adjustments;

added lake tropic width adjustment
added an extra large setting to the coasts (51radius)
set minimum width for rivers and lakes to 2 (setting it to 1 actually CTD'd the game)
made max for rivers and lakes be 51 tiles to match the 51tiles of the coast setting.

src/landscape.cpp

@@ -1043,6 +1043,17 @@ static void CreateDesertOrRainForest(uint desert_tropic_line)
 				SetTropicZone(tile, TROPICZONE_DESERT);
 			}
 		}
+
+		if (_settings_game.game_creation.coast_tropics_width == 3) {
+			for (data = _make_desert_or_rainforest_data_extralarge;
+				data != endof(_make_desert_or_rainforest_data_extralarge); ++data) {
+				TileIndex t = AddTileIndexDiffCWrap(tile, *data);
+				if (t != INVALID_TILE && (TileHeight(t) >= desert_tropic_line || IsTileType(t, MP_WATER))) break;
+			}
+			if (data == endof(_make_desert_or_rainforest_data_extralarge)) {
+				SetTropicZone(tile, TROPICZONE_DESERT);
+			}
+		}
 	}
 
 	for (uint i = 0; i != 256; i++) {
@@ -1088,6 +1099,17 @@ static void CreateDesertOrRainForest(uint desert_tropic_line)
 				SetTropicZone(tile, TROPICZONE_RAINFOREST);
 			}
 		}
+
+		if (_settings_game.game_creation.coast_tropics_width == 3) {
+			for (data = _make_desert_or_rainforest_data_extralarge;
+				data != endof(_make_desert_or_rainforest_data_extralarge); ++data) {
+				TileIndex t = AddTileIndexDiffCWrap(tile, *data);
+				if (t != INVALID_TILE && IsTileType(t, MP_CLEAR) && IsClearGround(t, CLEAR_DESERT)) break;
+			}
+			if (data == endof(_make_desert_or_rainforest_data_extralarge)) {
+				SetTropicZone(tile, TROPICZONE_RAINFOREST);
+			}
+		}
 	}
 }
 
@@ -1176,7 +1198,7 @@ static bool MakeLake(TileIndex tile, void *user_data)
 			MarkTileDirtyByTile(tile);
 			/* Remove desert directly around the river tile. */
 			TileIndex t = tile;
-			CircularTileSearch(&t, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
+			CircularTileSearch(&t, _settings_game.game_creation.lake_tropics_width, RiverModifyDesertZone, nullptr);
 			return false;
 		}
 	}

src/lang/english.txt

@@ -1679,12 +1679,15 @@ STR_CONFIG_SETTING_RIVERS_TOP_OF_HILL                           :Rivers require
 STR_CONFIG_SETTING_RIVERS_TOP_OF_HILL_HELPTEXT                  :Choose whether rivers require their springs to generate towards the top of hills.
 STR_CONFIG_SETTING_RIVER_TROPICS_WIDTH                          :Tropics width around rivers: {STRING}
 STR_CONFIG_SETTING_RIVER_TROPICS_WIDTH_HELPTEXT                 :Controls the width of the tropic zone that surrounds rivers in sub-tropic landscape.
+STR_CONFIG_SETTING_LAKE_TROPICS_WIDTH                           :Tropics width around lakes: {STRING}
+STR_CONFIG_SETTING_LAKE_TROPICS_WIDTH_HELPTEXT                  :Controls the width of the tropic zone that surrounds lakes in sub-tropic landscape.
 STR_CONFIG_SETTING_COAST_TROPICS_WIDTH                          :Tropics width around coasts: {STRING}
 STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_HELPTEXT                 :Controls the width of the tropic zone that surrounds coasts in sub-tropic landscape.
-###length 3
-STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_DEFAULT                  :Default
-STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_MEDIUM                   :Medium
-STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_LARGE                    :Large
+###length 4
+STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_DEFAULT                  :Default (13)
+STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_MEDIUM                   :Medium (19)
+STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_LARGE                    :Large (25)
+STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_EXTRALARGE               :Extra Large (51)
 STR_CONFIG_SETTING_LAKE_SIZE                                    :Size of lakes: {STRING}
 STR_CONFIG_SETTING_LAKE_SIZE_HELPTEXT                           :Controls the size of lakes that are generated along rivers.
 STR_CONFIG_SETTING_LAKE_SIZE_VALUE                              :{NUM}

src/settings_gui.cpp

@@ -2108,6 +2108,7 @@ static SettingsContainer &GetSettingsTree()
 				rivers->Add(new SettingEntry("game_creation.river_route_random"));
 				rivers->Add(new SettingEntry("game_creation.rivers_top_of_hill"));
 				rivers->Add(new SettingEntry("game_creation.river_tropics_width"));
+				rivers->Add(new SettingEntry("game_creation.lake_tropics_width"));
 				rivers->Add(new SettingEntry("game_creation.coast_tropics_width"));
 				rivers->Add(new SettingEntry("game_creation.lake_size"));
 				rivers->Add(new SettingEntry("game_creation.lakes_allowed_in_deserts"));

src/settings_type.h

@@ -413,6 +413,7 @@ struct GameCreationSettings {
 	byte   amount_of_rivers;                 ///< the amount of rivers
 	bool   rivers_top_of_hill;               ///< do rivers require starting near the tops of hills?
 	uint8  river_tropics_width;              ///< the configured width of tropics around rivers
+	uint8  lake_tropics_width;               ///< the configured width of tropics around lakes
 	uint8  coast_tropics_width;              ///< the configured width of tropics around coasts
 	uint8  lake_size;                        ///< how large can lakes get?
 	bool   lakes_allowed_in_deserts;         ///< are lakes allowed in deserts?

src/table/settings/settings.ini

@@ -3881,8 +3881,8 @@ var      = game_creation.river_tropics_width
 type     = SLE_UINT8
 flags    = SF_NEWGAME_ONLY | SF_SCENEDIT_TOO
 def      = 5
-min      = 1
-max      = 12
+min      = 2
+max      = 51
 interval = 1
 str      = STR_CONFIG_SETTING_RIVER_TROPICS_WIDTH
 strhelp  = STR_CONFIG_SETTING_RIVER_TROPICS_WIDTH_HELPTEXT
@@ -3890,13 +3890,27 @@ strval   = STR_JUST_COMMA
 cat      = SC_BASIC
 patxname = ""rivers.game_creation.river_tropics_width""
 
+[SDT_VAR]
+var      = game_creation.lake_tropics_width
+type     = SLE_UINT8
+flags    = SF_NEWGAME_ONLY | SF_SCENEDIT_TOO
+def      = 5
+min      = 2
+max      = 51
+interval = 1
+str      = STR_CONFIG_SETTING_LAKE_TROPICS_WIDTH
+strhelp  = STR_CONFIG_SETTING_LAKE_TROPICS_WIDTH_HELPTEXT
+strval   = STR_JUST_COMMA
+cat      = SC_BASIC
+patxname = ""rivers.game_creation.lake_tropics_width""
+
 [SDT_VAR]
 var      = game_creation.coast_tropics_width
 type     = SLE_UINT8
 flags    = SF_GUI_DROPDOWN | SF_NEWGAME_ONLY
 def      = 0
 min      = 0
-max      = 2
+max      = 3
 interval = 1
 str      = STR_CONFIG_SETTING_COAST_TROPICS_WIDTH
 strhelp  = STR_CONFIG_SETTING_COAST_TROPICS_WIDTH_HELPTEXT