN;
01453           return VETSB_ENTERED_WORMHOLE;
01454         }
01455       }
01456 
01457       if (dir == ReverseDiagDir(vdir) && fc == _tunnel_fractcoord_3[dir] && z == 0) {
01458         /* We're at the tunnel exit ?? */
01459         t->tile = tile;
01460         t->track = (TrackBits)_exit_tunnel_track[dir];
01461         assert(t->track);
01462         t->vehstatus &= ~VS_HIDDEN;
01463         return VETSB_ENTERED_WORMHOLE;
01464       }
01465     } else if (v->type == VEH_ROAD) {
01466       RoadVehicle *rv = RoadVehicle::From(v);
01467       fc = (x & 0xF) + (y << 4);
01468       vdir = DirToDiagDir(v->direction);
01469 
01470       /* Enter tunnel? */
01471       if (rv->state != RVSB_WORMHOLE && dir == vdir) {
01472         if (fc == _tunnel_fractcoord_4[dir] ||
01473             fc == _tunnel_fractcoord_5[dir]) {
01474           rv->tile = tile;
01475           rv->state = RVSB_WORMHOLE;
01476           rv->vehstatus |= VS_HIDDEN;
01477           return VETSB_ENTERED_WORMHOLE;
01478         } else {
01479           return VETSB_CONTINUE;
01480         }
01481       }
01482 
01483       if (dir == ReverseDiagDir(vdir) && (
01484             /* We're at the tunnel exit ?? */
01485             fc == _tunnel_fractcoord_6[dir] ||
01486             fc == _tunnel_fractcoord_7[dir]
01487           ) &&
01488           z == 0) {
01489         rv->tile = tile;
01490         rv->state = _road_exit_tunnel_state[dir];
01491         rv->frame = _road_exit_tunnel_frame[dir];
01492         rv->vehstatus &= ~VS_HIDDEN;
01493         return VETSB_ENTERED_WORMHOLE;
01494       }
01495     }
01496   } else { // IsBridge(tile)
01497 
01498     if (v->IsPrimaryVehicle() && v->type != VEH_SHIP) {
01499       /* modify speed of vehicle */
01500       uint16 spd = GetBridgeSpec(GetBridgeType(tile))->speed;
01501 
01502       if (v->type == VEH_ROAD) spd *= 2;
01503       if (v->cur_speed > spd) v->cur_speed = spd;
01504     }
01505 
01506     if (DirToDiagDir(v->direction) == dir) {
01507       switch (dir) {
01508         default: NOT_REACHED();
01509         case DIAGDIR_NE: if ((x & 0xF) != 0)             return VETSB_CONTINUE; break;
01510         case DIAGDIR_SE: if ((y & 0xF) != TILE_SIZE - 1) return VETSB_CONTINUE; break;
01511         case DIAGDIR_SW: if ((x & 0xF) != TILE_SIZE - 1) return VETSB_CONTINUE; break;
01512         case DIAGDIR_NW: if ((y & 0xF) != 0)             return VETSB_CONTINUE; break;
01513       }
01514       switch (v->type) {
01515         case VEH_TRAIN: {
01516           Train *t = Train::From(v);
01517           t->track = TRACK_BIT_WORMHOLE;
01518           ClrBit(t->flags, VRF_GOINGUP);
01519           ClrBit(t->flags, VRF_GOINGDOWN);
01520         } break;
01521 
01522         case VEH_ROAD:
01523           RoadVehicle::From(v)->state = RVSB_WORMHOLE;
01524           break;
01525 
01526         case VEH_SHIP:
01527           Ship::From(v)->state = TRACK_BIT_WORMHOLE;
01528           break;
01529 
01530         default: NOT_REACHED();
01531       }
01532       return VETSB_ENTERED_WORMHOLE;
01533     } else if (DirToDiagDir(v->direction) == ReverseDiagDir(dir)) {
01534       v->tile = tile;
01535       switch (v->type) {
01536         case VEH_TRAIN: {
01537           Train *t = Train::From(v);
