diff --git a/src/elrail.cpp b/src/elrail.cpp
new file mode 100644
--- /dev/null
+++ b/src/elrail.cpp
@@ -0,0 +1,445 @@
+/* $Id$ */
+/** @file elrail.c
+ * This file deals with displaying wires and pylons for electric railways.
+ * Basics
+ *
+ * Tile Types
+ *
+ * We have two different types of tiles in the drawing code:
+ * Normal Railway Tiles (NRTs) which can have more than one track on it, and
+ * Special Railways tiles (SRTs) which have only one track (like crossings, depots
+ * stations, etc).
+ *
+ * Location Categories
+ *
+ * All tiles are categorized into three location groups (TLG):
+ * Group 0: Tiles with both an even X coordinate and an even Y coordinate
+ * Group 1: Tiles with an even X and an odd Y coordinate
+ * Group 2: Tiles with an odd X and an even Y coordinate
+ * Group 3: Tiles with both an odd X and Y coordnate.
+ *
+ * Pylon Points
+ * Control Points
+ * A Pylon Control Point (PCP) is a position where a wire (or rather two)
+ * is mounted onto a pylon.
+ * Each NRT does contain 4 PCPs which are bitmapped to a byte
+ * variable and are represented by the DiagDirection enum
+ *
+ * Each track ends on two PCPs and thus requires one pylon on each end. However,
+ * there is one exception: Straight-and-level tracks only have one pylon every
+ * other tile.
+ *
+ * Now on each edge there are two PCPs: One from each adjacent tile. Both PCPs
+ * are merged using an OR operation (i. e. if one tile needs a PCP at the postion
+ * in question, both tiles get it).
+ *
+ * Position Points
+ * A Pylon Position Point (PPP) is a position where a pylon is located on the
+ * ground. Each PCP owns 8 in (45 degree steps) PPPs that are located around
+ * it. PPPs are represented using the Direction enum. Each track bit has PPPs
+ * that are impossible (because the pylon would be situated on the track) and
+ * some that are preferred (because the pylon would be rectangular to the track).
+ *
+ * 
+ * 
+ *
+ */
+
+#include "stdafx.h"
+#include "openttd.h"
+#include "station_map.h"
+#include "tile.h"
+#include "viewport.h"
+#include "functions.h" /* We should REALLY get rid of this goddamn file, as it is butt-ugly */
+#include "variables.h" /* ... same here */
+#include "rail.h"
+#include "debug.h"
+#include "tunnel_map.h"
+#include "road_map.h"
+#include "bridge_map.h"
+#include "bridge.h"
+#include "rail_map.h"
+#include "table/sprites.h"
+#include "table/elrail_data.h"
+#include "vehicle.h"
+#include "train.h"
+#include "gui.h"
+
+static inline TLG GetTLG(TileIndex t)
+{
+ return (HASBIT(TileX(t), 0) << 1) + HASBIT(TileY(t), 0);
+}
+
+/** Finds which Rail Bits are present on a given tile. For bridge tiles,
+ * returns track bits under the bridge
+ */
+static TrackBits GetRailTrackBitsUniversal(TileIndex t, byte *override)
+{
+ switch (GetTileType(t)) {
+ case MP_RAILWAY:
+ if (GetRailType(t) != RAILTYPE_ELECTRIC) return 0;
+ switch (GetRailTileType(t)) {
+ case RAIL_TILE_NORMAL: case RAIL_TILE_SIGNALS:
+ return GetTrackBits(t);
+ case RAIL_TILE_DEPOT_WAYPOINT:
+ if (GetRailTileSubtype(t) == RAIL_SUBTYPE_WAYPOINT) return GetRailWaypointBits(t);
+ default:
+ return 0;
+ }
+ break;
+
+ case MP_TUNNELBRIDGE:
+ if (IsTunnel(t)) {
+ if (GetRailType(t) != RAILTYPE_ELECTRIC) return 0;
+ if (override != NULL) *override = 1 << GetTunnelDirection(t);
+ return AxisToTrackBits(DiagDirToAxis(GetTunnelDirection(t)));
+ } else {
+ if (GetRailType(t) != RAILTYPE_ELECTRIC) return 0;
+ if (override != NULL && DistanceMax(t, GetOtherBridgeEnd(t)) > 1) {
+ *override = 1 << GetBridgeRampDirection(t);
+ }
+ return AxisToTrackBits(DiagDirToAxis(GetBridgeRampDirection(t)));
+ }
+
+ case MP_STREET:
+ if (GetRoadTileType(t) != ROAD_TILE_CROSSING) return 0;
+ if (GetRailTypeCrossing(t) != RAILTYPE_ELECTRIC) return 0;
+ return GetCrossingRailBits(t);
+
+ case MP_STATION:
+ if (!IsRailwayStation(t)) return 0;
+ if (GetRailType(t) != RAILTYPE_ELECTRIC) return 0;
+ if (!IsStationTileElectrifiable(t)) return 0;
+ return TrackToTrackBits(GetRailStationTrack(t));
+
+ default:
+ return 0;
+ }
+}
+
+/** Corrects the tileh for certain tile types. Returns an effective tileh for the track on the tile.
