(svn r11172) -Codechange: rewrite of town road building and addition of the possibility to clean up unconnected road bits during the local road reconstructions. Based on a patch by skidd13.

11 files changed, 379 insertions, 160 deletions

diff --git a/src/direction.h b/src/direction.h
index 84d6b952e..9e678c9c9 100644
--- a/src/direction.h
+++ b/src/direction.h
@@ -165,6 +165,9 @@ enum DiagDirDiff {
 	DIAGDIRDIFF_90LEFT  = 3         ///< 90 degrees left
 };
 
+/** Allow incrementing of DiagDirDiff variables */
+DECLARE_POSTFIX_INCREMENT(DiagDirDiff);
+
 /**
  * Applies a difference on a DiagDirection
  *
diff --git a/src/lang/english.txt b/src/lang/english.txt
index 22972d9e3..8297e20ef 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -1187,6 +1187,7 @@ STR_CONFIG_PATCHES_TOWN_GROWTH_VERY_FAST                        :Very fast
 STR_CONFIG_PATCHES_LARGER_TOWNS                                 :{LTBLUE}Proportion of towns that will become cities: {ORANGE}1 in {STRING1}
 STR_CONFIG_PATCHES_LARGER_TOWNS_DISABLED                        :{LTBLUE}Proportion of towns that will become cities: {ORANGE}None
 STR_CONFIG_PATCHES_CITY_SIZE_MULTIPLIER                         :{LTBLUE}Initial city size multiplier: {ORANGE}{STRING1}
+STR_CONFIG_MODIFIED_ROAD_REBUILD                                :{LTBLUE}Remove absurd road-elements during the road construction
 
 STR_CONFIG_PATCHES_GUI                                          :{BLACK}Interface
 STR_CONFIG_PATCHES_CONSTRUCTION                                 :{BLACK}Construction
diff --git a/src/map.h b/src/map.h
index 9e28b0732..064e595c1 100644
--- a/src/map.h
+++ b/src/map.h
@@ -390,6 +390,18 @@ static inline TileIndexDiff TileOffsByDir(Direction dir)
 }
 
 /**
+ * Adds a DiagDir to a tile.
+ *
+ * @param tile The current tile
+ * @param dir The direction in which we want to step
+ * @return the moved tile
+ */
+static inline TileIndex TileAddByDiagDir(TileIndex tile, DiagDirection dir)
+{
+	return TILE_ADD(tile, TileOffsByDiagDir(dir));
+}
+
+/**
  * A callback function type for searching tiles.
  *
  * @param tile The tile to test
diff --git a/src/road.cpp b/src/road.cpp
new file mode 100644
index 000000000..ae806647f
--- /dev/null
+++ b/src/road.cpp
@@ -0,0 +1,69 @@
+#include "stdafx.h"
+#include "openttd.h"
+#include "functions.h"
+#include "rail_map.h"
+#include "road.h"
+#include "road_map.h"
+#include "water_map.h"
+#include "macros.h"
+
+bool IsPossibleCrossing(const TileIndex tile, Axis ax)
+{
+	return (IsTileType(tile, MP_RAILWAY) &&
+		!HasSignals(tile) &&
+		GetTrackBits(tile) == (ax == AXIS_X ?  TRACK_BIT_Y : TRACK_BIT_X) &&
+		GetTileSlope(tile, NULL) == SLOPE_FLAT);
+}
+
+RoadBits CleanUpRoadBits(const TileIndex tile, RoadBits org_rb)
+{
+	for (DiagDirection dir = DIAGDIR_BEGIN; dir < DIAGDIR_END; dir++) {
+		const TileIndex neighbor_tile = TileAddByDiagDir(tile, dir);
+
+		/* Get the Roadbit pointing to the neighbor_tile */
+		const RoadBits target_rb = DiagDirToRoadBits(dir);
+
+		/* If the roadbit is in the current plan */
+		if (org_rb & target_rb) {
+			bool connective = false;
+			const RoadBits mirrored_rb = MirrorRoadBits(target_rb);
+
+			switch (GetTileType(neighbor_tile)) {
+				/* Allways connective ones */
+				case MP_CLEAR: case MP_TREES:
+					connective = true;
+					break;
+
+				/* The conditionaly connective ones */
+				case MP_TUNNELBRIDGE:
+				case MP_STATION:
+				case MP_ROAD: {
+					const RoadBits neighbor_rb = GetAnyRoadBits(neighbor_tile, ROADTYPE_ROAD) | GetAnyRoadBits(neighbor_tile, ROADTYPE_TRAM);
+
+					/* Accept only connective tiles */
+					connective = (neighbor_rb & mirrored_rb) || // Neighbor has got the fitting RoadBit
+							COUNTBITS(neighbor_rb) == 1; // Neighbor has got only one Roadbit
+
+				} break;
+
+				case MP_RAILWAY:
+					connective = IsPossibleCrossing(neighbor_tile, DiagDirToAxis(dir));
+					break;
+
+				case MP_WATER:
+					/* Check for real water tile */
+					connective = !IsWater(neighbor_tile);
+					break;
+
+				/* The defentetly not connective ones */
+				default: break;
+			}
+
+			/* If the neighbor tile is inconnective remove the planed road connection to it */
+			if (!connective) org_rb ^= target_rb;
+
+		}
+	}
+
+	return org_rb;
+}
diff --git a/src/road.h b/src/road.h
index 051508971..e97600f1a 100644
--- a/src/road.h
+++ b/src/road.h
@@ -116,6 +116,36 @@ static inline RoadBits ComplementRoadBits(RoadBits r)
 }
 
