Implement improved breakdown speed reductions for ships

src/saveload/extended_ver_sl.cpp

@@ -86,7 +86,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_TIMETABLES_START_TICKS, XSCF_NULL,                2,   2, "timetable_start_ticks",     nullptr, nullptr, nullptr        },
 	{ XSLFI_TOWN_CARGO_ADJ,         XSCF_IGNORABLE_UNKNOWN,   2,   2, "town_cargo_adj",            nullptr, nullptr, nullptr        },
 	{ XSLFI_SIG_TUNNEL_BRIDGE,      XSCF_NULL,                9,   9, "signal_tunnel_bridge",      nullptr, nullptr, "XBSS"      },
-	{ XSLFI_IMPROVED_BREAKDOWNS,    XSCF_NULL,                7,   7, "improved_breakdowns",       nullptr, nullptr, nullptr        },
+	{ XSLFI_IMPROVED_BREAKDOWNS,    XSCF_NULL,                8,   8, "improved_breakdowns",       nullptr, nullptr, nullptr        },
 	{ XSLFI_CONSIST_BREAKDOWN_FLAG, XSCF_NULL,                1,   1, "consist_breakdown_flag",    nullptr, nullptr, nullptr        },
 	{ XSLFI_TT_WAIT_IN_DEPOT,       XSCF_NULL,                1,   1, "tt_wait_in_depot",          nullptr, nullptr, nullptr        },
 	{ XSLFI_AUTO_TIMETABLE,         XSCF_NULL,                5,   5, "auto_timetables",           nullptr, nullptr, nullptr        },

src/saveload/vehicle_sl.cpp

@@ -844,6 +844,7 @@ const SaveLoad *GetVehicleDescription(VehicleType vt)
 		SLE_CONDDEQUE(Ship, path,                      SLE_UINT8,                  SLV_SHIP_PATH_CACHE, SL_MAX_VERSION),
 		  SLE_CONDVAR(Ship, rotation,                  SLE_UINT8,                  SLV_SHIP_ROTATION, SL_MAX_VERSION),
 		SLE_CONDVAR_X(Ship, lost_count,                SLE_UINT8,                     SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_SHIP_LOST_COUNTER)),
+		SLE_CONDVAR_X(Ship, critical_breakdown_count,  SLE_UINT8,                     SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_IMPROVED_BREAKDOWNS, 8)),
 
 		SLE_CONDNULL(16, SLV_2, SLV_144), // old reserved space
 

src/ship.h

@@ -32,6 +32,7 @@ struct Ship FINAL : public SpecializedVehicle<Ship, VEH_SHIP> {
 	int16 rotation_x_pos; ///< NOSAVE: X Position before rotation.
 	int16 rotation_y_pos; ///< NOSAVE: Y Position before rotation.
 	uint8 lost_count;     ///< Count of number of failed pathfinder attempts
+	byte critical_breakdown_count; ///< Counter for the number of critical breakdowns since last service
 
 	/** We don't want GCC to zero our struct! It already is zeroed and has an index! */
 	Ship() : SpecializedVehicleBase() {}
@@ -47,7 +48,9 @@ struct Ship FINAL : public SpecializedVehicle<Ship, VEH_SHIP> {
 	Direction GetMapImageDirection() const { return this->rotation; }
 	int GetDisplaySpeed() const { return this->cur_speed / 2; }
 	int GetDisplayMaxSpeed() const { return this->vcache.cached_max_speed / 2; }
-	int GetCurrentMaxSpeed() const { return std::min<int>(this->vcache.cached_max_speed, this->current_order.GetMaxSpeed() * 2); }
+	int GetEffectiveMaxSpeed() const;
+	int GetDisplayEffectiveMaxSpeed() const { return this->GetEffectiveMaxSpeed() / 2; }
+	int GetCurrentMaxSpeed() const { return std::min<int>(this->GetEffectiveMaxSpeed(), this->current_order.GetMaxSpeed() * 2); }
 	Money GetRunningCost() const;
 	bool IsInDepot() const { return this->state == TRACK_BIT_DEPOT; }
 	bool Tick();