01538           if (t->track == TRACK_BIT_WORMHOLE) {
01539             t->track = (DiagDirToAxis(dir) == AXIS_X ? TRACK_BIT_X : TRACK_BIT_Y);
01540             return VETSB_ENTERED_WORMHOLE;
01541           }
01542         } break;
01543 
01544         case VEH_ROAD: {
01545           RoadVehicle *rv = RoadVehicle::From(v);
01546           if (rv->state == RVSB_WORMHOLE) {
01547             rv->state = _road_exit_tunnel_state[dir];
01548             rv->frame = 0;
01549             return VETSB_ENTERED_WORMHOLE;
01550           }
01551         } break;
01552 
01553         case VEH_SHIP: {
01554           Ship *ship = Ship::From(v);
01555           if (ship->state == TRACK_BIT_WORMHOLE) {
01556             ship->state = (DiagDirToAxis(dir) == AXIS_X ? TRACK_BIT_X : TRACK_BIT_Y);
01557             return VETSB_ENTERED_WORMHOLE;
01558           }
01559         } break;
01560 
01561         default: NOT_REACHED();
01562       }
01563     }
01564   }
01565   return VETSB_CONTINUE;
01566 }
01567 
01568 static CommandCost TerraformTile_TunnelBridge(TileIndex tile, DoCommandFlag flags, uint z_new, Slope tileh_new)
01569 {
01570   if (_settings_game.construction.build_on_slopes && AutoslopeEnabled() && IsBridge(tile) && GetTunnelBridgeTransportType(tile) != TRANSPORT_WATER) {
01571     DiagDirection direction = GetTunnelBridgeDirection(tile);
01572     Axis axis = DiagDirToAxis(direction);
01573     CommandCost res;
01574     uint z_old;
01575     Slope tileh_old = GetTileSlope(tile, &z_old);
01576 
01577     /* Check if new slope is valid for bridges in general (so we can safely call GetBridgeFoundation()) */
01578     if ((direction == DIAGDIR_NW) || (direction == DIAGDIR_NE)) {
01579       CheckBridgeSlopeSouth(axis, &tileh_old, &z_old);
01580       res = CheckBridgeSlopeSouth(axis, &tileh_new, &z_new);
01581     } else {
01582       CheckBridgeSlopeNorth(axis, &tileh_old, &z_old);
01583       res = CheckBridgeSlopeNorth(axis, &tileh_new, &z_new);
01584     }
01585 
01586     /* Surface slope is valid and remains unchanged? */
01587     if (res.Succeeded() && (z_old == z_new) && (tileh_old == tileh_new)) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
01588   }
01589 
01590   return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
01591 }
01592 
01593 extern const TileTypeProcs _tile_type_tunnelbridge_procs = {
01594   DrawTile_TunnelBridge,           // draw_tile_proc
01595   GetSlopeZ_TunnelBridge,          // get_slope_z_proc
01596   ClearTile_TunnelBridge,          // clear_tile_proc
01597   NULL,                            // add_accepted_cargo_proc
01598   GetTileDesc_TunnelBridge,        // get_tile_desc_proc
01599   GetTileTrackStatus_TunnelBridge, // get_tile_track_status_proc
01600   NULL,                            // click_tile_proc
01601   NULL,                            // animate_tile_proc
01602   TileLoop_TunnelBridge,           // tile_loop_clear
01603   ChangeTileOwner_TunnelBridge,    // change_tile_owner_clear
01604   NULL,                            // add_produced_cargo_proc
01605   VehicleEnter_TunnelBridge,       // vehicle_enter_tile_proc
01606   GetFoundation_TunnelBridge,      // get_foundation_proc
01607   TerraformTile_TunnelBridge,      // terraform_tile_proc
01608 };

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