+ * @param tile The tile to analyse
+ * @param *tileh the tileh
+ */
+static void AdjustTileh(TileIndex tile, Slope *tileh)
+{
+ if (IsTileType(tile, MP_TUNNELBRIDGE)) {
+ if (IsTunnel(tile)) {
+ *tileh = SLOPE_FLAT;
+ } else {
+ if (*tileh != SLOPE_FLAT) {
+ *tileh = SLOPE_FLAT;
+ } else {
+ switch (GetBridgeRampDirection(tile)) {
+ case DIAGDIR_NE: *tileh = SLOPE_NE; break;
+ case DIAGDIR_SE: *tileh = SLOPE_SE; break;
+ case DIAGDIR_SW: *tileh = SLOPE_SW; break;
+ case DIAGDIR_NW: *tileh = SLOPE_NW; break;
+ default: NOT_REACHED();
+ }
+ }
+ }
+ }
+}
+
+/** Draws wires and, if required, pylons on a given tile
+ * @param ti The Tileinfo to draw the tile for
+ */
+static void DrawCatenaryRailway(const TileInfo *ti)
+{
+ /* Pylons are placed on a tile edge, so we need to take into account
+ * the track configuration of 2 adjacent tiles. trackconfig[0] stores the
+ * current tile (home tile) while [1] holds the neighbour */
+ TrackBits trackconfig[TS_END];
+ bool isflat[TS_END];
+ /* Note that ti->tileh has already been adjusted for Foundations */
+ Slope tileh[TS_END] = { ti->tileh, SLOPE_FLAT };
+
+ TLG tlg = GetTLG(ti->tile);
+ byte PCPstatus = 0;
+ byte OverridePCP = 0;
+ byte PPPpreferred[DIAGDIR_END];
+ byte PPPallowed[DIAGDIR_END];
+ DiagDirection i;
+ Track t;
+
+ /* Find which rail bits are present, and select the override points.
+ * We don't draw a pylon:
+ * 1) INSIDE a tunnel (we wouldn't see it anyway)
+ * 2) on the "far" end of a bridge head (the one that connects to bridge middle),
+ * because that one is drawn on the bridge. Exception is for length 0 bridges
+ * which have no middle tiles */
+ trackconfig[TS_HOME] = GetRailTrackBitsUniversal(ti->tile, &OverridePCP);
+ /* If a track bit is present that is not in the main direction, the track is level */
+ isflat[TS_HOME] = trackconfig[TS_HOME] & (TRACK_BIT_HORZ | TRACK_BIT_VERT);
+
+ AdjustTileh(ti->tile, &tileh[TS_HOME]);
+
+ for (i = DIAGDIR_NE; i < DIAGDIR_END; i++) {
+ TileIndex neighbour = ti->tile + TileOffsByDiagDir(i);
+ uint foundation = 0;
+ int k;
+
+ /* Here's one of the main headaches. GetTileSlope does not correct for possibly
+ * existing foundataions, so we do have to do that manually later on.*/
+ tileh[TS_NEIGHBOUR] = GetTileSlope(neighbour, NULL);
+ trackconfig[TS_NEIGHBOUR] = GetRailTrackBitsUniversal(neighbour, NULL);
+ if (IsTunnelTile(neighbour) && i != GetTunnelDirection(neighbour)) trackconfig[TS_NEIGHBOUR] = 0;
+ isflat[TS_NEIGHBOUR] = trackconfig[TS_NEIGHBOUR] & (TRACK_BIT_HORZ | TRACK_BIT_VERT);
+
+ PPPpreferred[i] = 0xFF; /* We start with preferring everything (end-of-line in any direction) */
