Introduce snow/desert-coverage and custom terrain type, and move "maximum map height" to settings only

src/cheat_gui.cpp

@@ -125,26 +125,26 @@ static int32 ClickChangeDateCheat(int32 p1, int32 p2)
  */
 static int32 ClickChangeMaxHlCheat(int32 p1, int32 p2)
 {
-	p1 = Clamp(p1, MIN_MAX_HEIGHTLEVEL, MAX_MAX_HEIGHTLEVEL);
+	p1 = Clamp(p1, MIN_MAP_HEIGHT_LIMIT, MAX_MAP_HEIGHT_LIMIT);
 
 	/* Check if at least one mountain on the map is higher than the new value.
 	 * If yes, disallow the change. */
 	for (TileIndex t = 0; t < MapSize(); t++) {
 		if ((int32)TileHeight(t) > p1) {
 			ShowErrorMessage(STR_CONFIG_SETTING_TOO_HIGH_MOUNTAIN, INVALID_STRING_ID, WL_ERROR);
 			/* Return old, unchanged value */
-			return _settings_game.construction.max_heightlevel;
+			return _settings_game.construction.map_height_limit;
 		}
 	}
 
 	/* Execute the change and reload GRF Data */
-	_settings_game.construction.max_heightlevel = p1;
+	_settings_game.construction.map_height_limit = p1;
 	ReloadNewGRFData();
 
 	/* The smallmap uses an index from heightlevels to colours. Trigger rebuilding it. */
 	InvalidateWindowClassesData(WC_SMALLMAP, 2);
 
-	return _settings_game.construction.max_heightlevel;
+	return _settings_game.construction.map_height_limit;
 }
 
 /** Available cheats. */
@@ -182,14 +182,14 @@ struct CheatEntry {
  * Order matches with the values of #CheatNumbers
  */
 static const CheatEntry _cheats_ui[] = {
-	{SLE_INT32, STR_CHEAT_MONEY,           &_money_cheat_amount,                    &_cheats.money.been_used,            &ClickMoneyCheat         },
-	{SLE_UINT8, STR_CHEAT_CHANGE_COMPANY,  &_local_company,                         &_cheats.switch_company.been_used,   &ClickChangeCompanyCheat },
-	{SLE_BOOL,  STR_CHEAT_EXTRA_DYNAMITE,  &_cheats.magic_bulldozer.value,          &_cheats.magic_bulldozer.been_used,  nullptr                     },
-	{SLE_BOOL,  STR_CHEAT_CROSSINGTUNNELS, &_cheats.crossing_tunnels.value,         &_cheats.crossing_tunnels.been_used, nullptr                     },
-	{SLE_BOOL,  STR_CHEAT_NO_JETCRASH,     &_cheats.no_jetcrash.value,              &_cheats.no_jetcrash.been_used,      nullptr                     },
-	{SLE_BOOL,  STR_CHEAT_SETUP_PROD,      &_cheats.setup_prod.value,               &_cheats.setup_prod.been_used,       &ClickSetProdCheat       },
-	{SLE_UINT8, STR_CHEAT_EDIT_MAX_HL,     &_settings_game.construction.max_heightlevel, &_cheats.edit_max_hl.been_used, &ClickChangeMaxHlCheat   },
-	{SLE_INT32, STR_CHEAT_CHANGE_DATE,     &_cur_year,                              &_cheats.change_date.been_used,      &ClickChangeDateCheat    },
+	{SLE_INT32, STR_CHEAT_MONEY,           &_money_cheat_amount,                          &_cheats.money.been_used,            &ClickMoneyCheat         },
+	{SLE_UINT8, STR_CHEAT_CHANGE_COMPANY,  &_local_company,                               &_cheats.switch_company.been_used,   &ClickChangeCompanyCheat },
+	{SLE_BOOL,  STR_CHEAT_EXTRA_DYNAMITE,  &_cheats.magic_bulldozer.value,                &_cheats.magic_bulldozer.been_used,  nullptr                  },
+	{SLE_BOOL,  STR_CHEAT_CROSSINGTUNNELS, &_cheats.crossing_tunnels.value,               &_cheats.crossing_tunnels.been_used, nullptr                  },
+	{SLE_BOOL,  STR_CHEAT_NO_JETCRASH,     &_cheats.no_jetcrash.value,                    &_cheats.no_jetcrash.been_used,      nullptr                  },
+	{SLE_BOOL,  STR_CHEAT_SETUP_PROD,      &_cheats.setup_prod.value,                     &_cheats.setup_prod.been_used,       &ClickSetProdCheat       },
+	{SLE_UINT8, STR_CHEAT_EDIT_MAX_HL,     &_settings_game.construction.map_height_limit, &_cheats.edit_max_hl.been_used,      &ClickChangeMaxHlCheat   },
+	{SLE_INT32, STR_CHEAT_CHANGE_DATE,     &_cur_year,                                    &_cheats.change_date.been_used,      &ClickChangeDateCheat    },
 };
 
