src/elrail.cpp

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /**
  11  * @file elrail.cpp
  12  * This file deals with displaying wires and pylons for electric railways.
  13  * <h2>Basics</h2>
  14  *
  15  * <h3>Tile Types</h3>
  16  *
  17  * We have two different types of tiles in the drawing code:
  18  * Normal Railway Tiles (NRTs) which can have more than one track on it, and
  19  * Special Railways tiles (SRTs) which have only one track (like crossings, depots
  20  * stations, etc).
  21  *
  22  * <h3>Location Categories</h3>
  23  *
  24  * All tiles are categorized into three location groups (TLG):
  25  * Group 0: Tiles with both an even X coordinate and an even Y coordinate
  26  * Group 1: Tiles with an even X and an odd Y coordinate
  27  * Group 2: Tiles with an odd X and an even Y coordinate
  28  * Group 3: Tiles with both an odd X and Y coordinate.
  29  *
  30  * <h3>Pylon Points</h3>
  31  * <h4>Control Points</h4>
  32  * A Pylon Control Point (PCP) is a position where a wire (or rather two)
  33  * is mounted onto a pylon.
  34  * Each NRT does contain 4 PCPs which are bitmapped to a byte
  35  * variable and are represented by the DiagDirection enum
  36  *
  37  * Each track ends on two PCPs and thus requires one pylon on each end. However,
  38  * there is one exception: Straight-and-level tracks only have one pylon every
  39  * other tile.
  40  *
  41  * Now on each edge there are two PCPs: One from each adjacent tile. Both PCPs
  42  * are merged using an OR operation (i. e. if one tile needs a PCP at the position
  43  * in question, both tiles get it).
  44  *
  45  * <h4>Position Points</h4>
  46  * A Pylon Position Point (PPP) is a position where a pylon is located on the
  47  * ground.  Each PCP owns 8 in (45 degree steps) PPPs that are located around
  48  * it. PPPs are represented using the Direction enum. Each track bit has PPPs
  49  * that are impossible (because the pylon would be situated on the track) and
  50  * some that are preferred (because the pylon would be rectangular to the track).
  51  *
  52  * @image html elrail_tile.png
  53  * @image html elrail_track.png
  54  *
  55  */
  56
  57 #include "stdafx.h"
  58 #include "station_map.h"
  59 #include "viewport_func.h"
  60 #include "train.h"
  61 #include "rail_gui.h"
  62 #include "tunnelbridge_map.h"
  63 #include "tunnelbridge.h"
  64 #include "elrail_func.h"
  65 #include "company_base.h"
  66 #include "newgrf_railtype.h"
  67
  68 #include "table/elrail_data.h"
  69
  70 #include "safeguards.h"
  71
  72 /**
  73  * Get the tile location group of a tile.
  74  * @param t The tile to get the tile location group of.
  75  * @return The tile location group.
  76  */
  77 static inline TLG GetTLG(TileIndex t)
  78 {
  79         return (TLG)((HasBit(TileX(t), 0) << 1) + HasBit(TileY(t), 0));
  80 }
  81
  82 /**
  83  * Finds which Electrified Rail Bits are present on a given tile.
  84  * @param t tile to check
  85  * @param override pointer to PCP override, can be NULL
  86  * @return trackbits of tile if it is electrified
  87  */
  88 static TrackBits GetRailTrackBitsUniversal(TileIndex t, byte *override)
  89 {
  90         switch (GetTileType(t)) {
  91                 case MP_RAILWAY:
  92                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
  93                         switch (GetRailTileType(t)) {
  94                                 case RAIL_TILE_NORMAL: case RAIL_TILE_SIGNALS:
  95                                         return GetTrackBits(t);
  96                                 default:
  97                                         return TRACK_BIT_NONE;
  98                         }
  99                         break;
 100
 101                 case MP_TUNNELBRIDGE:
 102                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
 103                         if (override != NULL && (IsTunnel(t) || GetTunnelBridgeLength(t, GetOtherBridgeEnd(t)) > 0)) {
 104                                 *override = 1 << GetTunnelBridgeDirection(t);
 105                         }
 106                         return DiagDirToDiagTrackBits(GetTunnelBridgeDirection(t));
 107
 108                 case MP_ROAD:
 109                         if (!IsLevelCrossing(t)) return TRACK_BIT_NONE;
 110                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
 111                         return GetCrossingRailBits(t);
 112
 113                 case MP_STATION:
 114                         if (!HasStationRail(t)) return TRACK_BIT_NONE;
 115                         if (!HasRailCatenary(GetRailType(t))) return TRACK_BIT_NONE;
 116                         return TrackToTrackBits(GetRailStationTrack(t));
 117
 118                 default:
 119                         return TRACK_BIT_NONE;
 120         }
 121 }
 122
 123 /**
 124  * Masks out track bits when neighbouring tiles are unelectrified.
