Improved breakdowns: Various changes and fixes.

* Revert breakdown_chance to (mostly) its original behaviour.
* Create a new breakdown_chance_factor to hold breakdown_chance
  from improved breakdowns logic.
* Revert airport crash probabilities back to original behaviour, with
  modified behaviour only during emergency landings.
* Low power breakdowns now only reduce the power of the engine which
  has broken down.
* Low power breakdowns no longer reduce speed directly.
* Add callback function to run whenever improved breakdowns setting
  is changed. Reset breakdown_chance_factor where required.
* More whitespace/formatting...

src/aircraft_cmd.cpp

@@ -308,7 +308,7 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, const Engine *
 		v->reliability_spd_dec = e->reliability_spd_dec;
 		/* higher speed means higher breakdown chance */
 		/* to somewhat compensate for the fact that fast aircraft spend less time in the air */
-		v->breakdown_chance = Clamp(64 + (AircraftVehInfo(v->engine_type)->max_speed >> 3), 0, 255);
+		v->breakdown_chance_factor = Clamp(64 + (AircraftVehInfo(v->engine_type)->max_speed >> 3), 0, 255);
 		v->max_age = e->GetLifeLengthInDays();
 
 		_new_vehicle_id = v->index;
@@ -1333,18 +1333,18 @@ static void MaybeCrashAirplane(Aircraft *v)
 	Station *st = Station::Get(v->targetairport);
 
 	/* FIXME -- MaybeCrashAirplane -> increase crashing chances of very modern airplanes on smaller than AT_METROPOLITAN airports */
-	uint32 prob = (_settings_game.vehicle.improved_breakdowns && _settings_game.difficulty.vehicle_breakdowns) ?
+	uint32 prob = (0x4000 << _settings_game.vehicle.plane_crashes);
-            0x10000 / 10000 : 0x4000 << _settings_game.vehicle.plane_crashes;
 
 	if ((st->airport.GetFTA()->flags & AirportFTAClass::SHORT_STRIP) &&
 			(AircraftVehInfo(v->engine_type)->subtype & AIR_FAST) &&
 			!_cheats.no_jetcrash.value) {
 		prob /= 20;
-	} else if (!_settings_game.vehicle.improved_breakdowns) {
+	} else {
 		prob /= 1500;
-	} else if (v->breakdown_ctr == 1 && v->breakdown_type == BREAKDOWN_AIRCRAFT_EM_LANDING) {
+	}
-                /* Airplanes that are attempting an emergency landing have a 2% chance to crash */
+	if (_settings_game.vehicle.improved_breakdowns && v->breakdown_ctr == 1 && v->breakdown_type == BREAKDOWN_AIRCRAFT_EM_LANDING) {
-		prob = 0x10000 / 50;
+		/* Airplanes that are attempting an emergency landing have a 2% chance to crash */
+		prob = max<uint32>(prob, 0x10000 / 50);
 	}
 
 	if (GB(Random(), 0, 22) > prob) return;

src/ground_vehicle.cpp

@@ -78,14 +78,15 @@ void GroundVehicle<T, Type>::CalculatePower(uint32& total_power, uint32& max_te,
 
 	for (const T *u = v; u != NULL; u = u->Next()) {
 		uint32 current_power = u->GetPower() + u->GetPoweredPartPower(u);
+
+		if (breakdowns && u->breakdown_ctr == 1 && u->breakdown_type == BREAKDOWN_LOW_POWER) {
+			current_power = current_power * u->breakdown_severity / 256;
+		}
+
 		total_power += current_power;
 
