src/elrail.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /**
   9  * @file elrail.cpp
  10  * This file deals with displaying wires and pylons for electric railways.
  11  * <h2>Basics</h2>
  12  *
  13  * <h3>Tile Types</h3>
  14  *
  15  * We have two different types of tiles in the drawing code:
  16  * Normal Railway Tiles (NRTs) which can have more than one track on it, and
  17  * Special Railways tiles (SRTs) which have only one track (like crossings, depots
  18  * stations, etc).
  19  *
  20  * <h3>Location Categories</h3>
  21  *
  22  * All tiles are categorized into three location groups (TLG):
  23  * Group 0: Tiles with both an even X coordinate and an even Y coordinate
  24  * Group 1: Tiles with an even X and an odd Y coordinate
  25  * Group 2: Tiles with an odd X and an even Y coordinate
  26  * Group 3: Tiles with both an odd X and Y coordinate.
  27  *
  28  * <h3>Pylon Points</h3>
  29  * <h4>Control Points</h4>
  30  * A Pylon Control Point (PCP) is a position where a wire (or rather two)
  31  * is mounted onto a pylon.
  32  * Each NRT does contain 4 PCPs which are bitmapped to a byte
  33  * variable and are represented by the DiagDirection enum
  34  *
  35  * Each track ends on two PCPs and thus requires one pylon on each end. However,
  36  * there is one exception: Straight-and-level tracks only have one pylon every
  37  * other tile.
  38  *
  39  * Now on each edge there are two PCPs: One from each adjacent tile. Both PCPs
  40  * are merged using an OR operation (i. e. if one tile needs a PCP at the position
  41  * in question, both tiles get it).
  42  *
  43  * <h4>Position Points</h4>
  44  * A Pylon Position Point (PPP) is a position where a pylon is located on the
  45  * ground.  Each PCP owns 8 in (45 degree steps) PPPs that are located around
  46  * it. PPPs are represented using the Direction enum. Each track bit has PPPs
  47  * that are impossible (because the pylon would be situated on the track) and
  48  * some that are preferred (because the pylon would be rectangular to the track).
  49  *
  50  * @image html elrail_tile.png
  51  * @image html elrail_track.png
  52  *
  53  */
  54
  55 #include "stdafx.h"
  56 #include "station_map.h"
  57 #include "viewport_func.h"
  58 #include "train.h"
  59 #include "rail_gui.h"
  60 #include "tunnelbridge_map.h"
  61 #include "tunnelbridge.h"
  62 #include "elrail_func.h"
  63 #include "company_base.h"
  64 #include "newgrf_railtype.h"
  65
  66 #include "table/elrail_data.h"
  67
  68 #include "safeguards.h"
  69
  70 /**
  71  * Get the tile location group of a tile.
  72  * @param t The tile to get the tile location group of.
  73  * @return The tile location group.
  74  */
  75 static inline TLG GetTLG(TileIndex t)
  76 {
  77         return (TLG)((HasBit(TileX(t), 0) << 1) + HasBit(TileY(t), 0));
  78 }
  79
  80 /**
  81  * Finds which Electrified Rail Bits are present on a given tile.
  82  * @param t tile to check
  83  * @param override pointer to PCP override, can be nullptr
  84  * @return trackbits of tile if it is electrified
  85  */
  86 static TrackBits GetRailTrackBitsUniversal(TileIndex t, byte *override)
  87 {
  88         switch (GetTileType(t)) {
  89                 case MP_RAILWAY:
  90                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
  91                         switch (GetRailTileType(t)) {
  92                                 case RAIL_TILE_NORMAL: case RAIL_TILE_SIGNALS:
  93                                         return GetTrackBits(t);
  94                                 default:
  95                                         return TRACK_BIT_NONE;
  96                         }
  97                         break;
  98
  99                 case MP_TUNNELBRIDGE:
 100                         if (GetTunnelBridgeTransportType(t) != TRANSPORT_RAIL) return TRACK_BIT_NONE;
 101                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
 102                         if (override != nullptr && (IsTunnel(t) || GetTunnelBridgeLength(t, GetOtherBridgeEnd(t)) > 0)) {
 103                                 *override = 1 << GetTunnelBridgeDirection(t);
 104                         }
 105                         return DiagDirToDiagTrackBits(GetTunnelBridgeDirection(t));
 106
 107                 case MP_ROAD:
 108                         if (!IsLevelCrossing(t)) return TRACK_BIT_NONE;
 109                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
 110                         return GetCrossingRailBits(t);
 111
 112                 case MP_STATION:
 113                         if (!HasStationRail(t)) return TRACK_BIT_NONE;
 114                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
 115                         return TrackToTrackBits(GetRailStationTrack(t));
 116
 117                 default:
 118                         return TRACK_BIT_NONE;
 119         }
 120 }
 121
 122 /**
 123  * Masks out track bits when neighbouring tiles are unelectrified.
