void FlattenAll(Terrain terrain)
        {
            Terrain[] terrains = TerrainFillUtility.GetTerrainsInGroup(terrain);

            for (int i = 0; i < terrains.Length; ++i)
            {
                Flatten(terrains[i]);
            }
        }
        // Fill Tiles
        private void FillAllTiles(Terrain terrain)
        {
            Terrain[] terrains = TerrainFillUtility.GetTerrainsInGroup(terrain);

            foreach (Terrain tile in terrains)
            {
                FillTile(tile);
            }
        }