road_cmd.cpp

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/*
 * This file is part of OpenTTD.
 * 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.
 * 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.
 * 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/>.
 */
 
#include "stdafx.h"
#include "road.h"
#include "road_internal.h"
#include "viewport_func.h"
#include "command_func.h"
#include "pathfinder/yapf/yapf_cache.h"
#include "depot_base.h"
#include "newgrf.h"
#include "autoslope.h"
#include "tunnelbridge_map.h"
#include "strings_func.h"
#include "vehicle_func.h"
#include "sound_func.h"
#include "tunnelbridge.h"
#include "cheat_type.h"
#include "effectvehicle_func.h"
#include "effectvehicle_base.h"
#include "elrail_func.h"
#include "roadveh.h"
#include "train.h"
#include "town.h"
#include "company_base.h"
#include "core/random_func.hpp"
#include "newgrf_debug.h"
#include "newgrf_railtype.h"
#include "newgrf_roadtype.h"
#include "date_func.h"
#include "genworld.h"
#include "company_gui.h"
#include "road_func.h"
#include "road_cmd.h"
#include "landscape_cmd.h"
#include "rail_cmd.h"
 
#include "table/strings.h"
#include "table/roadtypes.h"
 
#include "safeguards.h"
 
typedef std::vector<RoadVehicle *> RoadVehicleList;
 
RoadTypeInfo _roadtypes[ROADTYPE_END];
std::vector<RoadType> _sorted_roadtypes;
RoadTypes _roadtypes_hidden_mask;
 
RoadTypes _roadtypes_type;
 
void ResetRoadTypes()
{
  static_assert(lengthof(_original_roadtypes) <= lengthof(_roadtypes));
 
  uint i = 0;
  for (; i < lengthof(_original_roadtypes); i++) _roadtypes[i] = _original_roadtypes[i];
 
  static const RoadTypeInfo empty_roadtype = {
    { 0, 0, 0, 0, 0, 0 },
    { 0, 0, 0, 0, 0, 0 },
    { 0, 0, 0, 0, 0, 0, 0, 0, 0, {}, {}, 0, {}, {} },
    ROADTYPES_NONE, ROTFB_NONE, 0, 0, 0, 0,
    RoadTypeLabelList(), 0, 0, ROADTYPES_NONE, ROADTYPES_NONE, 0,
    {}, {} };
  for (; i < lengthof(_roadtypes);          i++) _roadtypes[i] = empty_roadtype;
 
  _roadtypes_hidden_mask = ROADTYPES_NONE;
  _roadtypes_type        = ROADTYPES_TRAM;
}
 
void ResolveRoadTypeGUISprites(RoadTypeInfo *rti)
{
  SpriteID cursors_base = GetCustomRoadSprite(rti, INVALID_TILE, ROTSG_CURSORS);
  if (cursors_base != 0) {
    rti->gui_sprites.build_y_road = cursors_base +  0;
    rti->gui_sprites.build_x_road = cursors_base +  1;
    rti->gui_sprites.auto_road    = cursors_base +  2;
    rti->gui_sprites.build_depot  = cursors_base +  3;
    rti->gui_sprites.build_tunnel = cursors_base +  4;
    rti->gui_sprites.convert_road = cursors_base +  5;
    rti->cursor.road_swne         = cursors_base +  6;
    rti->cursor.road_nwse         = cursors_base +  7;
    rti->cursor.autoroad          = cursors_base +  8;
    rti->cursor.depot             = cursors_base +  9;
    rti->cursor.tunnel            = cursors_base + 10;
    rti->cursor.convert_road      = cursors_base + 11;
  }
}
 
static bool CompareRoadTypes(const RoadType &first, const RoadType &second)
{
  if (RoadTypeIsRoad(first) == RoadTypeIsRoad(second)) {
    return GetRoadTypeInfo(first)->sorting_order < GetRoadTypeInfo(second)->sorting_order;
  }
  return RoadTypeIsTram(first) < RoadTypeIsTram(second);
}
 
void InitRoadTypes()
{
  for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
    RoadTypeInfo *rti = &_roadtypes[rt];
    ResolveRoadTypeGUISprites(rti);
    if (HasBit(rti->flags, ROTF_HIDDEN)) SetBit(_roadtypes_hidden_mask, rt);
  }
 
  _sorted_roadtypes.clear();
  for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
    if (_roadtypes[rt].label != 0 && !HasBit(_roadtypes_hidden_mask, rt)) {
      _sorted_roadtypes.push_back(rt);
    }
  }
  std::sort(_sorted_roadtypes.begin(), _sorted_roadtypes.end(), CompareRoadTypes);
}
 
RoadType AllocateRoadType(RoadTypeLabel label, RoadTramType rtt)
{
  for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
    RoadTypeInfo *rti = &_roadtypes[rt];
 
    if (rti->label == 0) {
      /* Set up new road type */
      *rti = _original_roadtypes[(rtt == RTT_TRAM) ? ROADTYPE_TRAM : ROADTYPE_ROAD];
      rti->label = label;
      rti->alternate_labels.clear();
      rti->flags = ROTFB_NONE;
      rti->introduction_date = INVALID_DATE;
 
      /* Make us compatible with ourself. */
      rti->powered_roadtypes = (RoadTypes)(1ULL << rt);
 
      /* We also introduce ourself. */
      rti->introduces_roadtypes = (RoadTypes)(1ULL << rt);
 
      /* Default sort order; order of allocation, but with some
       * offsets so it's easier for NewGRF to pick a spot without
       * changing the order of other (original) road types.
       * The << is so you can place other roadtypes in between the
       * other roadtypes, the 7 is to be able to place something
       * before the first (default) road type. */
      rti->sorting_order = rt << 2 | 7;
 
      /* Set bitmap of road/tram types */
      if (rtt == RTT_TRAM) {
        SetBit(_roadtypes_type, rt);
      } else {
        ClrBit(_roadtypes_type, rt);
      }
 
      return rt;
    }
  }
 
  return INVALID_ROADTYPE;
}
 
bool RoadVehiclesAreBuilt()
{
  return !RoadVehicle::Iterate().empty();
}
 
void UpdateCompanyRoadInfrastructure(RoadType rt, Owner o, int count)
{
  if (rt == INVALID_ROADTYPE) return;
 
  Company *c = Company::GetIfValid(o);
  if (c == nullptr) return;
 
  c->infrastructure.road[rt] += count;
  DirtyCompanyInfrastructureWindows(c->index);
}
 
static const RoadBits _invalid_tileh_slopes_road[2][15] = {
  /* The inverse of the mixable RoadBits on a leveled slope */
  {
    ROAD_NONE,         // SLOPE_FLAT
    ROAD_NE | ROAD_SE, // SLOPE_W
    ROAD_NE | ROAD_NW, // SLOPE_S
 
    ROAD_NE,           // SLOPE_SW
    ROAD_NW | ROAD_SW, // SLOPE_E
    ROAD_NONE,         // SLOPE_EW
 
    ROAD_NW,           // SLOPE_SE
    ROAD_NONE,         // SLOPE_WSE
    ROAD_SE | ROAD_SW, // SLOPE_N
 
    ROAD_SE,           // SLOPE_NW
    ROAD_NONE,         // SLOPE_NS
    ROAD_NONE,         // SLOPE_ENW
 
    ROAD_SW,           // SLOPE_NE
    ROAD_NONE,         // SLOPE_SEN
    ROAD_NONE          // SLOPE_NWS
  },
  /* The inverse of the allowed straight roads on a slope
   * (with and without a foundation). */
  {
    ROAD_NONE, // SLOPE_FLAT
    ROAD_NONE, // SLOPE_W    Foundation
    ROAD_NONE, // SLOPE_S    Foundation
 
    ROAD_Y,    // SLOPE_SW
    ROAD_NONE, // SLOPE_E    Foundation
    ROAD_ALL,  // SLOPE_EW
 
    ROAD_X,    // SLOPE_SE
    ROAD_ALL,  // SLOPE_WSE
    ROAD_NONE, // SLOPE_N    Foundation
 
    ROAD_X,    // SLOPE_NW
    ROAD_ALL,  // SLOPE_NS
    ROAD_ALL,  // SLOPE_ENW
 
    ROAD_Y,    // SLOPE_NE
    ROAD_ALL,  // SLOPE_SEN
    ROAD_ALL   // SLOPE_NW
  }
};
 
static Foundation GetRoadFoundation(Slope tileh, RoadBits bits);
 
CommandCost CheckAllowRemoveRoad(TileIndex tile, RoadBits remove, Owner owner, RoadTramType rtt, DoCommandFlag flags, bool town_check)
{
  if (_game_mode == GM_EDITOR || remove == ROAD_NONE) return CommandCost();
 
  /* Water can always flood and towns can always remove "normal" road pieces.
   * Towns are not be allowed to remove non "normal" road pieces, like tram
   * tracks as that would result in trams that cannot turn. */
  if (_current_company == OWNER_WATER ||
      (rtt == RTT_ROAD && !Company::IsValidID(_current_company))) return CommandCost();
 
  /* Only do the special processing if the road is owned
   * by a town */
  if (owner != OWNER_TOWN) {
    if (owner == OWNER_NONE) return CommandCost();
    CommandCost ret = CheckOwnership(owner);
    return ret;
  }
 
  if (!town_check) return CommandCost();
 
  if (_cheats.magic_bulldozer.value) return CommandCost();
 
  Town *t = ClosestTownFromTile(tile, UINT_MAX);
  if (t == nullptr) return CommandCost();
 
  /* check if you're allowed to remove the street owned by a town
   * removal allowance depends on difficulty setting */
  CommandCost ret = CheckforTownRating(flags, t, ROAD_REMOVE);
  if (ret.Failed()) return ret;
 
  /* Get a bitmask of which neighbouring roads has a tile */
  RoadBits n = ROAD_NONE;
  RoadBits present = GetAnyRoadBits(tile, rtt);
  if ((present & ROAD_NE) && (GetAnyRoadBits(TILE_ADDXY(tile, -1,  0), rtt) & ROAD_SW)) n |= ROAD_NE;
  if ((present & ROAD_SE) && (GetAnyRoadBits(TILE_ADDXY(tile,  0,  1), rtt) & ROAD_NW)) n |= ROAD_SE;
  if ((present & ROAD_SW) && (GetAnyRoadBits(TILE_ADDXY(tile,  1,  0), rtt) & ROAD_NE)) n |= ROAD_SW;
  if ((present & ROAD_NW) && (GetAnyRoadBits(TILE_ADDXY(tile,  0, -1), rtt) & ROAD_SE)) n |= ROAD_NW;
 
  int rating_decrease = RATING_ROAD_DOWN_STEP_EDGE;
  /* If 0 or 1 bits are set in n, or if no bits that match the bits to remove,
   * then allow it */
  if (KillFirstBit(n) != ROAD_NONE && (n & remove) != ROAD_NONE) {
    /* you can remove all kind of roads with extra dynamite */
    if (!_settings_game.construction.extra_dynamite) {
      SetDParam(0, t->index);
      return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
    }
    rating_decrease = RATING_ROAD_DOWN_STEP_INNER;
  }
  ChangeTownRating(t, rating_decrease, RATING_ROAD_MINIMUM, flags);
 
  return CommandCost();
}
 
 
static CommandCost RemoveRoad(TileIndex tile, DoCommandFlag flags, RoadBits pieces, RoadTramType rtt, bool crossing_check, bool town_check = true)
{
  assert(pieces != ROAD_NONE);
 
  RoadType existing_rt = MayHaveRoad(tile) ? GetRoadType(tile, rtt) : INVALID_ROADTYPE;
  /* The tile doesn't have the given road type */
  if (existing_rt == INVALID_ROADTYPE) return_cmd_error((rtt == RTT_TRAM) ? STR_ERROR_THERE_IS_NO_TRAMWAY : STR_ERROR_THERE_IS_NO_ROAD);
 
  switch (GetTileType(tile)) {
    case MP_ROAD: {
      CommandCost ret = EnsureNoVehicleOnGround(tile);
      if (ret.Failed()) return ret;
      break;
    }
 
    case MP_STATION: {
      if (!IsDriveThroughStopTile(tile)) return CMD_ERROR;
 
      CommandCost ret = EnsureNoVehicleOnGround(tile);
      if (ret.Failed()) return ret;
      break;
    }
 
    case MP_TUNNELBRIDGE: {
      if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) return CMD_ERROR;
      CommandCost ret = TunnelBridgeIsFree(tile, GetOtherTunnelBridgeEnd(tile));
      if (ret.Failed()) return ret;
      break;
    }
 
    default:
      return CMD_ERROR;
  }
 
  CommandCost ret = CheckAllowRemoveRoad(tile, pieces, GetRoadOwner(tile, rtt), rtt, flags, town_check);
  if (ret.Failed()) return ret;
 
  if (!IsTileType(tile, MP_ROAD)) {
    /* If it's the last roadtype, just clear the whole tile */
    if (GetRoadType(tile, OtherRoadTramType(rtt)) == INVALID_ROADTYPE) return Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
 
