private IEnumerable <ChessDraw> getForewardDraws(IChessBoard board, ChessPosition drawingPiecePosition)
{
var draws = new List <ChessDraw>();
var piece = board.GetPieceAt(drawingPiecePosition);
var coordsPosOneForeward = new Tuple <int, int>(drawingPiecePosition.Row + (piece.Color == ChessColor.White ? 1 : -1), drawingPiecePosition.Column);
var coordsPosTwoForeward = new Tuple <int, int>(drawingPiecePosition.Row + (piece.Color == ChessColor.White ? 2 : -2), drawingPiecePosition.Column);
if (ChessPosition.AreCoordsValid(coordsPosOneForeward))
{
var posOneForeward = new ChessPosition(coordsPosOneForeward);
bool oneForeward = !board.IsCapturedAt(posOneForeward);
if (oneForeward)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, posOneForeward));
if (!piece.WasMoved && ChessPosition.AreCoordsValid(coordsPosTwoForeward))
{
var posTwoForeward = new ChessPosition(coordsPosTwoForeward);
if (!board.IsCapturedAt(posTwoForeward))
{
draws.Add(new ChessDraw(board, drawingPiecePosition, posTwoForeward));
}
}
}
}
return(draws);
}
private static ChessDrawType getDrawType(IChessBoard board, ChessPosition oldPos,
ChessPosition newPos, ChessPieceType?peasantPromotionType)
{
var piece = board.GetPieceAt(oldPos);
var type = ChessDrawType.Standard;
// check for a peasant promotion
if (peasantPromotionType != null && piece.Type == ChessPieceType.Peasant &&
((newPos.Row == 7 && piece.Color == ChessColor.White) ||
(newPos.Row == 0 && piece.Color == ChessColor.Black)))
{
type = ChessDrawType.PeasantPromotion;
}
// check for a rochade
else if (piece.Type == ChessPieceType.King && Math.Abs(oldPos.Column - newPos.Column) == 2)
{
type = ChessDrawType.Rochade;
}
// check for an en-passant
else if (piece.Type == ChessPieceType.Peasant && !board.IsCapturedAt(newPos) &&
Math.Abs(oldPos.Column - newPos.Column) == 1)
{
type = ChessDrawType.EnPassant;
}
return(type);
}
/// <summary>
/// Compute the field positions that can be captured by the given chess piece.
/// </summary>
/// <param name="board">The chess board representing the game situation</param>
/// <param name="drawingPiecePosition">The chess position of the chess piece to be drawn</param>
/// <param name="precedingEnemyDraw">The last draw made by the opponent</param>
/// <param name="analyzeDrawIntoCheck">Indicates whether drawing into a check situation should be analyzed</param>
/// <returns>a list of all possible chess draws</returns>
public IEnumerable <ChessDraw> GetDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null, bool analyzeDrawIntoCheck = false)
{
// determine the drawing piece and the required draw generator
var piece = board.GetPieceAt(drawingPiecePosition);
var generator = _explicitGenerators[piece.Type];
// compute all possible chess draws for the given chess piece
var draws = generator.GetDraws(board, drawingPiecePosition, precedingEnemyDraw, analyzeDrawIntoCheck).ToArray();
return(draws);
}
private IEnumerable <ChessDraw> getRochadeDraws(IChessBoard board, ChessColor drawingSide)
{
// TODO: do optimizations!!!