 		/* Only powered parts add tractive effort. */
 		if (current_power > 0) max_te += u->GetWeight() * u->GetTractiveEffort();
-
-		if (breakdowns && u->breakdown_ctr == 1 && u->breakdown_type == BREAKDOWN_LOW_POWER) {
-			total_power = total_power * u->breakdown_severity / 256;
-                }
 	}
 
 	max_te *= 10000; // Tractive effort in (tonnes * 1000 * 10 =) N.
@@ -138,7 +139,6 @@ int GroundVehicle<T, Type>::GetAcceleration()
 	 * and km/h to m/s conversion below result in a maxium of
 	 * about 1.1E11, way more than 4.3E9 of int32. */
 	int64 power = this->gcache.cached_power * 746ll;
-	uint32 max_te = this->gcache.cached_max_te; // [N]
 
 	/* This is constructed from:
 	 *  - axle resistance:  U16 power * 10 for 128 vehicles.
@@ -171,6 +171,7 @@ int GroundVehicle<T, Type>::GetAcceleration()
 	AccelStatus mode = v->GetAccelerationStatus();
 
 	/* handle breakdown power reduction */
+	uint32 max_te = this->gcache.cached_max_te; // [N]
 	if (Type == VEH_TRAIN && mode == AS_ACCEL && HasBit(Train::From(this)->flags, VRF_BREAKDOWN_POWER)) {
 		/* We'd like to cache this, but changing cached_power has too many unwanted side-effects */
 		uint32 power_temp;
@@ -219,9 +220,7 @@ int GroundVehicle<T, Type>::GetAcceleration()
 			breakdown_factor /= (Train::From(this)->tcache.cached_num_engines + 2);
 		}
 		/* breakdown_chance is at least 5 (5 / 128 = ~4% of the normal chance) */
-		this->breakdown_chance = max(breakdown_factor >> 16, (uint64)5);
+		this->breakdown_chance_factor = max(breakdown_factor >> 16, (uint64)5);
-	} else {
-		this->breakdown_chance = 128;
 	}
 
 	if (mode == AS_ACCEL) {
@@ -235,7 +234,7 @@ int GroundVehicle<T, Type>::GetAcceleration()
 		 * same (maximum) speed. */
 		int accel = ClampToI32((force - resistance) / (mass * 4));
 		accel = force < resistance ? min(-1, accel) : max(1, accel);
-		if (this->type == VEH_TRAIN ) {
+		if (this->type == VEH_TRAIN) {
 			if(_settings_game.vehicle.train_acceleration_model == AM_ORIGINAL &&
 					HasBit(Train::From(this)->flags, VRF_BREAKDOWN_POWER)) {
 				/* We need to apply the power reducation for non-realistic acceleration here */

src/ground_vehicle.hpp

@@ -370,22 +370,23 @@ protected:
 		uint spd = this->subspeed + accel;
 		this->subspeed = (byte)spd;
 
+		int tempmax = max_speed;
+
 		/* When we are going faster than the maximum speed, reduce the speed
 		 * somewhat gradually. But never lower than the maximum speed. */
-		int tempmax = ((this->breakdown_ctr == 1) ? this->cur_speed : max_speed);
-
 		if (this->breakdown_ctr == 1) {
 			if (this->breakdown_type == BREAKDOWN_LOW_POWER) {
-				if ((this->tick_counter & 0x7) == 0) {
+				if ((this->tick_counter & 0x7) == 0 && _settings_game.vehicle.train_acceleration_model == AM_ORIGINAL) {
 					if (this->cur_speed > (this->breakdown_severity * max_speed) >> 8) {
 						tempmax = this->cur_speed - (this->cur_speed / 10) - 1;
 					} else {
 						tempmax = (this->breakdown_severity * max_speed) >> 8;
 					}
 				}
-			}
+			} else if (this->breakdown_type == BREAKDOWN_LOW_SPEED) {
-			if (this->breakdown_type == BREAKDOWN_LOW_SPEED) {
 				tempmax = min(max_speed, this->breakdown_severity);
+			} else {
+				tempmax = this->cur_speed;
 			}
 		}
 

src/roadveh_cmd.cpp

@@ -298,7 +298,7 @@ CommandCost CmdBuildRoadVehicle(TileIndex tile, DoCommandFlag flags, const Engin
 
