Allow various settings to be changed in multiplayer

If the corresponding TTDPatch flag bit has not been observed by a NewGRF

src/lang/english.txt

@@ -2538,6 +2538,9 @@ STR_CONFIG_SETTING_SCENARIO_HOUSE_IGNORE_ZONES_OFF              :Off
 STR_CONFIG_SETTING_SCENARIO_HOUSE_IGNORE_ZONES_WITHIN_TOWN      :Within town
 STR_CONFIG_SETTING_SCENARIO_HOUSE_IGNORE_ZONES_ANYWHERE         :Anywhere
 
+STR_CONFIG_SETTING_NETWORK_CHANGE_NOT_ALLOWED                   :{WHITE}Can't change setting...
+STR_CONFIG_SETTING_NETWORK_CHANGE_NOT_ALLOWED_NEWGRF            :{WHITE}...setting is observed by a NewGRF
+
 # Config errors
 STR_CONFIG_ERROR                                                :{WHITE}Error with the configuration file...
 STR_CONFIG_ERROR_ARRAY                                          :{WHITE}... error in array '{RAW_STRING}'

src/newgrf.cpp

@@ -86,6 +86,7 @@ byte _misc_grf_features = 0;
 
 /** 32 * 8 = 256 flags. Apparently TTDPatch uses this many.. */
 static uint32 _ttdpatch_flags[8];
+static uint32 _observed_ttdpatch_flags[8];
 
 /** Indicates which are the newgrf features currently loaded ingame */
 GRFLoadedFeatures _loaded_newgrf_features;
@@ -7315,8 +7316,14 @@ static uint32 GetParamVal(byte param, uint32 *cond_val)
 				return 0;
 			} else {
 				uint32 index = *cond_val / 0x20;
-				uint32 param_val = index < lengthof(_ttdpatch_flags) ? _ttdpatch_flags[index] : 0;
 				*cond_val %= 0x20;
+				uint32 param_val = 0;
+				if (index < lengthof(_ttdpatch_flags)) {
+					param_val = _ttdpatch_flags[index];
+					if (!HasBit(_cur.grfconfig->flags, GCF_STATIC) && !HasBit(_cur.grfconfig->flags, GCF_SYSTEM)) {
+						SetBit(_observed_ttdpatch_flags[index], *cond_val);
+					}
+				}
 				return param_val;
 			}
 
@@ -9954,6 +9961,15 @@ static void InitializeGRFSpecial()
 
 	_ttdpatch_flags[4] =                                                       (1U << 0x00)  // larger persistent storage
 	                   |             ((_settings_game.economy.inflation ? 1U : 0U) << 0x01); // inflation is on
+	MemSetT(_observed_ttdpatch_flags, 0, lengthof(_observed_ttdpatch_flags));
+}
+
+bool HasTTDPatchFlagBeenObserved(uint flag)
+{
+	uint index = flag / 0x20;
+	flag %= 0x20;
+	if (index >= lengthof(_ttdpatch_flags)) return false;
+	return HasBit(_observed_ttdpatch_flags[index], flag);
 }
 
 /** Reset and clear all NewGRF stations */

src/settings.cpp

@@ -1701,6 +1701,17 @@ static void TownZoneCustomValueChanged(int32 new_value)
 	if (_settings_game.economy.town_zone_calc_mode) UpdateTownRadii();
 }
 
+static bool CheckTTDPatchSettingFlag(uint flag)
+{
+	extern bool HasTTDPatchFlagBeenObserved(uint flag);
+	if (_networking && HasTTDPatchFlagBeenObserved(flag)) {
+		ShowErrorMessage(STR_CONFIG_SETTING_NETWORK_CHANGE_NOT_ALLOWED, STR_CONFIG_SETTING_NETWORK_CHANGE_NOT_ALLOWED_NEWGRF, WL_ERROR);
+		return false;
+	}
+
+	return true;
+}
+
 /**
  * Replace a passwords that are a literal asterisk with an empty string.
  * @param newval The new string value for this password field.

src/table/settings/settings.ini

@@ -71,6 +71,7 @@ static bool CheckSharingWater(int32 &new_value);
 static bool CheckSharingAir(int32 &new_value);
 static void TownZoneModeChanged(int32 new_value);
 static void TownZoneCustomValueChanged(int32 new_value);
+static bool CheckTTDPatchSettingFlag(uint flag);
 
