// Cloned by Mathias Bazin on 1 Aug 2018 from World "Chess : Mind vs Simple AI - Depth 1" by Mathias Bazin
// Please leave this clone trail here.
// Cloned by Mathias Bazin on 1 Aug 2018 from World "Chess : Mind vs Random" by Mathias Bazin
// Please leave this clone trail here.
//=== Explanations =============================================================
//The Score system
//Currently the scoring system works as follows :
// - The Mind starts with a base score of 200 (in other words, 200 is the neutral score for a perfect draw)
// - The Mind earns 100 points for winning the game (checkmate), loses 100 points for loosing (gets checkmated)
// - The Mind earns an amount of points for each of his pieces left and loses the same for each opposing pieces left at the end of the game
// Values of the pieces :
// pawn : 1
// rook : 5
// bishop : 3
// knight : 3
// queen : 9
// - If the game ends before turn 100, additional points for speed are added (in the case of a win) or removed (a lose)
// Formula for the time points : timePoints = 2 * ( 100 - turn )
//Avoiding threefold repetition
//In chess and some other abstract strategy games, the threefold repetition rule (also known as repetition of position)
//states that a player can claim a draw if the same position occurs three times, or will occur after their next move,
//with the same player to move. The repeated positions do not need to occur in succession.
//The idea behind the rule is that if the position occurs three times, no progress is being made.
//When 2 AIs play against each other it is very common that they enter a cycle and start doing the same moves over and over again,
//causing a draw because of this rule. To prevent this, the black AI will choose a random move rather than causing a threefold repetition to happen.
//Random
//Some random has to be put in the opponent playstyle or else the games will always be strictly the same.
//For now, the first move of the black player is picked randomly so that makes only 18 different possible openings so 18
//possible games. I have to think of a better way to do this. Maybe choosing rando;ly a turn at the beginning of the game
//and makig Black play random at this turn.
//TODO
//Make the AIs play multiple games and take the average score as the final one
//==============================================================================
AB.runReady = false;
AB.clockTick = 60;
let s = document.createElement("script");
s.src = "https://cdnjs.cloudflare.com/ajax/libs/chess.js/0.10.2/chess.js";
s.onload = function() {
console.log("chess loaded");
AB.runReady = true;
}; // function to be called when JS is loaded
document.head.appendChild(s);
function World()
{
let depth = 1; //This sets how many moves the opponent's AI will look ahead
//when computing its move. Therefore, it influences greatly the
//strength of the opponent.
//Its value should be within 1 and 3. If going farther than 3,
//the game will take a lot of time to compute, at least on a standard
//browser allowing only 1 CPU core per tab.
let chess;
let scl = 40;
let xoff = 100;
let yoff = $(document).height()/2;
let turn = 0;
let preventRepetition = true;
let randomTurn;
let ctx;
let self = this;
let bk, bq, bn, br, bb, bp, wk, wq, wn, wr, wb, wp, board;
let fens = [];
function drawBoard(board)
{
let square = 0;
for(let cur of board)
{
switch(cur)
{
case "r":
ctx.drawImage(br, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "n":
ctx.drawImage(bn, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "b":
ctx.drawImage(bb, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "q":
ctx.drawImage(bq, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "k":
ctx.drawImage(bk, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "p":
ctx.drawImage(bp, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "R":
ctx.drawImage(wr, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "N":
ctx.drawImage(wn, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "B":
ctx.drawImage(wb, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "Q":
ctx.drawImage(wq, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "K":
ctx.drawImage(wk, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "P":
ctx.drawImage(wp, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
// text(cur, xoff + scl*(square%8), yoff + scl*(Math.floor(square/8)));
square++;
break;
case "/":
break;
case " ":
return;
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
square += +cur;
break;
default:
console.log("Error in drawBoard");
}
}
}
function drawGrid()
{
ctx.drawImage(board,xoff,yoff);
}
this.newRun = function()
{
threeworld.init ( "white" );
ctx = threeworld.getContext ( "2d" );
chess = new Chess();
bk = new Image();
bk.src = '/uploads/mathias/bk.png';
bq = new Image();
bq.src = '/uploads/mathias/bq.png';
bn = new Image();
bn.src = '/uploads/mathias/bn.png';
br = new Image();
br.src = '/uploads/mathias/br.png';
bb = new Image();
bb.src = '/uploads/mathias/bb.png';
bp = new Image();
bp.src = '/uploads/mathias/bp.png';
wk = new Image();
wk.src = '/uploads/mathias/wk.png';
wq = new Image();