 		v->reliability = e->reliability;
 		v->reliability_spd_dec = e->reliability_spd_dec;
-		v->breakdown_chance = 128;
+		v->breakdown_chance_factor = 128;
 		v->max_age = e->GetLifeLengthInDays();
 		_new_vehicle_id = v->index;
 

src/saveload/afterload.cpp

@@ -2835,14 +2835,15 @@ bool AfterLoadGame()
 						v->reliability = min(v->First()->reliability, e->reliability);
 					}
 				}
+				/* FALL THROUGH */
 				case VEH_ROAD:
-					v->breakdown_chance = 128;
+					v->breakdown_chance_factor = 128;
 					break;
 				case VEH_SHIP:
-					v->breakdown_chance = 64;
+					v->breakdown_chance_factor = 64;
 					break;
 				case VEH_AIRCRAFT:
-					v->breakdown_chance = Clamp(64 + (AircraftVehInfo(v->engine_type)->max_speed >> 3), 0, 255);
+					v->breakdown_chance_factor = Clamp(64 + (AircraftVehInfo(v->engine_type)->max_speed >> 3), 0, 255);
 					v->breakdown_severity = 40;
 					break;
 				default: break;

src/saveload/vehicle_sl.cpp

@@ -671,6 +671,7 @@ const SaveLoad *GetVehicleDescription(VehicleType vt)
 		     SLE_VAR(Vehicle, breakdown_delay,       SLE_UINT8),
 		     SLE_VAR(Vehicle, breakdowns_since_last_service, SLE_UINT8),
 		     SLE_VAR(Vehicle, breakdown_chance,      SLE_UINT8),
+		 SLE_CONDVAR(Vehicle, breakdown_chance_factor, SLE_UINT8,              SL_IB, SL_MAX_VERSION),
 		 SLE_CONDVAR(Vehicle, breakdown_type,        SLE_UINT8,                SL_IB, SL_MAX_VERSION),
 		 SLE_CONDVAR(Vehicle, breakdown_severity,    SLE_UINT8,                SL_IB, SL_MAX_VERSION),
 		 SLE_CONDVAR(Vehicle, build_year,            SLE_FILE_U8 | SLE_VAR_I32,    0,  30),

src/settings.cpp

@@ -1020,7 +1020,7 @@ static bool RoadVehAccelerationModelChanged(int32 p1)
 		RoadVehicle *rv;
 		FOR_ALL_ROADVEHICLES(rv) {
 			if (rv->IsFrontEngine()) {
-				rv->breakdown_chance = 128;
+				rv->breakdown_chance_factor = 128;
 			}
 		}
 	}
@@ -1319,6 +1319,32 @@ static bool MaxVehiclesChanged(int32 p1)
 	return true;
 }
 
+static bool ImprovedBreakdownsSettingChanged(int32 p1)
+{
+	if (!_settings_game.vehicle.improved_breakdowns) return true;
+
+	Vehicle *v;
+	FOR_ALL_VEHICLES(v) {
+		switch(v->type) {
+			case VEH_TRAIN:
+				if (v->IsFrontEngine()) {
+					v->breakdown_chance_factor = 128;
+					Train::From(v)->UpdateAcceleration();
+				}
+				break;
+
+			case VEH_ROAD:
+				if (v->IsFrontEngine()) {
+					v->breakdown_chance_factor = 128;
+				}
+				break;
+
+			default:
+				break;
+		}
+	}
+	return true;
+}
 
