Codechange: Handle SnowTile state separately from ClearGround.

This removes the need for ClearGround to pretend that CLEAR_SNOW exists.

src/clear_cmd.cpp

@@ -25,7 +25,7 @@
 
 static CommandCost ClearTile_Clear(TileIndex tile, DoCommandFlags flags)
 {
-	static const Price clear_price_table[] = {
+	static constexpr Price clear_price_table[] = {
 		PR_CLEAR_GRASS,
 		PR_CLEAR_ROUGH,
 		PR_CLEAR_ROCKS,
@@ -35,7 +35,9 @@ static CommandCost ClearTile_Clear(TileIndex tile, DoCommandFlags flags)
 	};
 	CommandCost price(EXPENSES_CONSTRUCTION);
 
-	if (!IsClearGround(tile, CLEAR_GRASS) || GetClearDensity(tile) != 0) {
+	if (IsSnowTile(tile)) {
+		price.AddCost(_price[clear_price_table[CLEAR_SNOW]]);
+	} else if (!IsClearGround(tile, CLEAR_GRASS) || GetClearDensity(tile) != 0) {
 		price.AddCost(_price[clear_price_table[GetClearGround(tile)]]);
 	}
 
@@ -100,7 +102,9 @@ static void DrawClearLandFence(const TileInfo *ti)
 
 static void DrawTile_Clear(TileInfo *ti)
 {
-	switch (GetClearGround(ti->tile)) {
+	ClearGround ground = IsSnowTile(ti->tile) ? CLEAR_SNOW : GetClearGround(ti->tile);
+
+	switch (ground) {
 		case CLEAR_GRASS:
 			DrawClearLandTile(ti, GetClearDensity(ti->tile));
 			break;
@@ -237,6 +241,8 @@ static void TileLoop_Clear(TileIndex tile)
 		default: break;
 	}
 
+	if (IsSnowTile(tile)) return;
+
 	switch (GetClearGround(tile)) {
 		case CLEAR_GRASS:
 			if (GetClearDensity(tile) == 3) return;

src/clear_map.h

@@ -21,7 +21,7 @@ enum ClearGround : uint8_t {
 	CLEAR_ROUGH  = 1, ///< 3
 	CLEAR_ROCKS  = 2, ///< 3
 	CLEAR_FIELDS = 3, ///< 3
-	CLEAR_SNOW   = 4, ///< 0-3
+	CLEAR_SNOW   = 4, ///< 0-3 (Not stored in map.)
 	CLEAR_DESERT = 5, ///< 1,3
 };
 
@@ -38,18 +38,6 @@ inline bool IsSnowTile(Tile t)
 	return HasBit(t.m3(), 4);
 }
 
-/**
- * Get the type of clear tile but never return CLEAR_SNOW.
- * @param t the tile to get the clear ground type of
- * @pre IsTileType(t, MP_CLEAR)
- * @return the ground type
- */
-inline ClearGround GetRawClearGround(Tile t)
-{
-	assert(IsTileType(t, MP_CLEAR));
-	return (ClearGround)GB(t.m5(), 2, 3);
-}
-
 /**
  * Get the type of clear tile.
  * @param t the tile to get the clear ground type of
@@ -58,8 +46,8 @@ inline ClearGround GetRawClearGround(Tile t)
  */
 inline ClearGround GetClearGround(Tile t)
 {
-	if (IsSnowTile(t)) return CLEAR_SNOW;
+	assert(IsTileType(t, MP_CLEAR));
-	return GetRawClearGround(t);
+	return static_cast<ClearGround>(GB(t.m5(), 2, 3));
 }
 
 /**
@@ -295,13 +283,13 @@ inline void MakeField(Tile t, uint field_type, IndustryID industry)
  * Make a snow tile.
  * @param t the tile to make snowy
  * @param density The density of snowiness.
- * @pre GetClearGround(t) != CLEAR_SNOW
+ * @pre !IsSnowTile(t)
  */
 inline void MakeSnow(Tile t, uint density = 0)
 {
-	assert(GetClearGround(t) != CLEAR_SNOW);
+	assert(!IsSnowTile(t));
 	SetBit(t.m3(), 4);
-	if (GetRawClearGround(t) == CLEAR_FIELDS) {
+	if (GetClearGround(t) == CLEAR_FIELDS) {
 		SetClearGroundDensity(t, CLEAR_GRASS, density);
 	} else {
 		SetClearDensity(t, density);
@@ -311,11 +299,11 @@ inline void MakeSnow(Tile t, uint density = 0)
 /**
  * Clear the snow from a tile and return it to its previous type.
  * @param t the tile to clear of snow
- * @pre GetClearGround(t) == CLEAR_SNOW
+ * @pre IsSnowTile(t)
  */
 inline void ClearSnow(Tile t)
 {
-	assert(GetClearGround(t) == CLEAR_SNOW);
+	assert(IsSnowTile(t));
 	ClrBit(t.m3(), 4);
 	SetClearDensity(t, 3);
 }

src/industry_cmd.cpp

@@ -1004,7 +1004,7 @@ static const uint8_t _plantfarmfield_type[] = {1, 1, 1, 1, 1, 3, 3, 4, 4, 4, 5,
 static bool IsSuitableForFarmField(TileIndex tile, bool allow_fields)
 {
 	switch (GetTileType(tile)) {
-		case MP_CLEAR: return !IsClearGround(tile, CLEAR_SNOW) && !IsClearGround(tile, CLEAR_DESERT) && (allow_fields || !IsClearGround(tile, CLEAR_FIELDS));
+		case MP_CLEAR: return !IsSnowTile(tile) && !IsClearGround(tile, CLEAR_DESERT) && (allow_fields || !IsClearGround(tile, CLEAR_FIELDS));
 		case MP_TREES: return GetTreeGround(tile) != TREE_GROUND_SHORE;
 		default:       return false;
 	}

src/industry_gui.cpp

@@ -633,7 +633,7 @@ public:
 
