Cache current value of snow line height

src/date.cpp

@@ -21,6 +21,7 @@
 #include "newgrf_profiling.h"
 #include "console_func.h"
 #include "debug.h"
+#include "landscape.h"
 #include "widgets/statusbar_widget.h"
 
 #include "safeguards.h"
@@ -54,6 +55,7 @@ void SetDate(Date date, DateFract fract)
 	ConvertDateToYMD(date, &ymd);
 	_cur_date_ymd = ymd;
 	SetScaledTickVariables();
+	UpdateCachedSnowLine();
 }
 
 void SetScaledTickVariables()
@@ -322,6 +324,8 @@ void IncreaseDate()
 	/* update internal variables before calling the daily/monthly/yearly loops */
 	_cur_date_ymd = ymd;
 
+	UpdateCachedSnowLine();
+
 	/* yes, call various daily loops */
 	OnNewDay();
 

src/landscape.cpp

@@ -92,6 +92,8 @@ extern const byte _slope_to_sprite_offset[32] = {
  */
 static SnowLine *_snow_line = nullptr;
 
+byte _cached_snowline = 0;
+
 /**
  * Map 2D viewport or smallmap coordinate to 3D world or tile coordinate.
  * Function takes into account height of tiles and foundations.
@@ -643,6 +645,8 @@ void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS])
 			_snow_line->lowest_value = std::min(_snow_line->lowest_value, table[i][j]);
 		}
 	}
+
+	UpdateCachedSnowLine();
 }
 
 /**
@@ -650,13 +654,18 @@ void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS])
  * @return the snow line height.
  * @ingroup SnowLineGroup
  */
-byte GetSnowLine()
+byte GetSnowLineUncached()
 {
 	if (_snow_line == nullptr) return _settings_game.game_creation.snow_line_height;
 
 	return _snow_line->table[_cur_date_ymd.month][_cur_date_ymd.day];
 }
 
+void UpdateCachedSnowLine()
+{
+	_cached_snowline = GetSnowLineUncached();
+}
+
 /**
  * Get the highest possible snow line height, either variable or static.
  * @return the highest snow line height.
@@ -685,6 +694,7 @@ void ClearSnowLine()
 {
 	free(_snow_line);
 	_snow_line = nullptr;
+	UpdateCachedSnowLine();
 }
 
 /**

src/landscape.h

@@ -28,11 +28,18 @@ struct SnowLine {
 
 bool IsSnowLineSet();
 void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS]);
-byte GetSnowLine();
+byte GetSnowLineUncached();
+void UpdateCachedSnowLine();
 byte HighestSnowLine();
 byte LowestSnowLine();
 void ClearSnowLine();
 
+inline byte GetSnowLine()
+{
+	extern byte _cached_snowline;
+	return _cached_snowline;
+}
+
 int GetSlopeZInCorner(Slope tileh, Corner corner);
 Slope GetFoundationSlope(TileIndex tile, int *z = nullptr);
 

src/misc.cpp

@@ -100,6 +100,7 @@ void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settin
 	} else {
 		SetScaledTickVariables();
 	}
+	UpdateCachedSnowLine();
 
 	LinkGraphSchedule::Clear();
 	ClearTraceRestrictMapping();

src/newgrf.cpp

@@ -10387,6 +10387,7 @@ void LoadNewGRF(uint load_index, uint file_index, uint num_baseset)
 		_tick_counter = 0;
 		_tick_skip_counter = 0;
 		_display_opt  = 0;
+		UpdateCachedSnowLine();
 		SetScaledTickVariables();
 	}
 
@@ -10483,6 +10484,7 @@ void LoadNewGRF(uint load_index, uint file_index, uint num_baseset)
 	_tick_counter = tick_counter;
 	_tick_skip_counter = tick_skip_counter;
 	_display_opt  = display_opt;
+	UpdateCachedSnowLine();
 	SetScaledTickVariables();
 }
 

src/saveload/afterload.cpp

@@ -627,6 +627,7 @@ bool AfterLoadGame()
 
 	RebuildTownKdtree();
 	RebuildStationKdtree();
+	UpdateCachedSnowLine();
 
 	_viewport_sign_kdtree_valid = false;
 
@@ -1671,6 +1672,7 @@ bool AfterLoadGame()
 		_date += DAYS_TILL_ORIGINAL_BASE_YEAR;
 		SetScaledTickVariables();
 		ConvertDateToYMD(_date, &_cur_date_ymd);
+		UpdateCachedSnowLine();
 
 		for (Station *st : Station::Iterate())   st->build_date      += DAYS_TILL_ORIGINAL_BASE_YEAR;
 		for (Waypoint *wp : Waypoint::Iterate()) wp->build_date      += DAYS_TILL_ORIGINAL_BASE_YEAR;
@@ -3061,6 +3063,7 @@ bool AfterLoadGame()
 	/* This triggers only when old snow_lines were copied into the snow_line_height. */
 	if (IsSavegameVersionBefore(SLV_164) && _settings_game.game_creation.snow_line_height >= MIN_SNOWLINE_HEIGHT * TILE_HEIGHT && SlXvIsFeatureMissing(XSLFI_CHILLPP)) {
 		_settings_game.game_creation.snow_line_height /= TILE_HEIGHT;
+		UpdateCachedSnowLine();
 	}
 
 	if (IsSavegameVersionBefore(SLV_164) && !IsSavegameVersionBefore(SLV_32)) {