See raw JS.
// Cloned by Mathias Bazin on 31 Jul 2018 from Mind "Bad AI" by Mathias Bazin
// Please leave this clone trail here.
// Cloned by Mathias Bazin on 31 Jul 2018 from Mind "Simple AI - Depth 1" by Mathias Bazin
// Please leave this clone trail here.
// Cloned by Mathias Bazin on 31 Jul 2018 from Mind "Simple AI - Depth 2" by Mathias Bazin
// Please leave this clone trail here.
// Cloned by Mathias Bazin on 31 Jul 2018 from Mind "Simple AI - Depth 1" by Mathias Bazin
// Please leave this clone trail here.
// Cloned by Mathias Bazin on 30 Jul 2018 from Mind "First move always" by Mathias Bazin
// Please leave this clone trail here.
function Mind()
{
let positionCount;
/*The "AI" part starts here */
let minimaxRoot =function(depth, game, isMaximisingPlayer) {
let newGameMoves = game.moves();
let bestMove = -9999;
let bestMoveFound;
for(let i = 0; i < newGameMoves.length; i++) {
let newGameMove = newGameMoves[i]
game.move(newGameMove);
let value = minimax(depth - 1, game, -10000, 10000, !isMaximisingPlayer);
game.undo();
if(value >= bestMove) {
bestMove = value;
bestMoveFound = newGameMove;
}
}
return bestMoveFound;
};
let minimax = function (depth, game, alpha, beta, isMaximisingPlayer) {
positionCount++;
if (depth === 0) {
return -evaluateBoard(board(game));
}
let newGameMoves = game.moves();
if (isMaximisingPlayer) {
let bestMove = -9999;
for (let i = 0; i < newGameMoves.length; i++) {
game.move(newGameMoves[i]);
bestMove = Math.max(bestMove, minimax(depth - 1, game, alpha, beta, !isMaximisingPlayer));
game.undo();
alpha = Math.max(alpha, bestMove);
if (beta <= alpha) {
return bestMove;
}
}
return bestMove;
} else {
let bestMove = 9999;
for (let i = 0; i < newGameMoves.length; i++) {
game.move(newGameMoves[i]);
bestMove = Math.min(bestMove, minimax(depth - 1, game, alpha, beta, !isMaximisingPlayer));
game.undo();
beta = Math.min(beta, bestMove);
if (beta <= alpha) {
return bestMove;
}
}
return bestMove;
}
};
let evaluateBoard = function (board) {
let totalEvaluation = 0;
for (let i = 0; i < 8; i++) {
for (let j = 0; j < 8; j++) {
totalEvaluation = totalEvaluation + getPieceValue(board[i][j], i ,j);
}
}
return totalEvaluation;
};
let reverseArray = function(array) {
return array.slice().reverse();
};
let pawnEvalWhite =
[
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
[5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0],
[1.0, 1.0, 2.0, 3.0, 3.0, 2.0, 1.0, 1.0],
[0.5, 0.5, 1.0, 2.5, 2.5, 1.0, 0.5, 0.5],
[0.0, 0.0, 0.0, 2.0, 2.0, 0.0, 0.0, 0.0],
[0.5, -0.5, -1.0, 0.0, 0.0, -1.0, -0.5, 0.5],
[0.5, 1.0, 1.0, -2.0, -2.0, 1.0, 1.0, 0.5],
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
];
let pawnEvalBlack = reverseArray(pawnEvalWhite);
let knightEval =
[
[-5.0, -4.0, -3.0, -3.0, -3.0, -3.0, -4.0, -5.0],
[-4.0, -2.0, 0.0, 0.0, 0.0, 0.0, -2.0, -4.0],
[-3.0, 0.0, 1.0, 1.5, 1.5, 1.0, 0.0, -3.0],
[-3.0, 0.5, 1.5, 2.0, 2.0, 1.5, 0.5, -3.0],
[-3.0, 0.0, 1.5, 2.0, 2.0, 1.5, 0.0, -3.0],
[-3.0, 0.5, 1.0, 1.5, 1.5, 1.0, 0.5, -3.0],
[-4.0, -2.0, 0.0, 0.5, 0.5, 0.0, -2.0, -4.0],
[-5.0, -4.0, -3.0, -3.0, -3.0, -3.0, -4.0, -5.0]
];
let bishopEvalWhite = [
[ -2.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -2.0],
[ -1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -1.0],
[ -1.0, 0.0, 0.5, 1.0, 1.0, 0.5, 0.0, -1.0],
