Feature: setting to indicate desert coverage for tropic climate

This is an indication value; the game tries to get as close as it
can, but due to the complex tropic rules, that is unlikely to be
exact.

In the end, it picks a height-level to base the desert/tropic
line on. This is strictly seen not needed, as we can convert any
tile to either. But it is the simplest way to get started with
this without redoing all related functions.

1 files changed, 78 insertions, 12 deletions

diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index 94381fe89..20c12d8b4 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -111,7 +111,10 @@ static const NWidgetPart _nested_generate_landscape_widgets[] = {
 				NWidget(NWID_HORIZONTAL), SetPIP(0, 3, 0),
 					NWidget(NWID_VERTICAL, NC_EQUALSIZE), SetPIP(0, 4, 0),
 						NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_MAX_HEIGHTLEVEL, STR_NULL), SetFill(1, 1),
-						NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SNOW_COVERAGE, STR_NULL), SetFill(1, 1),
+						NWidget(NWID_SELECTION, INVALID_COLOUR, WID_GL_CLIMATE_SEL_LABEL),
+							NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SNOW_COVERAGE, STR_NULL), SetFill(1, 1),
+							NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_DESERT_COVERAGE, STR_NULL), SetFill(1, 1),
+						EndContainer(),
 						NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_DATE, STR_NULL), SetFill(1, 1),
 						NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SMOOTHNESS, STR_NULL), SetFill(1, 1),
 						NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_QUANTITY_OF_RIVERS, STR_NULL), SetFill(1, 1),
@@ -124,11 +127,19 @@ static const NWidgetPart _nested_generate_landscape_widgets[] = {
 							NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_MAX_HEIGHTLEVEL_TEXT), SetDataTip(STR_BLACK_INT, STR_NULL), SetFill(1, 0),
 							NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_MAX_HEIGHTLEVEL_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_MAX_HEIGHTLEVEL_UP), SetFill(0, 1),
 						EndContainer(),
-						/* Snow line. */
-						NWidget(NWID_HORIZONTAL),
-							NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_SNOW_COVERAGE_DOWN), SetFill(0, 1),
-							NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_TEXT), SetDataTip(STR_MAPGEN_SNOW_COVERAGE_TEXT, STR_NULL), SetFill(1, 0),
-							NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_SNOW_COVERAGE_UP), SetFill(0, 1),
+						NWidget(NWID_SELECTION, INVALID_COLOUR, WID_GL_CLIMATE_SEL_SELECTOR),
+							/* Snow coverage. */
+							NWidget(NWID_HORIZONTAL),
+								NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_SNOW_COVERAGE_DOWN), SetFill(0, 1),
+								NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_TEXT), SetDataTip(STR_MAPGEN_SNOW_COVERAGE_TEXT, STR_NULL), SetFill(1, 0),
+								NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_SNOW_COVERAGE_UP), SetFill(0, 1),
+							EndContainer(),
+							/* Desert coverage. */
+							NWidget(NWID_HORIZONTAL),
+								NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_DESERT_COVERAGE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_DESERT_COVERAGE_DOWN), SetFill(0, 1),
+								NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_DESERT_COVERAGE_TEXT), SetDataTip(STR_MAPGEN_DESERT_COVERAGE_TEXT, STR_NULL), SetFill(1, 0),
+								NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_DESERT_COVERAGE_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_DESERT_COVERAGE_UP), SetFill(0, 1),
+							EndContainer(),
 						EndContainer(),
 						/* Starting date. */
 						NWidget(NWID_HORIZONTAL),
@@ -228,7 +239,10 @@ static const NWidgetPart _nested_heightmap_load_widgets[] = {
 						NWidget(NWID_HORIZONTAL), SetPIP(0, 3, 0),
 							NWidget(NWID_VERTICAL, NC_EQUALSIZE), SetPIP(0, 4, 0),
 								NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_MAX_HEIGHTLEVEL, STR_NULL), SetFill(1, 1),
-								NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SNOW_COVERAGE, STR_NULL), SetFill(1, 1),
+								NWidget(NWID_SELECTION, INVALID_COLOUR, WID_GL_CLIMATE_SEL_LABEL),
+									NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SNOW_COVERAGE, STR_NULL), SetFill(1, 1),
+									NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_DESERT_COVERAGE, STR_NULL), SetFill(1, 1),
+								EndContainer(),
 								NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_DATE, STR_NULL), SetFill(1, 1),
 								NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_GAME_OPTIONS_TOWN_NAMES_FRAME, STR_NULL), SetFill(1, 1),
 							EndContainer(),
@@ -238,10 +252,17 @@ static const NWidgetPart _nested_heightmap_load_widgets[] = {
 									NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_MAX_HEIGHTLEVEL_TEXT), SetDataTip(STR_BLACK_INT, STR_NULL), SetFill(1, 0),
 									NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_MAX_HEIGHTLEVEL_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_MAX_HEIGHTLEVEL_UP), SetFill(0, 1),
 								EndContainer(),
-								NWidget(NWID_HORIZONTAL),
-									NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_SNOW_COVERAGE_DOWN), SetFill(0, 1),
-									NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_TEXT), SetDataTip(STR_BLACK_INT, STR_NULL), SetFill(1, 0),
-									NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_SNOW_COVERAGE_UP), SetFill(0, 1),
+								NWidget(NWID_SELECTION, INVALID_COLOUR, WID_GL_CLIMATE_SEL_SELECTOR),
+									NWidget(NWID_HORIZONTAL),
+										NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_SNOW_COVERAGE_DOWN), SetFill(0, 1),
+										NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_TEXT), SetDataTip(STR_MAPGEN_SNOW_COVERAGE_TEXT, STR_NULL), SetFill(1, 0),
+										NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_COVERAGE_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_SNOW_COVERAGE_UP), SetFill(0, 1),
+									EndContainer(),
+									NWidget(NWID_HORIZONTAL),
+										NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_DESERT_COVERAGE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_DESERT_COVERAGE_DOWN), SetFill(0, 1),
+										NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_DESERT_COVERAGE_TEXT), SetDataTip(STR_MAPGEN_DESERT_COVERAGE_TEXT, STR_NULL), SetFill(1, 0),
+										NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_DESERT_COVERAGE_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_DESERT_COVERAGE_UP), SetFill(0, 1),
+									EndContainer(),
 								EndContainer(),
 								NWidget(NWID_HORIZONTAL),
 									NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_START_DATE_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_SCENEDIT_TOOLBAR_TOOLTIP_MOVE_THE_STARTING_DATE_BACKWARD), SetFill(0, 1),
@@ -367,6 +388,7 @@ struct GenerateLandscapeWindow : public Window {
 			case WID_GL_MAPSIZE_Y_PULLDOWN:   SetDParam(0, 1LL << _settings_newgame.game_creation.map_y); break;
 			case WID_GL_MAX_HEIGHTLEVEL_TEXT: SetDParam(0, _settings_newgame.construction.max_heightlevel); break;
 			case WID_GL_SNOW_COVERAGE_TEXT:   SetDParam(0, _settings_newgame.game_creation.snow_coverage); break;
+			case WID_GL_DESERT_COVERAGE_TEXT: SetDParam(0, _settings_newgame.game_creation.desert_coverage); break;
 
 			case WID_GL_TOWN_PULLDOWN:
 				if (_game_mode == GM_EDITOR) {
@@ -458,6 +480,19 @@ struct GenerateLandscapeWindow : public Window {
 
 		/* Disable snowline if not arctic */
 		this->SetWidgetDisabledState(WID_GL_SNOW_COVERAGE_TEXT, _settings_newgame.game_creation.landscape != LT_ARCTIC);
+		/* Disable desert if not tropic */
+		this->SetWidgetDisabledState(WID_GL_DESERT_COVERAGE_TEXT, _settings_newgame.game_creation.landscape != LT_TROPIC);
+
+		/* Set snow/rainforest selections */
+		int climate_plane = 0;
+		switch (_settings_newgame.game_creation.landscape) {
+			case LT_TEMPERATE: climate_plane = SZSP_VERTICAL; break;
+			case LT_ARCTIC:    climate_plane = 0;             break;
+			case LT_TROPIC:    climate_plane = 1;             break;
+			case LT_TOYLAND:   climate_plane = SZSP_VERTICAL; break;
+		}
+		this->GetWidget<NWidgetStacked>(WID_GL_CLIMATE_SEL_LABEL)->SetDisplayedPlane(climate_plane);
+		this->GetWidget<NWidgetStacked>(WID_GL_CLIMATE_SEL_SELECTOR)->SetDisplayedPlane(climate_plane);
 
 		/* Update availability of decreasing / increasing start date and snow level */
 		this->SetWidgetDisabledState(WID_GL_MAX_HEIGHTLEVEL_DOWN, _settings_newgame.construction.max_heightlevel <= MIN_MAX_HEIGHTLEVEL);
@@ -466,6 +501,8 @@ struct GenerateLandscapeWindow : public Window {
 		this->SetWidgetDisabledState(WID_GL_START_DATE_UP,   _settings_newgame.game_creation.starting_year >= MAX_YEAR);
 		this->SetWidgetDisabledState(WID_GL_SNOW_COVERAGE_DOWN, _settings_newgame.game_creation.snow_coverage <= 0 || _settings_newgame.game_creation.landscape != LT_ARCTIC);
 		this->SetWidgetDisabledState(WID_GL_SNOW_COVERAGE_UP,   _settings_newgame.game_creation.snow_coverage >= 100 || _settings_newgame.game_creation.landscape != LT_ARCTIC);
+		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 &&
@@ -500,6 +537,11 @@ struct GenerateLandscapeWindow : public Window {
 				*size = maxdim(*size, GetStringBoundingBox(STR_MAPGEN_SNOW_COVERAGE_TEXT));
 				break;
 
+			case WID_GL_DESERT_COVERAGE_TEXT:
+				SetDParamMaxValue(0, MAX_TILE_HEIGHT);
+				*size = maxdim(*size, GetStringBoundingBox(STR_MAPGEN_DESERT_COVERAGE_TEXT));
+				break;
+
 			case WID_GL_HEIGHTMAP_SIZE_TEXT:
 				SetDParam(0, this->x);
 				SetDParam(1, this->y);
@@ -674,6 +716,24 @@ struct GenerateLandscapeWindow : public Window {
 				ShowQueryString(STR_JUST_INT, STR_MAPGEN_SNOW_COVERAGE_QUERY_CAPT, 4, this, CS_NUMERAL, QSF_ENABLE_DEFAULT);
 				break;
 
+			case WID_GL_DESERT_COVERAGE_DOWN:
+			case WID_GL_DESERT_COVERAGE_UP: // Desert coverage buttons
+				/* Don't allow too fast scrolling */
+				if (!(this->flags & WF_TIMEOUT) || this->timeout_timer <= 1) {
+					this->HandleButtonClick(widget);
+
+					_settings_newgame.game_creation.desert_coverage = Clamp(_settings_newgame.game_creation.desert_coverage + (widget - WID_GL_DESERT_COVERAGE_TEXT) * 10, 0, 100);
+					this->InvalidateData();
+				}
+				_left_button_clicked = false;
+				break;
+
+			case WID_GL_DESERT_COVERAGE_TEXT: // Desert line text
+				this->widget_id = WID_GL_DESERT_COVERAGE_TEXT;
+				SetDParam(0, _settings_newgame.game_creation.desert_coverage);
+				ShowQueryString(STR_JUST_INT, STR_MAPGEN_DESERT_COVERAGE_QUERY_CAPT, 4, this, CS_NUMERAL, QSF_ENABLE_DEFAULT);
+				break;
+
 			case WID_GL_LANDSCAPE_PULLDOWN: // Landscape generator
 				ShowDropDownMenu(this, _landscape, _settings_newgame.game_creation.land_generator, WID_GL_LANDSCAPE_PULLDOWN, 0, 0);
 				break;
@@ -739,7 +799,7 @@ struct GenerateLandscapeWindow : public Window {
 
 	void OnTimeout() override
 	{
-		static const int raise_widgets[] = {WID_GL_MAX_HEIGHTLEVEL_DOWN, WID_GL_MAX_HEIGHTLEVEL_UP, WID_GL_START_DATE_DOWN, WID_GL_START_DATE_UP, WID_GL_SNOW_COVERAGE_UP, WID_GL_SNOW_COVERAGE_DOWN, WIDGET_LIST_END};
+		static const int raise_widgets[] = {WID_GL_MAX_HEIGHTLEVEL_DOWN, WID_GL_MAX_HEIGHTLEVEL_UP, WID_GL_START_DATE_DOWN, WID_GL_START_DATE_UP, WID_GL_SNOW_COVERAGE_UP, WID_GL_SNOW_COVERAGE_DOWN, WID_GL_DESERT_COVERAGE_UP, WID_GL_DESERT_COVERAGE_DOWN, WIDGET_LIST_END};
 		for (const int *widget = raise_widgets; *widget != WIDGET_LIST_END; widget++) {
 			if (this->IsWidgetLowered(*widget)) {
 				this->RaiseWidget(*widget);
@@ -812,6 +872,7 @@ struct GenerateLandscapeWindow : public Window {
 				case WID_GL_MAX_HEIGHTLEVEL_TEXT: value = DEF_MAX_HEIGHTLEVEL; break;
 				case WID_GL_START_DATE_TEXT: value = DEF_START_YEAR; break;
 				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_WATER_PULLDOWN: value = CUSTOM_SEA_LEVEL_MIN_PERCENTAGE; break;
 				default: NOT_REACHED();
@@ -834,6 +895,11 @@ struct GenerateLandscapeWindow : public Window {
 				_settings_newgame.game_creation.snow_coverage = Clamp(value, 0, 100);
 				break;
 
+			case WID_GL_DESERT_COVERAGE_TEXT:
+				this->SetWidgetDirty(WID_GL_DESERT_COVERAGE_TEXT);
+				_settings_newgame.game_creation.desert_coverage = Clamp(value, 0, 100);
+				break;
+
 			case WID_GL_TOWN_PULLDOWN:
 				_settings_newgame.game_creation.custom_town_number = Clamp(value, 1, CUSTOM_TOWN_MAX_NUMBER);
 				break;