 124  */
 125 static TrackBits MaskWireBits(TileIndex t, TrackBits tracks)
 126 {
 127         /* Single track bits are never masked out. */
 128         if (likely(HasAtMostOneBit(tracks))) return tracks;
 129
 130         if (!IsPlainRailTile(t)) return tracks;
 131
 132         TrackdirBits neighbour_tdb = TRACKDIR_BIT_NONE;
 133         for (DiagDirection d = DIAGDIR_BEGIN; d < DIAGDIR_END; d++) {
 134                 /* If the neighbour tile is either not electrified or has no tracks that can be reached
 135                  * from this tile, mark all trackdirs that can be reached from the neighbour tile
 136                  * as needing no catenary. We make an exception for blocked station tiles with a matching
 137                  * axis that still display wires to preserve visual continuity. */
 138                 TileIndex next_tile = TileAddByDiagDir(t, d);
 139                 RailType rt = GetTileRailType(next_tile);
 140                 if (rt == INVALID_RAILTYPE || !HasRailCatenary(rt) ||
 141                                 ((TrackStatusToTrackBits(GetTileTrackStatus(next_tile, TRANSPORT_RAIL, 0)) & DiagdirReachesTracks(d)) == TRACK_BIT_NONE &&
 142                                 (!HasStationTileRail(next_tile) || GetRailStationAxis(next_tile) != DiagDirToAxis(d) || !CanStationTileHaveWires(next_tile)))) {
 143                         neighbour_tdb |= DiagdirReachesTrackdirs(ReverseDiagDir(d));
 144                 }
 145         }
 146
 147         /* If the tracks from either a diagonal crossing or don't overlap, both
 148          * trackdirs have to be marked to mask the corresponding track bit. Else
 149          * one marked trackdir is enough the mask the track bit. */
 150         TrackBits mask;
 151         if (tracks == TRACK_BIT_CROSS || !TracksOverlap(tracks)) {
 152                 /* If the tracks form either a diagonal crossing or don't overlap, both
 153                  * trackdirs have to be marked to mask the corresponding track bit. */
 154                 mask = ~(TrackBits)((neighbour_tdb & (neighbour_tdb >> 8)) & TRACK_BIT_MASK);
 155                 /* If that results in no masked tracks and it is not a diagonal crossing,
 156                  * require only one marked trackdir to mask. */
 157                 if (tracks != TRACK_BIT_CROSS && (mask & TRACK_BIT_MASK) == TRACK_BIT_MASK) mask = ~TrackdirBitsToTrackBits(neighbour_tdb);
 158         } else {
 159                 /* Require only one marked trackdir to mask the track. */
 160                 mask = ~TrackdirBitsToTrackBits(neighbour_tdb);
 161                 /* If that results in an empty set, require both trackdirs for diagonal track. */
 162                 if ((tracks & mask) == TRACK_BIT_NONE) {
 163                         if ((neighbour_tdb & TRACKDIR_BIT_X_NE) == 0 || (neighbour_tdb & TRACKDIR_BIT_X_SW) == 0) mask |= TRACK_BIT_X;
 164                         if ((neighbour_tdb & TRACKDIR_BIT_Y_NW) == 0 || (neighbour_tdb & TRACKDIR_BIT_Y_SE) == 0) mask |= TRACK_BIT_Y;
 165                         /* If that still is not enough, require both trackdirs for any track. */
 166                         if ((tracks & mask) == TRACK_BIT_NONE) mask = ~(TrackBits)((neighbour_tdb & (neighbour_tdb >> 8)) & TRACK_BIT_MASK);
 167                 }
 168         }
 169
 170         /* Mask the tracks only if at least one track bit would remain. */
 171         return (tracks & mask) != TRACK_BIT_NONE ? tracks & mask : tracks;
 172 }
 173
 174 /**
 175  * Get the base wire sprite to use.
 176  */
 177 static inline SpriteID GetWireBase(TileIndex tile, TileContext context = TCX_NORMAL)
 178 {
 179         const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
 180         SpriteID wires = GetCustomRailSprite(rti, tile, RTSG_WIRES, context);
 181         return wires == 0 ? SPR_WIRE_BASE : wires;
 182 }
 183
 184 /**
 185  * Get the base pylon sprite to use.
