this.moves = moves;
// Use fen string to initialize variables, flags and board
this.board = VariantRules.GetBoard(fen);
- this.flags = VariantRules.GetFlags(fen);
+ this.setFlags(fen);
this.initVariables(fen);
}
const position = fenParts[0].split("/");
for (let i=0; i<position.length; i++)
{
- let j = 0;
- while (j < position[i].length)
+ let k = 0; //column index on board
+ for (let j=0; j<position[i].length; j++)
{
switch (position[i].charAt(j))
{
case 'k':
- this.kingPos['b'] = [i,j];
- this.INIT_COL_KING['b'] = j;
+ this.kingPos['b'] = [i,k];
+ this.INIT_COL_KING['b'] = k;
break;
case 'K':
- this.kingPos['w'] = [i,j];
- this.INIT_COL_KING['w'] = j;
+ this.kingPos['w'] = [i,k];
+ this.INIT_COL_KING['w'] = k;
break;
case 'r':
if (this.INIT_COL_ROOK['b'][0] < 0)
- this.INIT_COL_ROOK['b'][0] = j;
+ this.INIT_COL_ROOK['b'][0] = k;
else
- this.INIT_COL_ROOK['b'][1] = j;
+ this.INIT_COL_ROOK['b'][1] = k;
break;
case 'R':
if (this.INIT_COL_ROOK['w'][0] < 0)
- this.INIT_COL_ROOK['w'][0] = j;
+ this.INIT_COL_ROOK['w'][0] = k;
else
- this.INIT_COL_ROOK['w'][1] = j;
+ this.INIT_COL_ROOK['w'][1] = k;
break;
default:
let num = parseInt(position[i].charAt(j));
if (!isNaN(num))
- j += (num-1);
+ k += (num-1);
}
- j++;
+ k++;
}
}
const epSq = this.moves.length > 0 ? this.getEpSquare(this.lastMove) : undefined;
}
// Overridable: flags can change a lot
- static GetFlags(fen)
+ setFlags(fen)
{
// white a-castle, h-castle, black a-castle, h-castle
- let flags = {'w': new Array(2), 'b': new Array(2)};
- let fenFlags = fen.split(" ")[1]; //flags right after position
+ this.castleFlags = {'w': new Array(2), 'b': new Array(2)};
+ let flags = fen.split(" ")[1]; //flags right after position
for (let i=0; i<4; i++)
- flags[i < 2 ? 'w' : 'b'][i%2] = (fenFlags.charAt(i) == '1');
- return flags;
+ this.castleFlags[i < 2 ? 'w' : 'b'][i%2] = (flags.charAt(i) == '1');
}
///////////////////
'r': [ [-1,0],[1,0],[0,-1],[0,1] ],
'n': [ [-1,-2],[-1,2],[1,-2],[1,2],[-2,-1],[-2,1],[2,-1],[2,1] ],
'b': [ [-1,-1],[-1,1],[1,-1],[1,1] ],
- 'q': [ [-1,0],[1,0],[0,-1],[0,1],[-1,-1],[-1,1],[1,-1],[1,1] ]
};
}
+ // Aggregates flags into one object
+ get flags() {
+ return this.castleFlags;
+ }
+
+ // Reverse operation
+ parseFlags(flags)
+ {
+ this.castleFlags = flags;
+ }
+
// En-passant square, if any
getEpSquare(move)
{
// Build a regular move from its initial and destination squares; tr: transformation
getBasicMove([sx,sy], [ex,ey], tr)
{
- var mv = new Move({
+ let mv = new Move({
appear: [
new PiPo({
x: ex,
getSlideNJumpMoves([x,y], steps, oneStep)
{
const color = this.getColor(x,y);
- var moves = [];
+ let moves = [];
const [sizeX,sizeY] = VariantRules.size;
outerLoop:
for (let step of steps)
// What are the pawn moves from square x,y considering color "color" ?
