public static List<Coordinate> EnPassant(Coordinate current, AI game)
{
List<Coordinate> moves = new List<Coordinate>();
Piece pawn = game.GetPieceAt(current);
int color = game.IsWhite(pawn) ? 1 : -1;
if (pawn.ExpectedRank == (color == 1 ? 4 : 5))
{
if (pawn.ExpectedFile - 1 == pawn.ExpectedFile || pawn.ExpectedFile + 1 == pawn.ExpectedFile)
{
moves.Add(current);
}
}
return moves;
}
public static List<Coordinate> GetAttackMoves(Coordinate current, AI game)
{
List<Coordinate> moves = new List<Coordinate>();
Piece piece = game.GetPieceAt(current);
int color = game.IsWhite(piece) ? 1 : -1;
// Attack!
if (game.EnemyPieceExistsAt(new Coordinate(current.File - 1, current.Rank + (1 * color))))
{
moves.Add(new Coordinate(current.File - 1, current.Rank + (1 * color)));
}
if (game.EnemyPieceExistsAt(new Coordinate(current.File + 1, current.Rank + (1 * color))))
{
moves.Add(new Coordinate(current.File + 1, current.Rank + (1 * color)));
}
return moves;
}
public static List<Coordinate> GetMoves(Coordinate current, AI game)
{
// The pawn, himself
Piece pawn = game.GetPieceAt(current);
// List of moves this pawn can make
List<Coordinate> moves = new List<Coordinate>();
// Rank multiplier dependant on piece color
int color = game.IsWhite(pawn) ? 1 : -1;
// If a pawn is in its corresponding start position (hasn't moved), then we want to handle
// it being able to move forward two spaces in addition to just one.
if (pawn.ExpectedRank == (color == 1 ? 2 : 7))
{
// There must be no pieces in the way to move forward two
if (!game.PieceExistsAt(new Coordinate(current.File, current.Rank + 1 * color)) &&
!game.PieceExistsAt(new Coordinate(current.File, current.Rank + 2 * color)))
{
moves.Add(new Coordinate(current.File, current.Rank + 2 * color));
}
}
// Straight move forward 1
if (!game.PieceExistsAt(new Coordinate(current.File, current.Rank + 1 * color)))
{
moves.Add(new Coordinate(current.File, current.Rank + 1 * color));
}
// Attack!
moves.AddRange(GetAttackMoves(current, game));
// En Passant
moves.AddRange(EnPassant(current, game));
return moves;
}