 static_assert(CHT_NUM_CHEATS == lengthof(_cheats_ui));

src/genworld.cpp

@@ -33,6 +33,7 @@
 #include "game/game_instance.hpp"
 #include "string_func.h"
 #include "thread.h"
+#include "tgp.h"
 
 #include "safeguards.h"
 
@@ -118,6 +119,8 @@ static void _GenerateWorld()
 
 			ConvertGroundTilesIntoWaterTiles();
 			IncreaseGeneratingWorldProgress(GWP_OBJECT);
+
+			_settings_game.game_creation.snow_line_height = DEF_SNOWLINE_HEIGHT;
 		} else {
 			GenerateLandscape(_gw.mode);
 			GenerateClearTile();
@@ -283,6 +286,22 @@ void GenerateWorld(GenWorldMode mode, uint size_x, uint size_y, bool reset_setti
 	InitializeGame(_gw.size_x, _gw.size_y, true, reset_settings);
 	PrepareGenerateWorldProgress();
 
+	if (_settings_game.construction.map_height_limit == 0) {
+		uint estimated_height = 0;
+
+		if (_gw.mode == GWM_EMPTY && _game_mode != GM_MENU) {
+			estimated_height = _settings_game.game_creation.se_flat_world_height;
+		} else if (_gw.mode == GWM_HEIGHTMAP) {
+			estimated_height = _settings_game.game_creation.heightmap_height;
+		} else if (_settings_game.game_creation.land_generator == LG_TERRAGENESIS) {
+			estimated_height = GetEstimationTGPMapHeight();
+		} else {
+			estimated_height = 0;
+		}
+
+		_settings_game.construction.map_height_limit = std::max(MAP_HEIGHT_LIMIT_AUTO_MINIMUM, std::min(MAX_MAP_HEIGHT_LIMIT, estimated_height + MAP_HEIGHT_LIMIT_AUTO_CEILING_ROOM));
+	}
+
 	/* Load the right landscape stuff, and the NewGRFs! */
 	GfxLoadSprites();
 	LoadStringWidthTable();

src/genworld.h

@@ -42,10 +42,15 @@ enum TgenSmoothness {
 	TGEN_SMOOTHNESS_END,        ///< Used to iterate.
 };
 
+static const uint CUSTOM_TERRAIN_TYPE_NUMBER_DIFFICULTY = 5; ///< Value for custom terrain type in difficulty settings.
+
 static const uint CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY = 4; ///< Value for custom sea level in difficulty settings.
 static const uint CUSTOM_SEA_LEVEL_MIN_PERCENTAGE = 1;    ///< Minimum percentage a user can specify for custom sea level.
 static const uint CUSTOM_SEA_LEVEL_MAX_PERCENTAGE = 90;   ///< Maximum percentage a user can specify for custom sea level.
 
+static const uint MAP_HEIGHT_LIMIT_AUTO_MINIMUM = 30; ///< When map height limit is auto, make this the lowest possible map height limit.
+static const uint MAP_HEIGHT_LIMIT_AUTO_CEILING_ROOM = 15; ///< When map height limit is auto, the map height limit will be the higest peak plus this value.
+
 typedef void GWDoneProc();  ///< Procedure called when the genworld process finishes
 typedef void GWAbortProc(); ///< Called when genworld is aborted