 186  */
 187 static inline SpriteID GetPylonBase(TileIndex tile, TileContext context = TCX_NORMAL)
 188 {
 189         const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
 190         SpriteID pylons = GetCustomRailSprite(rti, tile, RTSG_PYLONS, context);
 191         return pylons == 0 ? SPR_PYLON_BASE : pylons;
 192 }
 193
 194 /**
 195  * Corrects the tileh for certain tile types. Returns an effective tileh for the track on the tile.
 196  * @param tile The tile to analyse
 197  * @param *tileh the tileh
 198  */
 199 static void AdjustTileh(TileIndex tile, Slope *tileh)
 200 {
 201         if (IsTileType(tile, MP_TUNNELBRIDGE)) {
 202                 if (IsTunnel(tile)) {
 203                         *tileh = SLOPE_STEEP; // XXX - Hack to make tunnel entrances to always have a pylon
 204                 } else if (*tileh != SLOPE_FLAT) {
 205                         *tileh = SLOPE_FLAT;
 206                 } else {
 207                         *tileh = InclinedSlope(GetTunnelBridgeDirection(tile));
 208                 }
 209         }
 210 }
 211
 212 /**
 213  * Returns the Z position of a Pylon Control Point.
 214  *
 215  * @param tile The tile the pylon should stand on.
 216  * @param PCPpos The PCP of the tile.
 217  * @return The Z position of the PCP.
 218  */
 219 static int GetPCPElevation(TileIndex tile, DiagDirection PCPpos)
 220 {
 221         /* The elevation of the "pylon"-sprite should be the elevation at the PCP.
 222          * PCPs are always on a tile edge.
 223          *
 224          * This position can be outside of the tile, i.e. ?_pcp_offset == TILE_SIZE > TILE_SIZE - 1.
 225          * So we have to move it inside the tile, because if the neighboured tile has a foundation,
 226          * that does not smoothly connect to the current tile, we will get a wrong elevation from GetSlopePixelZ().
 227          *
 228          * When we move the position inside the tile, we will get a wrong elevation if we have a slope.
 229          * To catch all cases we round the Z position to the next (TILE_HEIGHT / 2).
 230          * This will return the correct elevation for slopes and will also detect non-continuous elevation on edges.
 231          *
 232          * Also note that the result of GetSlopePixelZ() is very special on bridge-ramps.
 233          */
 234
 235         int z = GetSlopePixelZ(TileX(tile) * TILE_SIZE + std::min<int8>(x_pcp_offsets[PCPpos], TILE_SIZE - 1),
 236                                TileY(tile) * TILE_SIZE + std::min<int8>(y_pcp_offsets[PCPpos], TILE_SIZE - 1));
 237         return (z + 2) & ~3; // this means z = (z + TILE_HEIGHT / 4) / (TILE_HEIGHT / 2) * (TILE_HEIGHT / 2);
 238 }
 239
 240 /**
 241  * Draws wires on a tunnel tile
 242  *
 243  * DrawTile_TunnelBridge() calls this function to draw the wires as SpriteCombine with the tunnel roof.
 244  *
 245  * @param ti The Tileinfo to draw the tile for
 246  */
 247 void DrawRailCatenaryOnTunnel(const TileInfo *ti)
 248 {
 249         /* xmin, ymin, xmax + 1, ymax + 1 of BB */
 250         static const int _tunnel_wire_BB[4][4] = {
 251                 { 0, 1, 16, 15 }, // NE
 252                 { 1, 0, 15, 16 }, // SE
 253                 { 0, 1, 16, 15 }, // SW
 254                 { 1, 0, 15, 16 }, // NW
 255         };
 256
 257         DiagDirection dir = GetTunnelBridgeDirection(ti->tile);
 258
 259         SpriteID wire_base = GetWireBase(ti->tile);
 260
 261         const SortableSpriteStruct *sss = &RailCatenarySpriteData_Tunnel[dir];
 262         const int *BB_data = _tunnel_wire_BB[dir];
 263         AddSortableSpriteToDraw(
 264                 wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 265                 BB_data[2] - sss->x_offset, BB_data[3] - sss->y_offset, BB_Z_SEPARATOR - sss->z_offset + 1,
 266                 GetTilePixelZ(ti->tile) + sss->z_offset,
 267                 IsTransparencySet(TO_CATENARY),
 268                 BB_data[0] - sss->x_offset, BB_data[1] - sss->y_offset, BB_Z_SEPARATOR - sss->z_offset
 269         );
 270 }
 271
 272 /**
 273  * Draws wires and, if required, pylons on a given tile
 274  * @param ti The Tileinfo to draw the tile for
 275  */
 276 static void DrawRailCatenaryRailway(const TileInfo *ti)
 277 {
 278         /* Pylons are placed on a tile edge, so we need to take into account
 279          * the track configuration of 2 adjacent tiles. trackconfig[0] stores the
 280          * current tile (home tile) while [1] holds the neighbour */
 281         TrackBits trackconfig[TS_END];
 282         TrackBits wireconfig[TS_END];
 283         bool isflat[TS_END];
 284         /* Note that ti->tileh has already been adjusted for Foundations */
 285         Slope tileh[TS_END] = { ti->tileh, SLOPE_FLAT };
 286
 287         /* Half tile slopes coincide only with horizontal/vertical track.
