Add a setting to turn off road vehicle slowdown in curves

Prior to this change, road vehicles would always slowdown in curves. This forces the player to build grid like roads. With new height levels and more mountainous maps and in the absense of diagonal roads this causes unnecessary pain. It should be an option to turn this off, so mountainous maps and curvy roads are not punishing the player unnecessarily. Nobody wants to build grid like roads outside of towns.

src/lang/english.txt

@@ -1807,6 +1807,8 @@ STR_CONFIG_SETTING_NOSERVICE                                    :Disable servici
 STR_CONFIG_SETTING_NOSERVICE_HELPTEXT                           :When enabled, vehicles do not get serviced if they cannot break down
 STR_CONFIG_SETTING_WAGONSPEEDLIMITS                             :Enable wagon speed limits: {STRING2}
 STR_CONFIG_SETTING_WAGONSPEEDLIMITS_HELPTEXT                    :When enabled, also use speed limits of wagons for deciding the maximum speed of a train
+STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES                 :Road vehicles slow down in curves: {STRING2}
+STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES_HELPTEXT        :When enabled, road vehicles slow down in curves. (Only with realistic acceleration)
 STR_CONFIG_SETTING_DISABLE_ELRAILS                              :Disable electric rails: {STRING2}
 STR_CONFIG_SETTING_DISABLE_ELRAILS_HELPTEXT                     :Enabling this setting disables the requirement to electrify tracks to make electric engines run on them
 

src/roadveh_cmd.cpp

@@ -496,7 +496,10 @@ inline int RoadVehicle::GetCurrentMaxSpeed() const
 			if (this->state <= RVSB_TRACKDIR_MASK && IsReversingRoadTrackdir((Trackdir)this->state)) {
 				max_speed = this->gcache.cached_max_track_speed / 2;
 				break;
-			} else if ((u->direction & 1) == 0) {
+			}
+
+			// Are we in a curve and should slow down?
+			if (((u->direction & 1) == 0) && _settings_game.vehicle.slow_road_vehicles_in_curves) {
 				max_speed = this->gcache.cached_max_track_speed * 3 / 4;
 			}
 		}

src/settings_gui.cpp

@@ -1929,6 +1929,7 @@ static SettingsContainer &GetSettingsTree()
 				physics->Add(new SettingEntry("vehicle.plane_speed"));
 				physics->Add(new SettingEntry("vehicle.ship_collision_avoidance"));
 				physics->Add(new SettingEntry("vehicle.roadveh_articulated_overtaking"));
+				physics->Add(new SettingEntry("vehicle.slow_road_vehicles_in_curves"));
 			}
 
 			SettingsPage *routing = vehicles->Add(new SettingsPage(STR_CONFIG_SETTING_VEHICLES_ROUTING));

src/settings_type.h

@@ -570,6 +570,7 @@ struct VehicleSettings {
 	uint8  train_slope_steepness;            ///< Steepness of hills for trains when using realistic acceleration
 	uint8  roadveh_slope_steepness;          ///< Steepness of hills for road vehicles when using realistic acceleration
 	bool   wagon_speed_limits;               ///< enable wagon speed limits
+	bool   slow_road_vehicles_in_curves;     ///< Road vehicles slow down in curves.
 	bool   disable_elrails;                  ///< when true, the elrails are disabled
 	UnitID max_trains;                       ///< max trains in game per company
 	UnitID max_roadveh;                      ///< max trucks in game per company

src/table/settings.ini

@@ -1647,9 +1647,18 @@ strhelp  = STR_CONFIG_SETTING_WAGONSPEEDLIMITS_HELPTEXT
 proc     = UpdateConsists
 
 ;; vehicle.slow_road_vehicles_in_curves
-[SDT_NULL]
-length   = 1
+[SDT_XREF]
 extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_JOKERPP, SL_JOKER_1_25)
+xref     = ""vehicle.slow_road_vehicles_in_curves""
+
+[SDT_BOOL]
+base     = GameSettings
+var      = vehicle.slow_road_vehicles_in_curves
+def      = true
+str      = STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES
+strhelp  = STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES_HELPTEXT
+cat      = SC_BASIC
+patxname = ""slow_road_vehicles_in_curves.vehicle.slow_road_vehicles_in_curves""
 
 ;; vehicle.train_speed_adaption
 [SDT_NULL]