Feature: House placer mode to replace existing houses (#14469)

src/lang/english.txt

@@ -2880,10 +2880,11 @@ STR_HOUSE_PICKER_CLASS_ZONE3                                    :Outer Suburbs
 STR_HOUSE_PICKER_CLASS_ZONE4                                    :Inner Suburbs
 STR_HOUSE_PICKER_CLASS_ZONE5                                    :Town centre
 
-STR_HOUSE_PICKER_PROTECT_TITLE                                  :Prevent upgrades
+STR_HOUSE_PICKER_PROTECT                                        :Prevent upgrades
 STR_HOUSE_PICKER_PROTECT_TOOLTIP                                :Choose whether this house will be protected from replacement as the town grows
-STR_HOUSE_PICKER_PROTECT_OFF                                    :Off
+
-STR_HOUSE_PICKER_PROTECT_ON                                     :On
+STR_HOUSE_PICKER_REPLACE                                        :Replace existing
+STR_HOUSE_PICKER_REPLACE_TOOLTIP                                :Choose whether to automatically remove an existing house on the tile where this house is placed
 
 STR_STATION_CLASS_DFLT                                          :Default
 STR_STATION_CLASS_DFLT_STATION                                  :Default station

src/town_cmd.cpp

@@ -2932,9 +2932,10 @@ static bool TryBuildTownHouse(Town *t, TileIndex tile, TownExpandModes modes)
  * @param tile Tile on which to place the house.
  * @param HouseID The HouseID of the house spec.
  * @param is_protected Whether the house is protected from the town upgrading it.
+ * @param replace Whether to automatically demolish an existing house on this tile, if present.
  * @return Empty cost or an error.
  */
-CommandCost CmdPlaceHouse(DoCommandFlags flags, TileIndex tile, HouseID house, bool is_protected)
+CommandCost CmdPlaceHouse(DoCommandFlags flags, TileIndex tile, HouseID house, bool is_protected, bool replace)
 {
 	if (_game_mode != GM_EDITOR && _settings_game.economy.place_houses == PH_FORBIDDEN) return CMD_ERROR;
 
@@ -2944,39 +2945,45 @@ CommandCost CmdPlaceHouse(DoCommandFlags flags, TileIndex tile, HouseID house, b
 	const HouseSpec *hs = HouseSpec::Get(house);
 	if (!hs->enabled) return CMD_ERROR;
 
-	Town *t = ClosestTownFromTile(tile, UINT_MAX);
-
-	/* cannot build on these slopes... */
-	Slope slope = GetTileSlope(tile);
-	if (IsSteepSlope(slope)) return CommandCost(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
-
-	/* building under a bridge? */
-	if (IsBridgeAbove(tile)) return CommandCost(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
-
-	/* can we clear the land? */
-	CommandCost cost = Command<CMD_LANDSCAPE_CLEAR>::Do({DoCommandFlag::Auto, DoCommandFlag::NoWater}, tile);
-	if (!cost.Succeeded()) return cost;
-
 	int maxz = GetTileMaxZ(tile);
 
-	/* Make sure there is no slope? */
+	/* Check each tile of a multi-tile house. */
-	bool noslope = hs->building_flags.Test(BuildingFlag::NotSloped);
+	TileArea ta(tile, 1, 1);
-	if (noslope && slope != SLOPE_FLAT) return CommandCost(STR_ERROR_FLAT_LAND_REQUIRED);
-
-	TileArea ta = tile;
 	if (hs->building_flags.Test(BuildingFlag::Size2x2)) ta.Add(TileAddXY(tile, 1, 1));
 	if (hs->building_flags.Test(BuildingFlag::Size2x1)) ta.Add(TileAddByDiagDir(tile, DIAGDIR_SW));
 	if (hs->building_flags.Test(BuildingFlag::Size1x2)) ta.Add(TileAddByDiagDir(tile, DIAGDIR_SE));
 
-	/* Check additional tiles covered by this house. */
+	for (const TileIndex subtile : ta) {
-	for (const TileIndex &subtile : ta) {
+		/* Houses cannot be built on steep slopes. */
-		cost = Command<CMD_LANDSCAPE_CLEAR>::Do({DoCommandFlag::Auto, DoCommandFlag::NoWater}, subtile);
+		Slope slope = GetTileSlope(subtile);
-		if (!cost.Succeeded()) return cost;
+		if (IsSteepSlope(slope)) return CommandCost(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
 