 288          * Faking a flat slope results in the correct sprites on positions. */
 289         Corner halftile_corner = CORNER_INVALID;
 290         if (IsHalftileSlope(tileh[TS_HOME])) {
 291                 halftile_corner = GetHalftileSlopeCorner(tileh[TS_HOME]);
 292                 tileh[TS_HOME] = SLOPE_FLAT;
 293         }
 294
 295         TLG tlg = GetTLG(ti->tile);
 296         byte PCPstatus = 0;
 297         byte OverridePCP = 0;
 298         byte PPPpreferred[DIAGDIR_END];
 299         byte PPPallowed[DIAGDIR_END];
 300
 301         /* Find which rail bits are present, and select the override points.
 302          * We don't draw a pylon:
 303          * 1) INSIDE a tunnel (we wouldn't see it anyway)
 304          * 2) on the "far" end of a bridge head (the one that connects to bridge middle),
 305          *    because that one is drawn on the bridge. Exception is for length 0 bridges
 306          *    which have no middle tiles */
 307         trackconfig[TS_HOME] = GetRailTrackBitsUniversal(ti->tile, &OverridePCP);
 308         wireconfig[TS_HOME] = MaskWireBits(ti->tile, trackconfig[TS_HOME]);
 309         /* If a track bit is present that is not in the main direction, the track is level */
 310         isflat[TS_HOME] = ((trackconfig[TS_HOME] & (TRACK_BIT_HORZ | TRACK_BIT_VERT)) != 0);
 311
 312         AdjustTileh(ti->tile, &tileh[TS_HOME]);
 313
 314         SpriteID pylon_normal = GetPylonBase(ti->tile);
 315         SpriteID pylon_halftile = (halftile_corner != CORNER_INVALID) ? GetPylonBase(ti->tile, TCX_UPPER_HALFTILE) : pylon_normal;
 316
 317         for (DiagDirection i = DIAGDIR_BEGIN; i < DIAGDIR_END; i++) {
 318                 static const uint edge_corners[] = {
 319                         1 << CORNER_N | 1 << CORNER_E, // DIAGDIR_NE
 320                         1 << CORNER_S | 1 << CORNER_E, // DIAGDIR_SE
 321                         1 << CORNER_S | 1 << CORNER_W, // DIAGDIR_SW
 322                         1 << CORNER_N | 1 << CORNER_W, // DIAGDIR_NW
 323                 };
 324                 SpriteID pylon_base = (halftile_corner != CORNER_INVALID && HasBit(edge_corners[i], halftile_corner)) ? pylon_halftile : pylon_normal;
 325                 TileIndex neighbour = ti->tile + TileOffsByDiagDir(i);
 326                 int elevation = GetPCPElevation(ti->tile, i);
 327
 328                 /* Here's one of the main headaches. GetTileSlope does not correct for possibly
 329                  * existing foundataions, so we do have to do that manually later on.*/
 330                 tileh[TS_NEIGHBOUR] = GetTileSlope(neighbour);
 331                 trackconfig[TS_NEIGHBOUR] = GetRailTrackBitsUniversal(neighbour, nullptr);
 332                 wireconfig[TS_NEIGHBOUR] = MaskWireBits(neighbour, trackconfig[TS_NEIGHBOUR]);
 333                 if (IsTunnelTile(neighbour) && i != GetTunnelBridgeDirection(neighbour)) wireconfig[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] = TRACK_BIT_NONE;
 334
 335                 /* Ignore station tiles that allow neither wires nor pylons. */
 336                 if (IsRailStationTile(neighbour) && !CanStationTileHavePylons(neighbour) && !CanStationTileHaveWires(neighbour)) wireconfig[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] = TRACK_BIT_NONE;
 337
 338                 /* If the neighboured tile does not smoothly connect to the current tile (because of a foundation),
 339                  * we have to draw all pillars on the current tile. */
 340                 if (elevation != GetPCPElevation(neighbour, ReverseDiagDir(i))) wireconfig[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] = TRACK_BIT_NONE;
 341