    CommandCost cost(EXPENSES_CONSTRUCTION);
    if (IsTileType(tile, MP_TUNNELBRIDGE)) {
      /* Removing any roadbit in the bridge axis removes the roadtype (that's the behaviour remove-long-roads needs) */
      if ((AxisToRoadBits(DiagDirToAxis(GetTunnelBridgeDirection(tile))) & pieces) == ROAD_NONE) return_cmd_error((rtt == RTT_TRAM) ? STR_ERROR_THERE_IS_NO_TRAMWAY : STR_ERROR_THERE_IS_NO_ROAD);
 
      TileIndex other_end = GetOtherTunnelBridgeEnd(tile);
      /* Pay for *every* tile of the bridge or tunnel */
      uint len = GetTunnelBridgeLength(other_end, tile) + 2;
      cost.AddCost(len * 2 * RoadClearCost(existing_rt));
      if (flags & DC_EXEC) {
        /* A full diagonal road tile has two road bits. */
        UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -(int)(len * 2 * TUNNELBRIDGE_TRACKBIT_FACTOR));
 
        SetRoadType(other_end, rtt, INVALID_ROADTYPE);
        SetRoadType(tile,      rtt, INVALID_ROADTYPE);
 
        /* If the owner of the bridge sells all its road, also move the ownership
         * to the owner of the other roadtype, unless the bridge owner is a town. */
        Owner other_owner = GetRoadOwner(tile, OtherRoadTramType(rtt));
        if (!IsTileOwner(tile, other_owner) && !IsTileOwner(tile, OWNER_TOWN)) {
          SetTileOwner(tile, other_owner);
          SetTileOwner(other_end, other_owner);
        }
 
        /* Mark tiles dirty that have been repaved */
        if (IsBridge(tile)) {
          MarkBridgeDirty(tile);
        } else {
          MarkTileDirtyByTile(tile);
          MarkTileDirtyByTile(other_end);
        }
      }
    } else {
      assert(IsDriveThroughStopTile(tile));
      cost.AddCost(RoadClearCost(existing_rt) * 2);
      if (flags & DC_EXEC) {
        /* A full diagonal road tile has two road bits. */
        UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -2);
        SetRoadType(tile, rtt, INVALID_ROADTYPE);
        MarkTileDirtyByTile(tile);
      }
    }
    return cost;
  }
 
  switch (GetRoadTileType(tile)) {
    case ROAD_TILE_NORMAL: {
      Slope tileh = GetTileSlope(tile);
 
      /* Steep slopes behave the same as slopes with one corner raised. */
      if (IsSteepSlope(tileh)) {
        tileh = SlopeWithOneCornerRaised(GetHighestSlopeCorner(tileh));
      }
 
      RoadBits present = GetRoadBits(tile, rtt);
      const RoadBits other = GetRoadBits(tile, OtherRoadTramType(rtt));
      const Foundation f = GetRoadFoundation(tileh, present);
 
      if (HasRoadWorks(tile) && _current_company != OWNER_WATER) return_cmd_error(STR_ERROR_ROAD_WORKS_IN_PROGRESS);
 
      /* Autocomplete to a straight road
       * @li if the bits of the other roadtypes result in another foundation
       * @li if build on slopes is disabled */
      if ((IsStraightRoad(other) && (other & _invalid_tileh_slopes_road[0][tileh & SLOPE_ELEVATED]) != ROAD_NONE) ||
          (tileh != SLOPE_FLAT && !_settings_game.construction.build_on_slopes)) {
        pieces |= MirrorRoadBits(pieces);
      }
 
      /* limit the bits to delete to the existing bits. */
      pieces &= present;
      if (pieces == ROAD_NONE) return_cmd_error((rtt == RTT_TRAM) ? STR_ERROR_THERE_IS_NO_TRAMWAY : STR_ERROR_THERE_IS_NO_ROAD);
 
      /* Now set present what it will be after the remove */
      present ^= pieces;
 
      /* Check for invalid RoadBit combinations on slopes */
      if (tileh != SLOPE_FLAT && present != ROAD_NONE &&
          (present & _invalid_tileh_slopes_road[0][tileh & SLOPE_ELEVATED]) == present) {
        return CMD_ERROR;
      }
 
      if (flags & DC_EXEC) {
        if (HasRoadWorks(tile)) {
          /* flooding tile with road works, don't forget to remove the effect vehicle too */
          assert(_current_company == OWNER_WATER);
          for (EffectVehicle *v : EffectVehicle::Iterate()) {
            if (TileVirtXY(v->x_pos, v->y_pos) == tile) {
              delete v;
            }
          }
        }
 
        UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -(int)CountBits(pieces));
 
        if (present == ROAD_NONE) {
          /* No other road type, just clear tile. */
          if (GetRoadType(tile, OtherRoadTramType(rtt)) == INVALID_ROADTYPE) {
            /* Includes MarkTileDirtyByTile() */
            DoClearSquare(tile);
          } else {
            if (rtt == RTT_ROAD && IsRoadOwner(tile, rtt, OWNER_TOWN)) {
              /* Update nearest-town index */
              const Town *town = CalcClosestTownFromTile(tile);
              SetTownIndex(tile, town == nullptr ? INVALID_TOWN : town->index);
            }
            SetRoadBits(tile, ROAD_NONE, rtt);
            SetRoadType(tile, rtt, INVALID_ROADTYPE);
            MarkTileDirtyByTile(tile);
          }
        } else {
          /* When bits are removed, you *always* end up with something that
           * is not a complete straight road tile. However, trams do not have
           * onewayness, so they cannot remove it either. */
          if (rtt == RTT_ROAD) SetDisallowedRoadDirections(tile, DRD_NONE);
          SetRoadBits(tile, present, rtt);
          MarkTileDirtyByTile(tile);
        }
      }
 
      CommandCost cost(EXPENSES_CONSTRUCTION, CountBits(pieces) * RoadClearCost(existing_rt));
      /* If we build a foundation we have to pay for it. */
      if (f == FOUNDATION_NONE && GetRoadFoundation(tileh, present) != FOUNDATION_NONE) cost.AddCost(_price[PR_BUILD_FOUNDATION]);
 
      return cost;
    }
 
    case ROAD_TILE_CROSSING: {
      if (pieces & ComplementRoadBits(GetCrossingRoadBits(tile))) {
        return CMD_ERROR;
      }
 
      if (flags & DC_EXEC) {
        UpdateAdjacentLevelCrossingTilesOnLevelCrossingRemoval(tile, GetCrossingRoadAxis(tile));
 
        /* A full diagonal road tile has two road bits. */
        UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -2);
 
        Track railtrack = GetCrossingRailTrack(tile);
        if (GetRoadType(tile, OtherRoadTramType(rtt)) == INVALID_ROADTYPE) {
          TrackBits tracks = GetCrossingRailBits(tile);
          bool reserved = HasCrossingReservation(tile);
          MakeRailNormal(tile, GetTileOwner(tile), tracks, GetRailType(tile));
          if (reserved) SetTrackReservation(tile, tracks);
 
          /* Update rail count for level crossings. The plain track should still be accounted
           * for, so only subtract the difference to the level crossing cost. */
          Company *c = Company::GetIfValid(GetTileOwner(tile));
          if (c != nullptr) {
            c->infrastructure.rail[GetRailType(tile)] -= LEVELCROSSING_TRACKBIT_FACTOR - 1;
            DirtyCompanyInfrastructureWindows(c->index);
          }
        } else {
          SetRoadType(tile, rtt, INVALID_ROADTYPE);
        }
        MarkTileDirtyByTile(tile);
        YapfNotifyTrackLayoutChange(tile, railtrack);
      }
      return CommandCost(EXPENSES_CONSTRUCTION, RoadClearCost(existing_rt) * 2);
    }
 
    default:
    case ROAD_TILE_DEPOT:
      return CMD_ERROR;
  }
}
 
 
static CommandCost CheckRoadSlope(Slope tileh, RoadBits *pieces, RoadBits existing, RoadBits other)
{
  /* Remove already build pieces */
  CLRBITS(*pieces, existing);
 
  /* If we can't build anything stop here */
  if (*pieces == ROAD_NONE) return CMD_ERROR;
 
  /* All RoadBit combos are valid on flat land */
  if (tileh == SLOPE_FLAT) return CommandCost();
 
  /* Steep slopes behave the same as slopes with one corner raised. */
  if (IsSteepSlope(tileh)) {
    tileh = SlopeWithOneCornerRaised(GetHighestSlopeCorner(tileh));
  }
 
  /* Save the merge of all bits of the current type */
  RoadBits type_bits = existing | *pieces;
 
  /* Roads on slopes */
  if (_settings_game.construction.build_on_slopes && (_invalid_tileh_slopes_road[0][tileh] & (other | type_bits)) == ROAD_NONE) {
 
    /* If we add leveling we've got to pay for it */
    if ((other | existing) == ROAD_NONE) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
 
    return CommandCost();
  }
 
  /* Autocomplete uphill roads */
  *pieces |= MirrorRoadBits(*pieces);
  type_bits = existing | *pieces;
 
  /* Uphill roads */
  if (IsStraightRoad(type_bits) && (other == type_bits || other == ROAD_NONE) &&
      (_invalid_tileh_slopes_road[1][tileh] & (other | type_bits)) == ROAD_NONE) {
 
    /* Slopes with foundation ? */
    if (IsSlopeWithOneCornerRaised(tileh)) {
 
      /* Prevent build on slopes if it isn't allowed */
      if (_settings_game.construction.build_on_slopes) {
 
        /* If we add foundation we've got to pay for it */
        if ((other | existing) == ROAD_NONE) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
 
        return CommandCost();
      }
    } else {
      if (HasExactlyOneBit(existing) && GetRoadFoundation(tileh, existing) == FOUNDATION_NONE) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
      return CommandCost();
    }
  }
  return CMD_ERROR;
}
 
CommandCost CmdBuildRoad(DoCommandFlag flags, TileIndex tile, RoadBits pieces, RoadType rt, DisallowedRoadDirections toggle_drd, TownID town_id)
{
  CompanyID company = _current_company;
  CommandCost cost(EXPENSES_CONSTRUCTION);
 
  RoadBits existing = ROAD_NONE;
  RoadBits other_bits = ROAD_NONE;
 
  /* Road pieces are max 4 bitset values (NE, NW, SE, SW) and town can only be non-zero
   * if a non-company is building the road */
  if ((Company::IsValidID(company) && town_id != 0) || (company == OWNER_TOWN && !Town::IsValidID(town_id)) || (company == OWNER_DEITY && town_id != 0)) return CMD_ERROR;
  if (company != OWNER_TOWN) {
    const Town *town = CalcClosestTownFromTile(tile);
    town_id = (town != nullptr) ? town->index : INVALID_TOWN;
 
    if (company == OWNER_DEITY) {
      company = OWNER_TOWN;
 
      /* If we are not within a town, we are not owned by the town */
      if (town == nullptr || DistanceSquare(tile, town->xy) > town->cache.squared_town_zone_radius[HZB_TOWN_EDGE]) {
        company = OWNER_NONE;
      }
    }
  }
 
  /* do not allow building 'zero' road bits, code wouldn't handle it */
  if (pieces == ROAD_NONE || !IsValidRoadBits(pieces) || !IsValidDisallowedRoadDirections(toggle_drd)) return CMD_ERROR;
  if (!ValParamRoadType(rt)) return CMD_ERROR;
 
  Slope tileh = GetTileSlope(tile);
  RoadTramType rtt = GetRoadTramType(rt);
 
  bool need_to_clear = false;
  switch (GetTileType(tile)) {
    case MP_ROAD:
      switch (GetRoadTileType(tile)) {
        case ROAD_TILE_NORMAL: {
          if (HasRoadWorks(tile)) return_cmd_error(STR_ERROR_ROAD_WORKS_IN_PROGRESS);
 
          other_bits = GetRoadBits(tile, OtherRoadTramType(rtt));
          if (!HasTileRoadType(tile, rtt)) break;
 
          existing = GetRoadBits(tile, rtt);
          bool crossing = !IsStraightRoad(existing | pieces);
          if (rtt == RTT_ROAD && (GetDisallowedRoadDirections(tile) != DRD_NONE || toggle_drd != DRD_NONE) && crossing) {
            /* Junctions cannot be one-way */
            return_cmd_error(STR_ERROR_ONEWAY_ROADS_CAN_T_HAVE_JUNCTION);
          }
          if ((existing & pieces) == pieces) {
            /* We only want to set the (dis)allowed road directions */
            if (toggle_drd != DRD_NONE && rtt == RTT_ROAD) {
              if (crossing) return_cmd_error(STR_ERROR_ONEWAY_ROADS_CAN_T_HAVE_JUNCTION);
 