-		if (!CheckBuildHouseSameZ(subtile, maxz, noslope)) return CommandCost(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
+		/* Houses cannot be built under bridges. */
+		if (IsBridgeAbove(subtile)) return CommandCost(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
+
+		/* Make sure there is no slope? */
+		bool noslope = hs->building_flags.Test(BuildingFlag::NotSloped);
+		if (noslope && slope != SLOPE_FLAT) return CommandCost(STR_ERROR_FLAT_LAND_REQUIRED);
+
+		/* All tiles of a multi-tile house must have the same z-level. */
+		if (GetTileMaxZ(subtile) != maxz) return CommandCost(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
+
+		/* We might be replacing an existing house, otherwise check if we can clear land. */
+		if (!(replace && GetTileType(subtile) == MP_HOUSE)) {
+			CommandCost cost = Command<CMD_LANDSCAPE_CLEAR>::Do({DoCommandFlag::Auto, DoCommandFlag::NoWater}, subtile);
+			if (!cost.Succeeded()) return cost;
+		}
 	}
 
 	if (flags.Test(DoCommandFlag::Execute)) {
+		/* If replacing, clear any existing houses first. */
+		if (replace) {
+			for (const TileIndex &subtile : ta) {
+				if (GetTileType(subtile) == MP_HOUSE) ClearTownHouse(Town::GetByTile(subtile), subtile);
+			}
+		}
+
+		Town *t = ClosestTownFromTile(tile, UINT_MAX);
 		bool house_completed = _settings_game.economy.place_houses == PH_ALLOWED_CONSTRUCTED;
 		BuildTownHouse(t, tile, hs, house, Random(), house_completed, is_protected);
 	}

src/town_cmd.h

@@ -27,7 +27,7 @@ CommandCost CmdTownCargoGoal(DoCommandFlags flags, TownID town_id, TownAcceptanc
 CommandCost CmdTownSetText(DoCommandFlags flags, TownID town_id, const EncodedString &text);
 CommandCost CmdExpandTown(DoCommandFlags flags, TownID town_id, uint32_t grow_amount, TownExpandModes modes);
 CommandCost CmdDeleteTown(DoCommandFlags flags, TownID town_id);
-CommandCost CmdPlaceHouse(DoCommandFlags flags, TileIndex tile, HouseID house, bool house_protected);
+CommandCost CmdPlaceHouse(DoCommandFlags flags, TileIndex tile, HouseID house, bool house_protected, bool replace);
 
 DEF_CMD_TRAIT(CMD_FOUND_TOWN,       CmdFoundTown,      CommandFlags({CommandFlag::Deity, CommandFlag::NoTest}),  CommandType::LandscapeConstruction) // founding random town can fail only in exec run
 DEF_CMD_TRAIT(CMD_RENAME_TOWN,      CmdRenameTown,     CommandFlags({CommandFlag::Deity, CommandFlag::Server}),  CommandType::OtherManagement)

src/town_gui.cpp

@@ -1645,6 +1645,7 @@ static CargoTypes GetProducedCargoOfHouse(const HouseSpec *hs)
 struct BuildHouseWindow : public PickerWindow {
 	std::string house_info{};
 	static inline bool house_protected;
+	static inline bool replace;
 
 	BuildHouseWindow(WindowDesc &desc, Window *parent) : PickerWindow(desc, parent, 0, HousePickerCallbacks::instance)
 	{
@@ -1749,11 +1750,17 @@ struct BuildHouseWindow : public PickerWindow {
 	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		switch (widget) {
-			case WID_BH_PROTECT_OFF:
+			case WID_BH_PROTECT_TOGGLE:
-			case WID_BH_PROTECT_ON:
+				BuildHouseWindow::house_protected = !BuildHouseWindow::house_protected;
-				BuildHouseWindow::house_protected = (widget == WID_BH_PROTECT_ON);
+				this->SetWidgetLoweredState(WID_BH_PROTECT_TOGGLE, BuildHouseWindow::house_protected);
-				this->SetWidgetLoweredState(WID_BH_PROTECT_OFF, !BuildHouseWindow::house_protected);
+
-				this->SetWidgetLoweredState(WID_BH_PROTECT_ON, BuildHouseWindow::house_protected);
+				SndClickBeep();
+				this->SetDirty();
+				break;
+
+			case WID_BH_REPLACE_TOGGLE:
+				BuildHouseWindow::replace = !BuildHouseWindow::replace;
+				this->SetWidgetLoweredState(WID_BH_REPLACE_TOGGLE, BuildHouseWindow::replace);
 
