Feature: allow setting a custom terrain type to define highest peak

At least, TGP will try to reach it. It heavily depends on the map
if it is reachable at all. But for sure it will do its atmost to
get there!

7 files changed, 67 insertions, 11 deletions

diff --git a/src/genworld.h b/src/genworld.h
index 71dae3f36..e6def6944 100644
--- a/src/genworld.h
+++ b/src/genworld.h
@@ -42,6 +42,8 @@ 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.
diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index f59e0ae46..46f2eac24 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -347,7 +347,7 @@ static DropDownList BuildTownNameDropDown()
 }
 
 
-static const StringID _elevations[]  = {STR_TERRAIN_TYPE_VERY_FLAT, STR_TERRAIN_TYPE_FLAT, STR_TERRAIN_TYPE_HILLY, STR_TERRAIN_TYPE_MOUNTAINOUS, STR_TERRAIN_TYPE_ALPINIST, INVALID_STRING_ID};
+static const StringID _elevations[]  = {STR_TERRAIN_TYPE_VERY_FLAT, STR_TERRAIN_TYPE_FLAT, STR_TERRAIN_TYPE_HILLY, STR_TERRAIN_TYPE_MOUNTAINOUS, STR_TERRAIN_TYPE_ALPINIST, STR_TERRAIN_TYPE_CUSTOM, INVALID_STRING_ID};
 static const StringID _sea_lakes[]   = {STR_SEA_LEVEL_VERY_LOW, STR_SEA_LEVEL_LOW, STR_SEA_LEVEL_MEDIUM, STR_SEA_LEVEL_HIGH, STR_SEA_LEVEL_CUSTOM, INVALID_STRING_ID};
 static const StringID _rivers[]      = {STR_RIVERS_NONE, STR_RIVERS_FEW, STR_RIVERS_MODERATE, STR_RIVERS_LOT, INVALID_STRING_ID};
 static const StringID _smoothness[]  = {STR_CONFIG_SETTING_ROUGHNESS_OF_TERRAIN_VERY_SMOOTH, STR_CONFIG_SETTING_ROUGHNESS_OF_TERRAIN_SMOOTH, STR_CONFIG_SETTING_ROUGHNESS_OF_TERRAIN_ROUGH, STR_CONFIG_SETTING_ROUGHNESS_OF_TERRAIN_VERY_ROUGH, INVALID_STRING_ID};
@@ -378,8 +378,9 @@ struct GenerateLandscapeWindow : public Window {
 		this->SetWidgetDisabledState(WID_GL_TOWN_PULLDOWN,     _game_mode == GM_EDITOR);
 		this->SetWidgetDisabledState(WID_GL_INDUSTRY_PULLDOWN, _game_mode == GM_EDITOR);
 
-		/* In case the map_height_limit is changed, clamp heightmap_height. */
+		/* In case the map_height_limit is changed, clamp heightmap_height and custom_terrain_type. */
 		_settings_newgame.game_creation.heightmap_height = Clamp(_settings_newgame.game_creation.heightmap_height, MIN_HEIGHTMAP_HEIGHT, GetMapHeightLimit());
+		_settings_newgame.game_creation.custom_terrain_type = Clamp(_settings_newgame.game_creation.custom_terrain_type, MIN_CUSTOM_TERRAIN_TYPE, GetMapHeightLimit());
 
 		this->OnInvalidateData();
 	}
@@ -417,7 +418,14 @@ struct GenerateLandscapeWindow : public Window {
 
 			case WID_GL_INDUSTRY_PULLDOWN:   SetDParam(0, _game_mode == GM_EDITOR ? STR_CONFIG_SETTING_OFF : _num_inds[_settings_newgame.difficulty.industry_density]); break;
 			case WID_GL_LANDSCAPE_PULLDOWN:  SetDParam(0, _landscape[_settings_newgame.game_creation.land_generator]); break;
-			case WID_GL_TERRAIN_PULLDOWN:    SetDParam(0, _elevations[_settings_newgame.difficulty.terrain_type]); break;
+			case WID_GL_TERRAIN_PULLDOWN:
+				if (_settings_newgame.difficulty.terrain_type == CUSTOM_TERRAIN_TYPE_NUMBER_DIFFICULTY) {
+					SetDParam(0, STR_TERRAIN_TYPE_CUSTOM_VALUE);
+					SetDParam(1, _settings_newgame.game_creation.custom_terrain_type);
+				} else {
+					SetDParam(0, _elevations[_settings_newgame.difficulty.terrain_type]); break;
+				}
+				break;
 