 125  */
 126 static TrackBits MaskWireBits(TileIndex t, TrackBits tracks)
 127 {
 128         if (!IsPlainRailTile(t)) return tracks;
 129
 130         TrackdirBits neighbour_tdb = TRACKDIR_BIT_NONE;
 131         for (DiagDirection d = DIAGDIR_BEGIN; d < DIAGDIR_END; d++) {
 132                 /* If the neighbour tile is either not electrified or has no tracks that can be reached
 133                  * from this tile, mark all trackdirs that can be reached from the neighbour tile
 134                  * as needing no catenary. We make an exception for blocked station tiles with a matching
 135                  * axis that still display wires to preserve visual continuity. */
 136                 TileIndex next_tile = TileAddByDiagDir(t, d);
 137                 RailType rt = GetTileRailType(next_tile);
 138                 if (rt == INVALID_RAILTYPE || !HasRailCatenary(rt) ||
 139                                 ((TrackStatusToTrackBits(GetTileTrackStatus(next_tile, TRANSPORT_RAIL, 0)) & DiagdirReachesTracks(d)) == TRACK_BIT_NONE &&
 140                                 (!HasStationTileRail(next_tile) || GetRailStationAxis(next_tile) != DiagDirToAxis(d) || !CanStationTileHaveWires(next_tile)))) {
 141                         neighbour_tdb |= DiagdirReachesTrackdirs(ReverseDiagDir(d));
 142                 }
 143         }
 144
 145         /* If the tracks from either a diagonal crossing or don't overlap, both
 146          * trackdirs have to be marked to mask the corresponding track bit. Else
 147          * one marked trackdir is enough the mask the track bit. */
 148         TrackBits mask;
 149         if (tracks == TRACK_BIT_CROSS || !TracksOverlap(tracks)) {
 150                 /* If the tracks form either a diagonal crossing or don't overlap, both
 151                  * trackdirs have to be marked to mask the corresponding track bit. */
 152                 mask = ~(TrackBits)((neighbour_tdb & (neighbour_tdb >> 8)) & TRACK_BIT_MASK);
 153                 /* If that results in no masked tracks and it is not a diagonal crossing,
 154                  * require only one marked trackdir to mask. */
 155                 if (tracks != TRACK_BIT_CROSS && (mask & TRACK_BIT_MASK) == TRACK_BIT_MASK) mask = ~TrackdirBitsToTrackBits(neighbour_tdb);
 156         } else {
 157                 /* Require only one marked trackdir to mask the track. */
 158                 mask = ~TrackdirBitsToTrackBits(neighbour_tdb);
 159                 /* If that results in an empty set, require both trackdirs for diagonal track. */
 160                 if ((tracks & mask) == TRACK_BIT_NONE) {
 161                         if ((neighbour_tdb & TRACKDIR_BIT_X_NE) == 0 || (neighbour_tdb & TRACKDIR_BIT_X_SW) == 0) mask |= TRACK_BIT_X;
 162                         if ((neighbour_tdb & TRACKDIR_BIT_Y_NW) == 0 || (neighbour_tdb & TRACKDIR_BIT_Y_SE) == 0) mask |= TRACK_BIT_Y;
 163                         /* If that still is not enough, require both trackdirs for any track. */
 164                         if ((tracks & mask) == TRACK_BIT_NONE) mask = ~(TrackBits)((neighbour_tdb & (neighbour_tdb >> 8)) & TRACK_BIT_MASK);
 165                 }
 166         }
 167
 168         /* Mask the tracks only if at least one track bit would remain. */
 169         return (tracks & mask) != TRACK_BIT_NONE ? tracks & mask : tracks;
 170 }
 171
 172 /**
 173  * Get the base wire sprite to use.
 174  */
 175 static inline SpriteID GetWireBase(TileIndex tile, TileContext context = TCX_NORMAL)
 176 {
 177         const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
 178         SpriteID wires = GetCustomRailSprite(rti, tile, RTSG_WIRES, context);
 179         return wires == 0 ? SPR_WIRE_BASE : wires;
 180 }
 181
 182 /**
 183  * Get the base pylon sprite to use.