// get enemy capturable positions
var enemyKing = (drawingSide == ChessColor.White) ? board.BlackKing : board.WhiteKing;
var enemyCapturablePositions =
board.GetPiecesOfColor(drawingSide.Opponent()).Where(x => x.Piece.Type != ChessPieceType.King)
.SelectMany(x => ChessDrawGenerator.Instance.GetDraws(board, x.Position, null, false)).Select(x => x.NewPosition)
.Concat(getStandardDrawPositions(enemyKing.Position));
// get the allied king and towers
int row = (drawingSide == ChessColor.White) ? 0 : 7;
var alliedKing = (drawingSide == ChessColor.White) ? board.WhiteKing : board.BlackKing;
var farAlliedTowerPos = new ChessPosition(row, 0);
var farAlliedTower = board.GetPieceAt(farAlliedTowerPos);
var nearAlliedTowerPos = new ChessPosition(row, 7);
var nearAlliedTower = board.GetPieceAt(nearAlliedTowerPos);
// define the fields that must not be capturable by the opponent
var bigRochadeKingPassagePositions = (drawingSide == ChessColor.White) ? whiteKingBigRochadePassagePositions : blackKingBigRochadePassagePositions;
var smallRochadeKingPassagePositions = (drawingSide == ChessColor.White) ? whiteKingSmallRochadePassagePositions : blackKingSmallRochadePassagePositions;
bool canBigRochade =
// check for preconditions of big rochade
(board.IsCapturedAt(farAlliedTowerPos) && !alliedKing.Piece.WasMoved && !farAlliedTower.WasMoved &&
bigRochadeKingPassagePositions.All(x => !board.IsCapturedAt(x) || (board.GetPieceAt(x).Color == drawingSide && board.GetPieceAt(x).Type == ChessPieceType.King)) &&
!board.IsCapturedAt(new ChessPosition(row, 1)))
// make sure that no rochade field can be captured by the opponent
&& !enemyCapturablePositions.Any(pos => bigRochadeKingPassagePositions.Contains(pos));
bool canSmallRochade =
// check for preconditions of small rochade
(board.IsCapturedAt(nearAlliedTowerPos) && !alliedKing.Piece.WasMoved && !nearAlliedTower.WasMoved &&
smallRochadeKingPassagePositions.All(x => !board.IsCapturedAt(x) || (board.GetPieceAt(x).Color == drawingSide && board.GetPieceAt(x).Type == ChessPieceType.King)))
// make sure that no rochade field can be captured by the opponent and the rochade field on the B-line is not captured
&& !enemyCapturablePositions.Any(pos => smallRochadeKingPassagePositions.Contains(pos));
// write result draws
int index = 0;
int drawsCount = (canSmallRochade ? 1 : 0) + (canBigRochade ? 1 : 0);
ChessDraw[] draws = new ChessDraw[drawsCount];
if (canSmallRochade)
{
draws[index++] = new ChessDraw(board, alliedKing.Position, new ChessPosition(row, 6));
}
if (canBigRochade)
{
draws[index++] = new ChessDraw(board, alliedKing.Position, new ChessPosition(row, 2));
}
return(draws);
}
/// <summary>
/// Compute the field positions that can be captured by the given chess piece.
/// </summary>
/// <param name="board">The chess board representing the game situation</param>
/// <param name="drawingPiecePosition">The chess position of the chess piece to be drawn</param>
/// <param name="precedingEnemyDraw">The last draw made by the opponent</param>
/// <param name="analyzeDrawIntoCheck">Indicates whether drawing into a check situation should be analyzed</param>
/// <returns>a list of all possible chess draws</returns>
public IEnumerable <ChessDraw> GetDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null, bool analyzeDrawIntoCheck = false)
{
var piece = board.GetPieceAt(drawingPiecePosition);
// make sure the chess piece is a queen
if (piece.Type != ChessPieceType.Queen)
{
throw new InvalidOperationException("The chess piece is not a queen.");
}
// combine the positions that a rock or a bishop could capture
var draws =
new RookChessDrawGenerator().GetDraws(board, drawingPiecePosition, precedingEnemyDraw, analyzeDrawIntoCheck)
.Union(new BishopChessDrawGenerator().GetDraws(board, drawingPiecePosition, precedingEnemyDraw, analyzeDrawIntoCheck));
return(draws);
}
public ChessDraw(IChessBoard board, ChessPosition oldPos, ChessPosition newPos, ChessPieceType?peasantPromotionType = null)
{
// get the drawing piece
var piece = board.GetPieceAt(oldPos);
// determine all property values
var type = getDrawType(board, oldPos, newPos, peasantPromotionType);
var drawingSide = piece.Color;
var drawingPieceType = piece.Type;
var takenPieceType =
(type == ChessDrawType.EnPassant)
? (ChessPieceType?)ChessPieceType.Peasant
: (board.IsCapturedAt(newPos) ? (ChessPieceType?)board.GetPieceAt(newPos).Type : null);
// transform property values to a hash code
_hashCode = toHashCode(type, drawingSide, drawingPieceType, takenPieceType, peasantPromotionType, oldPos, newPos, !piece.WasMoved);
}
/// <summary>
/// Compute the field positions that can be captured by the given chess piece.