 		/* Clear farmland. */
 		for (const auto tile : Map::Iterate()) {
-			if (IsTileType(tile, MP_CLEAR) && GetRawClearGround(tile) == CLEAR_FIELDS) {
+			if (IsTileType(tile, MP_CLEAR) && GetClearGround(tile) == CLEAR_FIELDS) {
 				MakeClear(tile, CLEAR_GRASS, 3);
 			}
 		}

src/saveload/afterload.cpp

@@ -2387,7 +2387,7 @@ bool AfterLoadGame()
 	if (IsSavegameVersionBefore(SLV_135)) {
 		for (auto t : Map::Iterate()) {
 			if (IsTileType(t, MP_CLEAR)) {
-				if (GetRawClearGround(t) == CLEAR_SNOW) {
+				if (GetClearGround(t) == CLEAR_SNOW) { // CLEAR_SNOW becomes CLEAR_GRASS with IsSnowTile() set.
 					SetClearGroundDensity(t, CLEAR_GRASS, GetClearDensity(t));
 					SetBit(t.m3(), 4);
 				} else {

src/script/api/script_tile.cpp

@@ -130,14 +130,14 @@
 {
 	if (!::IsValidTile(tile)) return false;
 
-	return (::IsTileType(tile, MP_CLEAR) && ::GetRawClearGround(tile) == ::CLEAR_ROCKS);
+	return (::IsTileType(tile, MP_CLEAR) && ::GetClearGround(tile) == ::CLEAR_ROCKS);
 }
 
 /* static */ bool ScriptTile::IsRoughTile(TileIndex tile)
 {
 	if (!::IsValidTile(tile)) return false;
 
-	return (::IsTileType(tile, MP_CLEAR) && ::GetRawClearGround(tile) == ::CLEAR_ROUGH);
+	return (::IsTileType(tile, MP_CLEAR) && ::GetClearGround(tile) == ::CLEAR_ROUGH);
 }
 
 /* static */ bool ScriptTile::IsSnowTile(TileIndex tile)

src/tree_cmd.cpp

@@ -74,7 +74,7 @@ static bool CanPlantTreesOnTile(TileIndex tile, bool allow_desert)
 			return !IsBridgeAbove(tile) && IsCoast(tile) && !IsSlopeWithOneCornerRaised(GetTileSlope(tile));
 
 		case MP_CLEAR:
-			return !IsBridgeAbove(tile) && !IsClearGround(tile, CLEAR_FIELDS) && GetRawClearGround(tile) != CLEAR_ROCKS &&
+			return !IsBridgeAbove(tile) && !IsClearGround(tile, CLEAR_FIELDS) && !IsClearGround(tile, CLEAR_ROCKS) &&
 			       (allow_desert || !IsClearGround(tile, CLEAR_DESERT));
 
 		default: return false;
@@ -106,15 +106,20 @@ static void PlantTreesOnTile(TileIndex tile, TreeType treetype, uint count, Tree
 			ClearNeighbourNonFloodingStates(tile);
 			break;
 
-		case MP_CLEAR:
+		case MP_CLEAR: {
-			switch (GetClearGround(tile)) {
+			ClearGround clearground = GetClearGround(tile);
-				case CLEAR_GRASS:  ground = TREE_GROUND_GRASS;       break;
+			if (IsSnowTile(tile)) {
-				case CLEAR_ROUGH:  ground = TREE_GROUND_ROUGH;       break;
+				ground = clearground == CLEAR_ROUGH ? TREE_GROUND_ROUGH_SNOW : TREE_GROUND_SNOW_DESERT;
-				case CLEAR_SNOW:   ground = GetRawClearGround(tile) == CLEAR_ROUGH ? TREE_GROUND_ROUGH_SNOW : TREE_GROUND_SNOW_DESERT; break;
+			} else {
-				default:           ground = TREE_GROUND_SNOW_DESERT; break;
+				switch (clearground) {
+					case CLEAR_GRASS:  ground = TREE_GROUND_GRASS;       break;
+					case CLEAR_ROUGH:  ground = TREE_GROUND_ROUGH;       break;
+					default:           ground = TREE_GROUND_SNOW_DESERT; break;
+				}
 			}
-			if (GetClearGround(tile) != CLEAR_ROUGH) density = GetClearDensity(tile);
+			if (clearground != CLEAR_ROUGH) density = GetClearDensity(tile);
 			break;
+		}
 
 		default: NOT_REACHED();
 	}
@@ -575,7 +580,7 @@ CommandCost CmdPlantTree(DoCommandFlags flags, TileIndex tile, TileIndex start_t
 
 				if (IsTileType(current_tile, MP_CLEAR)) {
 					/* Remove fields or rocks. Note that the ground will get barrened */
-					switch (GetRawClearGround(current_tile)) {
+					switch (GetClearGround(current_tile)) {
 						case CLEAR_FIELDS:
 						case CLEAR_ROCKS: {
 							CommandCost ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, current_tile);