              Owner owner = GetRoadOwner(tile, rtt);
              if (owner != OWNER_NONE) {
                CommandCost ret = CheckOwnership(owner, tile);
                if (ret.Failed()) return ret;
              }
 
              DisallowedRoadDirections dis_existing = GetDisallowedRoadDirections(tile);
              DisallowedRoadDirections dis_new      = dis_existing ^ toggle_drd;
 
              /* We allow removing disallowed directions to break up
               * deadlocks, but adding them can break articulated
               * vehicles. As such, only when less is disallowed,
               * i.e. bits are removed, we skip the vehicle check. */
              if (CountBits(dis_existing) <= CountBits(dis_new)) {
                CommandCost ret = EnsureNoVehicleOnGround(tile);
                if (ret.Failed()) return ret;
              }
 
              /* Ignore half built tiles */
              if ((flags & DC_EXEC) && IsStraightRoad(existing)) {
                SetDisallowedRoadDirections(tile, dis_new);
                MarkTileDirtyByTile(tile);
              }
              return CommandCost();
            }
            return_cmd_error(STR_ERROR_ALREADY_BUILT);
          }
          /* Disallow breaking end-of-line of someone else
           * so trams can still reverse on this tile. */
          if (rtt == RTT_TRAM && HasExactlyOneBit(existing)) {
            Owner owner = GetRoadOwner(tile, rtt);
            if (Company::IsValidID(owner)) {
              CommandCost ret = CheckOwnership(owner);
              if (ret.Failed()) return ret;
            }
          }
          break;
        }
 
        case ROAD_TILE_CROSSING:
          if (RoadNoLevelCrossing(rt)) {
            return_cmd_error(STR_ERROR_CROSSING_DISALLOWED_ROAD);
          }
 
          other_bits = GetCrossingRoadBits(tile);
          if (pieces & ComplementRoadBits(other_bits)) goto do_clear;
          pieces = other_bits; // we need to pay for both roadbits
 
          if (HasTileRoadType(tile, rtt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
          break;
 
        case ROAD_TILE_DEPOT:
          if ((GetAnyRoadBits(tile, rtt) & pieces) == pieces) return_cmd_error(STR_ERROR_ALREADY_BUILT);
          goto do_clear;
 
        default: NOT_REACHED();
      }
      break;
 
    case MP_RAILWAY: {
      if (IsSteepSlope(tileh)) {
        return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
      }
 
      /* Level crossings may only be built on these slopes */
      if (!HasBit(VALID_LEVEL_CROSSING_SLOPES, tileh)) {
        return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
      }
 
      if (GetRailTileType(tile) != RAIL_TILE_NORMAL) goto do_clear;
 
      if (RoadNoLevelCrossing(rt)) {
        return_cmd_error(STR_ERROR_CROSSING_DISALLOWED_ROAD);
      }
 
      if (RailNoLevelCrossings(GetRailType(tile))) {
        return_cmd_error(STR_ERROR_CROSSING_DISALLOWED_RAIL);
      }
 
      Axis roaddir;
      switch (GetTrackBits(tile)) {
        case TRACK_BIT_X:
          if (pieces & ROAD_X) goto do_clear;
          roaddir = AXIS_Y;
          break;
 
        case TRACK_BIT_Y:
          if (pieces & ROAD_Y) goto do_clear;
          roaddir = AXIS_X;
          break;
 
        default: goto do_clear;
      }
 
      CommandCost ret = EnsureNoVehicleOnGround(tile);
      if (ret.Failed()) return ret;
 
      if (flags & DC_EXEC) {
        Track railtrack = AxisToTrack(OtherAxis(roaddir));
        YapfNotifyTrackLayoutChange(tile, railtrack);
        /* Update company infrastructure counts. A level crossing has two road bits. */
        UpdateCompanyRoadInfrastructure(rt, company, 2);
 
        /* Update rail count for level crossings. The plain track is already
         * counted, so only add the difference to the level crossing cost. */
        Company *c = Company::GetIfValid(GetTileOwner(tile));
        if (c != nullptr) {
          c->infrastructure.rail[GetRailType(tile)] += LEVELCROSSING_TRACKBIT_FACTOR - 1;
          DirtyCompanyInfrastructureWindows(c->index);
        }
 
        /* Always add road to the roadtypes (can't draw without it) */
        bool reserved = HasBit(GetRailReservationTrackBits(tile), railtrack);
        MakeRoadCrossing(tile, company, company, GetTileOwner(tile), roaddir, GetRailType(tile), rtt == RTT_ROAD ? rt : INVALID_ROADTYPE, (rtt == RTT_TRAM) ? rt : INVALID_ROADTYPE, town_id);
        SetCrossingReservation(tile, reserved);
        UpdateLevelCrossing(tile, false);
        MarkDirtyAdjacentLevelCrossingTiles(tile, GetCrossingRoadAxis(tile));
        MarkTileDirtyByTile(tile);
      }
      return CommandCost(EXPENSES_CONSTRUCTION, 2 * RoadBuildCost(rt));
    }
 
    case MP_STATION: {
      if ((GetAnyRoadBits(tile, rtt) & pieces) == pieces) return_cmd_error(STR_ERROR_ALREADY_BUILT);
      if (!IsDriveThroughStopTile(tile)) goto do_clear;
 
      RoadBits curbits = AxisToRoadBits(DiagDirToAxis(GetRoadStopDir(tile)));
      if (pieces & ~curbits) goto do_clear;
      pieces = curbits; // we need to pay for both roadbits
 
      if (HasTileRoadType(tile, rtt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
      break;
    }
 
    case MP_TUNNELBRIDGE: {
      if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) goto do_clear;
      /* Only allow building the outern roadbit, so building long roads stops at existing bridges */
      if (MirrorRoadBits(DiagDirToRoadBits(GetTunnelBridgeDirection(tile))) != pieces) goto do_clear;
      if (HasTileRoadType(tile, rtt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
      /* Don't allow adding roadtype to the bridge/tunnel when vehicles are already driving on it */
      CommandCost ret = TunnelBridgeIsFree(tile, GetOtherTunnelBridgeEnd(tile));
      if (ret.Failed()) return ret;
      break;
    }
 
    default: {
do_clear:;
      need_to_clear = true;
      break;
    }
  }
 
  if (need_to_clear) {
    CommandCost ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
    if (ret.Failed()) return ret;
    cost.AddCost(ret);
  }
 
  if (other_bits != pieces) {
    /* Check the foundation/slopes when adding road/tram bits */
    CommandCost ret = CheckRoadSlope(tileh, &pieces, existing, other_bits);
    /* Return an error if we need to build a foundation (ret != 0) but the
     * current setting is turned off */
    if (ret.Failed() || (ret.GetCost() != 0 && !_settings_game.construction.build_on_slopes)) {
      return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
    }
    cost.AddCost(ret);
  }
 
  if (!need_to_clear) {
    if (IsTileType(tile, MP_ROAD)) {
      /* Don't put the pieces that already exist */
      pieces &= ComplementRoadBits(existing);
 
      /* Check if new road bits will have the same foundation as other existing road types */
      if (IsNormalRoad(tile)) {
        Slope slope = GetTileSlope(tile);
        Foundation found_new = GetRoadFoundation(slope, pieces | existing);
 
        RoadBits bits = GetRoadBits(tile, OtherRoadTramType(rtt));
        /* do not check if there are not road bits of given type */
        if (bits != ROAD_NONE && GetRoadFoundation(slope, bits) != found_new) {
          return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
        }
      }
    }
 
    CommandCost ret = EnsureNoVehicleOnGround(tile);
    if (ret.Failed()) return ret;
 
    if (IsNormalRoadTile(tile)) {
      /* If the road types don't match, try to convert only if vehicles of
       * the new road type are not powered on the present road type and vehicles of
       * the present road type are powered on the new road type. */
      RoadType existing_rt = GetRoadType(tile, rtt);
      if (existing_rt != INVALID_ROADTYPE && existing_rt != rt) {
        if (HasPowerOnRoad(rt, existing_rt)) {
          rt = existing_rt;
        } else if (HasPowerOnRoad(existing_rt, rt)) {
          CommandCost ret = Command<CMD_CONVERT_ROAD>::Do(flags, tile, tile, rt);
          if (ret.Failed()) return ret;
          cost.AddCost(ret);
        } else {
          return CMD_ERROR;
        }
      }
    }
  }
 
  uint num_pieces = (!need_to_clear && IsTileType(tile, MP_TUNNELBRIDGE)) ?
      /* There are 2 pieces on *every* tile of the bridge or tunnel */
      2 * (GetTunnelBridgeLength(GetOtherTunnelBridgeEnd(tile), tile) + 2) :
      /* Count pieces */
      CountBits(pieces);
 
  cost.AddCost(num_pieces * RoadBuildCost(rt));
 
  if (flags & DC_EXEC) {
    switch (GetTileType(tile)) {
      case MP_ROAD: {
        RoadTileType rttype = GetRoadTileType(tile);
        if (existing == ROAD_NONE || rttype == ROAD_TILE_CROSSING) {
          SetRoadType(tile, rtt, rt);
          SetRoadOwner(tile, rtt, company);
          if (rtt == RTT_ROAD) SetTownIndex(tile, town_id);
        }
        if (rttype != ROAD_TILE_CROSSING) SetRoadBits(tile, existing | pieces, rtt);
        break;
      }
 
      case MP_TUNNELBRIDGE: {
        TileIndex other_end = GetOtherTunnelBridgeEnd(tile);
 
        SetRoadType(other_end, rtt, rt);
        SetRoadType(tile, rtt, rt);
        SetRoadOwner(other_end, rtt, company);
        SetRoadOwner(tile, rtt, company);
 
        /* Mark tiles dirty that have been repaved */
        if (IsBridge(tile)) {
          MarkBridgeDirty(tile);
        } else {
          MarkTileDirtyByTile(other_end);
          MarkTileDirtyByTile(tile);
        }
        break;
      }
 
      case MP_STATION: {
        assert(IsDriveThroughStopTile(tile));
        SetRoadType(tile, rtt, rt);
        SetRoadOwner(tile, rtt, company);
        break;
      }
 
      default:
        MakeRoadNormal(tile, pieces, (rtt == RTT_ROAD) ? rt : INVALID_ROADTYPE, (rtt == RTT_TRAM) ? rt : INVALID_ROADTYPE, town_id, company, company);
        break;
    }
 
    /* Update company infrastructure count. */
    if (IsTileType(tile, MP_TUNNELBRIDGE)) num_pieces *= TUNNELBRIDGE_TRACKBIT_FACTOR;
    UpdateCompanyRoadInfrastructure(rt, GetRoadOwner(tile, rtt), num_pieces);
 
    if (rtt == RTT_ROAD && IsNormalRoadTile(tile)) {
      existing |= pieces;
      SetDisallowedRoadDirections(tile, IsStraightRoad(existing) ?
          GetDisallowedRoadDirections(tile) ^ toggle_drd : DRD_NONE);
    }
 
    MarkTileDirtyByTile(tile);
  }
  return cost;
}
 
static bool CanConnectToRoad(TileIndex tile, RoadType rt, DiagDirection dir)
{
  tile += TileOffsByDiagDir(dir);
  if (!IsValidTile(tile) || !MayHaveRoad(tile)) return false;
 
  RoadTramType rtt = GetRoadTramType(rt);
  RoadType existing = GetRoadType(tile, rtt);
  if (existing == INVALID_ROADTYPE) return false;
  if (!HasPowerOnRoad(existing, rt) && !HasPowerOnRoad(rt, existing)) return false;
 
  RoadBits bits = GetAnyRoadBits(tile, rtt, false);
  return (bits & DiagDirToRoadBits(ReverseDiagDir(dir))) != 0;
}
 
CommandCost CmdBuildLongRoad(DoCommandFlag flags, TileIndex end_tile, TileIndex start_tile, RoadType rt, Axis axis, DisallowedRoadDirections drd, bool start_half, bool end_half, bool is_ai)
{
  if (start_tile >= MapSize()) return CMD_ERROR;
 
  if (!ValParamRoadType(rt) || !IsValidAxis(axis) || !IsValidDisallowedRoadDirections(drd)) return CMD_ERROR;
 
  /* Only drag in X or Y direction dictated by the direction variable */
  if (axis == AXIS_X && TileY(start_tile) != TileY(end_tile)) return CMD_ERROR; // x-axis
  if (axis == AXIS_Y && TileX(start_tile) != TileX(end_tile)) return CMD_ERROR; // y-axis
 
  DiagDirection dir = AxisToDiagDir(axis);
 
  /* Swap direction, also the half-tile drag vars. */
  if (start_tile > end_tile || (start_tile == end_tile && start_half)) {
    dir = ReverseDiagDir(dir);
    start_half = !start_half;
    end_half = !end_half;
    if (drd == DRD_NORTHBOUND || drd == DRD_SOUTHBOUND) drd ^= DRD_BOTH;
  }
 
