Result MiniMax(ChessGameMgr.BoardState board, ChessGameMgr.EChessTeam team, int currentDepth, int alpha, int beta)
{
aiCount++;
ChessGameMgr.EChessTeam otherTeam = (team == ChessGameMgr.EChessTeam.White) ? ChessGameMgr.EChessTeam.Black : ChessGameMgr.EChessTeam.White;
if (board.DoesTeamLoseForCustomBoard(ChessGameMgr.EChessTeam.White, board) || board.DoesTeamLoseForCustomBoard(ChessGameMgr.EChessTeam.Black, board) || currentDepth == maxDepth)
{
Result res = new Result();
res.score = ChessGameMgr.Instance.Evaluate(team, board);
return(res);
}
ChessGameMgr.Move bestMove = new ChessGameMgr.Move();
int bestScore = int.MaxValue;
if (ChessGameMgr.Instance.TeamTurn == team)
{
bestScore = int.MinValue;
}
List <ChessGameMgr.Move> moves = new List <ChessGameMgr.Move>();
ChessGameMgr.Instance.GetBoardState().GetValidMoves(team, moves);
foreach (ChessGameMgr.Move move in moves)
{
ChessGameMgr.BoardState newBoard = board.Clone();
ChessGameMgr.PieceData dataFrom = newBoard.bitBoard.GetPieceFromPos(move.From);
ChessGameMgr.PieceData dataTo = newBoard.bitBoard.GetPieceFromPos(move.To);
ChessGameMgr.Instance.MakeMove(team, move, newBoard);
ChessGameMgr.Instance.UpdatePieces(newBoard);
// recurse MiniMax
Result recursedRes = MiniMax(newBoard, otherTeam, currentDepth + 1, alpha, beta);
ChessGameMgr.Move tmpMove = new ChessGameMgr.Move();
tmpMove.From = move.To;
tmpMove.To = move.From;
ChessGameMgr.Instance.MakeMove(team, tmpMove, newBoard);
if (dataTo.piece != ChessGameMgr.EPieceType.None)
{
newBoard.SetPieceAtSquare(dataTo.pos, dataTo.team, dataTo.piece);
}
ChessGameMgr.Instance.UpdatePieces(newBoard);
// update the best score
if (ChessGameMgr.Instance.TeamTurn == team)
{
if (recursedRes.score > bestScore) // maximize score
{
bestScore = recursedRes.score;
bestMove = move;
}
alpha = Mathf.Max(alpha, bestScore);
}
else
{
if (recursedRes.score < bestScore) // minimize score
{
bestScore = recursedRes.score;
bestMove = move;
}
beta = Mathf.Min(beta, bestScore);
}
if (beta <= alpha)
{
break;
}
}
Result bestRes = new Result();
bestRes.move = bestMove;
bestRes.score = bestScore;
return(bestRes);
}
public Result(ChessGameMgr.Move _move, int _score)
{
move = _move;
score = _score;
}