 			case WID_GL_WATER_PULLDOWN:
 				if (_settings_newgame.difficulty.quantity_sea_lakes == CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY) {
@@ -511,10 +519,14 @@ struct GenerateLandscapeWindow : public Window {
 		this->SetWidgetDisabledState(WID_GL_DESERT_COVERAGE_DOWN, _settings_newgame.game_creation.desert_coverage <= 0 || _settings_newgame.game_creation.landscape != LT_TROPIC);
 		this->SetWidgetDisabledState(WID_GL_DESERT_COVERAGE_UP,   _settings_newgame.game_creation.desert_coverage >= 100 || _settings_newgame.game_creation.landscape != LT_TROPIC);
 
-		/* Do not allow a custom sea level with the original land generator. */
-		if (_settings_newgame.game_creation.land_generator == LG_ORIGINAL &&
-				_settings_newgame.difficulty.quantity_sea_lakes == CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY) {
-			_settings_newgame.difficulty.quantity_sea_lakes = CUSTOM_SEA_LEVEL_MIN_PERCENTAGE;
+		/* Do not allow a custom sea level or terrain type with the original land generator. */
+		if (_settings_newgame.game_creation.land_generator == LG_ORIGINAL) {
+			if (_settings_newgame.difficulty.quantity_sea_lakes == CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY) {
+				_settings_newgame.difficulty.quantity_sea_lakes = 1;
+			}
+			if (_settings_newgame.difficulty.terrain_type == CUSTOM_TERRAIN_TYPE_NUMBER_DIFFICULTY) {
+				_settings_newgame.difficulty.terrain_type = 1;
+			}
 		}
 
 	}
@@ -563,7 +575,13 @@ struct GenerateLandscapeWindow : public Window {
 
 			case WID_GL_INDUSTRY_PULLDOWN:   strs = _num_inds; break;
 			case WID_GL_LANDSCAPE_PULLDOWN:  strs = _landscape; break;
-			case WID_GL_TERRAIN_PULLDOWN:    strs = _elevations; break;
+
+			case WID_GL_TERRAIN_PULLDOWN:
+				strs = _elevations;
+				SetDParamMaxValue(0, MAX_MAP_HEIGHT_LIMIT);
+				*size = maxdim(*size, GetStringBoundingBox(STR_TERRAIN_TYPE_CUSTOM_VALUE));
+				break;
+
 			case WID_GL_WATER_PULLDOWN:
 				strs = _sea_lakes;
 				SetDParamMaxValue(0, CUSTOM_SEA_LEVEL_MAX_PERCENTAGE);
@@ -854,7 +872,15 @@ struct GenerateLandscapeWindow : public Window {
 				break;
 
 			case WID_GL_INDUSTRY_PULLDOWN: _settings_newgame.difficulty.industry_density = index; break;
-			case WID_GL_TERRAIN_PULLDOWN:  _settings_newgame.difficulty.terrain_type     = index; break;
+			case WID_GL_TERRAIN_PULLDOWN: {
+				if ((uint)index == CUSTOM_TERRAIN_TYPE_NUMBER_DIFFICULTY) {
+					this->widget_id = widget;
+					SetDParam(0, _settings_newgame.game_creation.custom_terrain_type);
+					ShowQueryString(STR_JUST_INT, STR_MAPGEN_TERRAIN_TYPE_QUERY_CAPT, 4, this, CS_NUMERAL, QSF_NONE);
+				}
+				_settings_newgame.difficulty.terrain_type = index;
+				break;
+			}
 
