(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

1 files changed, 53 insertions, 9 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);
 	}