 342                 isflat[TS_NEIGHBOUR] = ((trackconfig[TS_NEIGHBOUR] & (TRACK_BIT_HORZ | TRACK_BIT_VERT)) != 0);
 343
 344                 PPPpreferred[i] = 0xFF; // We start with preferring everything (end-of-line in any direction)
 345                 PPPallowed[i] = AllowedPPPonPCP[i];
 346
 347                 /* We cycle through all the existing tracks at a PCP and see what
 348                  * PPPs we want to have, or may not have at all */
 349                 for (uint k = 0; k < NUM_TRACKS_AT_PCP; k++) {
 350                         /* Next to us, we have a bridge head, don't worry about that one, if it shows away from us */
 351                         if (TrackSourceTile[i][k] == TS_NEIGHBOUR &&
 352                             IsBridgeTile(neighbour) &&
 353                             GetTunnelBridgeDirection(neighbour) == ReverseDiagDir(i)) {
 354                                 continue;
 355                         }
 356
 357                         /* We check whether the track in question (k) is present in the tile
 358                          * (TrackSourceTile) */
 359                         DiagDirection PCPpos = i;
 360                         if (HasBit(wireconfig[TrackSourceTile[i][k]], TracksAtPCP[i][k])) {
 361                                 /* track found, if track is in the neighbour tile, adjust the number
 362                                  * of the PCP for preferred/allowed determination*/
 363                                 PCPpos = (TrackSourceTile[i][k] == TS_HOME) ? i : ReverseDiagDir(i);
 364                                 SetBit(PCPstatus, i); // This PCP is in use
 365                                 PPPpreferred[i] &= PreferredPPPofTrackAtPCP[TracksAtPCP[i][k]][PCPpos];
 366                         }
 367
 368                         if (HasBit(trackconfig[TrackSourceTile[i][k]], TracksAtPCP[i][k])) {
 369                                 PPPallowed[i] &= ~DisallowedPPPofTrackAtPCP[TracksAtPCP[i][k]][PCPpos];
 370                         }
 371                 }
 372
 373                 /* Deactivate all PPPs if PCP is not used */
 374                 if (!HasBit(PCPstatus, i)) {
 375                         PPPpreferred[i] = 0;
 376                         PPPallowed[i] = 0;
 377                 }
 378
 379                 Foundation foundation = FOUNDATION_NONE;
 380
 381                 /* Station and road crossings are always "flat", so adjust the tileh accordingly */
 382                 if (IsTileType(neighbour, MP_STATION) || IsTileType(neighbour, MP_ROAD)) tileh[TS_NEIGHBOUR] = SLOPE_FLAT;
 383
 384                 /* Read the foundations if they are present, and adjust the tileh */
 385                 if (trackconfig[TS_NEIGHBOUR] != TRACK_BIT_NONE && IsTileType(neighbour, MP_RAILWAY) && HasRailCatenary(GetRailType(neighbour))) foundation = GetRailFoundation(tileh[TS_NEIGHBOUR], trackconfig[TS_NEIGHBOUR]);
 386                 if (IsBridgeTile(neighbour)) {
 387                         foundation = GetBridgeFoundation(tileh[TS_NEIGHBOUR], DiagDirToAxis(GetTunnelBridgeDirection(neighbour)));
 388                 }
 389
 390                 ApplyFoundationToSlope(foundation, &tileh[TS_NEIGHBOUR]);
 391
 392                 /* Half tile slopes coincide only with horizontal/vertical track.
 393                  * Faking a flat slope results in the correct sprites on positions. */
 394                 if (IsHalftileSlope(tileh[TS_NEIGHBOUR])) tileh[TS_NEIGHBOUR] = SLOPE_FLAT;
 395
 396                 AdjustTileh(neighbour, &tileh[TS_NEIGHBOUR]);
 397
 398                 /* If we have a straight (and level) track, we want a pylon only every 2 tiles
 399                  * Delete the PCP if this is the case.