 #ifdef ENABLE_NETWORK
 

src/ship_cmd.cpp

@@ -714,7 +714,7 @@ CommandCost CmdBuildShip(TileIndex tile, DoCommandFlag flags, const Engine *e, u
 
 		v->reliability = e->reliability;
 		v->reliability_spd_dec = e->reliability_spd_dec;
-		v->breakdown_chance = 64; // ships have a 50% lower breakdown chance than normal
+		v->breakdown_chance_factor = 64; // ships have a 50% lower breakdown chance than normal
 		v->max_age = e->GetLifeLengthInDays();
 		_new_vehicle_id = v->index;
 

src/table/settings.ini

@@ -42,6 +42,7 @@ static bool InvalidateCompanyInfrastructureWindow(int32 p1);
 static bool InvalidateCompanyWindow(int32 p1);
 static bool ZoomMinMaxChanged(int32 p1);
 static bool MaxVehiclesChanged(int32 p1);
+static bool ImprovedBreakdownsSettingChanged(int32 p1);
 
 #ifdef ENABLE_NETWORK
 static bool UpdateClientName(int32 p1);
@@ -1143,7 +1144,7 @@ from     = SL_IB
 guiflags = SGF_NO_NETWORK
 def      = false
 str      = STR_CONFIG_SETTING_IMPROVED_BREAKDOWNS
-
+proc     = ImprovedBreakdownsSettingChanged
 
 ; station.join_stations
 [SDT_NULL]

src/train.h

@@ -292,7 +292,7 @@ protected: // These functions should not be called outside acceleration code.
 	 */
 	inline AccelStatus GetAccelerationStatus() const
 	{
-		return (this->vehstatus & VS_STOPPED) || HasBit(this->flags, VRF_REVERSING) || HasBit(this->flags, VRF_TRAIN_STUCK ) || HasBit(this->flags, VRF_BREAKDOWN_BRAKING) ? AS_BRAKE : AS_ACCEL;
+		return ((this->vehstatus & VS_STOPPED) || HasBit(this->flags, VRF_REVERSING) || HasBit(this->flags, VRF_TRAIN_STUCK) || HasBit(this->flags, VRF_BREAKDOWN_BRAKING)) ? AS_BRAKE : AS_ACCEL;
 	}
 
 	/**

src/train_cmd.cpp

@@ -129,7 +129,7 @@ void CheckTrainsLengths()
 void CheckBreakdownFlags(Train *v)
 {
 	assert(v->IsFrontEngine());
-	/* clear the flags we're gonna check first, we'll set them again later (if applicable ) */
+	/* clear the flags we're gonna check first, we'll set them again later (if applicable) */
 	CLRBITS(v->flags, (1 << VRF_BREAKDOWN_BRAKING) | VRF_IS_BROKEN);
 
 	for (const Train *w = v; w != NULL; w = w->Next()) {
@@ -492,10 +492,8 @@ void Train::UpdateAcceleration()
 
 	if (_settings_game.vehicle.improved_breakdowns) {
 		if (_settings_game.vehicle.train_acceleration_model == AM_ORIGINAL) {
-			this->breakdown_chance = max(128 * 3 / (this->tcache.cached_num_engines + 2), 5);
+			this->breakdown_chance_factor = max(128 * 3 / (this->tcache.cached_num_engines + 2), 5);
 		}
-	} else {
-		this->breakdown_chance = 128;
 	}
 }
 
@@ -4055,7 +4053,6 @@ void Train::OnNewDay()
 	if ((++this->day_counter & 7) == 0) DecreaseVehicleValue(this);
 
 	if (this->IsFrontEngine()) {
-
 		CheckIfTrainNeedsService(this);
 
 		CheckOrders(this);

src/vehicle.cpp

@@ -123,6 +123,8 @@ void VehicleServiceInDepot(Vehicle *v)
 		v->date_of_last_service = _date;
 		v->breakdowns_since_last_service = 0;
 		v->reliability = v->GetEngine()->reliability;
+		/* Prevent vehicles from breaking down directly after exiting the depot. */
+		v->breakdown_chance = 0;
 		v = v->Next();
 	} while (v != NULL && v->HasEngineType());
 }
@@ -144,7 +146,7 @@ bool Vehicle::NeedsServicing() const
 	if ((this->ServiceIntervalIsPercent() ?
 			(this->reliability >= this->GetEngine()->reliability * (100 - this->service_interval) / 100) :
 			(this->date_of_last_service + this->service_interval >= _date))
-			&& !(this->type == VEH_TRAIN && HasBit(Train::From(this)->flags ,VRF_NEED_REPAIR))) {
+			&& !(this->type == VEH_TRAIN && HasBit(Train::From(this)->flags, VRF_NEED_REPAIR))) {
 		return false;
 	}
 