 /**
+ * Calculate the mirrored RoadBits
+ *
+ * Simply move the bits to their new position.
+ *
+ * @param r The given RoadBits value
+ * @return the mirrored
+ */
+static inline RoadBits MirrorRoadBits(RoadBits r)
+{
+	return (RoadBits)(GB(r, 0, 2) << 2 | GB(r, 2, 2));
+}
+
+/**
+ * Calculate rotated RoadBits
+ *
+ * Move the Roadbits clockwise til they are in their final position.
+ *
+ * @param r The given RoadBits value
+ * @param rot The given Rotation angle
+ * @return the rotated
+ */
+static inline RoadBits RotateRoadBits(RoadBits r, DiagDirDiff rot)
+{
+	for (; rot > (DiagDirDiff)0; rot--){
+		r = (RoadBits)(GB(r, 0, 1) << 3 | GB(r, 1, 3));
+	}
+	return r;
+}
+
+/**
  * Create the road-part which belongs to the given DiagDirection
  *
  * This function returns a RoadBits value which belongs to
@@ -130,6 +160,16 @@ static inline RoadBits DiagDirToRoadBits(DiagDirection d)
 }
 
 /**
+ * Return if the tile is a valid tile for a crossing.
+ *
+ * @note function is overloaded
+ * @param tile the curent tile
+ * @param ax the axis of the road over the rail
+ * @return true if it is a valid tile
+ */
+bool IsPossibleCrossing(const TileIndex tile, Axis ax);
+
+/**
  * Checks whether the trackdir means that we are reversing.
  * @param dir the trackdir to check
  * @return true if it is a reversing road trackdir
@@ -150,6 +190,14 @@ static inline bool IsStraightRoadTrackdir(Trackdir dir)
 }
 
 /**
+ * Clean up unneccesary RoadBits of a planed tile.
+ * @param tile current tile
+ * @param org_rb planed RoadBits
+ * @return optimised RoadBits
+ */
+RoadBits CleanUpRoadBits(const TileIndex tile, RoadBits org_rb);
+
+/**
  * Is it allowed to remove the given road bits from the given tile?
  * @param tile      the tile to remove the road from
  * @param remove    the roadbits that are going to be removed
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index 34062376d..f63c20b20 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -259,70 +259,121 @@ CommandCost CmdRemoveRoad(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 static const RoadBits _valid_tileh_slopes_road[][15] = {
 	/* set of normal ones */
 	{
-		ROAD_ALL, ROAD_NONE, ROAD_NONE,
-		ROAD_X,   ROAD_NONE, ROAD_NONE,  // 3, 4, 5
-		ROAD_Y,   ROAD_NONE, ROAD_NONE,
-		ROAD_Y,   ROAD_NONE, ROAD_NONE,  // 9, 10, 11
-		ROAD_X,   ROAD_NONE, ROAD_NONE
+		ROAD_ALL,  // SLOPE_FLAT
+		ROAD_NONE, // SLOPE_W
+		ROAD_NONE, // SLOPE_S
+
+		ROAD_X,    // SLOPE_SW
+		ROAD_NONE, // SLOPE_E
+		ROAD_NONE, // SLOPE_EW
+
+		ROAD_Y,    // SLOPE_SE
+		ROAD_NONE, // SLOPE_WSE
+		ROAD_NONE, // SLOPE_N
+
+		ROAD_Y,    // SLOPE_NW
+		ROAD_NONE, // SLOPE_NS
+		ROAD_NONE, // SLOPE_NE
+
+		ROAD_X,    // SLOPE_ENW
+		ROAD_NONE, // SLOPE_SEN
+		ROAD_NONE  // SLOPE_ELEVATED
 	},
 	/* allowed road for an evenly raised platform */
 	{
-		ROAD_NONE,
-		ROAD_SW | ROAD_NW,
-		ROAD_SW | ROAD_SE,
-		ROAD_Y  | ROAD_SW,
-
-		ROAD_SE | ROAD_NE, // 4
-		ROAD_ALL,
-		ROAD_X  | ROAD_SE,
-		ROAD_ALL,
-
-		ROAD_NW | ROAD_NE, // 8
-		ROAD_X  | ROAD_NW,
-		ROAD_ALL,
-		ROAD_ALL,
-
-		ROAD_Y  | ROAD_NE, // 12
-		ROAD_ALL,
-		ROAD_ALL
+		ROAD_NONE,         // SLOPE_FLAT
+		ROAD_SW | ROAD_NW, // SLOPE_W
+		ROAD_SW | ROAD_SE, // SLOPE_S
+
+		ROAD_Y  | ROAD_SW, // SLOPE_SW
+		ROAD_SE | ROAD_NE, // SLOPE_E
+		ROAD_ALL,          // SLOPE_EW
+
+		ROAD_X  | ROAD_SE, // SLOPE_SE
+		ROAD_ALL,          // SLOPE_WSE
+		ROAD_NW | ROAD_NE, // SLOPE_N
+
+		ROAD_X  | ROAD_NW, // SLOPE_NW
+		ROAD_ALL,          // SLOPE_NS
+		ROAD_ALL,          // SLOPE_NE
+
+		ROAD_Y  | ROAD_NE, // SLOPE_ENW
+		ROAD_ALL,          // SLOPE_SEN
+		ROAD_ALL           // SLOPE_ELEVATED
 	},
-};
+	/* Singe bits on slopes */
+	{
+		ROAD_ALL,          // 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_ALL,          // SLOPE_EW
 
