public void AiPonderMove()
{
Thinking = true;
ChessBoard.BlackMate = false;
ChessBoard.WhiteMate = false;
PieceValidMoves.GenerateValidMoves(ChessBoard);
NodesSearched = 0;
var resultBoards = new ResultBoards
{
Positions = new List <Board>()
};
// First search if human move might have caused a mate
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
return;
}
var bestMove = new MoveContent();
//If there is no playbook move search for the best move
if (FindPlayBookMove(ref bestMove, ChessBoard, OpeningBook) == false ||
ChessBoard.HalfMoveClock > 90 ||
ChessBoard.RepeatedMove >= 2)
{
if (FindPlayBookMove(ref bestMove, ChessBoard, CurrentGameBook) == false ||
ChessBoard.HalfMoveClock > 90 ||
ChessBoard.RepeatedMove >= 2)
{
bestMove = Search.IterativeSearch(
ChessBoard,
PlyDepthSearched,
ref NodesSearched,
ref NodesQuiessence,
ref pvLine,
ref PlyDepthReached,
ref RootMovesSearched,
CurrentGameBook);
}
}
//Make the move
PreviousChessBoard = new Board(ChessBoard);
RootMovesSearched = (byte)resultBoards.Positions.Count;
Board.MovePiece(ChessBoard,
bestMove.MovingPiecePrimary.SrcPosition,
bestMove.MovingPiecePrimary.DstPosition,
ChessPieceType.Queen);
ChessBoard.LastMove.GeneratePGNString(ChessBoard);
FileIO.SaveCurrentGameMove(ChessBoard, PreviousChessBoard, CurrentGameBook, bestMove);
for (byte x = 0; x < 64; x++)
{
var sqr = ChessBoard.Squares[x];
if (sqr.Piece == null)
{
continue;
}
sqr.Piece.DefendedValue = 0;
sqr.Piece.AttackedValue = 0;
}
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
PieceTakenAdd(ChessBoard.LastMove);
MoveHistory.Push(ChessBoard.LastMove);
//Second Call if computer move might have caused a mate
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
if (ChessBoard.WhiteMate || ChessBoard.BlackMate)
{
LastMove.PgnMove += "#";
}
return;
}
if (ChessBoard.WhiteCheck || ChessBoard.BlackCheck)
{
LastMove.PgnMove += "+";
}
Thinking = false;
}
//Quiescence Search
private static int Quiescence(Board examineBoard, int alpha, int beta, ref int nodesSearched)
{
nodesSearched++;
//Evaluate Score
Evaluation.EvaluateBoardScore(examineBoard);
//Invert Score to support Negamax
examineBoard.Score = SideToMoveScore(examineBoard.Score, examineBoard.WhoseMove);
if (examineBoard.Score >= beta)
{
return(beta);
}
if (examineBoard.Score > alpha)
{
alpha = examineBoard.Score;
}
List <Position> positions;
if (examineBoard.WhiteCheck || examineBoard.BlackCheck)
{
positions = EvaluateMoves(examineBoard, 0);
}
else
{
positions = EvaluateMovesQ(examineBoard);
}
if (positions.Count == 0)
{
return(examineBoard.Score);
}
positions.Sort(Sort);
foreach (var move in positions)
{
if (StaticExchangeEvaluation(examineBoard.Squares[move.DstPosition]) >= 0)
{
continue;
}
//Make a copy
var board = examineBoard.FastCopy();
//Move Piece
Board.MovePiece(board, move.SrcPosition, move.DstPosition, ChessPieceType.Queen);
//We Generate Valid Moves for Board
PieceValidMoves.GenerateValidMoves(board);
if (board.BlackCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
continue;
}
}
if (board.WhiteCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.White)
{
continue;
}
}
var value = -Quiescence(board,
-beta,
-alpha,
ref nodesSearched);
if (value >= beta)
{
KillerMove[2, 0].SrcPosition = move.SrcPosition;
KillerMove[2, 0].DstPosition = move.DstPosition;
return(beta);
}
if (value > alpha)
{
alpha = value;
}
}
return(alpha);
}
// Not used anymore
// ReSharper disable once UnusedMember.Local
private static int MinMax(Board examineBoard, byte depth)
{
if (depth == 0)
{
//Evaluate Score
Evaluation.EvaluateBoardScore(examineBoard);
//Invert Score to support Negamax
return(SideToMoveScore(examineBoard.Score, examineBoard.WhoseMove));
}
var positions = EvaluateMoves(examineBoard, depth);
if (examineBoard.WhiteCheck || examineBoard.BlackCheck || positions.Count == 0)
{
if (SearchForMate(examineBoard.WhoseMove, examineBoard, ref examineBoard.BlackMate,
ref examineBoard.WhiteMate, ref examineBoard.StaleMate))
{