+ PPPallowed[i] = AllowedPPPonPCP[i];
+
+ /* We cycle through all the existing tracks at a PCP and see what
+ * PPPs we want to have, or may not have at all */
+ for (k = 0; k < NUM_TRACKS_AT_PCP; k++) {
+ /* Next to us, we have a bridge head, don't worry about that one, if it shows away from us */
+ if (TrackSourceTile[i][k] == TS_NEIGHBOUR &&
+ IsBridgeTile(neighbour) &&
+ GetBridgeRampDirection(neighbour) == ReverseDiagDir(i)) {
+ continue;
+ }
+
+ /* We check whether the track in question (k) is present in the tile
+ * (TrackSourceTile) */
+ if (HASBIT(trackconfig[TrackSourceTile[i][k]], TracksAtPCP[i][k])) {
+ /* track found, if track is in the neighbour tile, adjust the number
+ * of the PCP for preferred/allowed determination*/
+ DiagDirection PCPpos = (TrackSourceTile[i][k] == TS_HOME) ? i : ReverseDiagDir(i);
+ SETBIT(PCPstatus, i); /* This PCP is in use */
+
+ PPPpreferred[i] &= PreferredPPPofTrackAtPCP[TracksAtPCP[i][k]][PCPpos];
+ PPPallowed[i] &= ~DisallowedPPPofTrackAtPCP[TracksAtPCP[i][k]][PCPpos];
+ }
+ }
+
+ /* Deactivate all PPPs if PCP is not used */
+ PPPpreferred[i] *= HASBIT(PCPstatus, i);
+ PPPallowed[i] *= HASBIT(PCPstatus, i);
+
+ /* A station is always "flat", so adjust the tileh accordingly */
+ if (IsTileType(neighbour, MP_STATION)) tileh[TS_NEIGHBOUR] = SLOPE_FLAT;
+
+ /* Read the foundataions if they are present, and adjust the tileh */
+ if (IsTileType(neighbour, MP_RAILWAY) && GetRailType(neighbour) == RAILTYPE_ELECTRIC) foundation = GetRailFoundation(tileh[TS_NEIGHBOUR], trackconfig[TS_NEIGHBOUR]);
+ if (IsBridgeTile(neighbour)) {
+ foundation = GetBridgeFoundation(tileh[TS_NEIGHBOUR], DiagDirToAxis(GetBridgeRampDirection(neighbour)));
+ }
+
+ if (foundation != 0) {
+ if (foundation < 15) {
+ tileh[TS_NEIGHBOUR] = SLOPE_FLAT;
+ } else {
+ tileh[TS_NEIGHBOUR] = _inclined_tileh[foundation - 15];
+ }
+ }
+
+ AdjustTileh(neighbour, &tileh[TS_NEIGHBOUR]);
+
+ /* If we have a straight (and level) track, we want a pylon only every 2 tiles
+ * Delete the PCP if this is the case. */
+ /* Level means that the slope is the same, or the track is flat */
+ if (tileh[TS_HOME] == tileh[TS_NEIGHBOUR] || (isflat[TS_HOME] && isflat[TS_NEIGHBOUR])) {
+ for (k = 0; k < NUM_IGNORE_GROUPS; k++)
+ if (PPPpreferred[i] == IgnoredPCP[k][tlg][i]) CLRBIT(PCPstatus, i);
+ }
+
+ /* Now decide where we draw our pylons. First try the preferred PPPs, but they may not exist.
+ * In that case, we try the any of the allowed ones. if they don't exist either, don't draw
+ * anything. Note that the preferred PPPs still contain the end-of-line markers.