/// </summary>
/// <param name="board">The chess board representing the game situation</param>
/// <param name="drawingPiecePosition">The chess position of the chess piece to be drawn</param>
/// <param name="precedingEnemyDraw">The last draw made by the opponent</param>
/// <param name="analyzeDrawIntoCheck">Indicates whether drawing into a check situation should be analyzed</param>
/// <returns>a list of all possible chess draws</returns>
public IEnumerable <ChessDraw> GetDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null, bool analyzeDrawIntoCheck = false)
{
var piece = board.GetPieceAt(drawingPiecePosition);
// make sure the chess piece is a king
if (piece.Type != ChessPieceType.King)
{
throw new InvalidOperationException("The chess piece is not a king.");
}
// get the possible draw positions
var positions = getStandardDrawPositions(drawingPiecePosition);
// only retrieve positions that are not captured by an allied chess piece
var alliedPieces = board.GetPiecesOfColor(piece.Color);
positions = positions.Except(alliedPieces.Select(x => x.Position));
// only retrieve positions that cannot be captured by the enemy king (-> avoid draw into check)
var enemyKing = piece.Color == ChessColor.White ? board.BlackKing : board.WhiteKing;
var enemyKingDrawPositons = getStandardDrawPositions(enemyKing.Position);
positions = positions.Except(enemyKingDrawPositons);
// transform positions to draws
IEnumerable <ChessDraw> draws = positions.Select(newPos => new ChessDraw(board, drawingPiecePosition, newPos)).ToArray();
// analyze draw into a check situation
if (analyzeDrawIntoCheck && draws?.Count() > 0)
{
draws = draws.Where(draw => !ChessDrawSimulator.Instance.IsDrawIntoCheck(board, draw)).ToArray();
}
// add rochade draws
bool canRochade = (drawingPiecePosition == new ChessPosition("E1") || drawingPiecePosition == new ChessPosition("E8"));
if (canRochade)
{
draws = draws.Concat(getRochadeDraws(board, piece.Color));
}
return(draws);
}
private IEnumerable <ChessPosition> getStandardDrawPositions(ChessPosition position)
{
// get positions next to the current position of the king (all permutations of { -1, 0, +1 }^2 except (0, 0))
var coords = new Tuple <int, int>[]
{
new Tuple <int, int>(position.Row - 1, position.Column - 1),
new Tuple <int, int>(position.Row - 1, position.Column),
new Tuple <int, int>(position.Row - 1, position.Column + 1),
new Tuple <int, int>(position.Row, position.Column - 1),
new Tuple <int, int>(position.Row, position.Column + 1),
new Tuple <int, int>(position.Row + 1, position.Column - 1),
new Tuple <int, int>(position.Row + 1, position.Column),
new Tuple <int, int>(position.Row + 1, position.Column + 1),
};
// only retrieve positions that are actually onto the chess board (and not off scale)
var positions = coords.Where(x => ChessPosition.AreCoordsValid(x)).Select(x => new ChessPosition(x.Item1, x.Item2));
return(positions);
}
private static int toHashCode(ChessDrawType drawType, ChessColor drawingSide, ChessPieceType drawingPieceType, ChessPieceType?takenPieceType,
ChessPieceType?promotionPieceType, ChessPosition oldPosition, ChessPosition newPosition, bool isFirstMove)
{
// TODO: try to remove if/else branchings to make this more efficient
// shift the bits to the right position (preparation for bitwise OR)
int isFirstMoveBits = (isFirstMove ? 1 : 0) << IS_FIRST_MOVE_TRAILING_BITS;
int drawTypeBits = ((int)drawType) << DRAW_TYPE_TRAILING_BITS;
int drawingSideBits = ((int)drawingSide) << DRAWING_SIDE_TRAILING_BITS;
int drawingPieceTypeBits = ((int)drawingPieceType) << DRAWING_PIECE_TYPE_TRAILING_BITS;
int takenPieceTypeBits = ((takenPieceType != null) ? (int)takenPieceType.Value : CHESS_PIECE_TYPE_NULL) << TAKEN_PIECE_TYPE_TRAILING_BITS;
int promotionPieceTypeBits = ((promotionPieceType != null) ? (int)promotionPieceType.Value : CHESS_PIECE_TYPE_NULL) << PROMOTION_PIECE_TYPE_TRAILING_BITS;
int oldPositionBits = oldPosition.GetHashCode() << OLD_POSITION_TRAILING_BITS;
int newPositionBits = newPosition.GetHashCode();
// fuse the shifted bits to the hash code (by bitwise OR)
int hashCode = (isFirstMoveBits | drawTypeBits | drawingSideBits | drawingPieceTypeBits
| takenPieceTypeBits | promotionPieceTypeBits | oldPositionBits | newPositionBits);
return(hashCode);
}
/// <summary>
/// Compute the field positions that can be captured by the given chess piece.
