Used curved instead of square circular area for mapgen water desert removal

src/landscape.cpp

@@ -1116,8 +1116,7 @@ static bool MakeLake(TileIndex tile, void *user_data)
 			MakeRiver(tile, Random());
 			MarkTileDirtyByTile(tile);
 			/* Remove desert directly around the river tile. */
-			TileIndex t = tile;
+			IterateCurvedCircularTileArea(tile, _settings_game.game_creation.lake_tropics_width, RiverModifyDesertZone, nullptr);
-			CircularTileSearch(&t, _settings_game.game_creation.lake_tropics_width, RiverModifyDesertZone, nullptr);
 			return false;
 		}
 	}
@@ -1187,10 +1186,9 @@ static bool RiverMakeWider(TileIndex tile, void *data)
 	if (IsValidTile(tile) && !IsWaterTile(tile) && GetTileSlope(tile) == GetTileSlope(*(TileIndex *)data)) {
 		MakeRiver(tile, Random());
 		/* Remove desert directly around the river tile. */
-		TileIndex cur_tile = tile;
 
-		MarkTileDirtyByTile(cur_tile);
+		MarkTileDirtyByTile(tile);
-		CircularTileSearch(&cur_tile, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
+		IterateCurvedCircularTileArea(tile, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
 	}
 	return false;
 }
@@ -1214,7 +1212,7 @@ static void River_FoundEndNode(AyStar *aystar, OpenListNode *current)
 				CircularTileSearch(&tile, radius + RandomRange(1), RiverMakeWider, (void *)&path->node.tile);
 			} else {
 				/* Remove desert directly around the river tile. */
-				CircularTileSearch(&tile, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
+				IterateCurvedCircularTileArea(tile, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
 			}
 		}
 	}
@@ -1327,8 +1325,7 @@ static bool FlowRiver(TileIndex spring, TileIndex begin, uint min_river_length)
 			MakeRiver(lakeCenter, Random());
 			MarkTileDirtyByTile(lakeCenter);
 			/* Remove desert directly around the river tile. */
-			CircularTileSearch(&lakeCenter, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
+			IterateCurvedCircularTileArea(lakeCenter, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
-			lakeCenter = end;
 
 			// Setting lake size +- 25%
 			const auto random_percentage = 75 + RandomRange(50);

src/water.h

@@ -40,7 +40,7 @@ void DrawShoreTile(Slope tileh);
 void MakeWaterKeepingClass(TileIndex tile, Owner o);
 void CheckForDockingTile(TileIndex t);
 
-bool RiverModifyDesertZone(TileIndex tile, void *data);
+void RiverModifyDesertZone(TileIndex tile, void *data);
 void MakeRiverAndModifyDesertZoneAround(TileIndex tile);
 static const uint RIVER_OFFSET_DESERT_DISTANCE = 5; ///< Circular tile search radius to create non-desert around a river tile.
 

src/water_cmd.cpp

@@ -444,10 +444,9 @@ CommandCost CmdBuildLock(TileIndex tile, DoCommandFlag flags, uint32_t p1, uint3
 }
 
 /** Callback to create non-desert around a river tile. */
-bool RiverModifyDesertZone(TileIndex tile, void *)
+void RiverModifyDesertZone(TileIndex tile, void *)
 {
 	if (GetTropicZone(tile) == TROPICZONE_DESERT) SetTropicZone(tile, TROPICZONE_NORMAL);
-	return false;
 }
 
 /**
@@ -460,7 +459,7 @@ void MakeRiverAndModifyDesertZoneAround(TileIndex tile)
 	MarkTileDirtyByTile(tile);
 
 	/* Remove desert directly around the river tile. */
-	CircularTileSearch(&tile, RIVER_OFFSET_DESERT_DISTANCE, RiverModifyDesertZone, nullptr);
+	IterateCurvedCircularTileArea(tile, RIVER_OFFSET_DESERT_DISTANCE, RiverModifyDesertZone, nullptr);
 }
 
 /**
@@ -526,8 +525,7 @@ CommandCost CmdBuildCanal(TileIndex tile, DoCommandFlag flags, uint32_t p1, uint
 				case WATER_CLASS_RIVER:
 					MakeRiver(current_tile, Random());
 					if (_game_mode == GM_EDITOR) {
-						TileIndex tile2 = current_tile;
+						IterateCurvedCircularTileArea(current_tile, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
-						CircularTileSearch(&tile2, _settings_game.game_creation.river_tropics_width, RiverModifyDesertZone, nullptr);
 					}
 					break;