 400                  * Level means that the slope is the same, or the track is flat */
 401                 if (tileh[TS_HOME] == tileh[TS_NEIGHBOUR] || (isflat[TS_HOME] && isflat[TS_NEIGHBOUR])) {
 402                         for (uint k = 0; k < NUM_IGNORE_GROUPS; k++) {
 403                                 if (PPPpreferred[i] == IgnoredPCP[k][tlg][i]) ClrBit(PCPstatus, i);
 404                         }
 405                 }
 406
 407                 /* Now decide where we draw our pylons. First try the preferred PPPs, but they may not exist.
 408                  * In that case, we try the any of the allowed ones. if they don't exist either, don't draw
 409                  * anything. Note that the preferred PPPs still contain the end-of-line markers.
 410                  * Remove those (simply by ANDing with allowed, since these markers are never allowed) */
 411                 if ((PPPallowed[i] & PPPpreferred[i]) != 0) PPPallowed[i] &= PPPpreferred[i];
 412
 413                 if (IsBridgeAbove(ti->tile)) {
 414                         Track bridgetrack = GetBridgeAxis(ti->tile) == AXIS_X ? TRACK_X : TRACK_Y;
 415                         int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
 416
 417                         if ((height <= GetTileMaxZ(ti->tile) + 1) &&
 418                                         (i == PCPpositions[bridgetrack][0] || i == PCPpositions[bridgetrack][1])) {
 419                                 SetBit(OverridePCP, i);
 420                         }
 421                 }
 422
 423                 if (PPPallowed[i] != 0 && HasBit(PCPstatus, i) && !HasBit(OverridePCP, i) &&
 424                                 (!IsRailStationTile(ti->tile) || CanStationTileHavePylons(ti->tile))) {
 425                         for (Direction k = DIR_BEGIN; k < DIR_END; k++) {
 426                                 byte temp = PPPorder[i][GetTLG(ti->tile)][k];
 427
 428                                 if (HasBit(PPPallowed[i], temp)) {
 429                                         uint x  = ti->x + x_pcp_offsets[i] + x_ppp_offsets[temp];
 430                                         uint y  = ti->y + y_pcp_offsets[i] + y_ppp_offsets[temp];
 431
 432                                         /* Don't build the pylon if it would be outside the tile */
 433                                         if (!HasBit(OwnedPPPonPCP[i], temp)) {
 434                                                 /* We have a neighbour that will draw it, bail out */
 435                                                 if (trackconfig[TS_NEIGHBOUR] != TRACK_BIT_NONE) break;
 436                                                 continue; // No neighbour, go looking for a better position
 437                                         }
 438
 439                                         AddSortableSpriteToDraw(pylon_base + pylon_sprites[temp], PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE,
 440                                                 elevation, IsTransparencySet(TO_CATENARY), -1, -1);
 441
 442                                         break; // We already have drawn a pylon, bail out
 443                                 }
 444                         }
 445                 }
 446         }
 447
 448         /* The wire above the tunnel is drawn together with the tunnel-roof (see DrawRailCatenaryOnTunnel()) */
 449         if (IsTunnelTile(ti->tile)) return;
 450
 451         /* Don't draw a wire under a low bridge */
 452         if (IsBridgeAbove(ti->tile) && !IsTransparencySet(TO_BRIDGES)) {
 453                 int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
 454
 455                 if (height <= GetTileMaxZ(ti->tile) + 1) return;
 456         }
 457
 458         /* Don't draw a wire if the station tile does not want any */
 459         if (IsRailStationTile(ti->tile) && !CanStationTileHaveWires(ti->tile)) return;
 460
 461         SpriteID wire_normal = GetWireBase(ti->tile);
 462         SpriteID wire_halftile = (halftile_corner != CORNER_INVALID) ? GetWireBase(ti->tile, TCX_UPPER_HALFTILE) : wire_normal;
 463         Track halftile_track;
 464         switch (halftile_corner) {
 465                 case CORNER_W: halftile_track = TRACK_LEFT; break;
 466                 case CORNER_S: halftile_track = TRACK_LOWER; break;
 467                 case CORNER_E: halftile_track = TRACK_RIGHT; break;
 468                 case CORNER_N: halftile_track = TRACK_UPPER; break;
 469                 default:       halftile_track = INVALID_TRACK; break;
 470         }
 471
 472         /* Drawing of pylons is finished, now draw the wires */
 473         for (Track t : SetTrackBitIterator(wireconfig[TS_HOME])) {
 474                 SpriteID wire_base = (t == halftile_track) ? wire_halftile : wire_normal;
 475                 byte PCPconfig = HasBit(PCPstatus, PCPpositions[t][0]) +
 476                         (HasBit(PCPstatus, PCPpositions[t][1]) << 1);
 477
 478                 const SortableSpriteStruct *sss;
 479                 int tileh_selector = !(tileh[TS_HOME] % 3) * tileh[TS_HOME] / 3; // tileh for the slopes, 0 otherwise
 480
 481                 assert(PCPconfig != 0); // We have a pylon on neither end of the wire, that doesn't work (since we have no sprites for that)
 482                 assert(!IsSteepSlope(tileh[TS_HOME]));
 483                 sss = &RailCatenarySpriteData[Wires[tileh_selector][t][PCPconfig]];
 484
 485                 /*
 486                  * The "wire"-sprite position is inside the tile, i.e. 0 <= sss->?_offset < TILE_SIZE.