getPotentialPawnMoves([x,y])
{
- const color = this.getColor(x,y);
- var moves = [];
- var V = VariantRules;
+ const color = this.turn;
+ let moves = [];
+ const V = VariantRules;
const [sizeX,sizeY] = VariantRules.size;
- let shift = (color == "w" ? -1 : 1);
- let startRank = (color == "w" ? sizeY-2 : 1);
- let lastRank = (color == "w" ? 0 : sizeY-1);
+ const shift = (color == "w" ? -1 : 1);
+ const firstRank = (color == 'w' ? sizeY-1 : 0);
+ const startRank = (color == "w" ? sizeY-2 : 1);
+ const lastRank = (color == "w" ? 0 : sizeY-1);
if (x+shift >= 0 && x+shift < sizeX && x+shift != lastRank)
{
if (this.board[x+shift][y] == V.EMPTY)
{
moves.push(this.getBasicMove([x,y], [x+shift,y]));
- if (x==startRank && this.board[x+2*shift][y] == V.EMPTY)
+ // Next condition because variants with pawns on 1st rank generally allow them to jump
+ if ([startRank,firstRank].includes(x) && this.board[x+2*shift][y] == V.EMPTY)
{
// Two squares jump
moves.push(this.getBasicMove([x,y], [x+2*shift,y]));
// What are the queen moves from square x,y ?
getPotentialQueenMoves(sq)
{
- return this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.QUEEN]);
+ const V = VariantRules;
+ return this.getSlideNJumpMoves(sq, V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
}
// What are the king moves from square x,y ?
getPotentialKingMoves(sq)
{
+ const V = VariantRules;
// Initialize with normal moves
- let moves = this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.QUEEN], "oneStep");
+ let moves = this.getSlideNJumpMoves(sq,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
return moves.concat(this.getCastleMoves(sq));
}
getCastleMoves([x,y])
{
const c = this.getColor(x,y);
- if (x != (c=="w" ? 7 : 0) || y != this.INIT_COL_KING[c])
+ const [sizeX,sizeY] = VariantRules.size;
+ if (x != (c=="w" ? sizeX-1 : 0) || y != this.INIT_COL_KING[c])
return []; //x isn't first rank, or king has moved (shortcut)
const V = VariantRules;
const oppCol = this.getOppCol(c);
let moves = [];
let i = 0;
- const finalSquares = [ [2,3], [6,5] ]; //king, then rook
+ const finalSquares = [ [2,3], [sizeY-2,sizeY-3] ]; //king, then rook
castlingCheck:
for (let castleSide=0; castleSide < 2; castleSide++) //large, then small
{
- if (!this.flags[c][castleSide])
+ if (!this.castleFlags[c][castleSide])
continue;
// If this code is reached, rooks and king are on initial position
{
if (moves.length == 0)
return [];
- let color = this.turn;
- return moves.filter(m => { return !this.underCheck(m, color); });
+ return moves.filter(m => { return !this.underCheck(m); });
}
// Search for all valid moves considering current turn (for engine and game end)
{
const color = this.turn;
const oppCol = this.getOppCol(color);
- var potentialMoves = [];
- let [sizeX,sizeY] = VariantRules.size;
+ let potentialMoves = [];
+ const [sizeX,sizeY] = VariantRules.size;
for (var i=0; i<sizeX; i++)
{
for (var j=0; j<sizeY; j++)
// No: if happen on last 1/2 move, could lead to forbidden moves, wrong evals
return this.filterValid(potentialMoves);
}
-
+
// Stop at the first move found
atLeastOneMove()
{
const color = this.turn;
const oppCol = this.getOppCol(color);
- let [sizeX,sizeY] = VariantRules.size;
- for (var i=0; i<sizeX; i++)
+ const [sizeX,sizeY] = VariantRules.size;
+ for (let i=0; i<sizeX; i++)
{
- for (var j=0; j<sizeY; j++)
+ for (let j=0; j<sizeY; j++)
{
if (this.board[i][j] != VariantRules.EMPTY && this.getColor(i,j) != oppCol)
{
const moves = this.getPotentialMovesFrom([i,j]);
if (moves.length > 0)
{
- for (let i=0; i<moves.length; i++)
+ for (let k=0; k<moves.length; k++)
{
- if (this.filterValid([moves[i]]).length > 0)
+ if (this.filterValid([moves[k]]).length > 0)
return true;
}
}
// Is square x,y attacked by queens of color c ?
isAttackedByQueen(sq, colors)
{
- return this.isAttackedBySlideNJump(sq, colors,
- VariantRules.QUEEN, VariantRules.steps[VariantRules.QUEEN]);
+ const V = VariantRules;
+ return this.isAttackedBySlideNJump(sq, colors, V.QUEEN,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
}
// Is square x,y attacked by king of color c ?
isAttackedByKing(sq, colors)
{
- return this.isAttackedBySlideNJump(sq, colors,
- VariantRules.KING, VariantRules.steps[VariantRules.QUEEN], "oneStep");
+ const V = VariantRules;
+ return this.isAttackedBySlideNJump(sq, colors, V.KING,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
}
// Generic method for non-pawn pieces ("sliding or jumping"): is x,y attacked by piece != color ?
getCheckSquares(move)
{
this.play(move);
- const color = this.turn;
+ const color = this.turn; //opponent
let res = this.isAttacked(this.kingPos[color], this.getOppCol(color))
? [ JSON.parse(JSON.stringify(this.kingPos[color])) ] //need to duplicate!
