Safer level crossings: add setting to improve RV level crossing safety.

docs/landscape.html

@@ -650,6 +650,7 @@
          <li>m5 bit 5: set if crossing lights are on</li>
          <li>m7 bits 4..0: <a href="#OwnershipInfo">owner</a> of the road type 0 (normal road)</li>
          <li>m5 bit 4: pbs reservation state</li>
+         <li style="color: blue">m5 bit 1: set if crossing is possibly occupied by a road vehicle</li>
         </ul>
        </li>
       </ul>

docs/landscape_grid.html

@@ -150,7 +150,7 @@ the array so you can quickly see what is used and what is not.
       <td class="bits">-inherit-</td>
       <td class="bits">XXXX XXXX</td>
       <td class="bits">-inherit-</td>
-      <td class="bits">XXXX<span class="free"> OOO</span>X</td>
+      <td class="bits">XXXX<span class="free"> OO</span><span class="used_p">P</span>X</td>
       <td class="bits"><span class="free">OO</span>XX X<span class="free">OOO</span></td>
       <td class="bits">XXXX XXXX</td>
     </tr>

src/lang/english.txt

@@ -1850,6 +1850,8 @@ STR_CONFIG_SETTING_QUERY_CAPTION                                :{WHITE}Change s
 
 STR_CONFIG_SETTING_ADJACENT_CROSSINGS                           :Close adjacent level crossings: {STRING2}
 STR_CONFIG_SETTING_ADJACENT_CROSSINGS_HELPTEXT                  :Closes all adjacent level crossings on parallel tracks whenever one or more is occupied
+STR_CONFIG_SETTING_SAFER_CROSSINGS                              :Safer level crossings: {STRING2}
+STR_CONFIG_SETTING_SAFER_CROSSINGS_HELPTEXT                     :Changes to level crossings to improve road vehicle safety
 
 STR_CONFIG_SETTING_PAY_FOR_REPAIR_VEHICLE                       :Pay for repairing vehicles: {STRING2}
 STR_CONFIG_SETTING_PAY_FOR_REPAIR_VEHICLE_HELPTEXT              :Pay for repairing vehicles which have broken down

src/pbs.cpp

@@ -125,6 +125,18 @@ bool TryReserveRailTrack(TileIndex tile, Track t, bool trigger_stations)
 
 		case MP_ROAD:
 			if (IsLevelCrossing(tile) && !HasCrossingReservation(tile)) {
+				if (_settings_game.vehicle.safer_crossings) {
+					if (IsCrossingOccupiedByRoadVehicle(tile)) return false;
+					if (_settings_game.vehicle.adjacent_crossings) {
+						const Axis axis = GetCrossingRoadAxis(tile);
+						for (TileIndex t = tile; IsLevelCrossingTile(t) && GetCrossingRoadAxis(t) == axis; t = TileAddByDiagDir(t, AxisToDiagDir(GetCrossingRoadAxis(t)))) {
+							if (IsCrossingOccupiedByRoadVehicle(t)) return false;
+						}
+						for (TileIndex t = tile; IsLevelCrossingTile(t) && GetCrossingRoadAxis(t) == axis; t = TileAddByDiagDir(t, ReverseDiagDir(AxisToDiagDir(GetCrossingRoadAxis(t))))) {
+							if (IsCrossingOccupiedByRoadVehicle(t)) return false;
+						}
+					}
+				}
 				SetCrossingReservation(tile, true);
 				UpdateLevelCrossing(tile, false);
 				return true;

src/road_cmd.cpp

@@ -1887,6 +1887,12 @@ static VehicleEnterTileStatus VehicleEnter_Road(Vehicle *v, TileIndex tile, int
 			break;
 		}
 
+		case ROAD_TILE_CROSSING: {
+			if (v->type != VEH_ROAD) break;
+			SetCrossingOccupiedByRoadVehicle(tile, true);
+			break;
+		}
+
 		default: break;
 	}
 	return VETSB_CONTINUE;

src/road_func.h

@@ -180,5 +180,6 @@ bool ValParamRoadType(const RoadType rt);
 RoadTypes GetCompanyRoadtypes(const CompanyID company);
 
 void UpdateLevelCrossing(TileIndex tile, bool sound = true);
+bool IsCrossingOccupiedByRoadVehicle(TileIndex t);
 
 #endif /* ROAD_FUNC_H */

src/road_map.h

@@ -402,21 +402,27 @@ static inline void SetCrossingBarred(TileIndex t, bool barred)
 }
 