 487                  * Therefore it is safe to use GetSlopePixelZ() for the elevation.
 488                  * Also note that the result of GetSlopePixelZ() is very special for bridge-ramps.
 489                  */
 490                 AddSortableSpriteToDraw(wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 491                         sss->x_size, sss->y_size, sss->z_size, GetSlopePixelZ(ti->x + sss->x_offset, ti->y + sss->y_offset) + sss->z_offset,
 492                         IsTransparencySet(TO_CATENARY));
 493         }
 494 }
 495
 496 /**
 497  * Draws wires on a tunnel tile
 498  *
 499  * DrawTile_TunnelBridge() calls this function to draw the wires on the bridge.
 500  *
 501  * @param ti The Tileinfo to draw the tile for
 502  */
 503 void DrawRailCatenaryOnBridge(const TileInfo *ti)
 504 {
 505         TileIndex end = GetSouthernBridgeEnd(ti->tile);
 506         TileIndex start = GetOtherBridgeEnd(end);
 507
 508         uint length = GetTunnelBridgeLength(start, end);
 509         uint num = GetTunnelBridgeLength(ti->tile, start) + 1;
 510         uint height;
 511
 512         const SortableSpriteStruct *sss;
 513         Axis axis = GetBridgeAxis(ti->tile);
 514         TLG tlg = GetTLG(ti->tile);
 515
 516         RailCatenarySprite offset = (RailCatenarySprite)(axis == AXIS_X ? 0 : WIRE_Y_FLAT_BOTH - WIRE_X_FLAT_BOTH);
 517
 518         if ((length % 2) && num == length) {
 519                 /* Draw the "short" wire on the southern end of the bridge
 520                  * only needed if the length of the bridge is odd */
 521                 sss = &RailCatenarySpriteData[WIRE_X_FLAT_BOTH + offset];
 522         } else {
 523                 /* Draw "long" wires on all other tiles of the bridge (one pylon every two tiles) */
 524                 sss = &RailCatenarySpriteData[WIRE_X_FLAT_SW + (num % 2) + offset];
 525         }
 526
 527         height = GetBridgePixelHeight(end);
 528
 529         SpriteID wire_base = GetWireBase(end, TCX_ON_BRIDGE);
 530
 531         AddSortableSpriteToDraw(wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 532                 sss->x_size, sss->y_size, sss->z_size, height + sss->z_offset,
 533                 IsTransparencySet(TO_CATENARY)
 534         );
 535
 536         SpriteID pylon_base = GetPylonBase(end, TCX_ON_BRIDGE);
 537
 538         /* Finished with wires, draw pylons
 539          * every other tile needs a pylon on the northern end */
 540         if (num % 2) {
 541                 DiagDirection PCPpos = (axis == AXIS_X ? DIAGDIR_NE : DIAGDIR_NW);
 542                 Direction PPPpos = (axis == AXIS_X ? DIR_NW : DIR_NE);
 543                 if (HasBit(tlg, (axis == AXIS_X ? 0 : 1))) PPPpos = ReverseDir(PPPpos);
 544                 uint x = ti->x + x_pcp_offsets[PCPpos] + x_ppp_offsets[PPPpos];
 545                 uint y = ti->y + y_pcp_offsets[PCPpos] + y_ppp_offsets[PPPpos];
 546                 AddSortableSpriteToDraw(pylon_base + pylon_sprites[PPPpos], PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, height, IsTransparencySet(TO_CATENARY), -1, -1);
 547         }
 548
 549         /* need a pylon on the southern end of the bridge */
 550         if (GetTunnelBridgeLength(ti->tile, start) + 1 == length) {
 551                 DiagDirection PCPpos = (axis == AXIS_X ? DIAGDIR_SW : DIAGDIR_SE);
 552                 Direction PPPpos = (axis == AXIS_X ? DIR_NW : DIR_NE);
 553                 if (HasBit(tlg, (axis == AXIS_X ? 0 : 1))) PPPpos = ReverseDir(PPPpos);
 554                 uint x = ti->x + x_pcp_offsets[PCPpos] + x_ppp_offsets[PPPpos];
 555                 uint y = ti->y + y_pcp_offsets[PCPpos] + y_ppp_offsets[PPPpos];
 556                 AddSortableSpriteToDraw(pylon_base + pylon_sprites[PPPpos], PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, height, IsTransparencySet(TO_CATENARY), -1, -1);
 557         }
 558 }
 559
 560 /**
 561  * Draws overhead wires and pylons for electric railways.
