public Piece[] GetPieces(int index)
{
List<Piece> result = new List<Piece>();
AddPiece(result, new Intersection(index, index - 7, index - 1));
AddPiece(result, new Intersection(index, index - 7, index - 6));
AddPiece(result, new Intersection(index, index - 6, index + 1));
AddPiece(result, new Intersection(index, index + 1, index + 7));
AddPiece(result, new Intersection(index, index + 6, index + 7));
AddPiece(result, new Intersection(index, index + 6, index - 1));
return result.ToArray();
}