+		ROAD_NW,           // SLOPE_SE
+		ROAD_ALL,          // SLOPE_WSE
+		ROAD_SE | ROAD_SW, // SLOPE_N
 
+		ROAD_SE,           // SLOPE_NW
+		ROAD_ALL,          // SLOPE_NS
+		ROAD_ALL,          // SLOPE_NE
+
+		ROAD_SW,           // SLOPE_ENW
+		ROAD_ALL,          // SLOPE_SEN
+		ROAD_ALL,          // SLOPE_ELEVATED
+	},
+};
+
+/**
+ * Calculate the costs for roads on slopes
+ *  Aside modify the RoadBits to fit on the slopes
+ *
+ * @note The RoadBits are modified too!
+ * @param tileh The current slope
+ * @param pieces The RoadBits we want to add
+ * @param existing The existent RoadBits
+ * @return The costs for these RoadBits on this slope
+ */
 static CommandCost CheckRoadSlope(Slope tileh, RoadBits* pieces, RoadBits existing)
 {
-	RoadBits road_bits;
-
 	if (IsSteepSlope(tileh)) {
-		/* force full pieces. */
-		*pieces |= (RoadBits)((*pieces & 0xC) >> 2);
-		*pieces |= (RoadBits)((*pieces & 0x3) << 2);
+		/* Force straight roads. */
+		*pieces |= MirrorRoadBits(*pieces);
 
-		if (existing == 0 || existing == *pieces) {
+		if (existing == ROAD_NONE || existing == *pieces) {
 			if (*pieces == ROAD_X || *pieces == ROAD_Y) return _price.terraform;
 		}
 		return CMD_ERROR;
 	}
-	road_bits = *pieces | existing;
+
+	RoadBits road_bits = *pieces | existing;
+
+	/* Single bits on slopes.
+	 * We check for the roads that need at least 2 bits */
+	if (_patches.build_on_slopes && !_is_old_ai_player &&
+			existing == ROAD_NONE && COUNTBITS(*pieces) == 1 &&
+			(_valid_tileh_slopes_road[2][tileh] & *pieces) == ROAD_NONE) {
+		return CommandCost(_price.terraform);
+	}
 
 	/* no special foundation */
-	if ((~_valid_tileh_slopes_road[0][tileh] & road_bits) == 0) {
+	if ((~_valid_tileh_slopes_road[0][tileh] & road_bits) == ROAD_NONE) {
 		/* force that all bits are set when we have slopes */
 		if (tileh != SLOPE_FLAT) *pieces |= _valid_tileh_slopes_road[0][tileh];
 		return CommandCost(); // no extra cost
 	}
 
 	/* foundation is used. Whole tile is leveled up */
-	if ((~_valid_tileh_slopes_road[1][tileh] & road_bits) == 0) {
-		return CommandCost(existing != 0 ? 0 : _price.terraform);
+	if ((~_valid_tileh_slopes_road[1][tileh] & road_bits) == ROAD_NONE) {
+		return CommandCost(existing != ROAD_NONE ? 0 : _price.terraform);
 	}
 
-	*pieces |= (RoadBits)((*pieces & 0xC) >> 2);
-	*pieces |= (RoadBits)((*pieces & 0x3) << 2);
+	/* Force straight roads. */
+	*pieces |= MirrorRoadBits(*pieces);
 
 	/* partly leveled up tile, only if there's no road on that tile */
-	if ((existing == 0 || existing == *pieces) && (tileh == SLOPE_W || tileh == SLOPE_S || tileh == SLOPE_E || tileh == SLOPE_N)) {
-		/* force full pieces. */
+	if ((existing == ROAD_NONE || existing == *pieces) && (tileh == SLOPE_W || tileh == SLOPE_S || tileh == SLOPE_E || tileh == SLOPE_N)) {
 		if (*pieces == ROAD_X || *pieces == ROAD_Y) return _price.terraform;
 	}
 	return CMD_ERROR;
@@ -1182,8 +1233,8 @@ static void TileLoop_Road(TileIndex tile)
 
 	if (GetRoadTileType(tile) == ROAD_TILE_DEPOT) return;
 