  /* On the X-axis, we have to swap the initial bits, so they
   * will be interpreted correctly in the GTTS. Furthermore
   * when you just 'click' on one tile to build them. */
  if ((drd == DRD_NORTHBOUND || drd == DRD_SOUTHBOUND) && (axis == AXIS_Y) == (start_tile == end_tile && start_half == end_half)) drd ^= DRD_BOTH;
 
  CommandCost cost(EXPENSES_CONSTRUCTION);
  CommandCost last_error = CMD_ERROR;
  TileIndex tile = start_tile;
  bool had_bridge = false;
  bool had_tunnel = false;
  bool had_success = false;
 
  /* Start tile is the first tile clicked by the user. */
  for (;;) {
    RoadBits bits = AxisToRoadBits(axis);
 
    /* Determine which road parts should be built. */
    if (!is_ai && start_tile != end_tile) {
      /* Only build the first and last roadbit if they can connect to something. */
      if (tile == end_tile && !CanConnectToRoad(tile, rt, dir)) {
        bits = DiagDirToRoadBits(ReverseDiagDir(dir));
      } else if (tile == start_tile && !CanConnectToRoad(tile, rt, ReverseDiagDir(dir))) {
        bits = DiagDirToRoadBits(dir);
      }
    } else {
      /* Road parts only have to be built at the start tile or at the end tile. */
      if (tile == end_tile && !end_half) bits &= DiagDirToRoadBits(ReverseDiagDir(dir));
      if (tile == start_tile && start_half) bits &= DiagDirToRoadBits(dir);
    }
 
    CommandCost ret = Command<CMD_BUILD_ROAD>::Do(flags, tile, bits, rt, drd, 0);
    if (ret.Failed()) {
      last_error = ret;
      if (last_error.GetErrorMessage() != STR_ERROR_ALREADY_BUILT) {
        if (is_ai) return last_error;
        break;
      }
    } else {
      had_success = true;
      /* Only pay for the upgrade on one side of the bridges and tunnels */
      if (IsTileType(tile, MP_TUNNELBRIDGE)) {
        if (IsBridge(tile)) {
          if (!had_bridge || GetTunnelBridgeDirection(tile) == dir) {
            cost.AddCost(ret);
          }
          had_bridge = true;
        } else { // IsTunnel(tile)
          if (!had_tunnel || GetTunnelBridgeDirection(tile) == dir) {
            cost.AddCost(ret);
          }
          had_tunnel = true;
        }
      } else {
        cost.AddCost(ret);
      }
    }
 
    if (tile == end_tile) break;
 
    tile += TileOffsByDiagDir(dir);
  }
 
  return had_success ? cost : last_error;
}
 
std::tuple<CommandCost, Money> CmdRemoveLongRoad(DoCommandFlag flags, TileIndex end_tile, TileIndex start_tile, RoadType rt, Axis axis, bool start_half, bool end_half)
{
  CommandCost cost(EXPENSES_CONSTRUCTION);
 
  if (start_tile >= MapSize()) return { CMD_ERROR, 0 };
  if (!ValParamRoadType(rt) || !IsValidAxis(axis)) return { CMD_ERROR, 0 };
 
  /* Only drag in X or Y direction dictated by the direction variable */
  if (axis == AXIS_X && TileY(start_tile) != TileY(end_tile)) return { CMD_ERROR, 0 }; // x-axis
  if (axis == AXIS_Y && TileX(start_tile) != TileX(end_tile)) return { CMD_ERROR, 0 }; // y-axis
 
  /* Swap start and ending tile, also the half-tile drag vars. */
  if (start_tile > end_tile || (start_tile == end_tile && start_half)) {
    std::swap(start_tile, end_tile);
    std::swap(start_half, end_half);
  }
 
  Money money_available = GetAvailableMoneyForCommand();
  Money money_spent = 0;
  TileIndex tile = start_tile;
  CommandCost last_error = CMD_ERROR;
  bool had_success = false;
  /* Start tile is the small number. */
  for (;;) {
    RoadBits bits = AxisToRoadBits(axis);
 
    if (tile == end_tile && !end_half) bits &= ROAD_NW | ROAD_NE;
    if (tile == start_tile && start_half) bits &= ROAD_SE | ROAD_SW;
 
    /* try to remove the halves. */
    if (bits != 0) {
      RoadTramType rtt = GetRoadTramType(rt);
      CommandCost ret = RemoveRoad(tile, flags & ~DC_EXEC, bits, rtt, true);
      if (ret.Succeeded()) {
        if (flags & DC_EXEC) {
          money_spent += ret.GetCost();
          if (money_spent > 0 && money_spent > money_available) {
            return { cost, std::get<0>(Command<CMD_REMOVE_LONG_ROAD>::Do(flags & ~DC_EXEC, end_tile, start_tile, rt, axis, start_half, end_half)).GetCost() };
          }
          RemoveRoad(tile, flags, bits, rtt, true, false);
        }
        cost.AddCost(ret);
        had_success = true;
      } else {
        /* Some errors are more equal than others. */
        switch (last_error.GetErrorMessage()) {
          case STR_ERROR_OWNED_BY:
          case STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS:
            break;
          default:
            last_error = ret;
        }
      }
    }
 
    if (tile == end_tile) break;
 
    tile += (axis == AXIS_Y) ? TileDiffXY(0, 1) : TileDiffXY(1, 0);
  }
 
  return { had_success ? cost : last_error, 0 };
}
 
CommandCost CmdBuildRoadDepot(DoCommandFlag flags, TileIndex tile, RoadType rt, DiagDirection dir)
{
  if (!ValParamRoadType(rt) || !IsValidDiagDirection(dir)) return CMD_ERROR;
 
  CommandCost cost(EXPENSES_CONSTRUCTION);
 
  Slope tileh = GetTileSlope(tile);
  if (tileh != SLOPE_FLAT) {
    if (!_settings_game.construction.build_on_slopes || !CanBuildDepotByTileh(dir, tileh)) {
      return_cmd_error(STR_ERROR_FLAT_LAND_REQUIRED);
    }
    cost.AddCost(_price[PR_BUILD_FOUNDATION]);
  }
 
  cost.AddCost(Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile));
  if (cost.Failed()) return cost;
 
  if (IsBridgeAbove(tile)) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
 
  if (!Depot::CanAllocateItem()) return CMD_ERROR;
 
  if (flags & DC_EXEC) {
    Depot *dep = new Depot(tile);
    dep->build_date = _date;
 
    /* A road depot has two road bits. */
    UpdateCompanyRoadInfrastructure(rt, _current_company, ROAD_DEPOT_TRACKBIT_FACTOR);
 
    MakeRoadDepot(tile, _current_company, dep->index, dir, rt);
    MarkTileDirtyByTile(tile);
    MakeDefaultName(dep);
  }
  cost.AddCost(_price[PR_BUILD_DEPOT_ROAD]);
  return cost;
}
 
static CommandCost RemoveRoadDepot(TileIndex tile, DoCommandFlag flags)
{
  if (_current_company != OWNER_WATER) {
    CommandCost ret = CheckTileOwnership(tile);
    if (ret.Failed()) return ret;
  }
 
  CommandCost ret = EnsureNoVehicleOnGround(tile);
  if (ret.Failed()) return ret;
 
  if (flags & DC_EXEC) {
    Company *c = Company::GetIfValid(GetTileOwner(tile));
    if (c != nullptr) {
      /* A road depot has two road bits. */
      RoadType rt = GetRoadTypeRoad(tile);
      if (rt == INVALID_ROADTYPE) rt = GetRoadTypeTram(tile);
      c->infrastructure.road[rt] -= ROAD_DEPOT_TRACKBIT_FACTOR;
      DirtyCompanyInfrastructureWindows(c->index);
    }
 
    delete Depot::GetByTile(tile);
    DoClearSquare(tile);
  }
 
  return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_CLEAR_DEPOT_ROAD]);
}
 
static CommandCost ClearTile_Road(TileIndex tile, DoCommandFlag flags)
{
  switch (GetRoadTileType(tile)) {
    case ROAD_TILE_NORMAL: {
      RoadBits b = GetAllRoadBits(tile);
 
      /* Clear the road if only one piece is on the tile OR we are not using the DC_AUTO flag */
      if ((HasExactlyOneBit(b) && GetRoadBits(tile, RTT_TRAM) == ROAD_NONE) || !(flags & DC_AUTO)) {
        CommandCost ret(EXPENSES_CONSTRUCTION);
        for (RoadTramType rtt : _roadtramtypes) {
          if (!MayHaveRoad(tile) || GetRoadType(tile, rtt) == INVALID_ROADTYPE) continue;
 
          CommandCost tmp_ret = RemoveRoad(tile, flags, GetRoadBits(tile, rtt), rtt, true);
          if (tmp_ret.Failed()) return tmp_ret;
          ret.AddCost(tmp_ret);
        }
        return ret;
      }
      return_cmd_error(STR_ERROR_MUST_REMOVE_ROAD_FIRST);
    }
 
    case ROAD_TILE_CROSSING: {
      CommandCost ret(EXPENSES_CONSTRUCTION);
 
      if (flags & DC_AUTO) return_cmd_error(STR_ERROR_MUST_REMOVE_ROAD_FIRST);
 
      /* Must iterate over the roadtypes in a reverse manner because
       * tram tracks must be removed before the road bits. */
      for (RoadTramType rtt : { RTT_TRAM, RTT_ROAD }) {
        if (!MayHaveRoad(tile) || GetRoadType(tile, rtt) == INVALID_ROADTYPE) continue;
 
        CommandCost tmp_ret = RemoveRoad(tile, flags, GetCrossingRoadBits(tile), rtt, false);
        if (tmp_ret.Failed()) return tmp_ret;
        ret.AddCost(tmp_ret);
      }
 
      if (flags & DC_EXEC) {
        Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
      }
      return ret;
    }
 
    default:
    case ROAD_TILE_DEPOT:
      if (flags & DC_AUTO) {
        return_cmd_error(STR_ERROR_BUILDING_MUST_BE_DEMOLISHED);
      }
      return RemoveRoadDepot(tile, flags);
  }
}
 
 
struct DrawRoadTileStruct {
  uint16 image;
  byte subcoord_x;
  byte subcoord_y;
};
 
#include "table/road_land.h"
 
static Foundation GetRoadFoundation(Slope tileh, RoadBits bits)
{
  /* Flat land and land without a road doesn't require a foundation */
  if (tileh == SLOPE_FLAT || bits == ROAD_NONE) return FOUNDATION_NONE;
 
  /* Steep slopes behave the same as slopes with one corner raised. */
  if (IsSteepSlope(tileh)) {
    tileh = SlopeWithOneCornerRaised(GetHighestSlopeCorner(tileh));
  }
 
  /* Leveled RoadBits on a slope */
  if ((_invalid_tileh_slopes_road[0][tileh] & bits) == ROAD_NONE) return FOUNDATION_LEVELED;
 
  /* Straight roads without foundation on a slope */
  if (!IsSlopeWithOneCornerRaised(tileh) &&
      (_invalid_tileh_slopes_road[1][tileh] & bits) == ROAD_NONE)
    return FOUNDATION_NONE;
 
