(svn r21471) -Change [FS#4153]: make building aqueducts behave more like building tunnels. They can't be built on flat (or foundationed) tiles, so there is at most one destination tile like there is only one for tunnels

3 files changed, 55 insertions, 10 deletions

diff --git a/src/dock_gui.cpp b/src/dock_gui.cpp
index a0c676a05..1bc769c13 100644
--- a/src/dock_gui.cpp
+++ b/src/dock_gui.cpp
@@ -28,6 +28,7 @@
 #include "company_base.h"
 #include "station_type.h"
 #include "hotkeys.h"
+#include "bridge.h"
 
 #include "table/sprites.h"
 #include "table/strings.h"
@@ -90,9 +91,46 @@ static void PlaceDocks_BuildRiver(TileIndex tile)
 	VpStartPlaceSizing(tile, VPM_X_AND_Y, DDSP_CREATE_RIVER);
 }
 
+/**
+ * Gets the other end of the aqueduct, if possible.
+ * @param tile_from     The begin tile for the aqueduct.
+ * @param [out] tile_to The tile till where to show a selection for the aqueduct.
+ * @return The other end of the aqueduct, or otherwise a tile in line with the aqueduct to cause the right error message.
+ */
+static TileIndex GetOtherAqueductEnd(TileIndex tile_from, TileIndex *tile_to = NULL)
+{
+	uint z;
+	DiagDirection dir = GetInclinedSlopeDirection(GetTileSlope(tile_from, &z));
+
+	/* If the direction isn't right, just return the next tile so the command
+	 * complains about the wrong slope instead of the ends not matching up.
+	 * Make sure the coordinate is always a valid tile within the map, so we
+	 * don't go "off" the map. That would cause the wrong error message. */
+	if (!IsValidDiagDirection(dir)) return TILE_ADDXY(tile_from, TileX(tile_from) > 2 ? -1 : 1, 0);
+
+	/* Direction the aqueduct is built to. */
+	TileIndexDiff offset = TileOffsByDiagDir(ReverseDiagDir(dir));
+	/* The maximum length of the aqueduct. */
+	int max_length = min(_settings_game.construction.longbridges ? MAX_BRIDGE_LENGTH_LONGBRIDGES : MAX_BRIDGE_LENGTH, DistanceFromEdgeDir(tile_from, ReverseDiagDir(dir)) - 1);
+
+	TileIndex endtile = tile_from;
+	for (int length = 0; IsValidTile(endtile) && TileX(endtile) != 0 && TileY(endtile) != 0; length++) {
+		endtile = TILE_ADD(endtile, offset);
+
+		if (length > max_length) break;
+
+		if (GetTileMaxZ(endtile) > z) {
+			if (tile_to != NULL) *tile_to = endtile;
+			break;
+		}
+	}
+
+	return endtile;
+}
+
 static void PlaceDocks_Aqueduct(TileIndex tile)
 {
-	VpStartPlaceSizing(tile, VPM_X_OR_Y, DDSP_BUILD_BRIDGE);
+	DoCommandP(tile, GetOtherAqueductEnd(tile), TRANSPORT_WATER << 15, CMD_BUILD_BRIDGE | CMD_MSG(STR_ERROR_CAN_T_BUILD_AQUEDUCT_HERE), CcBuildBridge);
 }
 
 
@@ -184,7 +222,7 @@ static void BuildDocksClick_River(Window *w)
   */
 static void BuildDocksClick_Aqueduct(Window *w)
 {
-	HandlePlacePushButton(w, DTW_BUILD_AQUEDUCT, SPR_CURSOR_AQUEDUCT, HT_RECT, PlaceDocks_Aqueduct);
+	HandlePlacePushButton(w, DTW_BUILD_AQUEDUCT, SPR_CURSOR_AQUEDUCT, HT_SPECIAL, PlaceDocks_Aqueduct);
 }
 
 
@@ -253,10 +291,6 @@ struct BuildDocksToolbarWindow : Window {
 	{
 		if (pt.x != -1) {
 			switch (select_proc) {
-				case DDSP_BUILD_BRIDGE:
-					if (!_settings_client.gui.persistent_buildingtools) ResetObjectToPlace();
-					DoCommandP(end_tile, start_tile, TRANSPORT_WATER << 15, CMD_BUILD_BRIDGE | CMD_MSG(STR_ERROR_CAN_T_BUILD_AQUEDUCT_HERE), CcBuildBridge);
-
 				case DDSP_DEMOLISH_AREA:
 					GUIPlaceProcDragXY(select_proc, start_tile, end_tile);
 					break;
@@ -284,9 +318,19 @@ struct BuildDocksToolbarWindow : Window {
 
 	virtual void OnPlacePresize(Point pt, TileIndex tile_from)
 	{
-		DiagDirection dir = GetInclinedSlopeDirection(GetTileSlope(tile_from, NULL));
-		TileIndex tile_to = (dir != INVALID_DIAGDIR ? TileAddByDiagDir(tile_from, ReverseDiagDir(dir)) : tile_from);
-		tile_from = this->last_clicked_widget == DTW_LOCK && dir != INVALID_DIAGDIR ? TileAddByDiagDir(tile_from, dir) : tile_from;
+		TileIndex tile_to = tile_from;
+
+		if (this->last_clicked_widget == DTW_BUILD_AQUEDUCT) {
+			GetOtherAqueductEnd(tile_from, &tile_to);
+		} else {
+			DiagDirection dir = GetInclinedSlopeDirection(GetTileSlope(tile_from, NULL));
+			if (IsValidDiagDirection(dir)) {
+				/* Locks and docks always select the tile "down" the slope. */
+				tile_to = TileAddByDiagDir(tile_from, ReverseDiagDir(dir));
+				/* Locks also select the tile "up" the slope. */
+				if (this->last_clicked_widget == DTW_LOCK) tile_from = TileAddByDiagDir(tile_from, dir);
+			}
+		}
 
 		VpSetPresizeRange(tile_from, tile_to);
 	}
diff --git a/src/lang/english.txt b/src/lang/english.txt
index 2732d7452..6a131e314 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -3668,6 +3668,7 @@ STR_ERROR_BRIDGE_TOO_LOW_FOR_TERRAIN                            :{WHITE}Bridge i
 STR_ERROR_START_AND_END_MUST_BE_IN                              :{WHITE}Start and end must be in line
 STR_ERROR_ENDS_OF_BRIDGE_MUST_BOTH                              :{WHITE}... ends of bridge must both be on land
 STR_ERROR_BRIDGE_TOO_LONG                                       :{WHITE}... bridge too long
+STR_ERROR_BRIDGE_THROUGH_MAP_BORDER                             :{WHITE}Bridge would end out of the map
 
 # Tunnel related errors
 STR_ERROR_CAN_T_BUILD_TUNNEL_HERE                               :{WHITE}Can't build tunnel here...
diff --git a/src/tunnelbridge_cmd.cpp b/src/tunnelbridge_cmd.cpp
index 6a4309445..f47708ce7 100644
--- a/src/tunnelbridge_cmd.cpp
+++ b/src/tunnelbridge_cmd.cpp
@@ -211,7 +211,7 @@ CommandCost CmdBuildBridge(TileIndex end_tile, DoCommandFlag flags, uint32 p1, u
 	/* unpack parameters */
 	BridgeType bridge_type = GB(p2, 0, 8);
 
-	if (!IsValidTile(p1)) return CMD_ERROR;
+	if (!IsValidTile(p1)) return_cmd_error(STR_ERROR_BRIDGE_THROUGH_MAP_BORDER);
 
 	TransportType transport_type = Extract<TransportType, 15, 2>(p2);