+	const Town* t = ClosestTownFromTile(tile, (uint)-1);
 	if (!HasRoadWorks(tile)) {
-		const Town* t = ClosestTownFromTile(tile, (uint)-1);
 		int grp = 0;
 
 		if (t != NULL) {
@@ -1192,8 +1243,8 @@ static void TileLoop_Road(TileIndex tile)
 			/* Show an animation to indicate road work */
 			if (t->road_build_months != 0 &&
 					(DistanceManhattan(t->xy, tile) < 8 || grp != 0) &&
-					GetRoadTileType(tile) == ROAD_TILE_NORMAL && (GetAllRoadBits(tile) == ROAD_X || GetAllRoadBits(tile) == ROAD_Y)) {
-				if (GetTileSlope(tile, NULL) == SLOPE_FLAT && EnsureNoVehicleOnGround(tile) && CHANCE16(1, 20)) {
+					GetRoadTileType(tile) == ROAD_TILE_NORMAL && COUNTBITS(GetAllRoadBits(tile)) > 1 ) {
+				if (GetTileSlope(tile, NULL) == SLOPE_FLAT && EnsureNoVehicleOnGround(tile) && CHANCE16(1, 40)) {
 					StartRoadWorks(tile);
 
 					SndPlayTileFx(SND_21_JACKHAMMER, tile);
@@ -1231,6 +1282,17 @@ static void TileLoop_Road(TileIndex tile)
 		}
 	} else if (IncreaseRoadWorksCounter(tile)) {
 		TerminateRoadWorks(tile);
+
+		if (_patches.mod_road_rebuild) {
+			/* Generate a nicer town surface */
+			const RoadBits old_rb = GetAnyRoadBits(tile, ROADTYPE_ROAD);
+			const RoadBits new_rb = CleanUpRoadBits(tile, old_rb);
+
+			if (old_rb != new_rb) {
+				DoCommand(tile, (old_rb ^ new_rb), t->index, DC_EXEC | DC_AUTO | DC_NO_WATER, CMD_REMOVE_ROAD);
+			}
+		}
+
 		MarkTileDirtyByTile(tile);
 	}
 }
diff --git a/src/saveload.cpp b/src/saveload.cpp
index 60e8ae7e2..a02b16a2f 100644
--- a/src/saveload.cpp
+++ b/src/saveload.cpp
@@ -29,7 +29,7 @@
 #include "strings.h"
 #include <list>
 
-extern const uint16 SAVEGAME_VERSION = 76;
+extern const uint16 SAVEGAME_VERSION = 77;
 uint16 _sl_version;       ///< the major savegame version identifier
 byte   _sl_minor_version; ///< the minor savegame version, DO NOT USE!
 
diff --git a/src/settings.cpp b/src/settings.cpp
index e650cce29..b0e0d00fd 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -1438,6 +1438,7 @@ const SettingDesc _patch_settings[] = {
 	SDT_CONDVAR(Patches, town_growth_rate,  SLE_UINT8, 54, SL_MAX_VERSION, 0, MS, 2, 0,   4, 0, STR_CONFIG_PATCHES_TOWN_GROWTH,          NULL),
 	SDT_CONDVAR(Patches, larger_towns,      SLE_UINT8, 54, SL_MAX_VERSION, 0, D0, 4, 0, 255, 1, STR_CONFIG_PATCHES_LARGER_TOWNS,         NULL),
 	SDT_CONDVAR(Patches, initial_city_size, SLE_UINT8, 56, SL_MAX_VERSION, 0, 0,  2, 1,  10, 1, STR_CONFIG_PATCHES_CITY_SIZE_MULTIPLIER, NULL),
+	SDT_CONDBOOL(Patches, mod_road_rebuild,            77, SL_MAX_VERSION, 0, 0, false,         STR_CONFIG_MODIFIED_ROAD_REBUILD,        NULL),
 
 	/***************************************************************************/
 	/* AI section of the GUI-configure patches window */
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index bb773df0e..d50a1a576 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -672,7 +672,6 @@ static const char *_patches_construction[] = {
 	"drag_signals_density",
 	"oil_refinery_limit",
 	"semaphore_build_before",
-	"town_layout",
 };
 
 static const char *_patches_stations[] = {
@@ -700,6 +699,8 @@ static const char *_patches_economy[] = {
 	"ending_year",
 	"smooth_economy",
 	"allow_shares",
+	"town_layout",
+	"mod_road_rebuild",
 	"town_growth_rate",
 	"larger_towns",
 	"initial_city_size",
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
index 7649f925a..c89401e11 100644
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -133,18 +133,6 @@ static inline DiagDirection RandomDiagDir()
 }
 
 /**
- * Move a TileIndex into a diagonal direction.
- *
- * @param tile The current tile
- * @param dir The direction in which we want to step
- * @return the moved tile
- */
-static inline TileIndex AddDiagDirToTileIndex(TileIndex tile, DiagDirection dir)
-{
-	return TILE_ADD(tile, TileOffsByDiagDir(dir));
-}
-
-/**
  * House Tile drawing handler.
  * Part of the tile loop process
  * @param ti TileInfo of the tile to draw
@@ -661,7 +649,7 @@ static RoadBits GetTownRoadBits(TileIndex tile)
  */
 static bool IsNeighborRoadTile(TileIndex tile, DiagDirection dir, uint dist_multi)
 {
-	static TileIndexDiff tid_lt[3]; ///< lookup table for the used diff values
+	static TileIndexDiff tid_lt[3]; // lookup table for the used diff values
 	tid_lt[0] = TileOffsByDiagDir(ChangeDiagDir(dir, DIAGDIRDIFF_90RIGHT));
 	tid_lt[1] = TileOffsByDiagDir(ChangeDiagDir(dir, DIAGDIRDIFF_90LEFT));
 	tid_lt[2] = TileOffsByDiagDir(ReverseDiagDir(dir));
@@ -681,7 +669,7 @@ static bool IsNeighborRoadTile(TileIndex tile, DiagDirection dir, uint dist_mult
 		cur += tid_lt[(pos & 1) ? 0 : 1];
 		if (pos & 2) cur += tid_lt[2];
 