  /* Roads on steep Slopes or on Slopes with one corner raised */
  return (bits == ROAD_X ? FOUNDATION_INCLINED_X : FOUNDATION_INCLINED_Y);
}
 
const byte _road_sloped_sprites[14] = {
  0,  0,  2,  0,
  0,  1,  0,  0,
  3,  0,  0,  0,
  0,  0
};
 
static uint GetRoadSpriteOffset(Slope slope, RoadBits bits)
{
  if (slope != SLOPE_FLAT) {
    switch (slope) {
      case SLOPE_NE: return 11;
      case SLOPE_SE: return 12;
      case SLOPE_SW: return 13;
      case SLOPE_NW: return 14;
      default: NOT_REACHED();
    }
  } else {
    static const uint offsets[] = {
      0, 18, 17, 7,
      16, 0, 10, 5,
      15, 8, 1, 4,
      9, 3, 6, 2
    };
    return offsets[bits];
  }
}
 
static bool DrawRoadAsSnowDesert(TileIndex tile, Roadside roadside)
{
  return (IsOnSnow(tile) &&
      !(_settings_game.game_creation.landscape == LT_TROPIC && HasGrfMiscBit(GMB_DESERT_PAVED_ROADS) &&
        roadside != ROADSIDE_BARREN && roadside != ROADSIDE_GRASS && roadside != ROADSIDE_GRASS_ROAD_WORKS));
}
 
void DrawRoadTypeCatenary(const TileInfo *ti, RoadType rt, RoadBits rb)
{
  /* Don't draw the catenary under a low bridge */
  if (IsBridgeAbove(ti->tile) && !IsTransparencySet(TO_CATENARY)) {
    int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
 
    if (height <= GetTileMaxZ(ti->tile) + 1) return;
  }
 
  if (CountBits(rb) > 2) {
    /* On junctions we check whether neighbouring tiles also have catenary, and possibly
     * do not draw catenary towards those neighbours, which do not have catenary. */
    RoadBits rb_new = ROAD_NONE;
    for (DiagDirection dir = DIAGDIR_BEGIN; dir < DIAGDIR_END; dir++) {
      if (rb & DiagDirToRoadBits(dir)) {
        TileIndex neighbour = TileAddByDiagDir(ti->tile, dir);
        if (MayHaveRoad(neighbour)) {
          RoadType rt_road = GetRoadTypeRoad(neighbour);
          RoadType rt_tram = GetRoadTypeTram(neighbour);
 
          if ((rt_road != INVALID_ROADTYPE && HasRoadCatenary(rt_road)) ||
              (rt_tram != INVALID_ROADTYPE && HasRoadCatenary(rt_tram))) {
            rb_new |= DiagDirToRoadBits(dir);
          }
        }
      }
    }
    if (CountBits(rb_new) >= 2) rb = rb_new;
  }
 
  const RoadTypeInfo* rti = GetRoadTypeInfo(rt);
  SpriteID front = GetCustomRoadSprite(rti, ti->tile, ROTSG_CATENARY_FRONT);
  SpriteID back = GetCustomRoadSprite(rti, ti->tile, ROTSG_CATENARY_BACK);
 
  if (front != 0 || back != 0) {
    if (front != 0) front += GetRoadSpriteOffset(ti->tileh, rb);
    if (back != 0) back += GetRoadSpriteOffset(ti->tileh, rb);
  } else if (ti->tileh != SLOPE_FLAT) {
    back  = SPR_TRAMWAY_BACK_WIRES_SLOPED  + _road_sloped_sprites[ti->tileh - 1];
    front = SPR_TRAMWAY_FRONT_WIRES_SLOPED + _road_sloped_sprites[ti->tileh - 1];
  } else {
    back  = SPR_TRAMWAY_BASE + _road_backpole_sprites_1[rb];
    front = SPR_TRAMWAY_BASE + _road_frontwire_sprites_1[rb];
  }
 
  /* Catenary uses 1st company colour to help identify owner.
   * For tiles with OWNER_TOWN or OWNER_NONE, recolour CC to grey as a neutral colour. */
  Owner owner = GetRoadOwner(ti->tile, GetRoadTramType(rt));
  PaletteID pal = (owner == OWNER_NONE || owner == OWNER_TOWN ? GENERAL_SPRITE_COLOUR(COLOUR_GREY) : COMPANY_SPRITE_COLOUR(owner));
  int z_wires = (ti->tileh == SLOPE_FLAT ? 0 : TILE_HEIGHT) + BB_HEIGHT_UNDER_BRIDGE;
  if (back != 0) {
    /* The "back" sprite contains the west, north and east pillars.
     * We cut the sprite at 3/8 of the west/east edges to create 3 sprites.
     * 3/8 is chosen so that sprites can somewhat graphically extend into the tile. */
    static const int INF = 1000; 
    static const SubSprite west  = { -INF, -INF, -12, INF };
    static const SubSprite north = {  -12, -INF,  12, INF };
    static const SubSprite east  = {   12, -INF, INF, INF };
    AddSortableSpriteToDraw(back, pal, ti->x, ti->y, 16,  1, z_wires, ti->z, IsTransparencySet(TO_CATENARY), 15,  0, GetSlopePixelZInCorner(ti->tileh, CORNER_W), &west);
    AddSortableSpriteToDraw(back, pal, ti->x, ti->y,  1,  1, z_wires, ti->z, IsTransparencySet(TO_CATENARY),  0,  0, GetSlopePixelZInCorner(ti->tileh, CORNER_N), &north);
    AddSortableSpriteToDraw(back, pal, ti->x, ti->y,  1, 16, z_wires, ti->z, IsTransparencySet(TO_CATENARY),  0, 15, GetSlopePixelZInCorner(ti->tileh, CORNER_E), &east);
  }
  if (front != 0) {
    /* Draw the "front" sprite (containing south pillar and wires) at a Z height that is both above the vehicles and above the "back" pillars. */
    AddSortableSpriteToDraw(front, pal, ti->x, ti->y, 16, 16, z_wires + 1, ti->z, IsTransparencySet(TO_CATENARY), 0, 0, z_wires);
  }
}
 
void DrawRoadCatenary(const TileInfo *ti)
{
  RoadBits road = ROAD_NONE;
  RoadBits tram = ROAD_NONE;
 
  if (IsTileType(ti->tile, MP_ROAD)) {
    if (IsNormalRoad(ti->tile)) {
      road = GetRoadBits(ti->tile, RTT_ROAD);
      tram = GetRoadBits(ti->tile, RTT_TRAM);
    } else if (IsLevelCrossing(ti->tile)) {
      tram = road = (GetCrossingRailAxis(ti->tile) == AXIS_Y ? ROAD_X : ROAD_Y);
    }
  } else if (IsTileType(ti->tile, MP_STATION)) {
    if (IsRoadStop(ti->tile)) {
      if (IsDriveThroughStopTile(ti->tile)) {
        Axis axis = GetRoadStopDir(ti->tile) == DIAGDIR_NE ? AXIS_X : AXIS_Y;
        tram = road = (axis == AXIS_X ? ROAD_X : ROAD_Y);
      } else {
        tram = road = DiagDirToRoadBits(GetRoadStopDir(ti->tile));
      }
    }
  } else {
    // No road here, no catenary to draw
    return;
  }
 
  RoadType rt = GetRoadTypeRoad(ti->tile);
  if (rt != INVALID_ROADTYPE && HasRoadCatenaryDrawn(rt)) {
    DrawRoadTypeCatenary(ti, rt, road);
  }
 
  rt = GetRoadTypeTram(ti->tile);
  if (rt != INVALID_ROADTYPE && HasRoadCatenaryDrawn(rt)) {
    DrawRoadTypeCatenary(ti, rt, tram);
  }
}
 
static void DrawRoadDetail(SpriteID img, const TileInfo *ti, int dx, int dy, int h, bool transparent)
{
  int x = ti->x | dx;
  int y = ti->y | dy;
  int z = ti->z;
  if (ti->tileh != SLOPE_FLAT) z = GetSlopePixelZ(x, y);
  AddSortableSpriteToDraw(img, PAL_NONE, x, y, 2, 2, h, z, transparent);
}
 
void DrawRoadOverlays(const TileInfo *ti, PaletteID pal, const RoadTypeInfo *road_rti, const RoadTypeInfo *tram_rti, uint road_offset, uint tram_offset, bool draw_underlay)
{
  if (draw_underlay) {
    /* Road underlay takes precedence over tram */
    if (road_rti != nullptr) {
      if (road_rti->UsesOverlay()) {
        SpriteID ground = GetCustomRoadSprite(road_rti, ti->tile, ROTSG_GROUND);
        DrawGroundSprite(ground + road_offset, pal);
      }
    } else {
      if (tram_rti->UsesOverlay()) {
        SpriteID ground = GetCustomRoadSprite(tram_rti, ti->tile, ROTSG_GROUND);
        DrawGroundSprite(ground + tram_offset, pal);
      } else {
        DrawGroundSprite(SPR_TRAMWAY_TRAM + tram_offset, pal);
      }
    }
  }
 
  /* Draw road overlay */
  if (road_rti != nullptr) {
    if (road_rti->UsesOverlay()) {
      SpriteID ground = GetCustomRoadSprite(road_rti, ti->tile, ROTSG_OVERLAY);
      if (ground != 0) DrawGroundSprite(ground + road_offset, pal);
    }
  }
 
  /* Draw tram overlay */
  if (tram_rti != nullptr) {
    if (tram_rti->UsesOverlay()) {
      SpriteID ground = GetCustomRoadSprite(tram_rti, ti->tile, ROTSG_OVERLAY);
      if (ground != 0) DrawGroundSprite(ground + tram_offset, pal);
    } else if (road_rti != nullptr) {
      DrawGroundSprite(SPR_TRAMWAY_OVERLAY + tram_offset, pal);
    }
  }
}
 
static SpriteID GetRoadGroundSprite(const TileInfo *ti, Roadside roadside, const RoadTypeInfo *rti, uint offset, PaletteID *pal)
{
  /* Draw bare ground sprite if no road or road uses overlay system. */
  if (rti == nullptr || rti->UsesOverlay()) {
    if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
      return SPR_FLAT_SNOW_DESERT_TILE + SlopeToSpriteOffset(ti->tileh);
    }
 
    switch (roadside) {
      case ROADSIDE_BARREN:           *pal = PALETTE_TO_BARE_LAND;
                                      return SPR_FLAT_GRASS_TILE + SlopeToSpriteOffset(ti->tileh);
      case ROADSIDE_GRASS:
      case ROADSIDE_GRASS_ROAD_WORKS: return SPR_FLAT_GRASS_TILE + SlopeToSpriteOffset(ti->tileh);
      default:                        break; // Paved
    }
  }
 
  /* Draw original road base sprite */
  SpriteID image = SPR_ROAD_Y + offset;
  if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
    image += 19;
  } else {
    switch (roadside) {
      case ROADSIDE_BARREN:           *pal = PALETTE_TO_BARE_LAND; break;
      case ROADSIDE_GRASS:            break;
      case ROADSIDE_GRASS_ROAD_WORKS: break;
      default:                        image -= 19; break; // Paved
    }
  }
 
  return image;
}
 
static void DrawRoadBits(TileInfo *ti)
{
  RoadBits road = GetRoadBits(ti->tile, RTT_ROAD);
  RoadBits tram = GetRoadBits(ti->tile, RTT_TRAM);
 
  RoadType road_rt = GetRoadTypeRoad(ti->tile);
  RoadType tram_rt = GetRoadTypeTram(ti->tile);
  const RoadTypeInfo *road_rti = road_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(road_rt);
  const RoadTypeInfo *tram_rti = tram_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(tram_rt);
 
  if (ti->tileh != SLOPE_FLAT) {
    DrawFoundation(ti, GetRoadFoundation(ti->tileh, road | tram));
    /* DrawFoundation() modifies ti. */
  }
 
  /* Determine sprite offsets */
  uint road_offset = GetRoadSpriteOffset(ti->tileh, road);
  uint tram_offset = GetRoadSpriteOffset(ti->tileh, tram);
 
  /* Draw baseset underlay */
  Roadside roadside = GetRoadside(ti->tile);
 
  PaletteID pal = PAL_NONE;
  SpriteID image = GetRoadGroundSprite(ti, roadside, road_rti, road == ROAD_NONE ? tram_offset : road_offset, &pal);
  DrawGroundSprite(image, pal);
 
  DrawRoadOverlays(ti, pal, road_rti, tram_rti, road_offset, tram_offset);
 
  /* Draw one way */
  if (road_rti != nullptr) {
    DisallowedRoadDirections drd = GetDisallowedRoadDirections(ti->tile);
    if (drd != DRD_NONE) {
      SpriteID oneway = GetCustomRoadSprite(road_rti, ti->tile, ROTSG_ONEWAY);
 
      if (oneway == 0) oneway = SPR_ONEWAY_BASE;
 
      if ((ti->tileh == SLOPE_NE) || (ti->tileh == SLOPE_NW)) {
        oneway += SPR_ONEWAY_SLOPE_N_OFFSET;
      } else if ((ti->tileh == SLOPE_SE) || (ti->tileh == SLOPE_SW)) {
        oneway += SPR_ONEWAY_SLOPE_S_OFFSET;
      }
 
      DrawGroundSpriteAt(oneway + drd - 1 + ((road == ROAD_X) ? 0 : 3), PAL_NONE, 8, 8, GetPartialPixelZ(8, 8, ti->tileh));
    }
  }
 
  if (HasRoadWorks(ti->tile)) {
    /* Road works */
    DrawGroundSprite((road | tram) & ROAD_X ? SPR_EXCAVATION_X : SPR_EXCAVATION_Y, PAL_NONE);
    return;
  }
 
  /* Draw road, tram catenary */
  DrawRoadCatenary(ti);
 
  /* Return if full detail is disabled, or we are zoomed fully out. */
  if (!HasBit(_display_opt, DO_FULL_DETAIL) || _cur_dpi->zoom > ZOOM_LVL_DETAIL) return;
 
  /* Do not draw details (street lights, trees) under low bridge */
  if (IsBridgeAbove(ti->tile) && (roadside == ROADSIDE_TREES || roadside == ROADSIDE_STREET_LIGHTS)) {
    int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
    int minz = GetTileMaxZ(ti->tile) + 2;
 
    if (roadside == ROADSIDE_TREES) minz++;
 
    if (height < minz) return;
  }
 
  /* If there are no road bits, return, as there is nothing left to do */
  if (HasAtMostOneBit(road)) return;
 
  if (roadside == ROADSIDE_TREES && IsInvisibilitySet(TO_TREES)) return;
  bool is_transparent = roadside == ROADSIDE_TREES && IsTransparencySet(TO_TREES);
 
