Add setting to limit length of continuous inclined roads built by towns

Default to max 4 tiles

src/lang/english.txt

@@ -2195,6 +2195,11 @@ STR_CONFIG_SETTING_TOWN_TUNNELS_FORBIDDEN                       :Forbidden
 STR_CONFIG_SETTING_TOWN_TUNNELS_ALLOWED_OBSTRUCTION             :Allowed only for small obstructions
 STR_CONFIG_SETTING_TOWN_TUNNELS_ALLOWED                         :Allowed
 
+STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE                          :Limit towns building continuous inclined roads: {STRING2}
+STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE_HELPTEXT                 :Limit the length of consecutive sloped road tiles which towns will build. This can be used to prevent towns from growing long straight road segments up or down mountain sides
+STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE_VALUE                    :{NUM} tile{P "" s}
+STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE_ZERO                     :No limit
+
 STR_CONFIG_SETTING_NOISE_LEVEL                                  :Allow town controlled noise level for airports: {STRING2}
 STR_CONFIG_SETTING_NOISE_LEVEL_HELPTEXT                         :With this setting disabled, there can be two airports in each town. With this setting enabled, the number of airports in a town is limited by the noise acceptance of the town, which depends on population and airport size and distance
 

src/road_cmd.cpp

@@ -494,7 +494,7 @@ extern const RoadBits _invalid_tileh_slopes_road[2][15] = {
 	}
 };
 
-static Foundation GetRoadFoundation(Slope tileh, RoadBits bits);
+Foundation GetRoadFoundation(Slope tileh, RoadBits bits);
 
 void NotifyRoadLayoutChangedIfTileNonLeaf(TileIndex tile, RoadTramType rtt, RoadBits present_bits)
 {
@@ -1831,7 +1831,7 @@ struct DrawRoadTileStruct {
  * @param bits The RoadBits part
  * @return The resulting Foundation
  */
-static Foundation GetRoadFoundation(Slope tileh, RoadBits bits)
+Foundation GetRoadFoundation(Slope tileh, RoadBits bits)
 {
 	/* Flat land and land without a road doesn't require a foundation */
 	if (tileh == SLOPE_FLAT || bits == ROAD_NONE) return FOUNDATION_NONE;

src/settings_gui.cpp

@@ -2192,6 +2192,7 @@ static SettingsContainer &GetSettingsTree()
 				towns->Add(new SettingEntry("economy.allow_town_roads"));
 				towns->Add(new SettingEntry("economy.allow_town_level_crossings"));
 				towns->Add(new SettingEntry("economy.town_build_tunnels"));
+				towns->Add(new SettingEntry("economy.town_max_road_slope"));
 				towns->Add(new SettingEntry("economy.found_town"));
 				towns->Add(new SettingEntry("economy.town_cargogen_mode"));
 				towns->Add(new SettingEntry("economy.town_cargo_scale_factor"));

src/settings_type.h

@@ -689,6 +689,7 @@ struct EconomySettings {
 	bool   sharing_payment_in_debt;          ///< allow fee payment for companies with more loan than money (switch off to prevent MP exploits)
 	bool   allow_town_level_crossings;       ///< towns are allowed to build level crossings
 	TownTunnelMode town_build_tunnels;       ///< if/when towns are allowed to build road tunnels
+	uint8  town_max_road_slope;              ///< maximum number of consecutive sloped road tiles which towns are allowed to build
 	int8   old_town_cargo_factor;            ///< old power-of-two multiplier for town (passenger, mail) generation. May be negative.
 	int16  town_cargo_scale_factor;          ///< scaled power-of-two multiplier for town (passenger, mail) generation. May be negative.
 	int16  industry_cargo_scale_factor;      ///< scaled power-of-two multiplier for primary industry generation. May be negative.

src/table/settings/settings.ini

@@ -949,6 +949,20 @@ strval   = STR_CONFIG_SETTING_TOWN_TUNNELS_FORBIDDEN
 cat      = SC_BASIC
 patxname = ""economy.town_build_tunnels""
 
+[SDT_VAR]
+var      = economy.town_max_road_slope
+type     = SLE_UINT8
+flags    = SF_GUI_0_IS_SPECIAL
+def      = 4
+min      = 0
+max      = 8
+interval = 1
+str      = STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE
+strhelp  = STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE_HELPTEXT
+strval   = STR_CONFIG_SETTING_TOWN_MAX_ROAD_SLOPE_VALUE
+cat      = SC_BASIC
+patxname = ""economy.town_max_road_slope""
+
 [SDT_XREF]
 xref     = ""economy.old_town_cargo_factor""
 extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_CHILLPP)

src/town_cmd.cpp

@@ -1592,6 +1592,35 @@ static void GrowTownInTile(TileIndex *tile_ptr, RoadBits cur_rb, DiagDirection t
 				break;
 		}
 
+		if (_settings_game.economy.town_max_road_slope > 0 && ((rcmd == ROAD_X) || (rcmd == ROAD_Y))) {
+			/* Limit consecutive sloped road tiles */
+
+			auto get_road_slope = [rcmd](TileIndex t) -> Slope {
+				Slope slope = GetTileSlope(t);
+				extern Foundation GetRoadFoundation(Slope tileh, RoadBits bits);
+				ApplyFoundationToSlope(GetRoadFoundation(slope, rcmd), &slope);
+				return slope;
+			};
+
+			const Slope slope = get_road_slope(tile);
+			if (slope != SLOPE_FLAT) {
+				const int delta = TileOffsByDiagDir(ReverseDiagDir(target_dir));
+				bool ok = false;
+				TileIndex t = tile;
+				for (uint i = 0; i < _settings_game.economy.town_max_road_slope; i++) {
+					t += delta;
+					if (!IsValidTile(t) || !IsNormalRoadTile(t) || GetRoadBits(t, RTT_ROAD) != rcmd || get_road_slope(t) != slope) {
+						ok = true;
+						break;
+					}
+				}
+				if (!ok) {
+					/* All tested tiles had the same incline, disallow road */
+					return;
+				}
+			}
+		}
+
 	} else if (target_dir < DIAGDIR_END && !(cur_rb & DiagDirToRoadBits(ReverseDiagDir(target_dir)))) {
 		/* Continue building on a partial road.
 		 * Should be always OK, so we only generate