 562  * @param ti The TileInfo struct of the tile being drawn
 563  * @see DrawRailCatenaryRailway
 564  */
 565 void DrawRailCatenary(const TileInfo *ti)
 566 {
 567         switch (GetTileType(ti->tile)) {
 568                 case MP_RAILWAY:
 569                         if (IsRailDepot(ti->tile)) {
 570                                 const SortableSpriteStruct *sss = &RailCatenarySpriteData_Depot[GetRailDepotDirection(ti->tile)];
 571
 572                                 SpriteID wire_base = GetWireBase(ti->tile);
 573
 574                                 /* This wire is not visible with the default depot sprites */
 575                                 AddSortableSpriteToDraw(
 576                                         wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 577                                         sss->x_size, sss->y_size, sss->z_size,
 578                                         GetTileMaxPixelZ(ti->tile) + sss->z_offset,
 579                                         IsTransparencySet(TO_CATENARY)
 580                                 );
 581                                 return;
 582                         }
 583                         break;
 584
 585                 case MP_TUNNELBRIDGE:
 586                 case MP_ROAD:
 587                 case MP_STATION:
 588                         break;
 589
 590                 default: return;
 591         }
 592         DrawRailCatenaryRailway(ti);
 593 }
 594
 595 void SettingsDisableElrail(int32 new_value)
 596 {
 597         bool disable = (new_value != 0);
 598
 599         /* we will now walk through all electric train engines and change their railtypes if it is the wrong one*/
 600         const RailType old_railtype = disable ? RAILTYPE_ELECTRIC : RAILTYPE_RAIL;
 601         const RailType new_railtype = disable ? RAILTYPE_RAIL : RAILTYPE_ELECTRIC;
 602
 603         /* walk through all train engines */
 604         for (Engine *e : Engine::IterateType(VEH_TRAIN)) {
 605                 RailVehicleInfo *rv_info = &e->u.rail;
 606                 /* if it is an electric rail engine and its railtype is the wrong one */
 607                 if (rv_info->engclass == 2 && rv_info->railtype == old_railtype) {
 608                         /* change it to the proper one */
 609                         rv_info->railtype = new_railtype;
 610                 }
 611         }
 612
 613         /* when disabling elrails, make sure that all existing trains can run on
 614          *  normal rail too */
 615         if (disable) {
 616                 for (Train *t : Train::Iterate()) {
 617                         if (t->railtype == RAILTYPE_ELECTRIC) {
 618                                 /* this railroad vehicle is now compatible only with elrail,
 619                                  *  so add there also normal rail compatibility */
 620                                 t->compatible_railtypes |= RAILTYPES_RAIL;
 621                                 t->railtype = RAILTYPE_RAIL;
 622                                 SetBit(t->flags, VRF_EL_ENGINE_ALLOWED_NORMAL_RAIL);
 623                         }
 624                 }
 625         }
 626
 627         /* Fix the total power and acceleration for trains */
 628         for (Train *t : Train::Iterate()) {
 629                 /* power and acceleration is cached only for front engines */
 630                 if (t->IsFrontEngine()) {
 631                         t->ConsistChanged(CCF_TRACK);
 632                 }
 633         }
 634
 635         for (Company *c : Company::Iterate()) c->avail_railtypes = GetCompanyRailtypes(c->index);
 636
 637         /* This resets the _last_built_railtype, which will be invalid for electric
 638          * rails. It may have unintended consequences if that function is ever
 639          * extended, though. */
 640         ReinitGuiAfterToggleElrail(disable);
 641 }