Feature: Settings to scale cargo production of towns and industries

src/economy_func.h

@@ -15,6 +15,8 @@
 #include "cargo_type.h"
 #include "vehicle_type.h"
 #include "company_type.h"
+#include "settings_type.h"
+#include "core/random_func.hpp"
 
 void ResetPriceBaseMultipliers();
 void SetPriceBaseMultiplier(Price price, int factor);
@@ -49,4 +51,48 @@ inline bool EconomyIsInRecession()
 	return _economy.fluct <= 0;
 }
 
+/**
+ * Scale a number by the inverse of the cargo scale setting, e.g. a scale of 25% multiplies the number by 4.
+ * @param num The number to scale.
+ * @param town Are we scaling town production, or industry production?
+ * @return The number scaled by the inverse of the cargo scale setting, minimum of 1.
+ */
+static uint ScaleByInverseCargoScale(uint num, bool town)
+{
+	uint16_t percentage = (town ? _settings_game.economy.town_cargo_scale : _settings_game.economy.industry_cargo_scale);
+
+	/* We might not need to do anything. */
+	if (percentage == 100) return num;
+
+	/* Never return 0, since we often divide by this number. */
+	return std::max((num * 100) / percentage, 1u);
+}
+
+/**
+ * Scale a number by the cargo scale setting.
+ * @param num The number to scale.
+ * @param town Are we scaling town production, or industry production?
+ * @return The number scaled by the current cargo scale setting. May be 0.
+ */
+inline uint ScaleByCargoScale(uint num, bool town)
+{
+	/* Don't bother scaling in the menu, especially since settings don't exist when starting OpenTTD and trying to read them crashes the game. */
+	if (_game_mode == GM_MENU) return num;
+
+	if (num == 0) return num;
+
+	uint16_t percentage = (town ? _settings_game.economy.town_cargo_scale : _settings_game.economy.industry_cargo_scale);
+
+	/* We might not need to do anything. */
+	if (percentage == 100) return num;
+
+	uint scaled = (num * percentage) / 100;
+
+	/* We might round down to 0, so we compensate with a random chance approximately equal to the economy scale,
+	 *  e.g. at 25% scale there's a 1/4 chance to round up to 1. */
+	if (scaled == 0 && Chance16(1, ScaleByInverseCargoScale(1, town))) return 1;
+
+	return scaled;
+}
+
 #endif /* ECONOMY_FUNC_H */

src/industry_cmd.cpp

@@ -1131,7 +1131,24 @@ static void ChopLumberMillTrees(Industry *i)
 
 	TileIndex tile = i->location.tile;
 	if (CircularTileSearch(&tile, 40, SearchLumberMillTrees, nullptr)) { // 40x40 tiles  to search.
-		i->produced[0].waiting = ClampTo<uint16_t>(i->produced[0].waiting + 45); // Found a tree, add according value to waiting cargo.
+		i->produced[0].waiting = ClampTo<uint16_t>(i->produced[0].waiting + ScaleByCargoScale(45, false)); // Found a tree, add according value to waiting cargo.
+	}
+}
+
+/**
+ * Helper for ProduceIndustryGoods that scales and produces cargos.
+ * @param i The industry
+ * @param scale Should we scale production of this cargo directly?
+ */
+static void ProduceIndustryGoodsHelper(Industry *i, bool scale)
+{
+	for (auto &p : i->produced) {
+		if (!IsValidCargoID(p.cargo)) continue;
+
+		uint16_t amount = p.rate;
+		if (scale) amount = ScaleByCargoScale(amount, false);
+
+		p.waiting = ClampTo<uint16_t>(p.waiting + amount);
 	}
 }
 
@@ -1154,15 +1171,20 @@ static void ProduceIndustryGoods(Industry *i)
 
 	i->counter--;
 
-	/* produce some cargo */
+	/* If using an industry callback, scale the callback interval by cargo scale percentage. */
+	if (HasBit(indsp->callback_mask, CBM_IND_PRODUCTION_256_TICKS)) {
+		if (i->counter % ScaleByInverseCargoScale(Ticks::INDUSTRY_PRODUCE_TICKS, false) == 0) {
+			IndustryProductionCallback(i, 1);
+			ProduceIndustryGoodsHelper(i, false);
+		}
+	}
+
+	/* All other production and special effects happen every 256 ticks, and cargo production is just scaled by the cargo scale percentage. */
 	if ((i->counter % Ticks::INDUSTRY_PRODUCE_TICKS) == 0) {
-		if (HasBit(indsp->callback_mask, CBM_IND_PRODUCTION_256_TICKS)) IndustryProductionCallback(i, 1);
+		/* Handle non-callback cargo production. */
+		if (!HasBit(indsp->callback_mask, CBM_IND_PRODUCTION_256_TICKS)) ProduceIndustryGoodsHelper(i, true);
 