 				SndClickBeep();
 				this->SetDirty();
@@ -1782,17 +1789,16 @@ struct BuildHouseWindow : public PickerWindow {
 		bool hasflag = spec->extra_flags.Test(HouseExtraFlag::BuildingIsProtected);
 		if (hasflag) BuildHouseWindow::house_protected = true;
 
-		this->SetWidgetLoweredState(WID_BH_PROTECT_OFF, !BuildHouseWindow::house_protected);
+		this->SetWidgetLoweredState(WID_BH_PROTECT_TOGGLE, BuildHouseWindow::house_protected);
-		this->SetWidgetLoweredState(WID_BH_PROTECT_ON, BuildHouseWindow::house_protected);
+		this->SetWidgetLoweredState(WID_BH_REPLACE_TOGGLE, BuildHouseWindow::replace);
 
-		this->SetWidgetDisabledState(WID_BH_PROTECT_OFF, hasflag);
+		this->SetWidgetDisabledState(WID_BH_PROTECT_TOGGLE, hasflag);
-		this->SetWidgetDisabledState(WID_BH_PROTECT_ON, hasflag);
 	}
 
 	void OnPlaceObject([[maybe_unused]] Point pt, TileIndex tile) override
 	{
 		const HouseSpec *spec = HouseSpec::Get(HousePickerCallbacks::sel_type);
-		Command<CMD_PLACE_HOUSE>::Post(STR_ERROR_CAN_T_BUILD_HOUSE, CcPlaySound_CONSTRUCTION_OTHER, tile, spec->Index(), BuildHouseWindow::house_protected);
+		Command<CMD_PLACE_HOUSE>::Post(STR_ERROR_CAN_T_BUILD_HOUSE, CcPlaySound_CONSTRUCTION_OTHER, tile, spec->Index(), BuildHouseWindow::house_protected, BuildHouseWindow::replace);
 	}
 
 	const IntervalTimer<TimerWindow> view_refresh_interval = {std::chrono::milliseconds(2500), [this](auto) {
@@ -1822,14 +1828,10 @@ static constexpr std::initializer_list<NWidgetPart> _nested_build_house_widgets
 			NWidget(WWT_PANEL, COLOUR_DARK_GREEN),
 				NWidget(NWID_VERTICAL), SetPIP(0, WidgetDimensions::unscaled.vsep_picker, 0), SetPadding(WidgetDimensions::unscaled.picker),
 					NWidget(WWT_EMPTY, INVALID_COLOUR, WID_BH_INFO), SetFill(1, 1), SetMinimalTextLines(10, 0),
-					NWidget(WWT_LABEL, INVALID_COLOUR), SetStringTip(STR_HOUSE_PICKER_PROTECT_TITLE, STR_NULL), SetFill(1, 0),
+					NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_BH_PROTECT_TOGGLE), SetMinimalSize(60, 12), SetStringTip(STR_HOUSE_PICKER_PROTECT, STR_HOUSE_PICKER_PROTECT_TOOLTIP),
-					NWidget(NWID_HORIZONTAL), SetPIPRatio(1, 0, 1),
+					NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_BH_REPLACE_TOGGLE), SetMinimalSize(60, 12), SetStringTip(STR_HOUSE_PICKER_REPLACE, STR_HOUSE_PICKER_REPLACE_TOOLTIP),
-						NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_BH_PROTECT_OFF), SetMinimalSize(60, 12), SetStringTip(STR_HOUSE_PICKER_PROTECT_OFF, STR_HOUSE_PICKER_PROTECT_TOOLTIP),
-						NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_BH_PROTECT_ON), SetMinimalSize(60, 12), SetStringTip(STR_HOUSE_PICKER_PROTECT_ON, STR_HOUSE_PICKER_PROTECT_TOOLTIP),
-					EndContainer(),
 				EndContainer(),
 			EndContainer(),
-
 		EndContainer(),
 		NWidgetFunction(MakePickerTypeWidgets),
 	EndContainer(),

src/widgets/town_widget.h

@@ -78,8 +78,8 @@ enum TownFoundingWidgets : WidgetID {
 /** Widgets of the #BuildHouseWindow class. */
 enum BuildHouseWidgets : WidgetID {
 	WID_BH_INFO, ///< Information panel of selected house.
-	WID_BH_PROTECT_OFF, ///< Button to protect the next house built.
+	WID_BH_PROTECT_TOGGLE, ///< Button to toggle protecting the next house built.
-	WID_BH_PROTECT_ON, ///< Button to not protect the next house built.
+	WID_BH_REPLACE_TOGGLE, ///< Button to toggle replacing existing houses.
 };
 
 #endif /* WIDGETS_TOWN_WIDGET_H */