 184  */
 185 static inline SpriteID GetPylonBase(TileIndex tile, TileContext context = TCX_NORMAL)
 186 {
 187         const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
 188         SpriteID pylons = GetCustomRailSprite(rti, tile, RTSG_PYLONS, context);
 189         return pylons == 0 ? SPR_PYLON_BASE : pylons;
 190 }
 191
 192 /**
 193  * Corrects the tileh for certain tile types. Returns an effective tileh for the track on the tile.
 194  * @param tile The tile to analyse
 195  * @param *tileh the tileh
 196  */
 197 static void AdjustTileh(TileIndex tile, Slope *tileh)
 198 {
 199         if (IsTileType(tile, MP_TUNNELBRIDGE)) {
 200                 if (IsTunnel(tile)) {
 201                         *tileh = SLOPE_STEEP; // XXX - Hack to make tunnel entrances to always have a pylon
 202                 } else if (*tileh != SLOPE_FLAT) {
 203                         *tileh = SLOPE_FLAT;
 204                 } else {
 205                         *tileh = InclinedSlope(GetTunnelBridgeDirection(tile));
 206                 }
 207         }
 208 }
 209
 210 /**
 211  * Returns the Z position of a Pylon Control Point.
 212  *
 213  * @param tile The tile the pylon should stand on.
 214  * @param PCPpos The PCP of the tile.
 215  * @return The Z position of the PCP.
 216  */
 217 static int GetPCPElevation(TileIndex tile, DiagDirection PCPpos)
 218 {
 219         /* The elevation of the "pylon"-sprite should be the elevation at the PCP.
 220          * PCPs are always on a tile edge.
 221          *
 222          * This position can be outside of the tile, i.e. ?_pcp_offset == TILE_SIZE > TILE_SIZE - 1.
 223          * So we have to move it inside the tile, because if the neighboured tile has a foundation,
 224          * that does not smoothly connect to the current tile, we will get a wrong elevation from GetSlopePixelZ().
 225          *
 226          * When we move the position inside the tile, we will get a wrong elevation if we have a slope.
 227          * To catch all cases we round the Z position to the next (TILE_HEIGHT / 2).
 228          * This will return the correct elevation for slopes and will also detect non-continuous elevation on edges.
 229          *
 230          * Also note that the result of GetSlopePixelZ() is very special on bridge-ramps.
 231          */
 232
 233         int z = GetSlopePixelZ(TileX(tile) * TILE_SIZE + min(x_pcp_offsets[PCPpos], TILE_SIZE - 1), TileY(tile) * TILE_SIZE + min(y_pcp_offsets[PCPpos], TILE_SIZE - 1));
 234         return (z + 2) & ~3; // this means z = (z + TILE_HEIGHT / 4) / (TILE_HEIGHT / 2) * (TILE_HEIGHT / 2);
 235 }
 236
 237 /**
 238  * Draws wires on a tunnel tile
 239  *
 240  * DrawTile_TunnelBridge() calls this function to draw the wires as SpriteCombine with the tunnel roof.
 241  *
 242  * @param ti The Tileinfo to draw the tile for
 243  */
 244 void DrawRailCatenaryOnTunnel(const TileInfo *ti)
 245 {
 246         /* xmin, ymin, xmax + 1, ymax + 1 of BB */
 247         static const int _tunnel_wire_BB[4][4] = {
 248                 { 0, 1, 16, 15 }, // NE
 249                 { 1, 0, 15, 16 }, // SE
 250                 { 0, 1, 16, 15 }, // SW
 251                 { 1, 0, 15, 16 }, // NW
 252         };
 253
 254         DiagDirection dir = GetTunnelBridgeDirection(ti->tile);
 255
 256         SpriteID wire_base = GetWireBase(ti->tile);
 257
 258         const SortableSpriteStruct *sss = &RailCatenarySpriteData_Tunnel[dir];
 259         const int *BB_data = _tunnel_wire_BB[dir];
 260         AddSortableSpriteToDraw(
 261                 wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 262                 BB_data[2] - sss->x_offset, BB_data[3] - sss->y_offset, BB_Z_SEPARATOR - sss->z_offset + 1,
 263                 GetTilePixelZ(ti->tile) + sss->z_offset,
 264                 IsTransparencySet(TO_CATENARY),
 265                 BB_data[0] - sss->x_offset, BB_data[1] - sss->y_offset, BB_Z_SEPARATOR - sss->z_offset
 266         );
 267 }
 268
 269 /**
 270  * Draws wires and, if required, pylons on a given tile
 271  * @param ti The Tileinfo to draw the tile for
 272  */
 273 static void DrawRailCatenaryRailway(const TileInfo *ti)
 274 {
 275         /* Pylons are placed on a tile edge, so we need to take into account
 276          * the track configuration of 2 adjacent tiles. trackconfig[0] stores the
 277          * current tile (home tile) while [1] holds the neighbour */
 278         TrackBits trackconfig[TS_END];
 279         TrackBits wireconfig[TS_END];
 280         bool isflat[TS_END];
 281         /* Note that ti->tileh has already been adjusted for Foundations */
 282         Slope tileh[TS_END] = { ti->tileh, SLOPE_FLAT };
 283
 284         /* Half tile slopes coincide only with horizontal/vertical track.