+ * Remove those (simply by ANDing with allowed, since these markers are never allowed) */
+ if ((PPPallowed[i] & PPPpreferred[i]) != 0) PPPallowed[i] &= PPPpreferred[i];
+
+ if (MayHaveBridgeAbove(ti->tile) && IsBridgeAbove(ti->tile)) {
+ Track bridgetrack = GetBridgeAxis(ti->tile) == AXIS_X ? TRACK_X : TRACK_Y;
+ uint height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
+
+ if ((height <= TilePixelHeight(ti->tile) + TILE_HEIGHT) &&
+ (i == PCPpositions[bridgetrack][0] || i == PCPpositions[bridgetrack][1])) SETBIT(OverridePCP, i);
+ }
+
+ if (PPPallowed[i] != 0 && HASBIT(PCPstatus, i) && !HASBIT(OverridePCP, i)) {
+ for (k = 0; k < DIR_END; k++) {
+ byte temp = PPPorder[i][GetTLG(ti->tile)][k];
+
+ if (HASBIT(PPPallowed[i], temp)) {
+ uint x = ti->x + x_pcp_offsets[i] + x_ppp_offsets[temp];
+ uint y = ti->y + y_pcp_offsets[i] + y_ppp_offsets[temp];
+
+ /* Don't build the pylon if it would be outside the tile */
+ if (!HASBIT(OwnedPPPonPCP[i], temp)) {
+ /* We have a neighour that will draw it, bail out */
+ if (trackconfig[TS_NEIGHBOUR] != 0) break;
+ continue; /* No neighbour, go looking for a better position */
+ }
+
+ AddSortableSpriteToDraw(pylons_normal[temp], x, y, 1, 1, 10,
+ GetSlopeZ(ti->x + x_pcp_offsets[i], ti->y + y_pcp_offsets[i]));
+ break; /* We already have drawn a pylon, bail out */
+ }
+ }
+ }
+ }
+
+ /* Don't draw a wire under a low bridge */
+ if (MayHaveBridgeAbove(ti->tile) && IsBridgeAbove(ti->tile) && !(_display_opt & DO_TRANS_BUILDINGS)) {
+ uint height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
+
+ if (height <= TilePixelHeight(ti->tile) + TILE_HEIGHT) return;
+ }
+
+ /* Drawing of pylons is finished, now draw the wires */
+ for (t = 0; t < TRACK_END; t++) {
+ if (HASBIT(trackconfig[TS_HOME], t)) {
+
+ byte PCPconfig = HASBIT(PCPstatus, PCPpositions[t][0]) +
+ (HASBIT(PCPstatus, PCPpositions[t][1]) << 1);
+
+ const SortableSpriteStruct *sss;
+ int tileh_selector = !(tileh[TS_HOME] % 3) * tileh[TS_HOME] / 3; /* tileh for the slopes, 0 otherwise */
+
+ assert(PCPconfig != 0); /* We have a pylon on neither end of the wire, that doesn't work (since we have no sprites for that) */
+ assert(!IsSteepSlope(tileh[TS_HOME]));
+ sss = &CatenarySpriteData[Wires[tileh_selector][t][PCPconfig]];
+
+ AddSortableSpriteToDraw( sss->image, ti->x + sss->x_offset, ti->y + sss->y_offset,
+ sss->x_size, sss->y_size, sss->z_size, GetSlopeZ(ti->x + min(sss->x_offset, TILE_SIZE - 1), ti->y + min(sss->y_offset, TILE_SIZE - 1)) + sss->z_offset);
+ }
+ }
+}
+
+static void DrawCatenaryOnBridge(const TileInfo *ti)
+{
+ TileIndex end = GetSouthernBridgeEnd(ti->tile);
+ TileIndex start = GetOtherBridgeEnd(end);
+
+ uint length = GetBridgeLength(start, end);
+ uint num = DistanceMax(ti->tile, start);
+ uint height;
+
+ const SortableSpriteStruct *sss;
+ Axis axis = GetBridgeAxis(ti->tile);
+ TLG tlg = GetTLG(ti->tile);
+
+ CatenarySprite offset = axis == AXIS_X ? 0 : WIRE_Y_FLAT_BOTH - WIRE_X_FLAT_BOTH;
+
+ if ((length % 2) && num == length) {
+ /* Draw the "short" wire on the southern end of the bridge
+ * only needed if the length of the bridge is odd */
+ sss = &CatenarySpriteData[WIRE_X_FLAT_BOTH + offset];
+ } else {
+ /* Draw "long" wires on all other tiles of the bridge (one pylon every two tiles) */
+ sss = &CatenarySpriteData[WIRE_X_FLAT_SW + (num % 2) + offset];
+ }
+
+ height = GetBridgeHeight(end);
+
+ AddSortableSpriteToDraw( sss->image, ti->x + sss->x_offset, ti->y + sss->y_offset,