-		cur = (uint)(pos / 4) * cur; ///< Multiply for the fitting distance
+		cur = (uint)(pos / 4) * cur; // Multiply for the fitting distance
 		if (GetTownRoadBits(TILE_ADD(tile, cur)) & DiagDirToRoadBits((pos & 2) ? dir : ReverseDiagDir(dir))) return true;
 	}
 	return false;
@@ -797,7 +785,7 @@ static void LevelTownLand(TileIndex tile)
 static RoadBits GetTownRoadGridElement(Town* t, TileIndex tile, DiagDirection dir)
 {
 	/* align the grid to the downtown */
-	TileIndexDiffC grid_pos = TileIndexToTileIndexDiffC(t->xy, tile); ///< Vector from downtown to the tile
+	TileIndexDiffC grid_pos = TileIndexToTileIndexDiffC(t->xy, tile); // Vector from downtown to the tile
 	RoadBits rcmd = ROAD_NONE;
 
 	switch (_patches.town_layout) {
@@ -849,32 +837,110 @@ static RoadBits GetTownRoadGridElement(Town* t, TileIndex tile, DiagDirection di
 }
 
 /**
- * Check there are enough neighbor house tiles next to the current tile
+ * Grows the town with an extra house.
+ *  Check if there are enough neighbor house tiles
+ *  next to the current tile. If there are enough
+ *  add another house.
  *
- * @param tile current tile
- * @return true if there are more than 2 house tiles next
- *  to the current one
+ * @param t The current town
+ * @param tile The target tile for the extra house
+ * @return true if an extra house has been added
  */
-static bool AreNeighborsHouseTiles(TileIndex tile)
+static bool GrowTownWithExtraHouse(Town *t, TileIndex tile)
 {
-	uint counter = 0; ///< counts the house neighbor tiles
-
 	/* We can't look further than that. */
-	if (TileX(tile) < 1 || TileY(tile) < 1) {
-		return false;
+	if (TileX(tile) < 2 || TileY(tile) < 2 || MapMaxX() <= TileX(tile) || MapMaxY() <= TileY(tile)) return false;
+
+	uint counter = 0; // counts the house neighbor tiles
+
+	/* Check the tiles E,N,W and S of the current tile for houses */
+	for (DiagDirection dir = DIAGDIR_BEGIN; dir < DIAGDIR_END; dir++) {
+
+		if (IsTileType(TileAddByDiagDir(tile, dir), MP_HOUSE)) counter++;
+
+		/* If there are enough neighbors stop here */
+		if (counter >= 3) {
+			if (BuildTownHouse(t, tile)) {
+				_grow_town_result = -1;
+				return true;
+			}
+			return false;
+		}
+	}
+	return false;
+}
+
+/**
+ * Grows the town with a road piece.
+ *
+ * @param t The current town
+ * @param tile The current tile
+ * @param rcmd The RoadBits we want to build on the tile
+ * @return true if the RoadBits have been added else false
+ */
+static bool GrowTownWithRoad(const Town *t, TileIndex tile, RoadBits rcmd)
+{
+	if (CmdSucceeded(DoCommand(tile, rcmd, t->index, DC_EXEC | DC_AUTO | DC_NO_WATER, CMD_BUILD_ROAD))) {
+		_grow_town_result = -1;
+		return true;
+	}
+	return false;
+}
+
+/**
+ * Grows the town with a bridge.
+ *  At first we check if a bridge is reasonable.
+ *  If so we check if we are able to build it.
+ *
+ * @param t The current town
+ * @param tile The current tile
+ * @param rcmd The RoadBits which are possible on this tile
+ * @return true if a bridge has been build else false
+ */
+static bool GrowTownWithBridge(const Town *t, TileIndex tile, RoadBits rcmd)
+{
+	DiagDirection bridge_dir; // The direction of a bridge we maybe want to build
+
+	/* Determine direction of slope,
+	 *  and build a road if not a special slope. */
+	switch (GetTileSlope(tile, NULL)) {
+		case SLOPE_SW: bridge_dir = DIAGDIR_NE; break;
+		case SLOPE_SE: bridge_dir = DIAGDIR_NW; break;
+		case SLOPE_NW: bridge_dir = DIAGDIR_SE; break;
+		case SLOPE_NE: bridge_dir = DIAGDIR_SW; break;
+
+		default: return false;
 	}
 