if (examineBoard.BlackMate)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
return(-32767 - depth);
}
return(32767 + depth);
}
// ReSharper disable once InvertIf
if (examineBoard.WhiteMate)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
return(32767 + depth);
}
return(-32767 - depth);
}
//If Not Mate then StaleMate
return(0);
}
}
var bestScore = -32767;
foreach (var move in positions)
{
//Make a copy
var board = examineBoard.FastCopy();
//Move Piece
Board.MovePiece(board, move.SrcPosition, move.DstPosition, ChessPieceType.Queen);
//We Generate Valid Moves for Board
PieceValidMoves.GenerateValidMoves(board);
if (board.BlackCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
continue;
}
}
if (board.WhiteCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.White)
{
continue;
}
}
var value = -MinMax(board, (byte)(depth - 1));
if (value > bestScore)
{
bestScore = value;
}
}
return(bestScore);
}
// Not used anymore
// ReSharper disable once UnusedMember.Local
private static int AlphaBeta(Board examineBoard, byte depth, int alpha, int beta, ref int nodesSearched)
{
nodesSearched++;
if (examineBoard.HalfMoveClock >= 100 || examineBoard.RepeatedMove >= 3)
{
return(0);
}
if (depth == 0)
{
//Evaluate Score
Evaluation.EvaluateBoardScore(examineBoard);
//Invert Score to support Negamax
return(SideToMoveScore(examineBoard.Score, examineBoard.WhoseMove));
}
var positions = EvaluateMoves(examineBoard, depth);
if (examineBoard.WhiteCheck || examineBoard.BlackCheck || positions.Count == 0)
{
if (SearchForMate(examineBoard.WhoseMove, examineBoard, ref examineBoard.BlackMate,
ref examineBoard.WhiteMate, ref examineBoard.StaleMate))
{
if (examineBoard.BlackMate)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
return(-32767 - depth);
}
return(32767 + depth);
}
// ReSharper disable once InvertIf
if (examineBoard.WhiteMate)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
return(32767 + depth);
}
return(-32767 - depth);
}
//If Not Mate then StaleMate
return(0);
}
}
positions.Sort(Sort);
foreach (var move in positions)
{
//Make a copy
var board = examineBoard.FastCopy();
//Move Piece
Board.MovePiece(board, move.SrcPosition, move.DstPosition, ChessPieceType.Queen);
//We Generate Valid Moves for Board
PieceValidMoves.GenerateValidMoves(board);
if (board.BlackCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
continue;
}
}
if (board.WhiteCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.White)
{
continue;
}
}
var value = -AlphaBeta(board,
(byte)(depth - 1),
-beta,
-alpha,
ref nodesSearched);
if (value >= beta)
{
return(beta);
}
if (value > alpha)
{
alpha = value;
}
}
return(alpha);
}
private static ResultBoards GetSortValidMoves(Board examineBoard)
{
var sortValidMoves = new ResultBoards {
Positions = new List <Board>(30)
};
piecesRemaining = 0;
for (byte x = 0; x < 64; x++)
{
var sqr = examineBoard.Squares[x];
//Make sure there is a piece on the square
if (sqr.Piece == null)
{
continue;
}
piecesRemaining++;
//Make sure the color is the same color as the one we are moving.
if (sqr.Piece.PieceColor != examineBoard.WhoseMove)
{
continue;
}
//For each valid move for this piece
foreach (var dst in sqr.Piece.ValidMoves)
{
//We make copies of the board and move so that we can move it without effecting the parent board
var board = examineBoard.FastCopy();
//Make move so we can examine it
Board.MovePiece(board, x, dst, ChessPieceType.Queen);
//We Generate Valid Moves for Board
PieceValidMoves.GenerateValidMoves(board);
//Invalid Move
if (board.WhiteCheck && examineBoard.WhoseMove == ChessPieceColor.White)
{
continue;
}
//Invalid Move
if (board.BlackCheck && examineBoard.WhoseMove == ChessPieceColor.Black)
{
continue;
}
//We calculate the board score
Evaluation.EvaluateBoardScore(board);
//Invert Score to support Negamax
board.Score = SideToMoveScore(board.Score, board.WhoseMove);
sortValidMoves.Positions.Add(board);
}
}
sortValidMoves.Positions.Sort(Sort);
return(sortValidMoves);
}
