Cache highest snowline value

src/genworld.cpp

@@ -128,6 +128,7 @@ static void _GenerateWorld()
 
 			_settings_game.game_creation.snow_line_height = DEF_SNOWLINE_HEIGHT;
 			UpdateCachedSnowLine();
+			UpdateCachedSnowLineBounds();
 		} else {
 			GenerateLandscape(_gw.mode);
 			GenerateClearTile();

src/landscape.cpp

@@ -103,6 +103,8 @@ static TileIndex _current_estuary = INVALID_TILE;
 static bool _is_main_river = false;
 
 byte _cached_snowline = 0;
+byte _cached_highest_snowline = 0;
+byte _cached_lowest_snowline = 0;
 
 /**
  * Map 2D viewport or smallmap coordinate to 3D world or tile coordinate.
@@ -657,6 +659,7 @@ void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS])
 	}
 
 	UpdateCachedSnowLine();
+	UpdateCachedSnowLineBounds();
 }
 
 /**
@@ -677,23 +680,13 @@ void UpdateCachedSnowLine()
 }
 
 /**
- * Get the highest possible snow line height, either variable or static.
- * @return the highest snow line height.
+ * Cache the lowest and highest possible snow line heights, either variable or static.
  * @ingroup SnowLineGroup
  */
-byte HighestSnowLine()
+void UpdateCachedSnowLineBounds()
 {
-	return _snow_line == nullptr ? _settings_game.game_creation.snow_line_height : _snow_line->highest_value;
-}
-
-/**
- * Get the lowest possible snow line height, either variable or static.
- * @return the lowest snow line height.
- * @ingroup SnowLineGroup
- */
-byte LowestSnowLine()
-{
-	return _snow_line == nullptr ? _settings_game.game_creation.snow_line_height : _snow_line->lowest_value;
+	_cached_highest_snowline = _snow_line == nullptr ? _settings_game.game_creation.snow_line_height : _snow_line->highest_value;
+	_cached_lowest_snowline = _snow_line == nullptr ? _settings_game.game_creation.snow_line_height : _snow_line->lowest_value;
 }
 
 /**
@@ -705,6 +698,7 @@ void ClearSnowLine()
 	free(_snow_line);
 	_snow_line = nullptr;
 	UpdateCachedSnowLine();
+	UpdateCachedSnowLineBounds();
 }
 
 /**
@@ -1540,6 +1534,7 @@ static void CalculateSnowLine()
 		_settings_game.game_creation.snow_line_height = std::max(CalculateCoverageLine(_settings_game.game_creation.snow_coverage, 0), 2u);
 	}
 	UpdateCachedSnowLine();
+	UpdateCachedSnowLineBounds();
 }
 
 /**

src/landscape.h

@@ -30,8 +30,7 @@ bool IsSnowLineSet();
 void SetSnowLine(byte table[SNOW_LINE_MONTHS][SNOW_LINE_DAYS]);
 byte GetSnowLineUncached();
 void UpdateCachedSnowLine();
-byte HighestSnowLine();
-byte LowestSnowLine();
+void UpdateCachedSnowLineBounds();
 void ClearSnowLine();
 
 inline byte GetSnowLine()
@@ -40,6 +39,18 @@ inline byte GetSnowLine()
 	return _cached_snowline;
 }
 
+inline byte HighestSnowLine()
+{
+	extern byte _cached_highest_snowline;
+	return _cached_highest_snowline;
+}
+
+inline byte LowestSnowLine()
+{
+	extern byte _cached_lowest_snowline;
+	return _cached_lowest_snowline;
+}
+
 int GetSlopeZInCorner(Slope tileh, Corner corner);
 Slope GetFoundationSlope(TileIndex tile, int *z = nullptr);
 

src/misc.cpp

@@ -111,6 +111,7 @@ void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settin
 		SetScaledTickVariables();
 	}
 	UpdateCachedSnowLine();
+	UpdateCachedSnowLineBounds();
 
 	ClearTraceRestrictMapping();
 	ClearBridgeSimulatedSignalMapping();

src/saveload/afterload.cpp

@@ -635,6 +635,7 @@ bool AfterLoadGame()
 	RebuildTownKdtree();
 	RebuildStationKdtree();
 	UpdateCachedSnowLine();
+	UpdateCachedSnowLineBounds();
 
 	_viewport_sign_kdtree_valid = false;
 
@@ -3129,6 +3130,7 @@ bool AfterLoadGame()
 	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();
+		UpdateCachedSnowLineBounds();
 	}
 
 	if (IsSavegameVersionBefore(SLV_164) && !IsSavegameVersionBefore(SLV_32)) {