 			case WID_GL_WATER_PULLDOWN: {
 				if ((uint)index == CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY) {
@@ -885,6 +911,7 @@ struct GenerateLandscapeWindow : public Window {
 				case WID_GL_SNOW_COVERAGE_TEXT: value = DEF_SNOW_COVERAGE; break;
 				case WID_GL_DESERT_COVERAGE_TEXT: value = DEF_DESERT_COVERAGE; break;
 				case WID_GL_TOWN_PULLDOWN: value = 1; break;
+				case WID_GL_TERRAIN_PULLDOWN: value = MIN_MAP_HEIGHT_LIMIT; break;
 				case WID_GL_WATER_PULLDOWN: value = CUSTOM_SEA_LEVEL_MIN_PERCENTAGE; break;
 				default: NOT_REACHED();
 			}
@@ -915,6 +942,10 @@ struct GenerateLandscapeWindow : public Window {
 				_settings_newgame.game_creation.custom_town_number = Clamp(value, 1, CUSTOM_TOWN_MAX_NUMBER);
 				break;
 
+			case WID_GL_TERRAIN_PULLDOWN:
+				_settings_newgame.game_creation.custom_terrain_type = Clamp(value, MIN_CUSTOM_TERRAIN_TYPE, GetMapHeightLimit());
+				break;
+
 			case WID_GL_WATER_PULLDOWN:
 				_settings_newgame.game_creation.custom_sea_level = Clamp(value, CUSTOM_SEA_LEVEL_MIN_PERCENTAGE, CUSTOM_SEA_LEVEL_MAX_PERCENTAGE);
 				break;
diff --git a/src/lang/english.txt b/src/lang/english.txt
index 2af2e7e58..2554a5a17 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -1124,6 +1124,8 @@ STR_TERRAIN_TYPE_FLAT                                           :Flat
 STR_TERRAIN_TYPE_HILLY                                          :Hilly
 STR_TERRAIN_TYPE_MOUNTAINOUS                                    :Mountainous
 STR_TERRAIN_TYPE_ALPINIST                                       :Alpinist
+STR_TERRAIN_TYPE_CUSTOM                                         :Custom height
+STR_TERRAIN_TYPE_CUSTOM_VALUE                                   :Custom height ({NUM})
 
 STR_CITY_APPROVAL_PERMISSIVE                                    :Permissive
 STR_CITY_APPROVAL_TOLERANT                                      :Tolerant
@@ -1206,7 +1208,7 @@ STR_CONFIG_SETTING_CITY_APPROVAL                                :Town council's
 STR_CONFIG_SETTING_CITY_APPROVAL_HELPTEXT                       :Choose how much noise and environmental damage by companies affect their town rating and further construction actions in their area
 
 STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT                             :Map height limit: {STRING2}
-STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT_HELPTEXT                    :Set the maximum allowed height of the map; neither the terrain generator nor you can build higher than this limit. On (auto) it will pick a good value after terrain generation
+STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT_HELPTEXT                    :Set the maximum height of the map terrain. With "(auto)" a good value will be picked after terrain generation
 STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT_VALUE                       :{NUM}
 STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT_AUTO                        :(auto)
 STR_CONFIG_SETTING_TOO_HIGH_MOUNTAIN                            :{WHITE}You can't set the map height limit to this value. At least one mountain on the map is higher
@@ -2936,6 +2938,7 @@ STR_MAPGEN_HEIGHTMAP_NAME                                       :{BLACK}Heightma
 STR_MAPGEN_HEIGHTMAP_SIZE_LABEL                                 :{BLACK}Size:
 STR_MAPGEN_HEIGHTMAP_SIZE                                       :{ORANGE}{NUM} x {NUM}
 
+STR_MAPGEN_TERRAIN_TYPE_QUERY_CAPT                              :{WHITE}Target peak height
 STR_MAPGEN_HEIGHTMAP_HEIGHT_QUERY_CAPT                          :{WHITE}Highest peak
 STR_MAPGEN_SNOW_COVERAGE_QUERY_CAPT                             :{WHITE}Snow coverage (in %)
 STR_MAPGEN_DESERT_COVERAGE_QUERY_CAPT                           :{WHITE}Desert coverage (in %)
diff --git a/src/settings_type.h b/src/settings_type.h
index 7d50d594b..42bdc27d4 100644
--- a/src/settings_type.h
+++ b/src/settings_type.h
@@ -309,6 +309,7 @@ struct GameCreationSettings {
 	byte   water_borders;                    ///< bitset of the borders that are water
 	uint16 custom_town_number;               ///< manually entered number of towns
 	byte   variety;                          ///< variety level applied to TGP
+	byte   custom_terrain_type;              ///< manually entered height for TGP to aim for
 	byte   custom_sea_level;                 ///< manually entered percentage of water in the map
 	byte   min_river_length;                 ///< the minimum river length
 	byte   river_route_random;               ///< the amount of randomicity for the route finding
diff --git a/src/table/settings.ini b/src/table/settings.ini
index 694268e76..9f5a9b212 100644
--- a/src/table/settings.ini
+++ b/src/table/settings.ini
@@ -266,7 +266,7 @@ from     = SLV_97
 guiflags = SGF_MULTISTRING | SGF_NEWGAME_ONLY
 def      = 1
 min      = 0
-max      = 4
+max      = 5
 interval = 1
 str      = STR_CONFIG_SETTING_TERRAIN_TYPE
 strhelp  = STR_CONFIG_SETTING_TERRAIN_TYPE_HELPTEXT
@@ -2465,6 +2465,17 @@ cat      = SC_BASIC
 
 [SDT_VAR]
 base     = GameSettings
+var      = game_creation.custom_terrain_type
+type     = SLE_UINT8
+flags    = SLF_NOT_IN_SAVE | SLF_NO_NETWORK_SYNC
+guiflags = SGF_NEWGAME_ONLY
+def      = MAP_HEIGHT_LIMIT_AUTO_MINIMUM
+min      = MIN_CUSTOM_TERRAIN_TYPE
+max      = MAX_MAP_HEIGHT_LIMIT
+interval = 1
+
+[SDT_VAR]
+base     = GameSettings
 var      = game_creation.custom_sea_level
 type     = SLE_UINT8
 from     = SLV_149
diff --git a/src/tgp.cpp b/src/tgp.cpp
index 3ced2a1b0..d86617ee2 100644
--- a/src/tgp.cpp
+++ b/src/tgp.cpp
@@ -215,6 +215,13 @@ static const amplitude_t _water_percent[4] = {70, 170, 270, 420};
  */
 static height_t TGPGetMaxHeight()
 {
+	if (_settings_game.difficulty.terrain_type == CUSTOM_TERRAIN_TYPE_NUMBER_DIFFICULTY) {
+		/* TGP never reaches this height; this means that if a user inputs "2",
+		 * it would create a flat map without the "+ 1". But that would
+		 * overflow on "255". So we reduce it by 1 to get back in range. */
+		return I2H(_settings_game.game_creation.custom_terrain_type + 1) - 1;
+	}
+
 	/**
 	 * Desired maximum height - indexed by:
 	 *  - _settings_game.difficulty.terrain_type
diff --git a/src/tile_type.h b/src/tile_type.h
index efc057d2b..73fd0e97e 100644
--- a/src/tile_type.h
+++ b/src/tile_type.h
@@ -22,6 +22,7 @@ static const int MAX_VEHICLE_PIXEL_Y  = 96;                    ///< Maximum heig
 static const uint MAX_TILE_HEIGHT     = 255;                   ///< Maximum allowed tile height
 
 static const uint MIN_HEIGHTMAP_HEIGHT = 1;                    ///< Lowest possible peak value for heightmap creation
+static const uint MIN_CUSTOM_TERRAIN_TYPE = 1;                 ///< Lowest possible peak value for world generation
 
 static const uint MIN_MAP_HEIGHT_LIMIT = 15;                   ///< Lower bound of maximum allowed heightlevel (in the construction settings)
 static const uint MAX_MAP_HEIGHT_LIMIT = MAX_TILE_HEIGHT;      ///< Upper bound of maximum allowed heightlevel (in the construction settings)