 285          * Faking a flat slope results in the correct sprites on positions. */
 286         Corner halftile_corner = CORNER_INVALID;
 287         if (IsHalftileSlope(tileh[TS_HOME])) {
 288                 halftile_corner = GetHalftileSlopeCorner(tileh[TS_HOME]);
 289                 tileh[TS_HOME] = SLOPE_FLAT;
 290         }
 291
 292         TLG tlg = GetTLG(ti->tile);
 293         byte PCPstatus = 0;
 294         byte OverridePCP = 0;
 295         byte PPPpreferred[DIAGDIR_END];
 296         byte PPPallowed[DIAGDIR_END];
 297
 298         /* Find which rail bits are present, and select the override points.
 299          * We don't draw a pylon:
 300          * 1) INSIDE a tunnel (we wouldn't see it anyway)
 301          * 2) on the "far" end of a bridge head (the one that connects to bridge middle),
 302          *    because that one is drawn on the bridge. Exception is for length 0 bridges
 303          *    which have no middle tiles */
 304         trackconfig[TS_HOME] = GetRailTrackBitsUniversal(ti->tile, &OverridePCP);
 305         wireconfig[TS_HOME] = MaskWireBits(ti->tile, trackconfig[TS_HOME]);
 306         /* If a track bit is present that is not in the main direction, the track is level */
 307         isflat[TS_HOME] = ((trackconfig[TS_HOME] & (TRACK_BIT_HORZ | TRACK_BIT_VERT)) != 0);
 308
 309         AdjustTileh(ti->tile, &tileh[TS_HOME]);
 310
 311         SpriteID pylon_normal = GetPylonBase(ti->tile);
 312         SpriteID pylon_halftile = (halftile_corner != CORNER_INVALID) ? GetPylonBase(ti->tile, TCX_UPPER_HALFTILE) : pylon_normal;
 313
 314         for (DiagDirection i = DIAGDIR_BEGIN; i < DIAGDIR_END; i++) {
 315                 static const uint edge_corners[] = {
 316                         1 << CORNER_N | 1 << CORNER_E, // DIAGDIR_NE
 317                         1 << CORNER_S | 1 << CORNER_E, // DIAGDIR_SE
 318                         1 << CORNER_S | 1 << CORNER_W, // DIAGDIR_SW
 319                         1 << CORNER_N | 1 << CORNER_W, // DIAGDIR_NW
 320                 };
 321                 SpriteID pylon_base = (halftile_corner != CORNER_INVALID && HasBit(edge_corners[i], halftile_corner)) ? pylon_halftile : pylon_normal;
 322                 TileIndex neighbour = ti->tile + TileOffsByDiagDir(i);
 323                 int elevation = GetPCPElevation(ti->tile, i);
 324
 325                 /* Here's one of the main headaches. GetTileSlope does not correct for possibly
 326                  * existing foundataions, so we do have to do that manually later on.*/
 327                 tileh[TS_NEIGHBOUR] = GetTileSlope(neighbour);
 328                 trackconfig[TS_NEIGHBOUR] = GetRailTrackBitsUniversal(neighbour, NULL);
 329                 wireconfig[TS_NEIGHBOUR] = MaskWireBits(neighbour, trackconfig[TS_NEIGHBOUR]);
 330                 if (IsTunnelTile(neighbour) && i != GetTunnelBridgeDirection(neighbour)) wireconfig[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] = TRACK_BIT_NONE;
 331
 332                 /* Ignore station tiles that allow neither wires nor pylons. */
 333                 if (IsRailStationTile(neighbour) && !CanStationTileHavePylons(neighbour) && !CanStationTileHaveWires(neighbour)) wireconfig[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] = TRACK_BIT_NONE;
 334
 335                 /* If the neighboured tile does not smoothly connect to the current tile (because of a foundation),
 336                  * we have to draw all pillars on the current tile. */
 337                 if (elevation != GetPCPElevation(neighbour, ReverseDiagDir(i))) wireconfig[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] = TRACK_BIT_NONE;
 338