/// </summary>
/// <param name="board">The chess board representing the game situation</param>
/// <param name="drawingPiecePosition">The chess position of the chess piece to be drawn</param>
/// <param name="precedingEnemyDraw">The last draw made by the opponent</param>
/// <param name="analyzeDrawIntoCheck">Indicates whether drawing into a check situation should be analyzed</param>
/// <returns>a list of all possible chess draws</returns>
public IEnumerable <ChessDraw> GetDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null, bool analyzeDrawIntoCheck = false)
{
var piece = board.GetPieceAt(drawingPiecePosition);
// make sure the chess piece is a king
if (piece.Type != ChessPieceType.Peasant)
{
throw new InvalidOperationException("The chess piece is not a peasant.");
}
// get all possible draws
var draws = getForewardDraws(board, drawingPiecePosition).Union(getCatchDraws(board, drawingPiecePosition, precedingEnemyDraw));
// handle peasant promotion
draws = draws.SelectMany(x => {
// check if the chess draw is a peasant promotion
if ((x.NewPosition.Row == 7 && piece.Color == ChessColor.White) || (x.NewPosition.Row == 0 && piece.Color == ChessColor.Black))
{
// return all 4 promotion options for the input draw
return(new ChessDraw[]
{
new ChessDraw(board, x.OldPosition, x.NewPosition, ChessPieceType.Queen),
new ChessDraw(board, x.OldPosition, x.NewPosition, ChessPieceType.Rook),
new ChessDraw(board, x.OldPosition, x.NewPosition, ChessPieceType.Bishop),
new ChessDraw(board, x.OldPosition, x.NewPosition, ChessPieceType.Knight),
});
}
// return the input draw unchanged
return(new ChessDraw[] { x });
});
if (analyzeDrawIntoCheck && draws?.Count() > 0)
{
// remove draws that would draw into a check situation
draws = draws.Where(x => !ChessDrawSimulator.Instance.IsDrawIntoCheck(board, x));
}
return(draws);
}
/// <summary>
/// Compute the field positions that can be captured by the given chess piece.
/// </summary>
/// <param name="board">The chess board representing the game situation</param>
/// <param name="drawingPiecePosition">The chess position of the chess piece to be drawn</param>
/// <param name="precedingEnemyDraw">The last draw made by the opponent</param>
/// <param name="analyzeDrawIntoCheck">Indicates whether drawing into a check situation should be analyzed</param>
/// <returns>a list of all possible chess draws</returns>
public IEnumerable <ChessDraw> GetDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null, bool analyzeDrawIntoCheck = false)
{
var piece = board.GetPieceAt(drawingPiecePosition);
// make sure the chess piece is a knight
if (piece.Type != ChessPieceType.Knight)
{
throw new InvalidOperationException("The chess piece is not a knight.");
}
// get positions next to the current position of the king (all permutations of { -1, 0, +1 }^2 except (0, 0))
var coords = new Tuple <int, int>[]
{
new Tuple <int, int>(drawingPiecePosition.Row - 2, drawingPiecePosition.Column - 1),
new Tuple <int, int>(drawingPiecePosition.Row - 2, drawingPiecePosition.Column + 1),
new Tuple <int, int>(drawingPiecePosition.Row - 1, drawingPiecePosition.Column - 2),
new Tuple <int, int>(drawingPiecePosition.Row - 1, drawingPiecePosition.Column + 2),
new Tuple <int, int>(drawingPiecePosition.Row + 1, drawingPiecePosition.Column - 2),
new Tuple <int, int>(drawingPiecePosition.Row + 1, drawingPiecePosition.Column + 2),
new Tuple <int, int>(drawingPiecePosition.Row + 2, drawingPiecePosition.Column - 1),
new Tuple <int, int>(drawingPiecePosition.Row + 2, drawingPiecePosition.Column + 1),
};
// only retrieve positions that are actually onto the chess board (and not off scale)
var positions = coords.Where(x => ChessPosition.AreCoordsValid(x)).Select(x => new ChessPosition(x));
// do not draw into positions captured by allied chess pieces
positions = positions.Where(x => !board.IsCapturedAt(x) || board.GetPieceAt(x).Color != piece.Color);
// transform positions to chess draws
