Add: Setting for scaling time in cargo payment calculations

src/core/math_func.hpp

@@ -352,4 +352,29 @@ constexpr int RoundDivSU(int a, uint b)
 
 uint32_t IntSqrt(uint32_t num);
 
+/**
+ * Scale a number by the required percentage.
+ *
+ * Calculation is performed in the type U of the num parameter.
+ * The result is clamped to the limits of type T if needed.
+ *
+ * @param num The number to scale.
+ * @param percentage The percentage value. 100% = don't scale.
+ * @return The number scaled by the percentage value.
+ */
+template <typename T, typename U>
+constexpr T ScaleByPercentage(U num, uint16_t percentage)
+{
+	U scaled;
+	/* We might not need to do anything. */
+	if (percentage == 100) {
+		scaled = num;
+	} else {
+		scaled = (num * static_cast<U>(percentage)) / 100;
+	}
+
+	/* Make sure the value fits resulting type T. */
+	return ClampTo<T>(scaled);
+}
+
 #endif /* MATH_FUNC_HPP */

src/economy.cpp

@@ -984,6 +984,9 @@ Money GetTransportedGoodsIncome(uint num_pieces, uint dist, uint16_t transit_per
 		return 0;
 	}
 
+	/* Scale transit periods according to the game setting. NewGRFs callbacks operate on scaled value for compatibility. */
+	transit_periods = ScaleByPercentage<uint16_t, uint32_t>(transit_periods, _settings_game.economy.payment_time_scale);
+
 	/* Use callback to calculate cargo profit, if available */
 	if (HasBit(cs->callback_mask, CBM_CARGO_PROFIT_CALC)) {
 		uint32_t var18 = ClampTo<uint16_t>(dist) | (ClampTo<uint8_t>(num_pieces) << 16) | (ClampTo<uint8_t>(transit_periods) << 24);

src/lang/english.txt

@@ -1520,6 +1520,9 @@ STR_CONFIG_SETTING_MINUTES_PER_YEAR_VALUE                       :{NUM}
 ###setting-zero-is-special
 STR_CONFIG_SETTING_MINUTES_PER_YEAR_FROZEN                      :0 (calendar time frozen)
 
+STR_CONFIG_SETTING_PAYMENT_TIME_SCALE                           :Time scale for cargo payments: {STRING2}
+STR_CONFIG_SETTING_PAYMENT_TIME_SCALE_HELPTEXT                  :Adjusts the time scale factor (in percentage) in the cargo payment calculations. A lower value means faster deliveries, resulting in higher payments.
+
 STR_CONFIG_SETTING_AUTORENEW_VEHICLE                            :Autorenew vehicle when it gets old: {STRING2}
 STR_CONFIG_SETTING_AUTORENEW_VEHICLE_HELPTEXT                   :When enabled, a vehicle nearing its end of life gets automatically replaced when the renew conditions are fulfilled
 

src/settings_gui.cpp

@@ -2093,6 +2093,7 @@ static SettingsContainer &GetSettingsTree()
 			accounting->Add(new SettingEntry("economy.infrastructure_maintenance"));
 			accounting->Add(new SettingEntry("difficulty.vehicle_costs"));
 			accounting->Add(new SettingEntry("difficulty.construction_cost"));
+			accounting->Add(new SettingEntry("economy.payment_time_scale"));
 		}
 
 		SettingsPage *vehicles = main->Add(new SettingsPage(STR_CONFIG_SETTING_VEHICLES));

src/settings_type.h

@@ -560,6 +560,7 @@ struct EconomySettings {
 	bool   infrastructure_maintenance;       ///< enable monthly maintenance fee for owner infrastructure
 	TimekeepingUnits timekeeping_units;      ///< time units to use for the game economy, either calendar or wallclock
 	uint16_t minutes_per_calendar_year;      ///< minutes per calendar year. Special value 0 means that calendar time is frozen.
+	uint16_t payment_time_scale;             ///< percentage of delivery time to use for payment calculations
 };
 
 struct LinkGraphSettings {

src/table/settings/economy_settings.ini

@@ -315,3 +315,16 @@ strval   = STR_CONFIG_SETTING_MINUTES_PER_YEAR_VALUE
 pre_cb   = [](auto) { return _game_mode == GM_MENU || _settings_game.economy.timekeeping_units == 1; }
 post_cb  = ChangeMinutesPerYear
 cat      = SC_BASIC
+
+[SDT_VAR]
+var      = economy.payment_time_scale
+type     = SLE_UINT16
+def      = 100
+min      = 0
+max      = 50000
+interval = 10
+str      = STR_CONFIG_SETTING_PAYMENT_TIME_SCALE
+strhelp  = STR_CONFIG_SETTING_PAYMENT_TIME_SCALE_HELPTEXT
+strval   = STR_CONFIG_SETTING_PERCENTAGE
+cat      = SC_EXPERT
+post_cb  = [](auto) { InvalidateWindowData(WC_PAYMENT_RATES, 0); }