-	/* Check the tiles E,N,W and S of the current tile. */
-	for (DiagDirection i = DIAGDIR_BEGIN; i < DIAGDIR_END; i++) {
-		if (IsTileType(AddDiagDirToTileIndex(tile, i), MP_HOUSE)) {
-			counter++;
+	/* Check if the bridge will be compatible to the RoadBits */
+	if (!(rcmd & DiagDirToRoadBits(ReverseDiagDir(bridge_dir)))) return false;
+
+	/* We are in the right direction */
+	uint32 bridge_length = 0;     // This value stores the length of the possible bridge
+	TileIndex bridge_tile = tile; // Used to store the other waterside
+
+	do {
+		if (bridge_length++ >= 11) {
+			/* Max 11 tile long bridges */
+			return false;
 		}
+		bridge_tile = TILE_MASK(bridge_tile + TileOffsByDiagDir(bridge_dir));
+	} while (IsClearWaterTile(bridge_tile));
 
-		/* If there are enougth neighbor's stop it here */
-		if (counter >= 3) {
+	/* no water tiles in between? */
+	if (bridge_length == 1) return false;
+
+	for (uint8 times = 0; times <= 22; times++) {
+		byte bridge_type = RandomRange(MAX_BRIDGES - 1);
+
+		/* Can we actually build the bridge? */
+		if (CmdSucceeded(DoCommand(tile, bridge_tile, bridge_type | ((0x80 | ROADTYPES_ROAD) << 8), DC_AUTO, CMD_BUILD_BRIDGE))) {
+			DoCommand(tile, bridge_tile, bridge_type | ((0x80 | ROADTYPES_ROAD) << 8), DC_EXEC | DC_AUTO, CMD_BUILD_BRIDGE);
+			_grow_town_result--;
 			return true;
 		}
 	}
+	/* Quit if it selecting an appropiate bridge type fails a large number of times. */
 	return false;
 }
 
@@ -882,25 +948,24 @@ static bool AreNeighborsHouseTiles(TileIndex tile)
  * Grows the given town.
  * There are at the moment 3 possible way's for
  * the town expansion:
- * @li Generate a random tile and check if there is a road allowed
- * 	@li TL_ORIGINAL
- * 	@li TL_BETTER_ROADS
- * @li Check if the town geometry allows a road and which one
- * 	@li TL_2X2_GRID
- * 	@li TL_3X3_GRID
- * @li Forbid roads, only build houses
- * 	@li TL_NO_ROADS
+ *  @li Generate a random tile and check if there is a road allowed
+ *  @li TL_ORIGINAL
+ *  @li TL_BETTER_ROADS
+ *  @li Check if the town geometry allows a road and which one
+ *  @li TL_2X2_GRID
+ *  @li TL_3X3_GRID
+ *  @li Forbid roads, only build houses
+ *  @li TL_NO_ROADS
  *
  * @param tile_ptr The current tile
  * @param cur_rb The current tiles RoadBits
  * @param target_dir The target road dir
  * @param t1 The current town
  */
-static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection target_dir, Town* t1)
+static void GrowTownInTile(TileIndex *tile_ptr, RoadBits cur_rb, DiagDirection target_dir, Town *t1)
 {
-	RoadBits rcmd = ROAD_NONE;  ///< RoadBits for the road construction command
-	TileIndex tmptile;          ///< Dummy tile for various things
-	TileIndex tile = *tile_ptr; ///< The main tile on which we base our growth
+	RoadBits rcmd = ROAD_NONE;  // RoadBits for the road construction command
+	TileIndex tile = *tile_ptr; // The main tile on which we base our growth
 
 	TILE_ASSERT(tile);
 
@@ -936,14 +1001,14 @@ static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection t
 					do target_dir = RandomDiagDir(); while (target_dir == source_dir);
 				}
 
-				if (!IsRoadAllowedHere(AddDiagDirToTileIndex(tile, target_dir), target_dir)) {
+				if (!IsRoadAllowedHere(TileAddByDiagDir(tile, target_dir), target_dir)) {
 					/* A road is not allowed to continue the randomized road,
 					 *  return if the road we're trying to build is curved. */
 					if (target_dir != ReverseDiagDir(source_dir)) return;
 
 					/* Return if neither side of the new road is a house */
-					if (!IsTileType(AddDiagDirToTileIndex(tile, ChangeDiagDir(target_dir, DIAGDIRDIFF_90RIGHT)), MP_HOUSE) &&
-							!IsTileType(AddDiagDirToTileIndex(tile, ChangeDiagDir(target_dir, DIAGDIRDIFF_90LEFT)), MP_HOUSE)) {
+					if (!IsTileType(TileAddByDiagDir(tile, ChangeDiagDir(target_dir, DIAGDIRDIFF_90RIGHT)), MP_HOUSE) &&
+							!IsTileType(TileAddByDiagDir(tile, ChangeDiagDir(target_dir, DIAGDIRDIFF_90LEFT)), MP_HOUSE)) {
 						return;
 					}
 
@@ -955,7 +1020,7 @@ static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection t
 				break;
 		}
 
-	} else if (target_dir < (DiagDirection)5 && !(cur_rb & DiagDirToRoadBits(ReverseDiagDir(target_dir)))) {
+	} else if (target_dir < DIAGDIR_END && !(cur_rb & DiagDirToRoadBits(ReverseDiagDir(target_dir)))) {
 		/* Continue building on a partial road.
 		 * Should be allways OK, so we only generate
 		 * the fitting RoadBits */
@@ -978,8 +1043,7 @@ static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection t
 				break;
 		}
 	} else {
-		bool allow_house = false; ///< Value which decides if we want to construct a house
-		TileIndex tmptile2;       ///< Yet another dummy tile
+		bool allow_house = false; // Value which decides if we want to construct a house
 