 		IndustryBehaviour indbehav = indsp->behaviour;
-		for (auto &p : i->produced) {
-			if (!IsValidCargoID(p.cargo)) continue;
-			p.waiting = ClampTo<uint16_t>(p.waiting + p.rate);
-		}
 
 		if ((indbehav & INDUSTRYBEH_PLANT_FIELDS) != 0) {
 			uint16_t cb_res = CALLBACK_FAILED;
@@ -1824,7 +1846,7 @@ static void DoCreateNewIndustry(Industry *i, TileIndex tile, IndustryType type,
 		}
 
 		for (auto &p : i->produced) {
-			p.history[LAST_MONTH].production += p.rate * 8;
+			p.history[LAST_MONTH].production += ScaleByCargoScale(p.rate * 8, false);
 		}
 	}
 

src/industry_gui.cpp

@@ -1169,7 +1169,7 @@ static void UpdateIndustryProduction(Industry *i)
 
 	for (auto &p : i->produced) {
 		if (IsValidCargoID(p.cargo)) {
-			p.history[LAST_MONTH].production = 8 * p.rate;
+			p.history[LAST_MONTH].production = ScaleByCargoScale(8 * p.rate, false);
 		}
 	}
 }

src/lang/english.txt

@@ -1455,6 +1455,12 @@ STR_CONFIG_SETTING_WARN_INCOME_LESS_HELPTEXT                    :When enabled, a
 STR_CONFIG_SETTING_NEVER_EXPIRE_VEHICLES                        :Vehicles never expire: {STRING2}
 STR_CONFIG_SETTING_NEVER_EXPIRE_VEHICLES_HELPTEXT               :When enabled, all vehicle models remain available forever after their introduction
 
+STR_CONFIG_SETTING_TOWN_CARGO_SCALE                             :Scale town cargo production: {STRING2}
+STR_CONFIG_SETTING_TOWN_CARGO_SCALE_HELPTEXT                    :Scale the cargo production of towns by this percentage.
+STR_CONFIG_SETTING_INDUSTRY_CARGO_SCALE                         :Scale industry cargo production: {STRING2}
+STR_CONFIG_SETTING_INDUSTRY_CARGO_SCALE_HELPTEXT                :Scale the cargo production of industries by this percentage.
+STR_CONFIG_SETTING_CARGO_SCALE_VALUE                            :{NUM}%
+
 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/object_cmd.cpp

@@ -685,7 +685,13 @@ static void TileLoop_Object(TileIndex tile)
 	/* Top town buildings generate 250, so the top HQ type makes 256. */
 	if (GB(r, 0, 8) < (256 / 4 / (6 - level))) {
 		uint amt = GB(r, 0, 8) / 8 / 4 + 1;
+
+		/* Production is halved during recessions. */
 		if (EconomyIsInRecession()) amt = (amt + 1) >> 1;
+
+		/* Scale by cargo scale setting. */
+		amt = ScaleByCargoScale(amt, true);
+
 		MoveGoodsToStation(CT_PASSENGERS, amt, SourceType::Headquarters, GetTileOwner(tile), stations.GetStations());
 	}
 
@@ -694,7 +700,13 @@ static void TileLoop_Object(TileIndex tile)
 	 * equations. */
 	if (GB(r, 8, 8) < (196 / 4 / (6 - level))) {
 		uint amt = GB(r, 8, 8) / 8 / 4 + 1;
+
+		/* Production is halved during recessions. */
 		if (EconomyIsInRecession()) amt = (amt + 1) >> 1;
+
+		/* Scale by cargo scale setting. */
+		amt = ScaleByCargoScale(amt, true);
+
 		MoveGoodsToStation(CT_MAIL, amt, SourceType::Headquarters, GetTileOwner(tile), stations.GetStations());
 	}
 }

src/settings_gui.cpp

@@ -2032,6 +2032,7 @@ static SettingsContainer &GetSettingsTree()
 