 /**
- * Unbar a level crossing.
- * @param t The tile to change.
+ * Check if the level crossing is possibly occupied by road vehicle(s).
+ * @param t The tile to query.
+ * @pre IsLevelCrossing(t)
+ * @return True if the level crossing is marked as occupied. This may return false positives.
  */
-static inline void UnbarCrossing(TileIndex t)
+static inline bool IsCrossingPossiblyOccupiedByRoadVehicle(TileIndex t)
 {
-	SetCrossingBarred(t, false);
+	assert(IsLevelCrossing(t));
+	return HasBit(_m[t].m5, 1);
 }
 
 /**
- * Bar a level crossing.
- * @param t The tile to change.
+ * Set whether the level crossing is occupied by road vehicle(s).
+ * @param t The tile to modify.
+ * @param barred True if the crossing should be marked as occupied, false otherwise.
+ * @pre IsLevelCrossing(t)
  */
-static inline void BarCrossing(TileIndex t)
+static inline void SetCrossingOccupiedByRoadVehicle(TileIndex t, bool occupied)
 {
-	SetCrossingBarred(t, true);
+	assert(IsLevelCrossing(t));
+	SB(_m[t].m5, 1, 1, occupied ? 1 : 0);
 }
 
 /** Check if a road tile has snow/desert. */

src/saveload/afterload.cpp

@@ -3386,6 +3386,14 @@ bool AfterLoadGame()
 		_settings_game.economy.day_length_factor = 1;
 	}
 
+	if (SlXvIsFeatureMissing(XSLFI_SAFER_CROSSINGS)) {
+		for (TileIndex t = 0; t < map_size; t++) {
+			if (IsLevelCrossingTile(t)) {
+				SetCrossingOccupiedByRoadVehicle(t, EnsureNoRoadVehicleOnGround(t).Failed());
+			}
+		}
+	}
+
 	/* Road stops is 'only' updating some caches */
 	AfterLoadRoadStops();
 	AfterLoadLabelMaps();

src/saveload/extended_ver_sl.cpp

@@ -51,6 +51,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_TRACE_RESTRICT_OWNER,   XSCF_NULL,                1,   1, "tracerestrict_owner",       NULL, NULL, NULL        },
 	{ XSLFI_PROG_SIGS,              XSCF_NULL,                1,   1, "programmable_signals",      NULL, NULL, "SPRG"      },
 	{ XSLFI_ADJACENT_CROSSINGS,     XSCF_NULL,                1,   1, "adjacent_crossings",        NULL, NULL, NULL        },
+	{ XSLFI_SAFER_CROSSINGS,        XSCF_NULL,                1,   1, "safer_crossings",           NULL, NULL, NULL        },
 	{ XSLFI_DEPARTURE_BOARDS,       XSCF_IGNORABLE_UNKNOWN,   1,   1, "departure_boards",          NULL, NULL, NULL        },
 	{ XSLFI_TIMETABLES_START_TICKS, XSCF_NULL,                2,   2, "timetable_start_ticks",     NULL, NULL, NULL        },
 	{ XSLFI_TOWN_CARGO_ADJ,         XSCF_IGNORABLE_UNKNOWN,   2,   2, "town_cargo_adj",            NULL, NULL, NULL        },

src/saveload/extended_ver_sl.h

@@ -25,6 +25,7 @@ enum SlXvFeatureIndex {
 	XSLFI_TRACE_RESTRICT_OWNER,                   ///< Trace restrict: train owner test
 	XSLFI_PROG_SIGS,                              ///< programmable signals patch
 	XSLFI_ADJACENT_CROSSINGS,                     ///< Adjacent level crossings closure patch
+	XSLFI_SAFER_CROSSINGS,                        ///< Safer level crossings
 	XSLFI_DEPARTURE_BOARDS,                       ///< Departure boards patch, in ticks mode
 	XSLFI_TIMETABLES_START_TICKS,                 ///< Timetable start time is in ticks, instead of days (from departure boards patch)
 	XSLFI_TOWN_CARGO_ADJ,                         ///< Town cargo adjustment patch

src/settings_gui.cpp

@@ -1694,6 +1694,7 @@ static SettingsContainer &GetSettingsTree()
 			vehicles->Add(new SettingEntry("order.no_servicing_if_no_breakdowns"));
 			vehicles->Add(new SettingEntry("order.serviceathelipad"));
 			vehicles->Add(new SettingEntry("vehicle.adjacent_crossings"));
+			vehicles->Add(new SettingEntry("vehicle.safer_crossings"));
 		}
 