 		/* Reached a tunnel/bridge? Then continue at the other side of it. */
 		if (IsTileType(tile, MP_TUNNELBRIDGE)) {
@@ -997,10 +1061,10 @@ static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection t
 		if (cur_rb & DiagDirToRoadBits(target_dir)) return;
 
 		/* This is the tile we will reach if we extend to this direction. */
-		tmptile = AddDiagDirToTileIndex(tile, target_dir);
+		TileIndex house_tile = TileAddByDiagDir(tile, target_dir); // position of a possible house
 
 		/* Don't walk into water. */
-		if (IsClearWaterTile(tmptile)) return;
+		if (IsClearWaterTile(house_tile)) return;
 
 		switch (_patches.town_layout) {
 			default: NOT_REACHED();
@@ -1010,41 +1074,35 @@ static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection t
 				break;
 
 			case TL_3X3_GRID: /* Use 2x2 grid afterwards! */
-				/* Fill gap if house has enougth neighbors */
-				tmptile2 = AddDiagDirToTileIndex(tmptile, target_dir);
-				if (AreNeighborsHouseTiles(tmptile2) && BuildTownHouse(t1, tmptile2)) {
-					_grow_town_result = -1;
-				}
+				GrowTownWithExtraHouse(t1, TileAddByDiagDir(house_tile, target_dir));
+				/* FALL THROUGH */
 
 			case TL_2X2_GRID:
-				rcmd = GetTownRoadGridElement(t1, tmptile, target_dir);
+				rcmd = GetTownRoadGridElement(t1, house_tile, target_dir);
 				allow_house = (rcmd == ROAD_NONE);
 				break;
 
 			case TL_BETTER_ROADS: /* Use original afterwards! */
-				/* Fill gap if house has enougth neighbors */
-				tmptile2 = AddDiagDirToTileIndex(tmptile, target_dir);
-				if (AreNeighborsHouseTiles(tmptile2) && BuildTownHouse(t1, tmptile2)) {
-					_grow_town_result = -1;
-				}
+				GrowTownWithExtraHouse(t1, TileAddByDiagDir(house_tile, target_dir));
+				/* FALL THROUGH */
 
 			case TL_ORIGINAL:
 				 /* Allow a house at the edge. 60% chance or
 				  * always ok if no road allowed. */
 				rcmd = DiagDirToRoadBits(target_dir);
-				allow_house = (!IsRoadAllowedHere(tmptile, target_dir) || CHANCE16(6, 10));
+				allow_house = (!IsRoadAllowedHere(house_tile, target_dir) || CHANCE16(6, 10));
 				break;
 		}
 
 		if (allow_house) {
 			/* Build a house, but not if there already is a house there. */
-			if (!IsTileType(tmptile, MP_HOUSE)) {
+			if (!IsTileType(house_tile, MP_HOUSE)) {
 				/* Level the land if possible */
-				LevelTownLand(tmptile);
+				LevelTownLand(house_tile);
 
 				/* And build a house.
 				 * Set result to -1 if we managed to build it. */
-				if (BuildTownHouse(t1, tmptile)) {
+				if (BuildTownHouse(t1, house_tile)) {
 					_grow_town_result = -1;
 				}
 			}
@@ -1057,51 +1115,13 @@ static void GrowTownInTile(TileIndex* tile_ptr, RoadBits cur_rb, DiagDirection t
 	/* Return if a water tile */
 	if (IsClearWaterTile(tile)) return;
 
-	DiagDirection bridge_dir; ///< The direction of a bridge we maybe want to build
-	/* Determine direction of slope,
-	 *  and build a road if not a special slope. */
-	switch (GetTileSlope(tile, NULL)) {
-		case SLOPE_SW: bridge_dir = DIAGDIR_NE; break;
-		case SLOPE_SE: bridge_dir = DIAGDIR_NW; break;
-		case SLOPE_NW: bridge_dir = DIAGDIR_SE; break;
-		case SLOPE_NE: bridge_dir = DIAGDIR_SW; break;
-
-		default:
-build_road_and_exit:
-			if (CmdSucceeded(DoCommand(tile, rcmd, t1->index, DC_EXEC | DC_AUTO | DC_NO_WATER, CMD_BUILD_ROAD))) {
-				_grow_town_result = -1;
-			}
-			return;
-	}
+	/* Make the roads look nicer */
+	rcmd = CleanUpRoadBits(tile, rcmd);
+	if (rcmd == ROAD_NONE) return;
 
-	/* Check if the bridge is in the right direction */
-	if (!(rcmd & DiagDirToRoadBits(bridge_dir))) goto build_road_and_exit;
+	if (GrowTownWithBridge(t1, tile, rcmd)) return;
 