: [ ];
{
const piece = this.getPiece(move.start.x,move.start.y);
const c = this.getColor(move.start.x,move.start.y);
- const firstRank = (c == "w" ? 7 : 0);
+ const [sizeX,sizeY] = VariantRules.size;
+ const firstRank = (c == "w" ? sizeX-1 : 0);
// Update king position + flags
if (piece == VariantRules.KING && move.appear.length > 0)
{
this.kingPos[c][0] = move.appear[0].x;
this.kingPos[c][1] = move.appear[0].y;
- this.flags[c] = [false,false];
+ this.castleFlags[c] = [false,false];
return;
}
const oppCol = this.getOppCol(c);
- const oppFirstRank = 7 - firstRank;
+ const oppFirstRank = (sizeX-1) - firstRank;
if (move.start.x == firstRank //our rook moves?
&& this.INIT_COL_ROOK[c].includes(move.start.y))
{
- const flagIdx = move.start.y == this.INIT_COL_ROOK[c][0] ? 0 : 1;
- this.flags[c][flagIdx] = false;
+ const flagIdx = (move.start.y == this.INIT_COL_ROOK[c][0] ? 0 : 1);
+ this.castleFlags[c][flagIdx] = false;
}
else if (move.end.x == oppFirstRank //we took opponent rook?
- && this.INIT_COL_ROOK[c].includes(move.end.y))
+ && this.INIT_COL_ROOK[oppCol].includes(move.end.y))
{
- const flagIdx = move.end.y == this.INIT_COL_ROOK[oppCol][0] ? 0 : 1;
- this.flags[oppCol][flagIdx] = false;
+ const flagIdx = (move.end.y == this.INIT_COL_ROOK[oppCol][0] ? 0 : 1);
+ this.castleFlags[oppCol][flagIdx] = false;
}
}
play(move, ingame)
{
+ // DEBUG:
+// if (!this.states) this.states = [];
+// if (!ingame) this.states.push(JSON.stringify(this.board));
+
if (!!ingame)
move.notation = this.getNotation(move);
- // Save flags (for undo)
- move.flags = JSON.stringify(this.flags); //TODO: less costly?
+ move.flags = JSON.stringify(this.flags); //save flags (for undo)
this.updateVariables(move);
this.moves.push(move);
this.epSquares.push( this.getEpSquare(move) );
this.epSquares.pop();
this.moves.pop();
this.unupdateVariables(move);
- this.flags = JSON.parse(move.flags);
+ this.parseFlags(JSON.parse(move.flags));
+
+ // DEBUG:
+// let state = this.states.pop();
+// if (JSON.stringify(this.board) != state)
+// debugger;
}
//////////////
// END OF GAME
- checkGameOver()
+ checkRepetition()
{
// Check for 3 repetitions
if (this.moves.length >= 8)
_.isEqual(this.moves[L-3], this.moves[L-7]) &&
_.isEqual(this.moves[L-4], this.moves[L-8]))
{
- return "1/2 (repetition)";
+ return true;
}
}
+ return false;
+ }
- if (this.atLeastOneMove())
- {
- // game not over
+ checkGameOver()
+ {
+ if (this.checkRepetition())
+ return "1/2";
+
+ if (this.atLeastOneMove()) // game not over
return "*";
- }
// Game over
return this.checkGameEnd();
};
}
+ static get INFINITY() {
+ return 9999; //"checkmate" (unreachable eval)
+ }
+
+ static get THRESHOLD_MATE() {
+ // At this value or above, the game is over
+ return VariantRules.INFINITY;
+ }
+
// Assumption: at least one legal move
- getComputerMove()
+ getComputerMove(moves1) //moves1 might be precomputed (Magnetic chess)
{
+ const maxeval = VariantRules.INFINITY;
const color = this.turn;
+ if (!moves1)
+ moves1 = this.getAllValidMoves();
// Rank moves using a min-max at depth 2
- let moves1 = this.getAllValidMoves();
-
for (let i=0; i<moves1.length; i++)
{
- moves1[i].eval = (color=="w" ? -1 : 1) * 1000; //very low, I'm checkmated
- let eval2 = (color=="w" ? 1 : -1) * 1000; //initialized with very high (checkmate) value
+ moves1[i].eval = (color=="w" ? -1 : 1) * maxeval; //very low, I'm checkmated
+ let eval2 = (color=="w" ? 1 : -1) * maxeval; //initialized with checkmate value
this.play(moves1[i]);
// Second half-move:
let moves2 = this.getAllValidMoves();
}
moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
- // TODO: show current analyzed move for depth 3, allow stopping eval (return moves1[0])
- for (let i=0; i<moves1.length; i++)
+ // Skip depth 3 if we found a checkmate (or if we are checkmated in 1...)