+ sss->x_size, sss->y_size, sss->z_size, height + sss->z_offset
+ );
+
+ /* Finished with wires, draw pylons */
+ /* every other tile needs a pylon on the northern end */
+ if (num % 2) {
+ if (axis == AXIS_X) {
+ AddSortableSpriteToDraw(pylons_bridge[0 + HASBIT(tlg, 0)], ti->x, ti->y + 4 + 8 * HASBIT(tlg, 0), 1, 1, 10, height);
+ } else {
+ AddSortableSpriteToDraw(pylons_bridge[2 + HASBIT(tlg, 1)], ti->x + 4 + 8 * HASBIT(tlg, 1), ti->y, 1, 1, 10, height);
+ }
+ }
+
+ /* need a pylon on the southern end of the bridge */
+ if (DistanceMax(ti->tile, start) == length) {
+ if (axis == AXIS_X) {
+ AddSortableSpriteToDraw(pylons_bridge[0 + HASBIT(tlg, 0)], ti->x + 16, ti->y + 4 + 8 * HASBIT(tlg, 0), 1, 1, 10, height);
+ } else {
+ AddSortableSpriteToDraw(pylons_bridge[2 + HASBIT(tlg, 1)], ti->x + 4 + 8 * HASBIT(tlg, 1), ti->y + 16, 1, 1, 10, height);
+ }
+ }
+}
+
+void DrawCatenary(const TileInfo *ti)
+{
+ if (MayHaveBridgeAbove(ti->tile) && IsBridgeAbove(ti->tile)) {
+ TileIndex head = GetNorthernBridgeEnd(ti->tile);
+
+ if (GetBridgeTransportType(head) == TRANSPORT_RAIL && GetRailType(head) == RAILTYPE_ELECTRIC) {
+ DrawCatenaryOnBridge(ti);
+ }
+ }
+ if (_patches.disable_elrails) return;
+
+ switch (GetTileType(ti->tile)) {
+ case MP_RAILWAY:
+ if (IsRailDepot(ti->tile)) {
+ const SortableSpriteStruct* sss = &CatenarySpriteData_Depot[GetRailDepotDirection(ti->tile)];
+
+ AddSortableSpriteToDraw(
+ sss->image, ti->x + sss->x_offset, ti->y + sss->y_offset,
+ sss->x_size, sss->y_size, sss->z_size,
+ GetTileMaxZ(ti->tile) + sss->z_offset
+ );
+ return;
+ }
+ break;
+
+ case MP_TUNNELBRIDGE:
+ case MP_STREET:
+ case MP_STATION:
+ break;
+
+ default: return;
+ }
+ DrawCatenaryRailway(ti);
+}
+
+int32 SettingsDisableElrail(int32 p1)
+{
+ EngineID e_id;
+ Vehicle* v;
+ Player *p;
+ bool disable = (p1 != 0);
+
+ /* we will now walk through all electric train engines and change their railtypes if it is the wrong one*/
+ const RailType old_railtype = disable ? RAILTYPE_ELECTRIC : RAILTYPE_RAIL;
+ const RailType new_railtype = disable ? RAILTYPE_RAIL : RAILTYPE_ELECTRIC;
+
+ /* walk through all train engines */
+ for (e_id = 0; e_id < NUM_TRAIN_ENGINES; e_id++) {
+ const RailVehicleInfo *rv_info = RailVehInfo(e_id);
+ Engine *e = GetEngine(e_id);
+ /* if it is an electric rail engine and its railtype is the wrong one */
+ if (rv_info->engclass == 2 && e->railtype == old_railtype) {
+ /* change it to the proper one */
+ e->railtype = new_railtype;
+ }
+ }
+
+ /* when disabling elrails, make sure that all existing trains can run on
+ * normal rail too */
+ if (disable) {
+ FOR_ALL_VEHICLES(v) {
+ if (v->type == VEH_Train && v->u.rail.railtype == RAILTYPE_ELECTRIC) {
+ /* this railroad vehicle is now compatible only with elrail,
+ * so add there also normal rail compatibility */
+ v->u.rail.compatible_railtypes |= (1 << RAILTYPE_RAIL);
+ v->u.rail.railtype = RAILTYPE_RAIL;
+ SETBIT(v->u.rail.flags, VRF_EL_ENGINE_ALLOWED_NORMAL_RAIL);
+ }
+ }
+ }
+
+ /* setup total power for trains */
+ FOR_ALL_VEHICLES(v) {
+ /* power is cached only for front engines */
+ if (v->type == VEH_Train && IsFrontEngine(v)) TrainPowerChanged(v);
+ }
+
+ FOR_ALL_PLAYERS(p) p->avail_railtypes = GetPlayerRailtypes(p->index);
+
+ /* This resets the _last_built_railtype, which will be invalid for electric
+ * rails. It may have unintended consequences if that function is ever
+ * extended, though. */
+ ReinitGuiAfterToggleElrail(disable);
+ return 0;
+}