 /* End - Callback Functions for the various settings */
 
@@ -777,7 +778,6 @@ strhelp  = STR_CONFIG_SETTING_EXTRADYNAMITE_HELPTEXT
 var      = construction.max_bridge_length
 type     = SLE_UINT16
 from     = SLV_159
-flags    = SF_NO_NETWORK
 def      = 64
 min      = 1
 max      = 4096
@@ -785,6 +785,7 @@ interval = 1
 str      = STR_CONFIG_SETTING_MAX_BRIDGE_LENGTH
 strhelp  = STR_CONFIG_SETTING_MAX_BRIDGE_LENGTH_HELPTEXT
 strval   = STR_CONFIG_SETTING_TILE_LENGTH
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x0F); }
 
 [SDT_XREF]
 extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_SPRINGPP, 2)
@@ -862,22 +863,23 @@ to       = SLV_159
 [SDT_VAR]
 var      = construction.train_signal_side
 type     = SLE_UINT8
-flags    = SF_GUI_DROPDOWN | SF_NO_NETWORK
+flags    = SF_GUI_DROPDOWN
 def      = 1
 min      = 0
 max      = 2
 str      = STR_CONFIG_SETTING_SIGNALSIDE
 strhelp  = STR_CONFIG_SETTING_SIGNALSIDE_HELPTEXT
 strval   = STR_CONFIG_SETTING_SIGNALSIDE_LEFT
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x3B); }
 post_cb  = [](auto) { MarkWholeScreenDirty(); }
 cat      = SC_BASIC
 
 [SDT_BOOL]
 var      = station.never_expire_airports
-flags    = SF_NO_NETWORK
 def      = false
 str      = STR_CONFIG_SETTING_NEVER_EXPIRE_AIRPORTS
 strhelp  = STR_CONFIG_SETTING_NEVER_EXPIRE_AIRPORTS_HELPTEXT
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x0C); }
 
 [SDT_VAR]
 var      = economy.town_layout
@@ -911,10 +913,10 @@ extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_SPRINGPP, 7)
 [SDT_BOOL]
 var      = economy.allow_town_roads
 from     = SLV_113
-flags    = SF_NO_NETWORK
 def      = true
 str      = STR_CONFIG_SETTING_ALLOW_TOWN_ROADS
 strhelp  = STR_CONFIG_SETTING_ALLOW_TOWN_ROADS_HELPTEXT
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x62); }
 
 [SDT_XREF]
 xref     = ""economy.old_town_cargo_factor""
@@ -1736,10 +1738,10 @@ strhelp  = STR_CONFIG_SETTING_NOSERVICE_HELPTEXT
 
 [SDT_BOOL]
 var      = vehicle.wagon_speed_limits
-flags    = SF_NO_NETWORK
 def      = true
 str      = STR_CONFIG_SETTING_WAGONSPEEDLIMITS
 strhelp  = STR_CONFIG_SETTING_WAGONSPEEDLIMITS_HELPTEXT
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x5D); }
 post_cb  = UpdateConsists
 
 ;; vehicle.slow_road_vehicles_in_curves
@@ -1782,7 +1784,6 @@ cat      = SC_EXPERT
 var      = vehicle.freight_trains
 type     = SLE_UINT8
 from     = SLV_39
-flags    = SF_NO_NETWORK
 def      = 1
 min      = 1
 max      = 255
@@ -1790,6 +1791,7 @@ interval = 1
 str      = STR_CONFIG_SETTING_FREIGHT_TRAINS
 strhelp  = STR_CONFIG_SETTING_FREIGHT_TRAINS_HELPTEXT
 strval   = STR_JUST_COMMA
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x58); }
 post_cb  = UpdateConsists
 
 ;; vehicle.freight_mult_to_passengers
@@ -2200,11 +2202,11 @@ extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_SPRINGPP)
 ##
 [SDT_BOOL]
 var      = economy.inflation
-flags    = SF_NO_NETWORK
 def      = false
 str      = STR_CONFIG_SETTING_INFLATION
 strhelp  = STR_CONFIG_SETTING_INFLATION_HELPTEXT
 cat      = SC_BASIC
+pre_cb   = [](int32 &new_value) -> bool { return CheckTTDPatchSettingFlag(0x81); }
 
 [SDT_BOOL]
 var      = economy.inflation_fixed_dates