  /* Draw extra details. */
  for (const DrawRoadTileStruct *drts = _road_display_table[roadside][road | tram]; drts->image != 0; drts++) {
    DrawRoadDetail(drts->image, ti, drts->subcoord_x, drts->subcoord_y, 0x10, is_transparent);
  }
}
 
static void DrawTile_Road(TileInfo *ti)
{
  switch (GetRoadTileType(ti->tile)) {
    case ROAD_TILE_NORMAL:
      DrawRoadBits(ti);
      break;
 
    case ROAD_TILE_CROSSING: {
      if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, FOUNDATION_LEVELED);
 
      Axis axis = GetCrossingRailAxis(ti->tile);
 
      const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
 
      RoadType road_rt = GetRoadTypeRoad(ti->tile);
      RoadType tram_rt = GetRoadTypeTram(ti->tile);
      const RoadTypeInfo *road_rti = road_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(road_rt);
      const RoadTypeInfo *tram_rti = tram_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(tram_rt);
 
      PaletteID pal = PAL_NONE;
 
      /* Draw base ground */
      if (rti->UsesOverlay()) {
        SpriteID image = SPR_ROAD_Y + axis;
 
        Roadside roadside = GetRoadside(ti->tile);
        if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
          image += 19;
        } else {
          switch (roadside) {
            case ROADSIDE_BARREN: pal = PALETTE_TO_BARE_LAND; break;
            case ROADSIDE_GRASS:  break;
            default:              image -= 19; break; // Paved
          }
        }
 
        DrawGroundSprite(image, pal);
      } else {
        SpriteID image = rti->base_sprites.crossing + axis;
        if (IsCrossingBarred(ti->tile)) image += 2;
 
        Roadside roadside = GetRoadside(ti->tile);
        if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
          image += 8;
        } else {
          switch (roadside) {
            case ROADSIDE_BARREN: pal = PALETTE_TO_BARE_LAND; break;
            case ROADSIDE_GRASS:  break;
            default:              image += 4; break; // Paved
          }
        }
 
        DrawGroundSprite(image, pal);
      }
 
      DrawRoadOverlays(ti, pal, road_rti, tram_rti, axis, axis);
 
      /* Draw rail/PBS overlay */
      bool draw_pbs = _game_mode != GM_MENU && _settings_client.gui.show_track_reservation && HasCrossingReservation(ti->tile);
      if (rti->UsesOverlay()) {
        PaletteID pal = draw_pbs ? PALETTE_CRASH : PAL_NONE;
        SpriteID rail = GetCustomRailSprite(rti, ti->tile, RTSG_CROSSING) + axis;
        DrawGroundSprite(rail, pal);
 
        const Axis road_axis = GetCrossingRoadAxis(ti->tile);
        const DiagDirection dir1 = AxisToDiagDir(road_axis);
        const DiagDirection dir2 = ReverseDiagDir(dir1);
        uint adjacent_diagdirs = 0;
        for (DiagDirection dir : { dir1, dir2 }) {
          const TileIndex t = TileAddByDiagDir(ti->tile, dir);
          if (t < MapSize() && IsLevelCrossingTile(t) && GetCrossingRoadAxis(t) == road_axis) {
            SetBit(adjacent_diagdirs, dir);
          }
        }
 
        switch (adjacent_diagdirs) {
          case 0:
            DrawRailTileSeq(ti, &_crossing_layout, TO_CATENARY, rail, 0, PAL_NONE);
            break;
 
          case (1 << DIAGDIR_NE):
            DrawRailTileSeq(ti, &_crossing_layout_SW, TO_CATENARY, rail, 0, PAL_NONE);
            break;
 
          case (1 << DIAGDIR_SE):
            DrawRailTileSeq(ti, &_crossing_layout_NW, TO_CATENARY, rail, 0, PAL_NONE);
            break;
 
          case (1 << DIAGDIR_SW):
            DrawRailTileSeq(ti, &_crossing_layout_NE, TO_CATENARY, rail, 0, PAL_NONE);
            break;
 
          case (1 << DIAGDIR_NW):
            DrawRailTileSeq(ti, &_crossing_layout_SE, TO_CATENARY, rail, 0, PAL_NONE);
            break;
 
          default:
            /* Show no sprites */
            break;
        }
      } else if (draw_pbs || tram_rti != nullptr || road_rti->UsesOverlay()) {
        /* Add another rail overlay, unless there is only the base road sprite. */
        PaletteID pal = draw_pbs ? PALETTE_CRASH : PAL_NONE;
        SpriteID rail = GetCrossingRoadAxis(ti->tile) == AXIS_Y ? GetRailTypeInfo(GetRailType(ti->tile))->base_sprites.single_x : GetRailTypeInfo(GetRailType(ti->tile))->base_sprites.single_y;
        DrawGroundSprite(rail, pal);
      }
 
      /* Draw road, tram catenary */
      DrawRoadCatenary(ti);
 
      /* Draw rail catenary */
      if (HasRailCatenaryDrawn(GetRailType(ti->tile))) DrawRailCatenary(ti);
 
      break;
    }
 
    default:
    case ROAD_TILE_DEPOT: {
      if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, FOUNDATION_LEVELED);
 
      PaletteID palette = COMPANY_SPRITE_COLOUR(GetTileOwner(ti->tile));
 
      RoadType road_rt = GetRoadTypeRoad(ti->tile);
      RoadType tram_rt = GetRoadTypeTram(ti->tile);
      const RoadTypeInfo *rti = GetRoadTypeInfo(road_rt == INVALID_ROADTYPE ? tram_rt : road_rt);
 
      int relocation = GetCustomRoadSprite(rti, ti->tile, ROTSG_DEPOT);
      bool default_gfx = relocation == 0;
      if (default_gfx) {
        if (HasBit(rti->flags, ROTF_CATENARY)) {
          if (_loaded_newgrf_features.tram == TRAMWAY_REPLACE_DEPOT_WITH_TRACK && road_rt == INVALID_ROADTYPE && !rti->UsesOverlay()) {
            /* Sprites with track only work for default tram */
            relocation = SPR_TRAMWAY_DEPOT_WITH_TRACK - SPR_ROAD_DEPOT;
            default_gfx = false;
          } else {
            /* Sprites without track are always better, if provided */
            relocation = SPR_TRAMWAY_DEPOT_NO_TRACK - SPR_ROAD_DEPOT;
          }
        }
      } else {
        relocation -= SPR_ROAD_DEPOT;
      }
 
      DiagDirection dir = GetRoadDepotDirection(ti->tile);
      const DrawTileSprites *dts = &_road_depot[dir];
      DrawGroundSprite(dts->ground.sprite, PAL_NONE);
 
      if (default_gfx) {
        uint offset = GetRoadSpriteOffset(SLOPE_FLAT, DiagDirToRoadBits(dir));
        if (rti->UsesOverlay()) {
          SpriteID ground = GetCustomRoadSprite(rti, ti->tile, ROTSG_OVERLAY);
          if (ground != 0) DrawGroundSprite(ground + offset, PAL_NONE);
        } else if (road_rt == INVALID_ROADTYPE) {
          DrawGroundSprite(SPR_TRAMWAY_OVERLAY + offset, PAL_NONE);
        }
      }
 
      DrawRailTileSeq(ti, dts, TO_BUILDINGS, relocation, 0, palette);
      break;
    }
  }
  DrawBridgeMiddle(ti);
}
 
void DrawRoadDepotSprite(int x, int y, DiagDirection dir, RoadType rt)
{
  PaletteID palette = COMPANY_SPRITE_COLOUR(_local_company);
 
  const RoadTypeInfo* rti = GetRoadTypeInfo(rt);
  int relocation = GetCustomRoadSprite(rti, INVALID_TILE, ROTSG_DEPOT);
  bool default_gfx = relocation == 0;
  if (default_gfx) {
    if (HasBit(rti->flags, ROTF_CATENARY)) {
      if (_loaded_newgrf_features.tram == TRAMWAY_REPLACE_DEPOT_WITH_TRACK && RoadTypeIsTram(rt) && !rti->UsesOverlay()) {
        /* Sprites with track only work for default tram */
        relocation = SPR_TRAMWAY_DEPOT_WITH_TRACK - SPR_ROAD_DEPOT;
        default_gfx = false;
      } else {
        /* Sprites without track are always better, if provided */
        relocation = SPR_TRAMWAY_DEPOT_NO_TRACK - SPR_ROAD_DEPOT;
      }
    }
  } else {
    relocation -= SPR_ROAD_DEPOT;
  }
 
  const DrawTileSprites *dts = &_road_depot[dir];
  DrawSprite(dts->ground.sprite, PAL_NONE, x, y);
 
  if (default_gfx) {
    uint offset = GetRoadSpriteOffset(SLOPE_FLAT, DiagDirToRoadBits(dir));
    if (rti->UsesOverlay()) {
      SpriteID ground = GetCustomRoadSprite(rti, INVALID_TILE, ROTSG_OVERLAY);
      if (ground != 0) DrawSprite(ground + offset, PAL_NONE, x, y);
    } else if (RoadTypeIsTram(rt)) {
      DrawSprite(SPR_TRAMWAY_OVERLAY + offset, PAL_NONE, x, y);
    }
  }
 
  DrawRailTileSeqInGUI(x, y, dts, relocation, 0, palette);
}
 
void UpdateNearestTownForRoadTiles(bool invalidate)
{
  assert(!invalidate || _generating_world);
 
  for (TileIndex t = 0; t < MapSize(); t++) {
    if (IsTileType(t, MP_ROAD) && !IsRoadDepot(t) && !HasTownOwnedRoad(t)) {
      TownID tid = INVALID_TOWN;
      if (!invalidate) {
        const Town *town = CalcClosestTownFromTile(t);
        if (town != nullptr) tid = town->index;
      }
      SetTownIndex(t, tid);
    }
  }
}
 
static int GetSlopePixelZ_Road(TileIndex tile, uint x, uint y)
{
 
  if (IsNormalRoad(tile)) {
    int z;
    Slope tileh = GetTilePixelSlope(tile, &z);
    if (tileh == SLOPE_FLAT) return z;
 
    Foundation f = GetRoadFoundation(tileh, GetAllRoadBits(tile));
    z += ApplyPixelFoundationToSlope(f, &tileh);
    return z + GetPartialPixelZ(x & 0xF, y & 0xF, tileh);
  } else {
    return GetTileMaxPixelZ(tile);
  }
}
 
static Foundation GetFoundation_Road(TileIndex tile, Slope tileh)
{
  if (IsNormalRoad(tile)) {
    return GetRoadFoundation(tileh, GetAllRoadBits(tile));
  } else {
    return FlatteningFoundation(tileh);
  }
}
 
static const Roadside _town_road_types[][2] = {
  { ROADSIDE_GRASS,         ROADSIDE_GRASS },
  { ROADSIDE_PAVED,         ROADSIDE_PAVED },
  { ROADSIDE_PAVED,         ROADSIDE_PAVED },
  { ROADSIDE_TREES,         ROADSIDE_TREES },
  { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED }
};
 
static const Roadside _town_road_types_2[][2] = {
  { ROADSIDE_GRASS,         ROADSIDE_GRASS },
  { ROADSIDE_PAVED,         ROADSIDE_PAVED },
  { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED },
  { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED },
  { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED }
};
 
 
static void TileLoop_Road(TileIndex tile)
{
  switch (_settings_game.game_creation.landscape) {
    case LT_ARCTIC:
      if (IsOnSnow(tile) != (GetTileZ(tile) > GetSnowLine())) {
        ToggleSnow(tile);
        MarkTileDirtyByTile(tile);
      }
      break;
 
    case LT_TROPIC:
      if (GetTropicZone(tile) == TROPICZONE_DESERT && !IsOnDesert(tile)) {
        ToggleDesert(tile);
        MarkTileDirtyByTile(tile);
      }
      break;
  }
 
  if (IsRoadDepot(tile)) return;
 
  const Town *t = ClosestTownFromTile(tile, UINT_MAX);
  if (!HasRoadWorks(tile)) {
    HouseZonesBits grp = HZB_TOWN_EDGE;
 
    if (t != nullptr) {
      grp = GetTownRadiusGroup(t, tile);
 
      /* Show an animation to indicate road work */
      if (t->road_build_months != 0 &&
          (DistanceManhattan(t->xy, tile) < 8 || grp != HZB_TOWN_EDGE) &&
          IsNormalRoad(tile) && !HasAtMostOneBit(GetAllRoadBits(tile))) {
        if (GetFoundationSlope(tile) == SLOPE_FLAT && EnsureNoVehicleOnGround(tile).Succeeded() && Chance16(1, 40)) {
          StartRoadWorks(tile);
 
          if (_settings_client.sound.ambient) SndPlayTileFx(SND_21_ROAD_WORKS, tile);
          CreateEffectVehicleAbove(
            TileX(tile) * TILE_SIZE + 7,
            TileY(tile) * TILE_SIZE + 7,
            0,
            EV_BULLDOZER);
          MarkTileDirtyByTile(tile);
          return;
        }
      }
    }
 