[ -1.0, 0.5, 0.5, 1.0, 1.0, 0.5, 0.5, -1.0],
[ -1.0, 0.0, 1.0, 1.0, 1.0, 1.0, 0.0, -1.0],
[ -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0],
[ -1.0, 0.5, 0.0, 0.0, 0.0, 0.0, 0.5, -1.0],
[ -2.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -2.0]
];
let bishopEvalBlack = reverseArray(bishopEvalWhite);
let rookEvalWhite = [
[ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
[ 0.5, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0.5],
[ -0.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.5],
[ -0.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.5],
[ -0.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.5],
[ -0.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.5],
[ -0.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.5],
[ 0.0, 0.0, 0.0, 0.5, 0.5, 0.0, 0.0, 0.0]
];
let rookEvalBlack = reverseArray(rookEvalWhite);
let evalQueen = [
[ -2.0, -1.0, -1.0, -0.5, -0.5, -1.0, -1.0, -2.0],
[ -1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -1.0],
[ -1.0, 0.0, 0.5, 0.5, 0.5, 0.5, 0.0, -1.0],
[ -0.5, 0.0, 0.5, 0.5, 0.5, 0.5, 0.0, -0.5],
[ 0.0, 0.0, 0.5, 0.5, 0.5, 0.5, 0.0, -0.5],
[ -1.0, 0.5, 0.5, 0.5, 0.5, 0.5, 0.0, -1.0],
[ -1.0, 0.0, 0.5, 0.0, 0.0, 0.0, 0.0, -1.0],
[ -2.0, -1.0, -1.0, -0.5, -0.5, -1.0, -1.0, -2.0]
];
let kingEvalWhite = [
[ -3.0, -4.0, -4.0, -5.0, -5.0, -4.0, -4.0, -3.0],
[ -3.0, -4.0, -4.0, -5.0, -5.0, -4.0, -4.0, -3.0],
[ -3.0, -4.0, -4.0, -5.0, -5.0, -4.0, -4.0, -3.0],
[ -3.0, -4.0, -4.0, -5.0, -5.0, -4.0, -4.0, -3.0],
[ -2.0, -3.0, -3.0, -4.0, -4.0, -3.0, -3.0, -2.0],
[ -1.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -1.0],
[ 2.0, 2.0, 0.0, 0.0, 0.0, 0.0, 2.0, 2.0 ],
[ 2.0, 3.0, 1.0, 0.0, 0.0, 1.0, 3.0, 2.0 ]
];
let kingEvalBlack = reverseArray(kingEvalWhite);
let getPieceValue = function (piece, x, y) {
if (piece === null) {
return 0;
}
let getAbsoluteValue = function (piece, isWhite, x ,y) {
if (piece.type === 'p') {
return 10 + ( isWhite ? pawnEvalWhite[y][x] : pawnEvalBlack[y][x] );
} else if (piece.type === 'r') {
return 50 + ( isWhite ? rookEvalWhite[y][x] : rookEvalBlack[y][x] );
} else if (piece.type === 'n') {
return 30 + knightEval[y][x];
} else if (piece.type === 'b') {
return 30 + ( isWhite ? bishopEvalWhite[y][x] : bishopEvalBlack[y][x] );
} else if (piece.type === 'q') {
return 90 + evalQueen[y][x];
} else if (piece.type === 'k') {
return 900 + ( isWhite ? kingEvalWhite[y][x] : kingEvalBlack[y][x] );
}
throw "Unknown piece type: " + piece.type;
};
let absoluteValue = getAbsoluteValue(piece, piece.color === 'w', x ,y);
return piece.color === 'w' ? absoluteValue : -absoluteValue;
};
function board(game)
{
let letters = ['a','b','c','d','e','f','g','h'];
let nbs = ['8','7','6','5','4','3','2','1'];
let b = new Array(8);
for (let i =0; i<8; i++)
{
b[i] = new Array(8);
for (let j = 0; j <8; j++)
{
let square = letters[j] + nbs[i];
b[i][j] = game.get(square);
}
}
return b;
}
function boardToString(b)
{
let s = "";
for (let i = 0; i<8; i++)
{
for (let j = 0; j<8; j++)
{
if (b[i][j] === null) s += " ";
else
{
if (b[i][j].color == 'b') s += b[i][j].type;
else s += b[i][j].type.toUpperCase();
}
}
s += "\n";
}
return s;
}
this.getAction = function ( state )
{
let game = new Chess(state);
let b = board(game);
let move = minimaxRoot(2, game, true);
return move;
};
}