src/ship_cmd.cpp

@@ -339,6 +339,20 @@ void Ship::UpdateDeltaXY()
 	}
 }
 
+int Ship::GetEffectiveMaxSpeed() const
+{
+	int max_speed = this->vcache.cached_max_speed;
+
+	if (this->critical_breakdown_count == 0) return max_speed;
+
+	for (uint i = 0; i < this->critical_breakdown_count; i++) {
+		max_speed = std::min(max_speed - (max_speed / 3) + 1, max_speed);
+	}
+
+	/* clamp speed to be no less than lower of 5mph and 1/8 of base speed */
+	return std::max<uint16>(max_speed, std::min<uint16>(10, (this->vcache.cached_max_speed + 7) >> 3));
+}
+
 /**
  * Test-procedure for HasVehicleOnPos to check for any ships which are visible and not stopped by the player.
  */
@@ -439,7 +453,7 @@ static bool ShipAccelerate(Vehicle *v)
 	uint spd;
 	byte t;
 
-	spd = std::min<uint>(v->cur_speed + 1, v->vcache.cached_max_speed);
+	spd = std::min<uint>(v->cur_speed + 1, Ship::From(v)->GetEffectiveMaxSpeed());
 	spd = std::min<uint>(spd, v->current_order.GetMaxSpeed() * 2);
 
 	if (v->breakdown_ctr == 1 && v->breakdown_type == BREAKDOWN_LOW_POWER && v->cur_speed > (v->breakdown_severity * ShipVehInfo(v->engine_type)->max_speed) >> 8) {

src/ship_gui.cpp

@@ -16,6 +16,7 @@
 #include "vehicle_func.h"
 #include "spritecache.h"
 #include "zoom_func.h"
+#include "ship.h"
 
 #include "table/strings.h"
 
@@ -84,4 +85,9 @@ void DrawShipDetails(const Vehicle *v, int left, int right, int y)
 	/* Draw Transfer credits text */
 	SetDParam(0, v->cargo.FeederShare());
 	DrawString(left, right, y + 3 * FONT_HEIGHT_NORMAL + 3, STR_VEHICLE_INFO_FEEDER_CARGO_VALUE);
+
+	if (Ship::From(v)->critical_breakdown_count > 0) {
+		SetDParam(0, Ship::From(v)->GetDisplayEffectiveMaxSpeed());
+		DrawString(left, right, y + 4 * FONT_HEIGHT_NORMAL + 4, STR_NEED_REPAIR);
+	}
 }

src/vehicle.cpp

@@ -194,6 +194,8 @@ void VehicleServiceInDepot(Vehicle *v)
 		}
 	} else if (v->type == VEH_ROAD) {
 		RoadVehicle::From(v)->critical_breakdown_count = 0;
+	} else if (v->type == VEH_SHIP) {
+		Ship::From(v)->critical_breakdown_count = 0;
 	}
 	v->vehstatus &= ~VS_AIRCRAFT_BROKEN;
 	SetWindowDirty(WC_VEHICLE_DETAILS, v->index); // ensure that last service date and reliability are updated
@@ -231,7 +233,8 @@ bool Vehicle::NeedsServicing() const
 			(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_ROAD && RoadVehicle::From(this)->critical_breakdown_count > 0)) {
+			&& !(this->type == VEH_ROAD && RoadVehicle::From(this)->critical_breakdown_count > 0)
+			&& !(this->type == VEH_SHIP && Ship::From(this)->critical_breakdown_count > 0)) {
 		return false;
 	}
 
@@ -2205,6 +2208,10 @@ bool Vehicle::HandleBreakdown()
 								if (RoadVehicle::From(this)->critical_breakdown_count != 255) {
 									RoadVehicle::From(this)->critical_breakdown_count++;
 								}
+							} else if (this->type == VEH_SHIP) {
+								if (Ship::From(this)->critical_breakdown_count != 255) {
+									Ship::From(this)->critical_breakdown_count++;
+								}
 							}
 						}
 					/* FALL THROUGH */

src/vehicle_gui.cpp

@@ -2823,7 +2823,7 @@ struct VehicleDetailsWindow : Window {
 						break;
 
 					case VEH_SHIP:
-						size->height = WD_FRAMERECT_TOP + 4 * FONT_HEIGHT_NORMAL + 3 + WD_FRAMERECT_BOTTOM;
+						size->height = WD_FRAMERECT_TOP + 5 * FONT_HEIGHT_NORMAL + 4 + WD_FRAMERECT_BOTTOM;
 						break;
 
 					case VEH_AIRCRAFT: