Feature: setting to indicate snow coverage for arctic climate (replaces snow line height)

Setting the snow coverage (in % of the map) makes a lot more sense
to the human, while still allowing the niche player to set (by
finding the correct %) a snow line height they like. This makes for
easier defaults, as it decoupled terrain height from amount of snow.

Maps can never be 100% snow, as we do not have sprites for coastal
tiles.

Internally, this calculates the best snow line height to approach
this coverage as close as possible.

1 files changed, 28 insertions, 28 deletions

diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index 14abd4b75..94381fe89 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -111,7 +111,7 @@ 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_LINE_HEIGHT, STR_NULL), SetFill(1, 1),
+						NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SNOW_COVERAGE, STR_NULL), SetFill(1, 1),
 						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),
@@ -126,9 +126,9 @@ static const NWidgetPart _nested_generate_landscape_widgets[] = {
 						EndContainer(),
 						/* Snow line. */
 						NWidget(NWID_HORIZONTAL),
-							NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_LEVEL_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_SNOW_LINE_DOWN), SetFill(0, 1),
-							NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_SNOW_LEVEL_TEXT), SetDataTip(STR_BLACK_INT, STR_NULL), SetFill(1, 0),
-							NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_LEVEL_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_SNOW_LINE_UP), SetFill(0, 1),
+							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(),
 						/* Starting date. */
 						NWidget(NWID_HORIZONTAL),
@@ -228,7 +228,7 @@ 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_LINE_HEIGHT, STR_NULL), SetFill(1, 1),
+								NWidget(WWT_TEXT, COLOUR_ORANGE), SetDataTip(STR_MAPGEN_SNOW_COVERAGE, STR_NULL), SetFill(1, 1),
 								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(),
@@ -239,9 +239,9 @@ static const NWidgetPart _nested_heightmap_load_widgets[] = {
 									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_LEVEL_DOWN), SetDataTip(SPR_ARROW_DOWN, STR_MAPGEN_SNOW_LINE_DOWN), SetFill(0, 1),
-									NWidget(WWT_TEXTBTN, COLOUR_ORANGE, WID_GL_SNOW_LEVEL_TEXT), SetDataTip(STR_BLACK_INT, STR_NULL), SetFill(1, 0),
-									NWidget(WWT_IMGBTN, COLOUR_ORANGE, WID_GL_SNOW_LEVEL_UP), SetDataTip(SPR_ARROW_UP, STR_MAPGEN_SNOW_LINE_UP), SetFill(0, 1),
+									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),
 								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),
@@ -366,7 +366,7 @@ struct GenerateLandscapeWindow : public Window {
 			case WID_GL_MAPSIZE_X_PULLDOWN:   SetDParam(0, 1LL << _settings_newgame.game_creation.map_x); break;
 			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_LEVEL_TEXT:      SetDParam(0, _settings_newgame.game_creation.snow_line_height); break;
+			case WID_GL_SNOW_COVERAGE_TEXT:   SetDParam(0, _settings_newgame.game_creation.snow_coverage); break;
 
 			case WID_GL_TOWN_PULLDOWN:
 				if (_game_mode == GM_EDITOR) {
@@ -457,15 +457,15 @@ struct GenerateLandscapeWindow : public Window {
 		}
 
 		/* Disable snowline if not arctic */
-		this->SetWidgetDisabledState(WID_GL_SNOW_LEVEL_TEXT, _settings_newgame.game_creation.landscape != LT_ARCTIC);
+		this->SetWidgetDisabledState(WID_GL_SNOW_COVERAGE_TEXT, _settings_newgame.game_creation.landscape != LT_ARCTIC);
 
 		/* 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);
 		this->SetWidgetDisabledState(WID_GL_MAX_HEIGHTLEVEL_UP, _settings_newgame.construction.max_heightlevel >= MAX_MAX_HEIGHTLEVEL);
 		this->SetWidgetDisabledState(WID_GL_START_DATE_DOWN, _settings_newgame.game_creation.starting_year <= MIN_YEAR);
 		this->SetWidgetDisabledState(WID_GL_START_DATE_UP,   _settings_newgame.game_creation.starting_year >= MAX_YEAR);
-		this->SetWidgetDisabledState(WID_GL_SNOW_LEVEL_DOWN, _settings_newgame.game_creation.snow_line_height <= MIN_SNOWLINE_HEIGHT || _settings_newgame.game_creation.landscape != LT_ARCTIC);
-		this->SetWidgetDisabledState(WID_GL_SNOW_LEVEL_UP,   _settings_newgame.game_creation.snow_line_height >= MAX_SNOWLINE_HEIGHT || _settings_newgame.game_creation.landscape != LT_ARCTIC);
+		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);
 
 		/* Do not allow a custom sea level with the original land generator. */
 		if (_settings_newgame.game_creation.land_generator == LG_ORIGINAL &&
@@ -495,9 +495,9 @@ struct GenerateLandscapeWindow : public Window {
 				*size = maxdim(*size, GetStringBoundingBox(STR_JUST_INT));
 				break;
 
