ctac.MapService.Expand C# (CSharp) Method

        public Dictionary<Vector2, Tile> Expand(List<Vector2> selection, int distance)
        {
            var ret = new Dictionary<Vector2, Tile>();
            if (distance <= 0) return ret;

            for (int i = 1; i <= distance; i++)
            {
                foreach (var pos in selection)
                {
                    //TODO: optimization for bigger distances would be to remove the 'inner' tiles from the selection
                    //so they aren't rechecked every iteration
                    var neighbors = GetNeighbors(pos);
                    var untouchedNeighbors = neighbors.Where(x => !selection.Contains(x.Key));
                    foreach (var neighbor in untouchedNeighbors)
                    {
                        if (ret.ContainsKey(neighbor.Key)) continue;

                        ret.Add(neighbor.Key, neighbor.Value);
                    }
                }

                selection.ForEach(s => ret.Add(s, mapModel.tiles[s]));
                selection = ret.Keys.ToList();
            }

            return ret;
        }