 			SettingsPage *towns = environment->Add(new SettingsPage(STR_CONFIG_SETTING_ENVIRONMENT_TOWNS));
 			{
+				towns->Add(new SettingEntry("economy.town_cargo_scale"));
 				towns->Add(new SettingEntry("economy.town_growth_rate"));
 				towns->Add(new SettingEntry("economy.allow_town_roads"));
 				towns->Add(new SettingEntry("economy.allow_town_level_crossings"));
@@ -2044,6 +2045,7 @@ static SettingsContainer &GetSettingsTree()
 
 			SettingsPage *industries = environment->Add(new SettingsPage(STR_CONFIG_SETTING_ENVIRONMENT_INDUSTRIES));
 			{
+				industries->Add(new SettingEntry("economy.industry_cargo_scale"));
 				industries->Add(new SettingEntry("difficulty.industry_density"));
 				industries->Add(new SettingEntry("construction.raw_industry_construction"));
 				industries->Add(new SettingEntry("construction.industry_platform"));

src/settings_type.h

@@ -551,6 +551,8 @@ struct EconomySettings {
 	uint16_t town_noise_population[4];         ///< population to base decision on noise evaluation (@see town_council_tolerance)
 	bool   allow_town_level_crossings;       ///< towns are allowed to build level crossings
 	bool   infrastructure_maintenance;       ///< enable monthly maintenance fee for owner infrastructure
+	uint16_t town_cargo_scale;               ///< scale cargo production of towns by this percentage.
+	uint16_t industry_cargo_scale;           ///< scale cargo production of industries by this percentage.
 };
 
 struct LinkGraphSettings {

src/table/settings/economy_settings.ini

@@ -280,3 +280,29 @@ str      = STR_CONFIG_SETTING_INFRASTRUCTURE_MAINTENANCE
 strhelp  = STR_CONFIG_SETTING_INFRASTRUCTURE_MAINTENANCE_HELPTEXT
 post_cb  = [](auto) { InvalidateWindowClassesData(WC_COMPANY_INFRASTRUCTURE); }
 cat      = SC_BASIC
+
+[SDT_VAR]
+var      = economy.town_cargo_scale
+type     = SLE_UINT16
+flags    = SF_NO_NETWORK
+def      = 100
+min      = 15
+max      = 400
+interval = 1
+str      = STR_CONFIG_SETTING_TOWN_CARGO_SCALE
+strhelp  = STR_CONFIG_SETTING_TOWN_CARGO_SCALE_HELPTEXT
+strval   = STR_CONFIG_SETTING_CARGO_SCALE_VALUE
+cat      = SC_BASIC
+
+[SDT_VAR]
+var      = economy.industry_cargo_scale
+type     = SLE_UINT16
+flags    = SF_NO_NETWORK
+def      = 100
+min      = 15
+max      = 400
+interval = 1
+str      = STR_CONFIG_SETTING_INDUSTRY_CARGO_SCALE
+strhelp  = STR_CONFIG_SETTING_INDUSTRY_CARGO_SCALE_HELPTEXT
+strval   = STR_CONFIG_SETTING_CARGO_SCALE_VALUE
+cat      = SC_BASIC

src/town_cmd.cpp

@@ -519,6 +519,36 @@ static void AdvanceHouseConstruction(TileIndex tile)
 }
 
 /**
+ * Generate cargo for a house, scaled by the current economy scale.
+ * @param t The current town.
+ * @param ct Type of cargo to generate, usually CT_PASSENGERS or CT_MAIL.
+ * @param amount The number of cargo units.
+ * @param stations Available stations for this house.
+ * @param affected_by_recession Is this cargo halved during recessions?
+ */
+static void TownGenerateCargo(Town *t, CargoID ct, uint amount, StationFinder &stations, bool affected_by_recession)
+{
+	if (amount == 0) return;
+
+	/* All production is halved during a recession (except for NewGRF-supplied town cargo). */
+	if (affected_by_recession && EconomyIsInRecession()) {
+		amount = (amount + 1) >> 1;
+	}
+
+	/* Scale by cargo scale setting. */
+	amount = ScaleByCargoScale(amount, true);
+
+	/* Actually generate cargo and update town statistics. */
+	uint moved = MoveGoodsToStation(ct, amount, SourceType::Town, t->index, stations.GetStations());
+
+	const CargoSpec *cs = CargoSpec::Get(ct);
+	t->supplied[cs->Index()].new_max += amount;
+	t->supplied[cs->Index()].new_act += moved;
+}
+
+/**
+ * Tile callback function.
+ *
  * Tile callback function. Periodic tick handler for the tiles of a town.
  * @param tile been asked to do its stuff
  */
@@ -563,30 +593,21 @@ static void TileLoop_Town(TileIndex tile)
 			uint amt = GB(callback, 0, 8);
 			if (amt == 0) continue;
 