var draws = positions.Select(newPos => new ChessDraw(board, drawingPiecePosition, newPos));
if (analyzeDrawIntoCheck && draws?.Count() > 0)
{
// remove draws that would draw into a check situation
draws = draws.Where(x => !ChessDrawSimulator.Instance.IsDrawIntoCheck(board, x));
}
return(draws);
}
private ChessPosition[] serialize()
{
ulong posCache = _hash;
// extract count and initialize result array
byte count = (byte)(posCache & 0xFuL);
var positions = new ChessPosition[count];
// shift the cache to the first position
posCache >>= 4;
// loop through positions
for (byte i = 0; i < count; i++)
{
// extract the position and apply it to the result array
byte pos = (byte)(posCache & 0x3FuL);
positions[i] = new ChessPosition(pos);
// shift the cache to the next position
posCache >>= 6;
}
return(positions);
}
public ChessPieceAtPos(ChessPosition position, ChessPiece piece)
{
_hashCode = (short)((position.GetHashCode() << 5) | piece.GetHashCode());
}
private IEnumerable <ChessDraw> getCatchDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null)
{
var draws = new List <ChessDraw>();
var piece = board.GetPieceAt(drawingPiecePosition);
// get the possible chess field positions (info: right / left from the point of view of the white side player)
var coordsPosCatchLeft = new Tuple <int, int>(drawingPiecePosition.Row + (piece.Color == ChessColor.White ? 1 : -1), drawingPiecePosition.Column + 1);
var coordsPosCatchRight = new Tuple <int, int>(drawingPiecePosition.Row + (piece.Color == ChessColor.White ? 1 : -1), drawingPiecePosition.Column - 1);
// check for en-passant precondition
bool wasLastDrawPeasantDoubleForeward =
precedingEnemyDraw != null && precedingEnemyDraw.Value.DrawingPieceType == ChessPieceType.Peasant &&
Math.Abs(precedingEnemyDraw.Value.OldPosition.Row - precedingEnemyDraw.Value.NewPosition.Row) == 2;
// check if left catch / en-passant is possible
if (ChessPosition.AreCoordsValid(coordsPosCatchLeft))
{
var posCatchLeft = new ChessPosition(coordsPosCatchLeft);
bool catchLeft = board.IsCapturedAt(posCatchLeft) && board.GetPieceAt(posCatchLeft).Color != piece.Color;
if (catchLeft)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, posCatchLeft));
}
if (wasLastDrawPeasantDoubleForeward)
{
// get the positions of an enemy chess piece taken by a possible en-passant
var posEnPassantEnemyLeft = new ChessPosition(drawingPiecePosition.Row, drawingPiecePosition.Column + 1);
bool isLeftFieldCapturedByEnemy =
precedingEnemyDraw.Value.NewPosition == posEnPassantEnemyLeft && board.IsCapturedAt(posEnPassantEnemyLeft) &&
board.GetPieceAt(posEnPassantEnemyLeft).Color != piece.Color;
bool enPassantLeft = isLeftFieldCapturedByEnemy && Math.Abs(posEnPassantEnemyLeft.Column - drawingPiecePosition.Column) == 1;
if (enPassantLeft)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, posCatchLeft));
}
}
}
// check if right catch / en-passant is possible
if (ChessPosition.AreCoordsValid(coordsPosCatchRight))
{
var posCatchRight = new ChessPosition(coordsPosCatchRight);
bool catchRight = board.IsCapturedAt(posCatchRight) && board.GetPieceAt(posCatchRight).Color != piece.Color;
if (catchRight)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, posCatchRight));
}
if (wasLastDrawPeasantDoubleForeward)
{
// get the positions of an enemy chess piece taken by a possible en-passant
var posEnPassantEnemyRight = new ChessPosition(drawingPiecePosition.Row, drawingPiecePosition.Column - 1);
bool isRightFieldCapturedByEnemy =
precedingEnemyDraw.Value.NewPosition == posEnPassantEnemyRight &&
board.IsCapturedAt(posEnPassantEnemyRight) && board.GetPieceAt(posEnPassantEnemyRight).Color != piece.Color;
bool enPassantRight = isRightFieldCapturedByEnemy && Math.Abs(posEnPassantEnemyRight.Column - drawingPiecePosition.Column) == 1;
if (enPassantRight)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, posCatchRight));
}
}
}
return(draws);
}
/// <summary>
/// Compute the field positions that can be captured by the given chess piece.