wq.src = '/uploads/mathias/wq.png';
wn = new Image();
wn.src = '/uploads/mathias/wn.png';
wr = new Image();
wr.src = '/uploads/mathias/wr.png';
wb = new Image();
wb.src = '/uploads/mathias/wb.png';
wp = new Image();
wp.src = '/uploads/mathias/wp.png';
board = new Image();
board.src = '/uploads/mathias/board.png'
drawBoard(chess.fen());
randomTurn = AB.randomIntAtoB(1,10);
let s = "Your mind plays against a depth " + depth + " AI";
$("#user_span1").html("<p>"+s+"</p>");
console.log(s);
console.log("Random turn for Black has been chosen to be turn", randomTurn);
};
this.takeAction = function ( action )
{
if (!chess.game_over())
{
if(chess.turn() == 'w')
{
turn++;
$("#user_span2").html("<p>Turn " + turn + "</p> <p>Black has to make a move</p>"); //must write black here so it is actually displayed at the right time, don't really know why
chess.move(action);
}
else //Black player makes his move
{
$("#user_span2").html("<p>Turn " + turn + "</p> <p>White has to make a move</p>");
if (turn == randomTurn) //at turn chosen randomly do a random move so games may vary
{
console.log("Black plays randomly");
let moves = chess.moves();
let move = moves[Math.floor(Math.random() * moves.length)];
chess.move(move); //random legal move
}
else
{
let move = minimaxRoot(depth, chess, true);
chess.move(move);
while (preventRepetition && in_threefold_repetition(chess))
{
console.log("Black tries to avoid threefold repetition");
chess.undo();
let moves = chess.moves();
move = moves[Math.floor(Math.random() * moves.length)];
chess.move(move); //random legal move
}
}
}
drawGrid();
drawBoard(chess.fen());
// console.log(chess.ascii());
}
else
{
ABRun.abortRun = true;
}
};
this.getState = function()
{
return chess.fen();
};
this.getScore = function()
{
let score = 200; //base score
let fen = chess.fen();
let i = 0;
//points for the pieces
while (fen[i] != " ")
{
switch(fen[i])
{
case 'r':
score -= 5;
break;
case 'n':
case 'b':
score -= 3;
break;
case 'p':
score -= 1;
break;
case 'q':
score -= 9;
break;
case 'R':
score += 5;
break;
case 'N':
case 'B':
score += 3;
break;
case 'P':
score += 1;
break;
case 'Q':
score += 9;
break;
}
i++;
}
console.log("pieces points : ", score - 200);
//points for the win/lose and time
if(chess.in_checkmate())
{
let timePoints = 100 - turn;
if (timePoints < 0) timePoints = 0;
timePoints *= 2;
if (chess.turn() == 'b')
{
console.log("time points : ", timePoints);
console.log("win points : ", 100);
score += 100;
score += timePoints;
}
else
{
console.log("time points : ", -timePoints);
console.log("lose points : ", -100);
score -= 100;
score -= timePoints;
}
}
return score;
}
this.endRun = function()
{
let s = "Game Over";
if (chess.in_draw())
{
s += " : Draw";
if (chess.insufficient_material()) s += " (insufficient material)";
if (chess.in_stalemate()) s += " (stalemate)";
if (in_threefold_repetition(chess)) s += " (threefold repetition)";
}
else if(chess.in_checkmate())
{
if (chess.turn() == 'b') s+= " : White wins (Black has been checkmated)";
else s+= " : Black wins (White has been checkmated)";
}
console.log(s);
$("#user_span3").html("<p>" + s + "</p>");
ctx.font = "20px Arial";
ctx.fillText(s,xoff,yoff - 20);
$("#user_span3").html("<p>" + s + "</p><p>Score : " + self.getScore() + "</p>");
$("#user_span4").html("<button id=replay>Replay</button>");
$("#replay").on("click", startReplay);
}
function startReplay()
{
let moves = chess.history();
let chess1 = new Chess();
fens.push( chess1.fen() );
for (let move of moves)
{
chess1.move(move);
fens.push( chess1.fen() );
}
$("#user_span2").html("<p>In total : "+ turn + " turns, " + fens.length + "moves.</p>" );
$("#user_span4").html("<p>Move # : <input id=replayMove type=number value=1 min=1 max=" + fens.length + "></p>");
$("#replayMove").on("keyPress", updateReplay);
$("#replayMove").on("change", updateReplay);
drawGrid();
drawBoard(fens[0]);
}
function updateReplay()
{
let moveIndex = $("#replayMove").val() - 1;
drawGrid();
drawBoard(fens[moveIndex]);
}
/*=========================The "AI" part starts here *====================*/
let positionCount;
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(toBoard(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 toBoard(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;
}
function in_threefold_repetition(game) {
/* to do: while this function is fine for casual use, a better
implementation would use a Zobrist key (instead of FEN). the
Zobrist key would be maintained in the make_move/undo_move functions,
avoiding the costly that we do below.
*/
var moves = [];
var positions = {};
var repetition = false;
while (true) {
var move = game.undo();
if (!move) break;
moves.push(move);
}
while (true) {
/* remove the last two fields in the FEN string, they're not needed
* when checking for draw by rep */
var fen = game.fen().split(' ').slice(0,4).join(' ');
/* has the position occurred three or move times */
positions[fen] = (fen in positions) ? positions[fen] + 1 : 1;
if (positions[fen] >= 3) {
repetition = true;
}
if (!moves.length) {
break;
}
game.move(moves.pop());
}
return repetition;
}
}