 339                 isflat[TS_NEIGHBOUR] = ((trackconfig[TS_NEIGHBOUR] & (TRACK_BIT_HORZ | TRACK_BIT_VERT)) != 0);
 340
 341                 PPPpreferred[i] = 0xFF; // We start with preferring everything (end-of-line in any direction)
 342                 PPPallowed[i] = AllowedPPPonPCP[i];
 343
 344                 /* We cycle through all the existing tracks at a PCP and see what
 345                  * PPPs we want to have, or may not have at all */
 346                 for (uint k = 0; k < NUM_TRACKS_AT_PCP; k++) {
 347                         /* Next to us, we have a bridge head, don't worry about that one, if it shows away from us */
 348                         if (TrackSourceTile[i][k] == TS_NEIGHBOUR &&
 349                             IsBridgeTile(neighbour) &&
 350                             GetTunnelBridgeDirection(neighbour) == ReverseDiagDir(i)) {
 351                                 continue;
 352                         }
 353
 354                         /* We check whether the track in question (k) is present in the tile
 355                          * (TrackSourceTile) */
 356                         DiagDirection PCPpos = i;
 357                         if (HasBit(wireconfig[TrackSourceTile[i][k]], TracksAtPCP[i][k])) {
 358                                 /* track found, if track is in the neighbour tile, adjust the number
 359                                  * of the PCP for preferred/allowed determination*/
 360                                 PCPpos = (TrackSourceTile[i][k] == TS_HOME) ? i : ReverseDiagDir(i);
 361                                 SetBit(PCPstatus, i); // This PCP is in use
 362                                 PPPpreferred[i] &= PreferredPPPofTrackAtPCP[TracksAtPCP[i][k]][PCPpos];
 363                         }
 364
 365                         if (HasBit(trackconfig[TrackSourceTile[i][k]], TracksAtPCP[i][k])) {
 366                                 PPPallowed[i] &= ~DisallowedPPPofTrackAtPCP[TracksAtPCP[i][k]][PCPpos];
 367                         }
 368                 }
 369
 370                 /* Deactivate all PPPs if PCP is not used */
 371                 if (!HasBit(PCPstatus, i)) {
 372                         PPPpreferred[i] = 0;
 373                         PPPallowed[i] = 0;
 374                 }
 375
 376                 Foundation foundation = FOUNDATION_NONE;
 377
 378                 /* Station and road crossings are always "flat", so adjust the tileh accordingly */
 379                 if (IsTileType(neighbour, MP_STATION) || IsTileType(neighbour, MP_ROAD)) tileh[TS_NEIGHBOUR] = SLOPE_FLAT;
 380
 381                 /* Read the foundations if they are present, and adjust the tileh */
 382                 if (trackconfig[TS_NEIGHBOUR] != TRACK_BIT_NONE && IsTileType(neighbour, MP_RAILWAY) && HasRailCatenary(GetRailType(neighbour))) foundation = GetRailFoundation(tileh[TS_NEIGHBOUR], trackconfig[TS_NEIGHBOUR]);
 383                 if (IsBridgeTile(neighbour)) {
 384                         foundation = GetBridgeFoundation(tileh[TS_NEIGHBOUR], DiagDirToAxis(GetTunnelBridgeDirection(neighbour)));
 385                 }
 386
 387                 ApplyFoundationToSlope(foundation, &tileh[TS_NEIGHBOUR]);
 388
 389                 /* Half tile slopes coincide only with horizontal/vertical track.
 390                  * Faking a flat slope results in the correct sprites on positions. */
 391                 if (IsHalftileSlope(tileh[TS_NEIGHBOUR])) tileh[TS_NEIGHBOUR] = SLOPE_FLAT;
 392
 393                 AdjustTileh(neighbour, &tileh[TS_NEIGHBOUR]);
 394
 395                 /* If we have a straight (and level) track, we want a pylon only every 2 tiles
 396                  * Delete the PCP if this is the case.