/// </summary>
/// <param name="board">The chess board representing the game situation</param>
/// <param name="drawingPiecePosition">The chess position of the chess piece to be drawn</param>
/// <param name="precedingEnemyDraw">The last draw made by the opponent</param>
/// <param name="analyzeDrawIntoCheck">Indicates whether drawing into a check situation should be analyzed</param>
/// <returns>a list of all possible chess draws</returns>
public IEnumerable <ChessDraw> GetDraws(IChessBoard board, ChessPosition drawingPiecePosition, ChessDraw?precedingEnemyDraw = null, bool analyzeDrawIntoCheck = false)
{
var piece = board.GetPieceAt(drawingPiecePosition);
// make sure the chess piece is bishop-like
if (piece.Type != ChessPieceType.Bishop && piece.Type != ChessPieceType.Queen)
{
throw new InvalidOperationException("The chess piece is not a bishop.");
}
var draws = new List <ChessDraw>();
// get upper left-side draws
for (int i = 1; i < 8; i++)
{
// get position and make sure it is valid (otherwise exit loop)
var coords = new Tuple <int, int>(drawingPiecePosition.Row + i, drawingPiecePosition.Column - i);
if (!ChessPosition.AreCoordsValid(coords))
{
break;
}
var newPos = new ChessPosition(coords);
if (!board.IsCapturedAt(newPos) || board.GetPieceAt(newPos).Color != piece.Color)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, newPos));
}
if (board.IsCapturedAt(newPos))
{
break;
}
}
// get lower left-side draws
for (int i = 1; i < 8; i++)
{
// get position and make sure it is valid (otherwise exit loop)
var coords = new Tuple <int, int>(drawingPiecePosition.Row - i, drawingPiecePosition.Column - i);
if (!ChessPosition.AreCoordsValid(coords))
{
break;
}
var newPos = new ChessPosition(coords);
if (!board.IsCapturedAt(newPos) || board.GetPieceAt(newPos).Color != piece.Color)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, newPos));
}
if (board.IsCapturedAt(newPos))
{
break;
}
}
// get upper right-side draws
for (int i = 1; i < 8; i++)
{
// get position and make sure it is valid (otherwise exit loop)
var coords = new Tuple <int, int>(drawingPiecePosition.Row + i, drawingPiecePosition.Column + i);
if (!ChessPosition.AreCoordsValid(coords))
{
break;
}
var newPos = new ChessPosition(coords);
if (!board.IsCapturedAt(newPos) || board.GetPieceAt(newPos).Color != piece.Color)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, newPos));
}
if (board.IsCapturedAt(newPos))
{
break;
}
}
// get lower right-side draws
for (int i = 1; i < 8; i++)
{
// get position and make sure it is valid (otherwise exit loop)
var coords = new Tuple <int, int>(drawingPiecePosition.Row - i, drawingPiecePosition.Column + i);
if (!ChessPosition.AreCoordsValid(coords))
{
break;
}
var newPos = new ChessPosition(coords);
if (!board.IsCapturedAt(newPos) || board.GetPieceAt(newPos).Color != piece.Color)
{
draws.Add(new ChessDraw(board, drawingPiecePosition, newPos));
}
if (board.IsCapturedAt(newPos))
{
break;
}
}
// analyze draw into a check situation
if (analyzeDrawIntoCheck && draws?.Count() > 0)
{
draws = draws.Where(draw => !ChessDrawSimulator.Instance.IsDrawIntoCheck(board, draw)).ToList();
}
return(draws);
}