+ if (Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
{
- this.play(moves1[i]);
- // 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
- moves1[i].eval = 0.1*moves1[i].eval + this.alphabeta(2, -1000, 1000);
- this.undo(moves1[i]);
+ // TODO: show current analyzed move for depth 3, allow stopping eval (return moves1[0])
+ for (let i=0; i<moves1.length; i++)
+ {
+ this.play(moves1[i]);
+ // 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
+ moves1[i].eval = 0.1*moves1[i].eval + this.alphabeta(2, -maxeval, maxeval);
+ this.undo(moves1[i]);
+ }
+ moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
}
- moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
let candidates = [0]; //indices of candidates moves
for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
candidates.push(j);
-
- //console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
+// console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
return moves1[_.sample(candidates, 1)];
}
alphabeta(depth, alpha, beta)
{
+ const maxeval = VariantRules.INFINITY;
const color = this.turn;
if (!this.atLeastOneMove())
{
switch (this.checkGameEnd())
{
case "1/2": return 0;
- default: return color=="w" ? -1000 : 1000;
+ default: return color=="w" ? -maxeval : maxeval;
}
}
if (depth == 0)
return this.evalPosition();
const moves = this.getAllValidMoves();
- let v = color=="w" ? -1000 : 1000;
+ let v = color=="w" ? -maxeval : maxeval;
if (color == "w")
{
for (let i=0; i<moves.length; i++)
for (let i of ['w','b'])
{
for (let j=0; j<2; j++)
- fen += this.flags[i][j] ? '1' : '0';
+ fen += this.castleFlags[i][j] ? '1' : '0';
}
return fen;
}
// Context: just before move is played, turn hasn't changed
getNotation(move)
{
- if (move.appear.length == 2)
+ if (move.appear.length == 2 && move.appear[0].p == VariantRules.KING)
{
// Castle
if (move.end.y < move.start.y)
}
// Translate final square
- let finalSquare =
+ const finalSquare =
String.fromCharCode(97 + move.end.y) + (VariantRules.size[0]-move.end.x);
- let piece = this.getPiece(move.start.x, move.start.y);
+ const piece = this.getPiece(move.start.x, move.start.y);
if (piece == VariantRules.PAWN)
{
// Pawn move
let notation = "";
- if (move.vanish.length > 1)
+ if (move.vanish.length > move.appear.length)
{
// Capture
- let startColumn = String.fromCharCode(97 + move.start.y);
+ const startColumn = String.fromCharCode(97 + move.start.y);
notation = startColumn + "x" + finalSquare;
}
else //no capture
else
{
// Piece movement
- return piece.toUpperCase() + (move.vanish.length > 1 ? "x" : "") + finalSquare;
+ return piece.toUpperCase() +
+ (move.vanish.length > move.appear.length ? "x" : "") + finalSquare;
}
}
pgn += '[Site "vchess.club"]<br>';
const d = new Date();
const opponent = mode=="human" ? "Anonymous" : "Computer";
+ pgn += '[Variant "' + variant + '"]<br>';
pgn += '[Date "' + d.getFullYear() + '-' + (d.getMonth()+1) + '-' + d.getDate() + '"]<br>';
pgn += '[White "' + (mycolor=='w'?'Myself':opponent) + '"]<br>';
pgn += '[Black "' + (mycolor=='b'?'Myself':opponent) + '"]<br>';