-	/* We are in the right direction */
-	uint32 bridge_length = 0; ///< This value stores the length of the possible bridge
-	tmptile = tile;           ///< Now we use this dummy to store the other waterside
-	do {
-		if (bridge_length++ >= 11) {
-			/* Max 11 tile long bridges */
-			goto build_road_and_exit;
-		}
-		tmptile = TILE_MASK(tmptile + TileOffsByDiagDir(bridge_dir));
-	} while (IsClearWaterTile(tmptile));
-
-	/* no water tiles in between? */
-	if (bridge_length == 1) goto build_road_and_exit;
-
-	for (uint times = 0; times <= 22; times++) {
-		byte bridge_type = RandomRange(MAX_BRIDGES - 1);
-
-		/* Can we actually build the bridge? */
-		if (CmdSucceeded(DoCommand(tile, tmptile, bridge_type | ((0x80 | ROADTYPES_ROAD) << 8), DC_AUTO, CMD_BUILD_BRIDGE))) {
-			DoCommand(tile, tmptile, bridge_type | ((0x80 | ROADTYPES_ROAD) << 8), DC_EXEC | DC_AUTO, CMD_BUILD_BRIDGE);
-			_grow_town_result = -1;
-			return;
-		}
-	}
-	/* Quit if it selecting an appropiate bridge type fails a large number of times. */
+	GrowTownWithRoad(t1, tile, rcmd);
 }
 
 /** Returns "growth" if a house was built, or no if the build failed.
@@ -1114,7 +1134,7 @@ static int GrowTownAtRoad(Town *t, TileIndex tile)
 	/* Special case.
 	 * @see GrowTownInTile Check the else if
 	 */
-	DiagDirection target_dir = (DiagDirection)5; ///< The direction in which we want to extend the town
+	DiagDirection target_dir = DIAGDIR_END; // The direction in which we want to extend the town
 
 	TILE_ASSERT(tile);
 
@@ -1137,7 +1157,7 @@ static int GrowTownAtRoad(Town *t, TileIndex tile)
 	}
 
 	do {
-		RoadBits cur_rb = GetTownRoadBits(tile); ///< The RoadBits of the current tile
+		RoadBits cur_rb = GetTownRoadBits(tile); // The RoadBits of the current tile
 
 		/* Try to grow the town from this point */
 		GrowTownInTile(&tile, cur_rb, target_dir, t);
@@ -1151,7 +1171,7 @@ static int GrowTownAtRoad(Town *t, TileIndex tile)
 		/* Select a random bit from the blockmask, walk a step
 		 * and continue the search from there. */
 		do target_dir = RandomDiagDir(); while (!(cur_rb & DiagDirToRoadBits(target_dir)));
-		tile = AddDiagDirToTileIndex(tile, target_dir);
+		tile = TileAddByDiagDir(tile, target_dir);
 
 		if (IsTileType(tile, MP_ROAD)) {
 			/* Don't allow building over roads of other cities */
@@ -1220,7 +1240,7 @@ static bool GrowTown(Town *t)
 	PlayerID old_player = _current_player;
 	_current_player = OWNER_TOWN;
 
-	TileIndex tile = t->xy; ///< The tile we are working with ATM
+	TileIndex tile = t->xy; // The tile we are working with ATM
 
 	/* Find a road that we can base the construction on. */
 	for (ptr = _town_coord_mod; ptr != endof(_town_coord_mod); ++ptr) {
@@ -2110,8 +2130,8 @@ static void UpdateTownGrowRate(Town *t)
 	/** Towns are processed every TOWN_GROWTH_FREQUENCY ticks, and this is the
 	 * number of times towns are processed before a new building is built. */
 	static const uint16 _grow_count_values[2][6] = {
-		{ 120, 120, 120, 100,  80,  60 }, ///< Fund new buildings has been activated
-		{ 320, 420, 300, 220, 160, 100 }  ///< Normal values
+		{ 120, 120, 120, 100,  80,  60 }, // Fund new buildings has been activated
+		{ 320, 420, 300, 220, 160, 100 }  // Normal values
 	};
 
 	if (t->fund_buildings_months != 0) {
@@ -2252,9 +2272,9 @@ void ChangeTownRating(Town *t, int add, int max)
 /* penalty for removing town-owned stuff */
 static const int _default_rating_settings [3][3] = {
 	/* ROAD_REMOVE, TUNNELBRIDGE_REMOVE, INDUSTRY_REMOVE */
-	{  0, 128, 384}, ///< Permissive
-	{ 48, 192, 480}, ///< Neutral
-	{ 96, 384, 768}, ///< Hostile
+	{  0, 128, 384}, // Permissive
+	{ 48, 192, 480}, // Neutral
+	{ 96, 384, 768}, // Hostile
 };
 
 bool CheckforTownRating(uint32 flags, Town *t, byte type)
diff --git a/src/variables.h b/src/variables.h
index 5fbd6ee26..0b385bb73 100644
--- a/src/variables.h
+++ b/src/variables.h
@@ -242,6 +242,8 @@ struct Patches {
 	bool timetable_in_ticks; ///< Whether to show the timetable in ticks rather than days.
 
 	bool autoslope;          ///< Allow terraforming under things.
+
+	bool mod_road_rebuild;   ///< Roadworks remove unneccesary RoadBits
 };
 
 VARDEF Patches _patches;