    {
      /* Adjust road ground type depending on 'grp' (grp is the distance to the center) */
      const Roadside *new_rs = (_settings_game.game_creation.landscape == LT_TOYLAND) ? _town_road_types_2[grp] : _town_road_types[grp];
      Roadside cur_rs = GetRoadside(tile);
 
      /* We have our desired type, do nothing */
      if (cur_rs == new_rs[0]) return;
 
      /* We have the pre-type of the desired type, switch to the desired type */
      if (cur_rs == new_rs[1]) {
        cur_rs = new_rs[0];
      /* We have barren land, install the pre-type */
      } else if (cur_rs == ROADSIDE_BARREN) {
        cur_rs = new_rs[1];
      /* We're totally off limits, remove any installation and make barren land */
      } else {
        cur_rs = ROADSIDE_BARREN;
      }
      SetRoadside(tile, cur_rs);
      MarkTileDirtyByTile(tile);
    }
  } else if (IncreaseRoadWorksCounter(tile)) {
    TerminateRoadWorks(tile);
 
    if (_settings_game.economy.mod_road_rebuild) {
      /* Generate a nicer town surface */
      const RoadBits old_rb = GetAnyRoadBits(tile, RTT_ROAD);
      const RoadBits new_rb = CleanUpRoadBits(tile, old_rb);
 
      if (old_rb != new_rb) {
        RemoveRoad(tile, DC_EXEC | DC_AUTO | DC_NO_WATER, (old_rb ^ new_rb), RTT_ROAD, true);
 
        /* If new_rb is 0, there are now no road pieces left and the tile is no longer a road tile */
        if (new_rb == 0) {
          MarkTileDirtyByTile(tile);
          return;
        }
      }
    }
 
    /* Possibly change road type */
    if (GetRoadOwner(tile, RTT_ROAD) == OWNER_TOWN) {
      RoadType rt = GetTownRoadType(t);
      if (rt != GetRoadTypeRoad(tile)) {
        SetRoadType(tile, RTT_ROAD, rt);
      }
    }
 
    MarkTileDirtyByTile(tile);
  }
}
 
static bool ClickTile_Road(TileIndex tile)
{
  if (!IsRoadDepot(tile)) return false;
 
  ShowDepotWindow(tile, VEH_ROAD);
  return true;
}
 
/* Converts RoadBits to TrackBits */
static const TrackBits _road_trackbits[16] = {
  TRACK_BIT_NONE,                                  // ROAD_NONE
  TRACK_BIT_NONE,                                  // ROAD_NW
  TRACK_BIT_NONE,                                  // ROAD_SW
  TRACK_BIT_LEFT,                                  // ROAD_W
  TRACK_BIT_NONE,                                  // ROAD_SE
  TRACK_BIT_Y,                                     // ROAD_Y
  TRACK_BIT_LOWER,                                 // ROAD_S
  TRACK_BIT_LEFT | TRACK_BIT_LOWER | TRACK_BIT_Y,  // ROAD_Y | ROAD_SW
  TRACK_BIT_NONE,                                  // ROAD_NE
  TRACK_BIT_UPPER,                                 // ROAD_N
  TRACK_BIT_X,                                     // ROAD_X
  TRACK_BIT_LEFT | TRACK_BIT_UPPER | TRACK_BIT_X,  // ROAD_X | ROAD_NW
  TRACK_BIT_RIGHT,                                 // ROAD_E
  TRACK_BIT_RIGHT | TRACK_BIT_UPPER | TRACK_BIT_Y, // ROAD_Y | ROAD_NE
  TRACK_BIT_RIGHT | TRACK_BIT_LOWER | TRACK_BIT_X, // ROAD_X | ROAD_SE
  TRACK_BIT_ALL,                                   // ROAD_ALL
};
 
static TrackStatus GetTileTrackStatus_Road(TileIndex tile, TransportType mode, uint sub_mode, DiagDirection side)
{
  TrackdirBits trackdirbits = TRACKDIR_BIT_NONE;
  TrackdirBits red_signals = TRACKDIR_BIT_NONE; // crossing barred
  switch (mode) {
    case TRANSPORT_RAIL:
      if (IsLevelCrossing(tile)) trackdirbits = TrackBitsToTrackdirBits(GetCrossingRailBits(tile));
      break;
 
    case TRANSPORT_ROAD: {
      RoadTramType rtt = (RoadTramType)sub_mode;
      if (!HasTileRoadType(tile, rtt)) break;
      switch (GetRoadTileType(tile)) {
        case ROAD_TILE_NORMAL: {
          const uint drd_to_multiplier[DRD_END] = { 0x101, 0x100, 0x1, 0x0 };
          RoadBits bits = GetRoadBits(tile, rtt);
 
          /* no roadbit at this side of tile, return 0 */
          if (side != INVALID_DIAGDIR && (DiagDirToRoadBits(side) & bits) == 0) break;
 
          uint multiplier = drd_to_multiplier[(rtt == RTT_TRAM) ? DRD_NONE : GetDisallowedRoadDirections(tile)];
          if (!HasRoadWorks(tile)) trackdirbits = (TrackdirBits)(_road_trackbits[bits] * multiplier);
          break;
        }
 
        case ROAD_TILE_CROSSING: {
          Axis axis = GetCrossingRoadAxis(tile);
 
          if (side != INVALID_DIAGDIR && axis != DiagDirToAxis(side)) break;
 
          trackdirbits = TrackBitsToTrackdirBits(AxisToTrackBits(axis));
          if (IsCrossingBarred(tile)) {
            red_signals = trackdirbits;
            if (TrainOnCrossing(tile)) break;
 
            auto mask_red_signal_bits_if_crossing_barred = [&](TileIndex t, TrackdirBits mask) {
              if (IsLevelCrossingTile(t) && IsCrossingBarred(t)) red_signals &= mask;
            };
            /* Check for blocked adjacent crossing to south, keep only southbound red signal trackdirs, allow northbound traffic */
            mask_red_signal_bits_if_crossing_barred(TileAddByDiagDir(tile, AxisToDiagDir(axis)), TRACKDIR_BIT_X_SW | TRACKDIR_BIT_Y_SE);
            /* Check for blocked adjacent crossing to north, keep only northbound red signal trackdirs, allow southbound traffic */
            mask_red_signal_bits_if_crossing_barred(TileAddByDiagDir(tile, ReverseDiagDir(AxisToDiagDir(axis))), TRACKDIR_BIT_X_NE | TRACKDIR_BIT_Y_NW);
          }
          break;
        }
 
        default:
        case ROAD_TILE_DEPOT: {
          DiagDirection dir = GetRoadDepotDirection(tile);
 
          if (side != INVALID_DIAGDIR && side != dir) break;
 
          trackdirbits = TrackBitsToTrackdirBits(DiagDirToDiagTrackBits(dir));
          break;
        }
      }
      break;
    }
 
    default: break;
  }
  return CombineTrackStatus(trackdirbits, red_signals);
}
 
static const StringID _road_tile_strings[] = {
  STR_LAI_ROAD_DESCRIPTION_ROAD,
  STR_LAI_ROAD_DESCRIPTION_ROAD,
  STR_LAI_ROAD_DESCRIPTION_ROAD,
  STR_LAI_ROAD_DESCRIPTION_ROAD_WITH_STREETLIGHTS,
  STR_LAI_ROAD_DESCRIPTION_ROAD,
  STR_LAI_ROAD_DESCRIPTION_TREE_LINED_ROAD,
  STR_LAI_ROAD_DESCRIPTION_ROAD,
  STR_LAI_ROAD_DESCRIPTION_ROAD,
};
 
static void GetTileDesc_Road(TileIndex tile, TileDesc *td)
{
  Owner rail_owner = INVALID_OWNER;
  Owner road_owner = INVALID_OWNER;
  Owner tram_owner = INVALID_OWNER;
 
  RoadType road_rt = GetRoadTypeRoad(tile);
  RoadType tram_rt = GetRoadTypeTram(tile);
  if (road_rt != INVALID_ROADTYPE) {
    const RoadTypeInfo *rti = GetRoadTypeInfo(road_rt);
    td->roadtype = rti->strings.name;
    td->road_speed = rti->max_speed / 2;
    road_owner = GetRoadOwner(tile, RTT_ROAD);
  }
  if (tram_rt != INVALID_ROADTYPE) {
    const RoadTypeInfo *rti = GetRoadTypeInfo(tram_rt);
    td->tramtype = rti->strings.name;
    td->tram_speed = rti->max_speed / 2;
    tram_owner = GetRoadOwner(tile, RTT_TRAM);
  }
 
  switch (GetRoadTileType(tile)) {
    case ROAD_TILE_CROSSING: {
      td->str = STR_LAI_ROAD_DESCRIPTION_ROAD_RAIL_LEVEL_CROSSING;
      rail_owner = GetTileOwner(tile);
 
      const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
      td->railtype = rti->strings.name;
      td->rail_speed = rti->max_speed;
 
      break;
    }
 
    case ROAD_TILE_DEPOT:
      td->str = STR_LAI_ROAD_DESCRIPTION_ROAD_VEHICLE_DEPOT;
      td->build_date = Depot::GetByTile(tile)->build_date;
      break;
 
    default: {
      td->str = (road_rt != INVALID_ROADTYPE ? _road_tile_strings[GetRoadside(tile)] : STR_LAI_ROAD_DESCRIPTION_TRAMWAY);
      break;
    }
  }
 
  /* Now we have to discover, if the tile has only one owner or many:
   *   - Find a first_owner of the tile. (Currently road or tram must be present, but this will break when the third type becomes available)
   *   - Compare the found owner with the other owners, and test if they differ.
   * Note: If road exists it will be the first_owner.
   */
  Owner first_owner = (road_owner == INVALID_OWNER ? tram_owner : road_owner);
  bool mixed_owners = (tram_owner != INVALID_OWNER && tram_owner != first_owner) || (rail_owner != INVALID_OWNER && rail_owner != first_owner);
 
  if (mixed_owners) {
    /* Multiple owners */
    td->owner_type[0] = (rail_owner == INVALID_OWNER ? STR_NULL : STR_LAND_AREA_INFORMATION_RAIL_OWNER);
    td->owner[0] = rail_owner;
    td->owner_type[1] = (road_owner == INVALID_OWNER ? STR_NULL : STR_LAND_AREA_INFORMATION_ROAD_OWNER);
    td->owner[1] = road_owner;
    td->owner_type[2] = (tram_owner == INVALID_OWNER ? STR_NULL : STR_LAND_AREA_INFORMATION_TRAM_OWNER);
    td->owner[2] = tram_owner;
  } else {
    /* One to rule them all */
    td->owner[0] = first_owner;
  }
}
 
static const byte _roadveh_enter_depot_dir[4] = {
  TRACKDIR_X_SW, TRACKDIR_Y_NW, TRACKDIR_X_NE, TRACKDIR_Y_SE
};
 
static VehicleEnterTileStatus VehicleEnter_Road(Vehicle *v, TileIndex tile, int x, int y)
{
  switch (GetRoadTileType(tile)) {
    case ROAD_TILE_DEPOT: {
      if (v->type != VEH_ROAD) break;
 
      RoadVehicle *rv = RoadVehicle::From(v);
      if (rv->frame == RVC_DEPOT_STOP_FRAME &&
          _roadveh_enter_depot_dir[GetRoadDepotDirection(tile)] == rv->state) {
        rv->state = RVSB_IN_DEPOT;
        rv->vehstatus |= VS_HIDDEN;
        rv->direction = ReverseDir(rv->direction);
        if (rv->Next() == nullptr) VehicleEnterDepot(rv->First());
        rv->tile = tile;
 
        InvalidateWindowData(WC_VEHICLE_DEPOT, rv->tile);
        return VETSB_ENTERED_WORMHOLE;
      }
      break;
    }
 
    default: break;
  }
  return VETSB_CONTINUE;
}
 
 
static void ChangeTileOwner_Road(TileIndex tile, Owner old_owner, Owner new_owner)
{
  if (IsRoadDepot(tile)) {
    if (GetTileOwner(tile) == old_owner) {
      if (new_owner == INVALID_OWNER) {
        Command<CMD_LANDSCAPE_CLEAR>::Do(DC_EXEC | DC_BANKRUPT, tile);
      } else {
        /* A road depot has two road bits. No need to dirty windows here, we'll redraw the whole screen anyway. */
        RoadType rt = GetRoadTypeRoad(tile);
        if (rt == INVALID_ROADTYPE) rt = GetRoadTypeTram(tile);
        Company::Get(old_owner)->infrastructure.road[rt] -= 2;
        Company::Get(new_owner)->infrastructure.road[rt] += 2;
 
