/* Create additional river tiles around possible lock locations to connect them. */

    for (uint tile = 0; tile != MapSize(); tile++) {

        if (IsValidTile(tile) && IsTileType(tile, MP_WATER) && IsRiver(tile) && IsInclinedSlope(GetTileSlope(tile))) {

 

            Slope slope = GetTileSlope(tile);

            DiagDirection dir = GetInclinedSlopeDirection(slope);

            int delta_side = TileOffsByDiagDir(ChangeDiagDir(dir, DIAGDIRDIFF_90RIGHT));

            int delta_mid = TileOffsByDiagDir(dir);

 

            TileIndex tile_upper_centre = tile + 2 * delta_mid;

            TileIndex tile_upper_right = tile + delta_mid + delta_side;

            TileIndex tile_upper_left = tile + delta_mid - delta_side;

            TileIndex tile_upper_upper = IsWaterTile(tile_upper_centre) ? INVALID_TILE : tile_upper_centre;

            TileIndex tile_upper_upper_right = IsWaterTile(tile_upper_right) ? tile_upper_centre + delta_side : INVALID_TILE;

            TileIndex tile_upper_upper_left = IsWaterTile(tile_upper_left) ? tile_upper_centre - delta_side : INVALID_TILE;

 

            TileIndex tile_lower_centre = tile - 2 * delta_mid;

            TileIndex tile_lower_right = tile - delta_mid + delta_side;

            TileIndex tile_lower_left = tile - delta_mid - delta_side;

            TileIndex tile_lower_lower = IsWaterTile(tile_lower_centre) ? INVALID_TILE : tile_lower_centre;

            TileIndex tile_lower_lower_right = IsWaterTile(tile_lower_right) ? tile_lower_centre + delta_side : INVALID_TILE;

            TileIndex tile_lower_lower_left = IsWaterTile(tile_lower_left) ? tile_lower_centre - delta_side : INVALID_TILE;

 

            TileIndex tiles[] = {tile_upper_upper, tile_upper_upper_right, tile_upper_upper_left, tile_lower_lower, tile_lower_lower_right, tile_lower_lower_left};

            for (int i = 0; i < lengthof(tiles); i++) {

                if (tiles[i] != INVALID_TILE && IsTileFlat(tiles[i])) {

                    assert(!IsWaterTile(tiles[i]));

                    MakeRiver(tiles[i], Random());

                    /* Remove desert directly around the river tile. */

                    CircularTileSearch(&tiles[i], 5, RiverModifyDesertZone, NULL);

                }

            }

        }

    }