(svn r5070) Merged the bridge branch

-Feature: Bridges can now be placed above:
	Any railway track combination (excluding depots and waypoints)
	Any road combination (excluding depots)
	Clear tiles (duh), including fields
	Tunnel entrances
	Bridge heads

Thanks to Tron for idea and implementation, KUDr for the yapf synchronization and many others for hours of testing

There are still a number of visual problems remaining, especially when electric railways are on or under the bridge.
DO NOT REPORT THOSE BUGS FOR THE TIME BEING please.

1 files changed, 18 insertions, 57 deletions

diff --git a/rail_cmd.c b/rail_cmd.c
index 8e7792601..61e316af2 100644
--- a/rail_cmd.c
+++ b/rail_cmd.c
@@ -231,29 +231,6 @@ int32 CmdBuildSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
 	switch (GetTileType(tile)) {
-		case MP_TUNNELBRIDGE:
-			if (!IsBridge(tile) ||
-					!IsBridgeMiddle(tile) ||
-					(GetBridgeAxis(tile) == AXIS_X ? TRACK_BIT_Y : TRACK_BIT_X) != trackbit) {
-				// Get detailed error message
-				return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
-			}
-
-			if (IsClearUnderBridge(tile)) {
-				ret = CheckRailSlope(tileh, trackbit, 0, tile);
-				if (CmdFailed(ret)) return ret;
-				cost += ret;
-
-				if (flags & DC_EXEC) SetRailUnderBridge(tile, _current_player, p1);
-			} else if (IsTransportUnderBridge(tile) &&
-					GetTransportTypeUnderBridge(tile) == TRANSPORT_RAIL) {
-				return_cmd_error(STR_1007_ALREADY_BUILT);
-			} else {
-				// Get detailed error message
-				return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
-			}
-			break;
-
 		case MP_RAILWAY:
 			if (!CheckTrackCombination(tile, trackbit, flags) ||
 					!EnsureNoVehicle(tile)) {
@@ -341,20 +318,6 @@ int32 CmdRemoveSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
 	switch (GetTileType(tile)) {
-		case MP_TUNNELBRIDGE:
-			if (!IsBridge(tile) ||
-					!IsBridgeMiddle(tile) ||
-					!IsTransportUnderBridge(tile) ||
-					GetTransportTypeUnderBridge(tile) != TRANSPORT_RAIL ||
-					GetRailBitsUnderBridge(tile) != trackbit ||
-					(_current_player != OWNER_WATER && !CheckTileOwnership(tile)) ||
-					!EnsureNoVehicleOnGround(tile)) {
-				return CMD_ERROR;
-			}
-
-			if (flags & DC_EXEC) SetClearUnderBridge(tile);
-			break;
-
 		case MP_STREET: {
 			if (!IsLevelCrossing(tile) ||
 					GetCrossingRailBits(tile) != trackbit ||
@@ -591,6 +554,8 @@ int32 CmdBuildTrainDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	if (CmdFailed(ret)) return CMD_ERROR;
 	cost = ret;
 
+	if (MayHaveBridgeAbove(tile) && IsBridgeAbove(tile)) return_cmd_error(STR_5007_MUST_DEMOLISH_BRIDGE_FIRST);
+
 	d = AllocateDepot();
 	if (d == NULL) return CMD_ERROR;
 
@@ -1416,6 +1381,7 @@ static void DrawTile_Track(TileInfo *ti)
 			);
 		}
 	}
+	DrawBridgeMiddle(ti);
 }
 
 void DrawTrainDepotSprite(int x, int y, int image, RailType railtype)
@@ -1525,19 +1491,11 @@ typedef struct SignalVehicleCheckStruct {
 static void *SignalVehicleCheckProc(Vehicle *v, void *data)
 {
 	const SignalVehicleCheckStruct* dest = data;
-	TileIndex tile;
 
 	if (v->type != VEH_Train) return NULL;
 
-	/* Find the tile outside the tunnel, for signalling */
-	if (v->u.rail.track == 0x40) {
-		tile = GetVehicleOutOfTunnelTile(v);
-	} else {
-		tile = v->tile;
-	}
-
 	/* Wrong tile, or no train? Not a match */
-	if (tile != dest->tile) return NULL;
+	if (v->tile != dest->tile) return NULL;
 
 	/* Are we on the same piece of track? */
 	if (dest->track & (v->u.rail.track + (v->u.rail.track << 8))) return v;
@@ -1553,15 +1511,18 @@ static bool SignalVehicleCheck(TileIndex tile, uint track)
 	dest.tile = tile;
 	dest.track = track;
 
-	/** @todo "Hackish" fix for the tunnel problems. This is needed because a tunnel
-	 * is some kind of invisible black hole, and there is some special magic going
-	 * on in there. This 'workaround' can be removed once the maprewrite is done.
-	 */
-	if (IsTunnelTile(tile)) {
-		// It is a tunnel we're checking, we need to do some special stuff
-		// because VehicleFromPos will not find the vihicle otherwise
-		TileIndex end = GetOtherTunnelEnd(tile);
-		DiagDirection direction = GetTunnelDirection(tile);
+	/* Locate vehicles in tunnels or on bridges */
+	if (IsTunnelTile(tile) || IsBridgeTile(tile)) {
+		TileIndex end;
+		DiagDirection direction;
+
+		if (IsTunnelTile(tile)) {
+			end = GetOtherTunnelEnd(tile);
+			direction = GetTunnelDirection(tile);
+		} else {
+			end = GetOtherBridgeEnd(tile);
+			direction = GetBridgeRampDirection(tile);
+		}
 
 		dest.track = 1 << (direction & 1); // get the trackbit the vehicle would have if it has not entered the tunnel yet (ie is still visible)
 
@@ -1571,9 +1532,9 @@ static bool SignalVehicleCheck(TileIndex tile, uint track)
 		// check for a vehicle with that trackdir on the end tile of the tunnel
 		if (VehicleFromPos(end, &dest, SignalVehicleCheckProc) != NULL) return true;
 
-		// now check all tiles from start to end for a "hidden" vehicle
+		// now check all tiles from start to end for a warping vehicle
 		// NOTE: the hashes for tiles may overlap, so this could maybe be optimised a bit by not checking every tile?
-		dest.track = 0x40; // trackbit for vehicles "hidden" inside a tunnel
+		dest.track = 0x40;
 		for (; tile != end; tile += TileOffsByDir(direction)) {
 			if (VehicleFromPos(tile, &dest, SignalVehicleCheckProc) != NULL)
 				return true;