 		SettingsPage *limitations = main->Add(new SettingsPage(STR_CONFIG_SETTING_LIMITATIONS));

src/settings_type.h

@@ -515,6 +515,7 @@ struct VehicleSettings {
 	byte   road_side;                        ///< the side of the road vehicles drive on
 	uint8  plane_crashes;                    ///< number of plane crashes, 0 = none, 1 = reduced, 2 = normal
 	bool   adjacent_crossings;               ///< enable closing of adjacent level crossings
+	bool   safer_crossings;                  ///< enable safer level crossings
 	bool   improved_breakdowns;              ///< different types, chances and severities of breakdowns
 	bool   pay_for_repair;                   ///< pay for repairing vehicle
 	uint8  repair_cost;                      ///< cost of repairing vehicle

src/signal.cpp

@@ -400,6 +400,7 @@ static SigInfo ExploreSegment(Owner owner)
 				if (DiagDirToAxis(enterdir) == GetCrossingRoadAxis(tile)) continue; // different axis
 
 				if (!(info.flags & SF_TRAIN) && HasVehicleOnPos(tile, NULL, &TrainOnTileEnum)) info.flags |= SF_TRAIN;
+				if (_settings_game.vehicle.safer_crossings) info.flags |= SF_PBS;
 				tile += TileOffsByDiagDir(exitdir);
 				break;
 

src/table/settings.ini

@@ -3057,6 +3057,15 @@ strhelp  = STR_CONFIG_SETTING_ADJACENT_CROSSINGS_HELPTEXT
 cat      = SC_BASIC
 patxname = ""adjacent_crossings.vehicle.adjacent_crossings""
 
+[SDT_BOOL]
+base     = GameSettings
+var      = vehicle.safer_crossings
+def      = false
+str      = STR_CONFIG_SETTING_SAFER_CROSSINGS
+strhelp  = STR_CONFIG_SETTING_SAFER_CROSSINGS_HELPTEXT
+cat      = SC_BASIC
+patxname = ""safer_crossings.vehicle.safer_crossings""
+
 
 ;***************************************************************************
 ; Unsaved setting variables.

src/train_cmd.cpp

@@ -1866,6 +1866,20 @@ void UpdateLevelCrossing(TileIndex tile, bool sound)
 	}
 }
 
+/**
+ * Check if the level crossing is occupied by road vehicle(s).
+ * @param t The tile to query.
+ * @pre IsLevelCrossing(t)
+ * @return True if the level crossing is marked as occupied.
+ */
+bool IsCrossingOccupiedByRoadVehicle(TileIndex t)
+{
+	if (!IsCrossingPossiblyOccupiedByRoadVehicle(t)) return false;
+	const bool occupied = EnsureNoRoadVehicleOnGround(t).Failed();
+	SetCrossingOccupiedByRoadVehicle(t, occupied);
+	return occupied;
+}
+
 
 /**
  * Bars crossing and plays ding-ding sound if not barred already

src/vehicle.cpp

@@ -575,6 +575,40 @@ CommandCost EnsureNoVehicleOnGround(TileIndex tile)
 	return CommandCost();
 }
 
+/**
+ * Callback that returns 'real' vehicles lower or at height \c *(int*)data, for road vehicles.
+ * @param v Vehicle to examine.
+ * @param data Pointer to height data.
+ * @return \a v if conditions are met, else \c NULL.
+ */
+static Vehicle *EnsureNoRoadVehicleProcZ(Vehicle *v, void *data)
+{
+	int z = *(int*)data;
+
+	if (v->type != VEH_ROAD) return NULL;
+	if (v->z_pos > z) return NULL;
+
+	return v;
+}
+
+/**
+ * Ensure there is no road vehicle at the ground at the given position.
+ * @param tile Position to examine.
+ * @return Succeeded command (ground is free) or failed command (a vehicle is found).
+ */
+CommandCost EnsureNoRoadVehicleOnGround(TileIndex tile)
+{
+	int z = GetTileMaxPixelZ(tile);
+
+	/* Value v is not safe in MP games, however, it is used to generate a local
+	 * error message only (which may be different for different machines).
+	 * Such a message does not affect MP synchronisation.
+	 */
+	Vehicle *v = VehicleFromPos(tile, &z, &EnsureNoRoadVehicleProcZ, true);
+	if (v != NULL) return_cmd_error(STR_ERROR_ROAD_VEHICLE_IN_THE_WAY);
+	return CommandCost();
+}
+
 /** Procedure called for every vehicle found in tunnel/bridge in the hash map */
 static Vehicle *GetVehicleTunnelBridgeProc(Vehicle *v, void *data)
 {

src/vehicle_func.h

@@ -165,6 +165,7 @@ static inline uint32 GetCmdSendToDepot(const BaseVehicle *v)
 }
 
 CommandCost EnsureNoVehicleOnGround(TileIndex tile);
+CommandCost EnsureNoRoadVehicleOnGround(TileIndex tile);
 CommandCost EnsureNoTrainOnTrackBits(TileIndex tile, TrackBits track_bits);
 
 extern VehicleID _new_vehicle_id;