public Move GetBestMove(Board board)
{
int bestValue = int.MinValue;
Move bestMove = null;
List <Move> pseudoLegalMoves = MoveGeneration.GenerateAllMoves(board, Piece.black);
SortMoves(board, pseudoLegalMoves);
foreach (var move in pseudoLegalMoves)
{
board.MakeMove(move, true);
if (MoveGeneration.IsInCheck(board, Piece.black))
{
board.UnMakeMove(true);
continue;
}
int value = Minimax(board, depth, int.MinValue, int.MaxValue, false);
board.UnMakeMove(true);
if (value >= bestValue)
{
bestValue = value;
bestMove = move;
}
}
return(bestMove);
}
private int Minimax(Board board, int depth, int alpha, int beta, bool isMaximizingPlayer)
{
if (depth == 0)
{
return(Evaluate(board));
}
if (isMaximizingPlayer)
{
int bestValue = int.MinValue;
List <Move> pseudoLegalMoves = MoveGeneration.GenerateAllMoves(board, Piece.black);
SortMoves(board, pseudoLegalMoves);
foreach (var move in pseudoLegalMoves)
{
board.MakeMove(move, true);
if (MoveGeneration.IsInCheck(board, Piece.black))
{
board.UnMakeMove(true);
continue;
}
int value = Minimax(board, depth - 1, alpha, beta, false);
board.UnMakeMove(true);
bestValue = Math.Max(value, bestValue);
alpha = Math.Max(alpha, value);
if (beta <= alpha)
{
break;
}
}
return(bestValue);
}
else
{
int bestValue = int.MaxValue;
List <Move> pseudoLegalMoves = MoveGeneration.GenerateAllMoves(board, Piece.white);
SortMoves(board, pseudoLegalMoves);
foreach (var move in pseudoLegalMoves)
{
board.MakeMove(move, true);
if (MoveGeneration.IsInCheck(board, Piece.white))
{
board.UnMakeMove(true);
continue;
}
int value = Minimax(board, depth - 1, alpha, beta, true);
board.UnMakeMove(true);
bestValue = Math.Min(value, bestValue);
beta = Math.Min(beta, value);
if (beta <= alpha)
{
break;
}
}
return(bestValue);
}
}
// Called every frame. 'delta' is the elapsed time since the previous frame.
public override void _Process(float delta)
{
if (!Engine.EditorHint)
{
if (turnPlayer)
{
if (Input.IsActionJustPressed("Select"))
{
// get mouse position
Vector2 mouse = GetViewport().GetMousePosition() - boardUI.Position;
// get position in grid
int squareX = (int)(mouse.x / boardUI.scale);
int squareY = (int)(mouse.y / boardUI.scale);
int selectedSquare = squareX + squareY * 8;
// check if it is inside the bounds
if (IsInBounds(squareX, squareY))
{
// get the piece if there is one
if (!Piece.IsPieceType(board.pieces[selectedSquare], Piece.none) && Piece.IsPieceColor(board.pieces[selectedSquare], Piece.white))
{
selectedPieceSquare = selectedSquare;
isPieceSelected = true;
legalMoves = MoveGeneration.GenerateLegalMoves(board, selectedSquare);
}
else
{
legalMoves.Clear();
}
}
else
{
legalMoves.Clear();
}
}
else if (Input.IsActionJustReleased("Select"))
{
if (isPieceSelected)
{
// get mouse position
Vector2 mouse = GetViewport().GetMousePosition() - boardUI.Position;
int squareX = (int)(mouse.x / boardUI.scale);
int squareY = (int)(mouse.y / boardUI.scale);
int targetSquare = squareX + squareY * 8;
// check if it is inside the bounds
if (IsInBounds(squareX, squareY))
{
foreach (var move in legalMoves)
{
if (targetSquare == move.targetSquare)
{
if (Piece.IsPieceType(board.pieces[targetSquare], Piece.none))
{
moveSound.Play();
}
else
{
captureSound.Play();
}
board.MakeMove(move);
turnPlayer = false;
legalMoves.Clear();
break;
}
}
}
boardUI.UpdateBoardPieces(board);
isPieceSelected = false;
}
}
if (Input.IsActionPressed("Select"))
{
if (isPieceSelected)
{
// get mouse position
Vector2 mouse = GetViewport().GetMousePosition() - boardUI.Position;
Sprite piece = boardUI.piecesSprites[selectedPieceSquare];
piece.Position = mouse + new Vector2(-boardUI.scale / 2f, -boardUI.scale / 2f);
piece.ZIndex = 1;
}
}
if (Input.IsActionJustPressed("Restore"))
{
// unmake both moves your move and black pieces move
board.UnMakeMove();
board.UnMakeMove();
boardUI.UpdateBoardPieces(board);
legalMoves.Clear();
}
}
else
{
/*
* I DONT THINK THIS IS THE RIGHT WAY TO DO THIS
* IF I DONT USE A THREAD, IF IT TAKES "TOO MUCH TIME"
* WINDOWS WILL THINK IT STOPPED WORKING,
* I AM NOT REALLY HAPPY WITH THIS SOLUTION
*/
if (!calculating)
{
calculating = true;
System.Threading.Thread t = new System.Threading.Thread(new ThreadStart(ComputerTurn));
t.Start();
}
}
boardUI.ResetBoardSquares();
boardUI.ViewLastMove(board);
boardUI.ViewLegalMovements(board, legalMoves);
}
}