-			uint moved = MoveGoodsToStation(cargo, amt, SourceType::Town, t->index, stations.GetStations());
-
-			const CargoSpec *cs = CargoSpec::Get(cargo);
-			t->supplied[cs->Index()].new_max += amt;
-			t->supplied[cs->Index()].new_act += moved;
+			/* NewGRF-supplied town cargos are not affected by recessions. */
+			TownGenerateCargo(t, cargo, amt, stations, false);
 		}
 	} else {
 		switch (_settings_game.economy.town_cargogen_mode) {
 			case TCGM_ORIGINAL:
 				/* Original (quadratic) cargo generation algorithm */
 				if (GB(r, 0, 8) < hs->population) {
 					uint amt = GB(r, 0, 8) / 8 + 1;
-
-					if (EconomyIsInRecession()) amt = (amt + 1) >> 1;
-					t->supplied[CT_PASSENGERS].new_max += amt;
-					t->supplied[CT_PASSENGERS].new_act += MoveGoodsToStation(CT_PASSENGERS, amt, SourceType::Town, t->index, stations.GetStations());
+					TownGenerateCargo(t, CT_PASSENGERS, amt, stations, true);
 				}
 
 				if (GB(r, 8, 8) < hs->mail_generation) {
 					uint amt = GB(r, 8, 8) / 8 + 1;
-
-					if (EconomyIsInRecession()) amt = (amt + 1) >> 1;
-					t->supplied[CT_MAIL].new_max += amt;
-					t->supplied[CT_MAIL].new_act += MoveGoodsToStation(CT_MAIL, amt, SourceType::Town, t->index, stations.GetStations());
+					TownGenerateCargo(t, CT_MAIL, amt, stations, true);
 				}
 				break;
 
@@ -601,18 +622,14 @@ static void TileLoop_Town(TileIndex tile)
 					/* Mask random value by potential pax and count number of actual pax */
 					uint amt = CountBits(r & genmask);
 					/* Adjust and apply */
-					if (EconomyIsInRecession()) amt = (amt + 1) >> 1;
-					t->supplied[CT_PASSENGERS].new_max += amt;
-					t->supplied[CT_PASSENGERS].new_act += MoveGoodsToStation(CT_PASSENGERS, amt, SourceType::Town, t->index, stations.GetStations());
+					TownGenerateCargo(t, CT_PASSENGERS, amt, stations, true);
 
 					/* Do the same for mail, with a fresh random */
 					r = Random();
 					genmax = (hs->mail_generation + 7) / 8;
 					genmask = (genmax >= 32) ? 0xFFFFFFFF : ((1 << genmax) - 1);
 					amt = CountBits(r & genmask);
-					if (EconomyIsInRecession()) amt = (amt + 1) >> 1;
-					t->supplied[CT_MAIL].new_max += amt;
-					t->supplied[CT_MAIL].new_act += MoveGoodsToStation(CT_MAIL, amt, SourceType::Town, t->index, stations.GetStations());
+					TownGenerateCargo(t, CT_MAIL, amt, stations, true);
 				}
 				break;
 
@@ -1866,8 +1883,8 @@ void UpdateTownRadius(Town *t)
  */
 void UpdateTownMaxPass(Town *t)
 {
-	t->supplied[CT_PASSENGERS].old_max = t->cache.population >> 3;
-	t->supplied[CT_MAIL].old_max = t->cache.population >> 4;
+	t->supplied[CT_PASSENGERS].old_max = ScaleByCargoScale(t->cache.population >> 3, true);
+	t->supplied[CT_MAIL].old_max = ScaleByCargoScale(t->cache.population >> 4, true);
 }
 
 static void UpdateTownGrowthRate(Town *t);