-			case WID_GL_SNOW_LEVEL_TEXT:
+			case WID_GL_SNOW_COVERAGE_TEXT:
 				SetDParamMaxValue(0, MAX_TILE_HEIGHT);
-				*size = maxdim(*size, GetStringBoundingBox(STR_JUST_INT));
+				*size = maxdim(*size, GetStringBoundingBox(STR_MAPGEN_SNOW_COVERAGE_TEXT));
 				break;
 
 			case WID_GL_HEIGHTMAP_SIZE_TEXT:
@@ -656,22 +656,22 @@ struct GenerateLandscapeWindow : public Window {
 				ShowQueryString(STR_JUST_INT, STR_MAPGEN_START_DATE_QUERY_CAPT, 8, this, CS_NUMERAL, QSF_ENABLE_DEFAULT);
 				break;
 
-			case WID_GL_SNOW_LEVEL_DOWN:
-			case WID_GL_SNOW_LEVEL_UP: // Snow line buttons
+			case WID_GL_SNOW_COVERAGE_DOWN:
+			case WID_GL_SNOW_COVERAGE_UP: // Snow coverage buttons
 				/* Don't allow too fast scrolling */
 				if (!(this->flags & WF_TIMEOUT) || this->timeout_timer <= 1) {
 					this->HandleButtonClick(widget);
 
-					_settings_newgame.game_creation.snow_line_height = Clamp(_settings_newgame.game_creation.snow_line_height + widget - WID_GL_SNOW_LEVEL_TEXT, MIN_SNOWLINE_HEIGHT, MAX_SNOWLINE_HEIGHT);
+					_settings_newgame.game_creation.snow_coverage = Clamp(_settings_newgame.game_creation.snow_coverage + (widget - WID_GL_SNOW_COVERAGE_TEXT) * 10, 0, 100);
 					this->InvalidateData();
 				}
 				_left_button_clicked = false;
 				break;
 
-			case WID_GL_SNOW_LEVEL_TEXT: // Snow line text
-				this->widget_id = WID_GL_SNOW_LEVEL_TEXT;
-				SetDParam(0, _settings_newgame.game_creation.snow_line_height);
-				ShowQueryString(STR_JUST_INT, STR_MAPGEN_SNOW_LINE_QUERY_CAPT, 4, this, CS_NUMERAL, QSF_ENABLE_DEFAULT);
+			case WID_GL_SNOW_COVERAGE_TEXT: // Snow coverage text
+				this->widget_id = WID_GL_SNOW_COVERAGE_TEXT;
+				SetDParam(0, _settings_newgame.game_creation.snow_coverage);
+				ShowQueryString(STR_JUST_INT, STR_MAPGEN_SNOW_COVERAGE_QUERY_CAPT, 4, this, CS_NUMERAL, QSF_ENABLE_DEFAULT);
 				break;
 
 			case WID_GL_LANDSCAPE_PULLDOWN: // Landscape generator
@@ -739,7 +739,7 @@ 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_LEVEL_UP, WID_GL_SNOW_LEVEL_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, WIDGET_LIST_END};
 		for (const int *widget = raise_widgets; *widget != WIDGET_LIST_END; widget++) {
 			if (this->IsWidgetLowered(*widget)) {
 				this->RaiseWidget(*widget);
@@ -811,9 +811,9 @@ struct GenerateLandscapeWindow : public Window {
 			switch (this->widget_id) {
 				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_LEVEL_TEXT: value = DEF_SNOWLINE_HEIGHT; break;
-				case WID_GL_TOWN_PULLDOWN:   value = 1; break;
-				case WID_GL_WATER_PULLDOWN:  value = CUSTOM_SEA_LEVEL_MIN_PERCENTAGE; break;
+				case WID_GL_SNOW_COVERAGE_TEXT: value = DEF_SNOW_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();
 			}
 		}
@@ -829,9 +829,9 @@ struct GenerateLandscapeWindow : public Window {
 				_settings_newgame.game_creation.starting_year = Clamp(value, MIN_YEAR, MAX_YEAR);
 				break;
 
-			case WID_GL_SNOW_LEVEL_TEXT:
-				this->SetWidgetDirty(WID_GL_SNOW_LEVEL_TEXT);
-				_settings_newgame.game_creation.snow_line_height = Clamp(value, MIN_SNOWLINE_HEIGHT, MAX_SNOWLINE_HEIGHT);
+			case WID_GL_SNOW_COVERAGE_TEXT:
+				this->SetWidgetDirty(WID_GL_SNOW_COVERAGE_TEXT);
+				_settings_newgame.game_creation.snow_coverage = Clamp(value, 0, 100);
 				break;
 
 			case WID_GL_TOWN_PULLDOWN: