Change and simplify algorithm for vehicle repair cost.

This is due to absurdly high repair costs for old vehicles with
old algorithm, due to implicit exponential increases.
Get rid of variable in vehicle struct.

src/saveload/extended_ver_sl.cpp

@@ -58,7 +58,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_IMPROVED_BREAKDOWNS,    XSCF_NULL,                4,   4, "improved_breakdowns",       NULL, NULL, NULL        },
 	{ XSLFI_TT_WAIT_IN_DEPOT,       XSCF_NULL,                1,   1, "tt_wait_in_depot",          NULL, NULL, NULL        },
 	{ XSLFI_AUTO_TIMETABLE,         XSCF_NULL,                4,   4, "auto_timetables",           NULL, NULL, NULL        },
-	{ XSLFI_VEHICLE_REPAIR_COST,    XSCF_NULL,                1,   1, "vehicle_repair_cost",       NULL, NULL, NULL        },
+	{ XSLFI_VEHICLE_REPAIR_COST,    XSCF_NULL,                2,   2, "vehicle_repair_cost",       NULL, NULL, NULL        },
 	{ XSLFI_ENH_VIEWPORT_PLANS,     XSCF_IGNORABLE_ALL,       1,   1, "enh_viewport_plans",        NULL, NULL, "PLAN,PLLN" },
 	{ XSLFI_INFRA_SHARING,          XSCF_NULL,                1,   1, "infra_sharing",             NULL, NULL, NULL        },
 	{ XSLFI_VARIABLE_DAY_LENGTH,    XSCF_NULL,                1,   1, "variable_day_length",       NULL, NULL, NULL        },

src/saveload/vehicle_sl.cpp

@@ -368,24 +368,6 @@ void AfterLoadVehicles(bool part_of_load)
 				v->SetServiceIntervalIsPercent(c->settings.vehicle.servint_ispercent);
 			}
 		}
-
-		if (SlXvIsFeatureMissing(XSLFI_VEHICLE_REPAIR_COST)) {
-			/* repair cost is value for new vehicles and each week +/256 part for old */
-			FOR_ALL_VEHICLES(v) {
-				if (!v->IsPrimaryVehicle()) continue;
-
-				v->repair_cost = v->value;
-				for (int w = 0; w < v->age / 7; w++, v->repair_cost += v->repair_cost >> 8);
-				//DEBUG(misc,0, "eid#%d, value=%lld, weeks=%d/%d, repair cost=%lld",
-				//	v->engine_type, (int64)v->value, v->age, v->max_age, (int64)v->repair_cost );
-
-				if (v->age > v->max_age) {
-					Date weeks = (v->age - v->max_age) / 7;
-					for (int w = 0; w < weeks; w++, v->repair_cost += v->repair_cost >> 8);
-					//DEBUG(misc,0, "OLD: value=%lld, weeks=%d, repair cost=%lld", (int64)v->value, weeks, (int64)v->repair_cost );
-				}
-			}
-		}
 	}
 
 	CheckValidVehicles();
@@ -714,7 +696,7 @@ const SaveLoad *GetVehicleDescription(VehicleType vt)
 		SLEG_CONDVAR(         _cargo_loaded_at_xy,   SLE_UINT32,                  51,  67),
 		 SLE_CONDVAR(Vehicle, value,                 SLE_FILE_I32 | SLE_VAR_I64,   0,  64),
 		 SLE_CONDVAR(Vehicle, value,                 SLE_INT64,                   65, SL_MAX_VERSION),
-		SLE_CONDVAR_X(Vehicle, repair_cost,          SLE_INT64,                   0, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_VEHICLE_REPAIR_COST)),
+		SLE_CONDNULL_X(8,                                                          0, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_VEHICLE_REPAIR_COST, 1, 1)),
 
 		 SLE_CONDVAR(Vehicle, random_bits,           SLE_UINT8,                    2, SL_MAX_VERSION),
 		 SLE_CONDVAR(Vehicle, waiting_triggers,      SLE_UINT8,                    2, SL_MAX_VERSION),

src/vehicle.cpp

@@ -191,8 +191,11 @@ void VehicleServiceInDepot(Vehicle *v)
 			}
 			assert(type != INVALID_EXPENSES);
 
+			Money vehicle_new_value = v->GetEngine()->GetCost();
+
 			// The static cast is to fix compilation on (old) MSVC as the overload for OverflowSafeInt operator / is ambiguous.
-			Money repair_cost = (v->breakdowns_since_last_service * v->repair_cost / static_cast<uint>(_settings_game.vehicle.repair_cost)) + 1;
+			Money repair_cost = (v->breakdowns_since_last_service * vehicle_new_value / static_cast<uint>(_settings_game.vehicle.repair_cost)) + 1;
+			if (v->age > v->max_age) repair_cost <<= 1;
 			CommandCost cost(type, repair_cost);
 			v->First()->profit_this_year -= cost.GetCost() << 8;
 			SubtractMoneyFromCompany(cost);
@@ -1379,9 +1382,6 @@ Vehicle *CheckClickOnVehicle(const ViewPort *vp, int x, int y)
 void DecreaseVehicleValue(Vehicle *v)
 {
 	v->value -= v->value >> 8;
-	if ( v->age > v->max_age ) { // double cost for each max_age days after max_age
-		v->repair_cost += v->repair_cost >> 8;
-	}
 	SetWindowDirty(WC_VEHICLE_DETAILS, v->index);
 }
 

src/vehicle_base.h

@@ -242,7 +242,6 @@ public:
 	Money profit_last_year;             ///< Profit last year << 8, low 8 bits are fract
 	Money profit_lifetime;              ///< Profit lifetime << 8, low 8 bits are fract
 	Money value;                        ///< Value of the vehicle
-	Money repair_cost;                  ///< Cost to repair one breakdown
 
 	CargoPayment *cargo_payment;        ///< The cargo payment we're currently in
 

src/vehicle_cmd.cpp

@@ -138,7 +138,6 @@ CommandCost CmdBuildVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 	if (value.Succeeded() && flags & DC_EXEC) {
 		v->unitnumber = unit_num;
 		v->value      = value.GetCost();
-		v->repair_cost = value.GetCost();
 
 		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
 		InvalidateWindowClassesData(GetWindowClassForVehicleType(type), 0);