 397                  * Level means that the slope is the same, or the track is flat */
 398                 if (tileh[TS_HOME] == tileh[TS_NEIGHBOUR] || (isflat[TS_HOME] && isflat[TS_NEIGHBOUR])) {
 399                         for (uint k = 0; k < NUM_IGNORE_GROUPS; k++) {
 400                                 if (PPPpreferred[i] == IgnoredPCP[k][tlg][i]) ClrBit(PCPstatus, i);
 401                         }
 402                 }
 403
 404                 /* Now decide where we draw our pylons. First try the preferred PPPs, but they may not exist.
 405                  * In that case, we try the any of the allowed ones. if they don't exist either, don't draw
 406                  * anything. Note that the preferred PPPs still contain the end-of-line markers.
 407                  * Remove those (simply by ANDing with allowed, since these markers are never allowed) */
 408                 if ((PPPallowed[i] & PPPpreferred[i]) != 0) PPPallowed[i] &= PPPpreferred[i];
 409
 410                 if (IsBridgeAbove(ti->tile)) {
 411                         Track bridgetrack = GetBridgeAxis(ti->tile) == AXIS_X ? TRACK_X : TRACK_Y;
 412                         int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
 413
 414                         if ((height <= GetTileMaxZ(ti->tile) + 1) &&
 415                                         (i == PCPpositions[bridgetrack][0] || i == PCPpositions[bridgetrack][1])) {
 416                                 SetBit(OverridePCP, i);
 417                         }
 418                 }
 419
 420                 if (PPPallowed[i] != 0 && HasBit(PCPstatus, i) && !HasBit(OverridePCP, i) &&
 421                                 (!IsRailStationTile(ti->tile) || CanStationTileHavePylons(ti->tile))) {
 422                         for (Direction k = DIR_BEGIN; k < DIR_END; k++) {
 423                                 byte temp = PPPorder[i][GetTLG(ti->tile)][k];
 424
 425                                 if (HasBit(PPPallowed[i], temp)) {
 426                                         uint x  = ti->x + x_pcp_offsets[i] + x_ppp_offsets[temp];
 427                                         uint y  = ti->y + y_pcp_offsets[i] + y_ppp_offsets[temp];
 428
 429                                         /* Don't build the pylon if it would be outside the tile */
 430                                         if (!HasBit(OwnedPPPonPCP[i], temp)) {
 431                                                 /* We have a neighbour that will draw it, bail out */
 432                                                 if (trackconfig[TS_NEIGHBOUR] != TRACK_BIT_NONE) break;
 433                                                 continue; // No neighbour, go looking for a better position
 434                                         }
 435
 436                                         AddSortableSpriteToDraw(pylon_base + pylon_sprites[temp], PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE,
 437                                                 elevation, IsTransparencySet(TO_CATENARY), -1, -1);
 438
 439                                         break; // We already have drawn a pylon, bail out
 440                                 }
 441                         }
 442                 }
 443         }
 444
 445         /* The wire above the tunnel is drawn together with the tunnel-roof (see DrawRailCatenaryOnTunnel()) */
 446         if (IsTunnelTile(ti->tile)) return;
 447
 448         /* Don't draw a wire under a low bridge */
 449         if (IsBridgeAbove(ti->tile) && !IsTransparencySet(TO_BRIDGES)) {
 450                 int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
 451
 452                 if (height <= GetTileMaxZ(ti->tile) + 1) return;
 453         }
 454
 455         /* Don't draw a wire if the station tile does not want any */
 456         if (IsRailStationTile(ti->tile) && !CanStationTileHaveWires(ti->tile)) return;
 457
 458         SpriteID wire_normal = GetWireBase(ti->tile);
 459         SpriteID wire_halftile = (halftile_corner != CORNER_INVALID) ? GetWireBase(ti->tile, TCX_UPPER_HALFTILE) : wire_normal;
 460         Track halftile_track;
 461         switch (halftile_corner) {
 462                 case CORNER_W: halftile_track = TRACK_LEFT; break;
 463                 case CORNER_S: halftile_track = TRACK_LOWER; break;
 464                 case CORNER_E: halftile_track = TRACK_RIGHT; break;
 465                 case CORNER_N: halftile_track = TRACK_UPPER; break;
 466                 default:       halftile_track = INVALID_TRACK; break;
 467         }
 468
 469         /* Drawing of pylons is finished, now draw the wires */
 470         Track t;
 471         FOR_EACH_SET_TRACK(t, wireconfig[TS_HOME]) {
 472                 SpriteID wire_base = (t == halftile_track) ? wire_halftile : wire_normal;
 473                 byte PCPconfig = HasBit(PCPstatus, PCPpositions[t][0]) +
 474                         (HasBit(PCPstatus, PCPpositions[t][1]) << 1);
 475
 476                 const SortableSpriteStruct *sss;
 477                 int tileh_selector = !(tileh[TS_HOME] % 3) * tileh[TS_HOME] / 3; // tileh for the slopes, 0 otherwise
 478
 479                 assert(PCPconfig != 0); // We have a pylon on neither end of the wire, that doesn't work (since we have no sprites for that)
 480                 assert(!IsSteepSlope(tileh[TS_HOME]));
 481                 sss = &RailCatenarySpriteData[Wires[tileh_selector][t][PCPconfig]];
 482
 483                 /*
 484                  * The "wire"-sprite position is inside the tile, i.e. 0 <= sss->?_offset < TILE_SIZE.
 485                  * Therefore it is safe to use GetSlopePixelZ() for the elevation.
 486                  * Also note that the result of GetSlopePixelZ() is very special for bridge-ramps.
 487                  */
 488                 AddSortableSpriteToDraw(wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 489                         sss->x_size, sss->y_size, sss->z_size, GetSlopePixelZ(ti->x + sss->x_offset, ti->y + sss->y_offset) + sss->z_offset,
 490                         IsTransparencySet(TO_CATENARY));
 491         }
 492 }
 493
 494 /**
 495  * Draws wires on a tunnel tile
 496  *
 497  * DrawTile_TunnelBridge() calls this function to draw the wires on the bridge.
 498  *
 499  * @param ti The Tileinfo to draw the tile for
 500  */
 501 void DrawRailCatenaryOnBridge(const TileInfo *ti)
 502 {
 503         TileIndex end = GetSouthernBridgeEnd(ti->tile);
 504         TileIndex start = GetOtherBridgeEnd(end);
 505
 506         uint length = GetTunnelBridgeLength(start, end);
 507         uint num = GetTunnelBridgeLength(ti->tile, start) + 1;
 508         uint height;
 509
 510         const SortableSpriteStruct *sss;
 511         Axis axis = GetBridgeAxis(ti->tile);
 512         TLG tlg = GetTLG(ti->tile);
 513
 514         RailCatenarySprite offset = (RailCatenarySprite)(axis == AXIS_X ? 0 : WIRE_Y_FLAT_BOTH - WIRE_X_FLAT_BOTH);
 515
 516         if ((length % 2) && num == length) {
 517                 /* Draw the "short" wire on the southern end of the bridge
 518                  * only needed if the length of the bridge is odd */
 519                 sss = &RailCatenarySpriteData[WIRE_X_FLAT_BOTH + offset];
 520         } else {
 521                 /* Draw "long" wires on all other tiles of the bridge (one pylon every two tiles) */
 522                 sss = &RailCatenarySpriteData[WIRE_X_FLAT_SW + (num % 2) + offset];
 523         }
 524
 525         height = GetBridgePixelHeight(end);
 526
 527         SpriteID wire_base = GetWireBase(end, TCX_ON_BRIDGE);
 528
 529         AddSortableSpriteToDraw(wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 530                 sss->x_size, sss->y_size, sss->z_size, height + sss->z_offset,
 531                 IsTransparencySet(TO_CATENARY)
 532         );
 533
 534         SpriteID pylon_base = GetPylonBase(end, TCX_ON_BRIDGE);
 535
 536         /* Finished with wires, draw pylons
 537          * every other tile needs a pylon on the northern end */
 538         if (num % 2) {
 539                 DiagDirection PCPpos = (axis == AXIS_X ? DIAGDIR_NE : DIAGDIR_NW);
 540                 Direction PPPpos = (axis == AXIS_X ? DIR_NW : DIR_NE);
 541                 if (HasBit(tlg, (axis == AXIS_X ? 0 : 1))) PPPpos = ReverseDir(PPPpos);
 542                 uint x = ti->x + x_pcp_offsets[PCPpos] + x_ppp_offsets[PPPpos];
 543                 uint y = ti->y + y_pcp_offsets[PCPpos] + y_ppp_offsets[PPPpos];
 544                 AddSortableSpriteToDraw(pylon_base + pylon_sprites[PPPpos], PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, height, IsTransparencySet(TO_CATENARY), -1, -1);
 545         }
 546
 547         /* need a pylon on the southern end of the bridge */
 548         if (GetTunnelBridgeLength(ti->tile, start) + 1 == length) {
 549                 DiagDirection PCPpos = (axis == AXIS_X ? DIAGDIR_SW : DIAGDIR_SE);
 550                 Direction PPPpos = (axis == AXIS_X ? DIR_NW : DIR_NE);
 551                 if (HasBit(tlg, (axis == AXIS_X ? 0 : 1))) PPPpos = ReverseDir(PPPpos);
 552                 uint x = ti->x + x_pcp_offsets[PCPpos] + x_ppp_offsets[PPPpos];
 553                 uint y = ti->y + y_pcp_offsets[PCPpos] + y_ppp_offsets[PPPpos];
 554                 AddSortableSpriteToDraw(pylon_base + pylon_sprites[PPPpos], PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, height, IsTransparencySet(TO_CATENARY), -1, -1);
 555         }
 556 }
 557
 558 /**
 559  * Draws overhead wires and pylons for electric railways.