@@ -1277,15 +1279,21 @@ void CheckVehicleBreakdown(Vehicle *v)
 		return;
 	}
 
-	uint32 r1 = Random();
+	uint32 r = Random();
-	uint32 r2 = Random();
+
+	/* increase chance of failure */
+	int chance = v->breakdown_chance + 1;
+	if (Chance16I(1, 25, r)) chance += 25;
+	chance = min(255, chance);
+	v->breakdown_chance = chance;
 
-	byte chance = 128;
 	if (_settings_game.vehicle.improved_breakdowns) {
-		/* Dual engines have their breakdown chances reduced to 70% of the normal value */
+		if (v->type == VEH_TRAIN && Train::From(v)->IsMultiheaded()) {
-		chance = (v->type == VEH_TRAIN && Train::From(v)->IsMultiheaded()) ? v->First()->breakdown_chance * 7 / 10 : v->First()->breakdown_chance;
+			/* Dual engines have their breakdown chances reduced to 70% of the normal value */
-	} else if(v->type == VEH_SHIP) {
+			chance = chance * 7 / 10;
-		chance = 64;
+		}
+		chance *= v->First()->breakdown_chance_factor;
+		chance >>= 7;
 	}
 	/**
 	 * Chance is (1 - reliability) * breakdown_setting * breakdown_chance / 10.
@@ -1295,9 +1303,12 @@ void CheckVehicleBreakdown(Vehicle *v)
 	 * However, because breakdowns are no longer by definition a complete stop,
 	 * their impact will be significantly less.
 	 */
+	uint32 r1 = Random();
 	if ((uint32) (0xffff - v->reliability) * _settings_game.difficulty.vehicle_breakdowns * chance > GB(r1, 0, 24) * 10) {
+		uint32 r2 = Random();
 		v->breakdown_ctr = GB(r1, 24, 6) + 0xF;
 		v->breakdown_delay = GB(r2, 0, 7) + 0x80;
+		v->breakdown_chance = 0;
 		DetermineBreakdownType(v, r2);
 	}
 }

src/vehicle_base.h

@@ -195,6 +195,7 @@ public:
 
 	byte breakdown_severity;            ///< severity of the breakdown. Note that lower means more severe
 	byte breakdown_type;                ///< Type of breakdown
+	byte breakdown_chance_factor;       ///< Improved breakdowns: current multiplier for breakdown_chance * 128, used for head vehicle only
 	SpriteID colourmap;                 ///< NOSAVE: cached colour mapping
 
 	/* Related to age and service time */

src/vehicle_gui.cpp

@@ -2632,7 +2632,15 @@ public:
 				if (w->breakdown_type == BREAKDOWN_LOW_SPEED) {
 					SetDParam(1, min( w->First()->GetDisplayMaxSpeed(), w->breakdown_severity >> ((v->type == VEH_TRAIN) ? 0 : 1)));
 				} else if (w->breakdown_type == BREAKDOWN_LOW_POWER) {
-					SetDParam(1, w->breakdown_severity * 100 / 256);
+					int percent;
+					if (v->type == VEH_TRAIN) {
+						uint32 power, te;
+						Train::From(v)->CalculatePower(power, te, true);
+						percent = (100 * power) / Train::From(v)->gcache.cached_power;
+					} else {
+						percent = w->breakdown_severity * 100 / 256;
+					}
+					SetDParam(1, percent);
 				}
 			}
 		} else if (v->vehstatus & VS_STOPPED) {