        SetTileOwner(tile, new_owner);
        for (RoadTramType rtt : _roadtramtypes) {
          if (GetRoadOwner(tile, rtt) == old_owner) {
            SetRoadOwner(tile, rtt, new_owner);
          }
        }
      }
    }
    return;
  }
 
  for (RoadTramType rtt : _roadtramtypes) {
    /* Update all roadtypes, no matter if they are present */
    if (GetRoadOwner(tile, rtt) == old_owner) {
      RoadType rt = GetRoadType(tile, rtt);
      if (rt != INVALID_ROADTYPE) {
        /* A level crossing has two road bits. No need to dirty windows here, we'll redraw the whole screen anyway. */
        uint num_bits = IsLevelCrossing(tile) ? 2 : CountBits(GetRoadBits(tile, rtt));
        Company::Get(old_owner)->infrastructure.road[rt] -= num_bits;
        if (new_owner != INVALID_OWNER) Company::Get(new_owner)->infrastructure.road[rt] += num_bits;
      }
 
      SetRoadOwner(tile, rtt, new_owner == INVALID_OWNER ? OWNER_NONE : new_owner);
    }
  }
 
  if (IsLevelCrossing(tile)) {
    if (GetTileOwner(tile) == old_owner) {
      if (new_owner == INVALID_OWNER) {
        Command<CMD_REMOVE_SINGLE_RAIL>::Do(DC_EXEC | DC_BANKRUPT, tile, GetCrossingRailTrack(tile));
      } else {
        /* Update infrastructure counts. No need to dirty windows here, we'll redraw the whole screen anyway. */
        Company::Get(old_owner)->infrastructure.rail[GetRailType(tile)] -= LEVELCROSSING_TRACKBIT_FACTOR;
        Company::Get(new_owner)->infrastructure.rail[GetRailType(tile)] += LEVELCROSSING_TRACKBIT_FACTOR;
 
        SetTileOwner(tile, new_owner);
      }
    }
  }
}
 
static CommandCost TerraformTile_Road(TileIndex tile, DoCommandFlag flags, int z_new, Slope tileh_new)
{
  if (_settings_game.construction.build_on_slopes && AutoslopeEnabled()) {
    switch (GetRoadTileType(tile)) {
      case ROAD_TILE_CROSSING:
        if (!IsSteepSlope(tileh_new) && (GetTileMaxZ(tile) == z_new + GetSlopeMaxZ(tileh_new)) && HasBit(VALID_LEVEL_CROSSING_SLOPES, tileh_new)) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
        break;
 
      case ROAD_TILE_DEPOT:
        if (AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, GetRoadDepotDirection(tile))) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
        break;
 
      case ROAD_TILE_NORMAL: {
        RoadBits bits = GetAllRoadBits(tile);
        RoadBits bits_copy = bits;
        /* Check if the slope-road_bits combination is valid at all, i.e. it is safe to call GetRoadFoundation(). */
        if (CheckRoadSlope(tileh_new, &bits_copy, ROAD_NONE, ROAD_NONE).Succeeded()) {
          /* CheckRoadSlope() sometimes changes the road_bits, if it does not agree with them. */
          if (bits == bits_copy) {
            int z_old;
            Slope tileh_old = GetTileSlope(tile, &z_old);
 
            /* Get the slope on top of the foundation */
            z_old += ApplyFoundationToSlope(GetRoadFoundation(tileh_old, bits), &tileh_old);
            z_new += ApplyFoundationToSlope(GetRoadFoundation(tileh_new, bits), &tileh_new);
 
            /* The surface slope must not be changed */
            if ((z_old == z_new) && (tileh_old == tileh_new)) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
          }
        }
        break;
      }
 
      default: NOT_REACHED();
    }
  }
 
  return Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
}
 
static Vehicle *UpdateRoadVehPowerProc(Vehicle *v, void *data)
{
  if (v->type != VEH_ROAD) return nullptr;
 
  RoadVehicleList *affected_rvs = static_cast<RoadVehicleList*>(data);
  include(*affected_rvs, RoadVehicle::From(v)->First());
 
  return nullptr;
}
 
static bool CanConvertUnownedRoadType(Owner owner, RoadTramType rtt)
{
  return (owner == OWNER_NONE || (owner == OWNER_TOWN && rtt == RTT_ROAD));
}
 
static void ConvertRoadTypeOwner(TileIndex tile, uint num_pieces, Owner owner, RoadType from_type, RoadType to_type)
{
  // Scenario editor, maybe? Don't touch the owners when converting roadtypes...
  if (_current_company >= MAX_COMPANIES) return;
 
  // We can't get a company from invalid owners but we can get ownership of roads without an owner
  if (owner >= MAX_COMPANIES && owner != OWNER_NONE) return;
 
  Company *c;
 
  switch (owner) {
  case OWNER_NONE:
    SetRoadOwner(tile, GetRoadTramType(to_type), (Owner)_current_company);
    UpdateCompanyRoadInfrastructure(to_type, _current_company, num_pieces);
    break;
 
  default:
    c = Company::Get(owner);
    c->infrastructure.road[from_type] -= num_pieces;
    c->infrastructure.road[to_type] += num_pieces;
    DirtyCompanyInfrastructureWindows(c->index);
    break;
  }
}
 
CommandCost CmdConvertRoad(DoCommandFlag flags, TileIndex tile, TileIndex area_start, RoadType to_type)
{
  TileIndex area_end = tile;
 
  if (!ValParamRoadType(to_type)) return CMD_ERROR;
  if (area_start >= MapSize()) return CMD_ERROR;
 
  RoadVehicleList affected_rvs;
  RoadTramType rtt = GetRoadTramType(to_type);
 
  CommandCost cost(EXPENSES_CONSTRUCTION);
  CommandCost error = CommandCost((rtt == RTT_TRAM) ? STR_ERROR_NO_SUITABLE_TRAMWAY : STR_ERROR_NO_SUITABLE_ROAD); // by default, there is no road to convert.
  bool found_convertible_road = false; // whether we actually did convert any road/tram (see bug #7633)
 
  TileIterator *iter = new OrthogonalTileIterator(area_start, area_end);
  for (; (tile = *iter) != INVALID_TILE; ++(*iter)) {
    /* Is road present on tile? */
    if (!MayHaveRoad(tile)) continue;
 
    /* Converting to the same subtype? */
    RoadType from_type = GetRoadType(tile, rtt);
    if (from_type == INVALID_ROADTYPE || from_type == to_type) continue;
 
    /* Check if there is any infrastructure on tile */
    TileType tt = GetTileType(tile);
    switch (tt) {
      case MP_STATION:
        if (!IsRoadStop(tile)) continue;
        break;
      case MP_ROAD:
        if (IsLevelCrossing(tile) && RoadNoLevelCrossing(to_type)) {
          error.MakeError(STR_ERROR_CROSSING_DISALLOWED_ROAD);
          continue;
        }
        break;
      case MP_TUNNELBRIDGE:
        if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) continue;
        break;
      default: continue;
    }
 
    /* Trying to convert other's road */
    Owner owner = GetRoadOwner(tile, rtt);
    if (!CanConvertUnownedRoadType(owner, rtt)) {
      CommandCost ret = CheckOwnership(owner, tile);
      if (ret.Failed()) {
        error = ret;
        continue;
      }
    }
 
    /* Base the ability to replace town roads and bridges on the town's
     * acceptance of destructive actions. */
    if (owner == OWNER_TOWN) {
      Town *t = ClosestTownFromTile(tile, _settings_game.economy.dist_local_authority);
      CommandCost ret = CheckforTownRating(DC_NONE, t, tt == MP_TUNNELBRIDGE ? TUNNELBRIDGE_REMOVE : ROAD_REMOVE);
      if (ret.Failed()) {
        error = ret;
        continue;
      }
    }
 
    /* Vehicle on the tile when not converting normal <-> powered
     * Tunnels and bridges have special check later */
    if (tt != MP_TUNNELBRIDGE) {
      if (!HasPowerOnRoad(from_type, to_type)) {
        CommandCost ret = EnsureNoVehicleOnGround(tile);
        if (ret.Failed()) {
          error = ret;
          continue;
        }
 
        if (rtt == RTT_ROAD && owner == OWNER_TOWN) {
          error.MakeError(STR_ERROR_OWNED_BY);
          GetNameOfOwner(OWNER_TOWN, tile);
          continue;
        }
      }
 
      uint num_pieces = CountBits(GetAnyRoadBits(tile, rtt));
      if (tt == MP_STATION && IsStandardRoadStopTile(tile)) {
        num_pieces *= ROAD_STOP_TRACKBIT_FACTOR;
      } else if (tt == MP_ROAD && IsRoadDepot(tile)) {
        num_pieces *= ROAD_DEPOT_TRACKBIT_FACTOR;
      }
 
      found_convertible_road = true;
      cost.AddCost(num_pieces * RoadConvertCost(from_type, to_type));
 
      if (flags & DC_EXEC) { // we can safely convert, too
        /* Call ConvertRoadTypeOwner() to update the company infrastructure counters. */
        if (owner == _current_company) {
          ConvertRoadTypeOwner(tile, num_pieces, owner, from_type, to_type);
        }
 
        /* Perform the conversion */
        SetRoadType(tile, rtt, to_type);
        MarkTileDirtyByTile(tile);
 
        /* update power of train on this tile */
        FindVehicleOnPos(tile, &affected_rvs, &UpdateRoadVehPowerProc);
 
        if (IsRoadDepotTile(tile)) {
          /* Update build vehicle window related to this depot */
          InvalidateWindowData(WC_VEHICLE_DEPOT, tile);
          InvalidateWindowData(WC_BUILD_VEHICLE, tile);
        }
      }
    } else {
      TileIndex endtile = GetOtherTunnelBridgeEnd(tile);
 
      /* If both ends of tunnel/bridge are in the range, do not try to convert twice -
       * it would cause assert because of different test and exec runs */
      if (endtile < tile) {
        if (OrthogonalTileArea(area_start, area_end).Contains(endtile)) continue;
      }
 
      /* When not converting rail <-> el. rail, any vehicle cannot be in tunnel/bridge */
      if (!HasPowerOnRoad(from_type, to_type)) {
        CommandCost ret = TunnelBridgeIsFree(tile, endtile);
        if (ret.Failed()) {
          error = ret;
          continue;
        }
 
        if (rtt == RTT_ROAD && owner == OWNER_TOWN) {
          error.MakeError(STR_ERROR_OWNED_BY);
          GetNameOfOwner(OWNER_TOWN, tile);
          continue;
        }
      }
 
      /* There are 2 pieces on *every* tile of the bridge or tunnel */
      uint num_pieces = (GetTunnelBridgeLength(tile, endtile) + 2) * 2;
      found_convertible_road = true;
      cost.AddCost(num_pieces * RoadConvertCost(from_type, to_type));
 
      if (flags & DC_EXEC) {
        /* Update the company infrastructure counters. */
        if (owner == _current_company) {
          /* Each piece should be counted TUNNELBRIDGE_TRACKBIT_FACTOR times
           * for the infrastructure counters (cause of #8297). */
          ConvertRoadTypeOwner(tile, num_pieces * TUNNELBRIDGE_TRACKBIT_FACTOR, owner, from_type, to_type);
          SetTunnelBridgeOwner(tile, endtile, _current_company);
        }
 
        /* Perform the conversion */
        SetRoadType(tile,    rtt, to_type);
        SetRoadType(endtile, rtt, to_type);
 
        FindVehicleOnPos(tile, &affected_rvs, &UpdateRoadVehPowerProc);
        FindVehicleOnPos(endtile, &affected_rvs, &UpdateRoadVehPowerProc);
 
        if (IsBridge(tile)) {
          MarkBridgeDirty(tile);
        } else {
          MarkTileDirtyByTile(tile);
          MarkTileDirtyByTile(endtile);
        }
      }
    }
  }
 
  if (flags & DC_EXEC) {
    /* Roadtype changed, update roadvehicles as when entering different track */
    for (RoadVehicle *v : affected_rvs) {
      v->CargoChanged();
    }
  }
 
  delete iter;
  return found_convertible_road ? cost : error;
}
 
 
extern const TileTypeProcs _tile_type_road_procs = {
  DrawTile_Road,           // draw_tile_proc
  GetSlopePixelZ_Road,     // get_slope_z_proc
  ClearTile_Road,          // clear_tile_proc
  nullptr,                    // add_accepted_cargo_proc
  GetTileDesc_Road,        // get_tile_desc_proc
  GetTileTrackStatus_Road, // get_tile_track_status_proc
  ClickTile_Road,          // click_tile_proc
  nullptr,                    // animate_tile_proc
  TileLoop_Road,           // tile_loop_proc
  ChangeTileOwner_Road,    // change_tile_owner_proc
  nullptr,                    // add_produced_cargo_proc
  VehicleEnter_Road,       // vehicle_enter_tile_proc
  GetFoundation_Road,      // get_foundation_proc
  TerraformTile_Road,      // terraform_tile_proc
};