 560  * @param ti The TileInfo struct of the tile being drawn
 561  * @see DrawRailCatenaryRailway
 562  */
 563 void DrawRailCatenary(const TileInfo *ti)
 564 {
 565         switch (GetTileType(ti->tile)) {
 566                 case MP_RAILWAY:
 567                         if (IsRailDepot(ti->tile)) {
 568                                 const SortableSpriteStruct *sss = &RailCatenarySpriteData_Depot[GetRailDepotDirection(ti->tile)];
 569
 570                                 SpriteID wire_base = GetWireBase(ti->tile);
 571
 572                                 /* This wire is not visible with the default depot sprites */
 573                                 AddSortableSpriteToDraw(
 574                                         wire_base + sss->image_offset, PAL_NONE, ti->x + sss->x_offset, ti->y + sss->y_offset,
 575                                         sss->x_size, sss->y_size, sss->z_size,
 576                                         GetTileMaxPixelZ(ti->tile) + sss->z_offset,
 577                                         IsTransparencySet(TO_CATENARY)
 578                                 );
 579                                 return;
 580                         }
 581                         break;
 582
 583                 case MP_TUNNELBRIDGE:
 584                 case MP_ROAD:
 585                 case MP_STATION:
 586                         break;
 587
 588                 default: return;
 589         }
 590         DrawRailCatenaryRailway(ti);
 591 }
 592
 593 bool SettingsDisableElrail(int32 p1)
 594 {
 595         Company *c;
 596         Train *t;
 597         bool disable = (p1 != 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         Engine *e;
 605         FOR_ALL_ENGINES_OF_TYPE(e, VEH_TRAIN) {
 606                 RailVehicleInfo *rv_info = &e->u.rail;
 607                 /* if it is an electric rail engine and its railtype is the wrong one */
 608                 if (rv_info->engclass == 2 && rv_info->railtype == old_railtype) {
 609                         /* change it to the proper one */
 610                         rv_info->railtype = new_railtype;
 611                 }
 612         }
 613
 614         /* when disabling elrails, make sure that all existing trains can run on
 615          *  normal rail too */
 616         if (disable) {
 617                 FOR_ALL_TRAINS(t) {
 618                         if (t->railtype == RAILTYPE_ELECTRIC) {
 619                                 /* this railroad vehicle is now compatible only with elrail,
 620                                  *  so add there also normal rail compatibility */
 621                                 t->compatible_railtypes |= RAILTYPES_RAIL;
 622                                 t->railtype = RAILTYPE_RAIL;
 623                                 SetBit(t->flags, VRF_EL_ENGINE_ALLOWED_NORMAL_RAIL);
 624                         }
 625                 }
 626         }
 627
 628         /* Fix the total power and acceleration for trains */
 629         FOR_ALL_TRAINS(t) {
 630                 /* power and acceleration is cached only for front engines */
 631                 if (t->IsFrontEngine()) {
 632                         t->ConsistChanged(CCF_TRACK);
 633                 }
 634         }
 635
 636         FOR_ALL_COMPANIES(c) c->avail_railtypes = GetCompanyRailtypes(c->index);
 637
 638         /* This resets the _last_built_railtype, which will be invalid for electric
 639          * rails. It may have unintended consequences if that function is ever
 640          * extended, though. */
 641         ReinitGuiAfterToggleElrail(disable);
 642         return true;
 643 }