return board;
}
- // Overridable: flags can change a lot
+ // Extract (relevant) flags from fen
setFlags(fen)
{
// white a-castle, h-castle, black a-castle, h-castle
///////////////////
// GETTERS, SETTERS
- // Simple useful getters
static get size() { return [8,8]; }
// Two next functions return 'undefined' if called on empty square
getColor(i,j) { return this.board[i][j].charAt(0); }
return undefined; //default
}
- // can thing on square1 take thing on square2
+ // Can thing on square1 take thing on square2
canTake([x1,y1], [x2,y2])
{
return this.getColor(x1,y1) != this.getColor(x2,y2);
{
let i = x + step[0];
let j = y + step[1];
- while (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j] == VariantRules.EMPTY)
+ while (i>=0 && i<sizeX && j>=0 && j<sizeY
+ && this.board[i][j] == VariantRules.EMPTY)
{
moves.push(this.getBasicMove([x,y], [i,j]));
if (oneStep !== undefined)
i += step[0];
j += step[1];
}
- if (i>=0 && i<8 && j>=0 && j<8 && this.canTake([x,y], [i,j]))
+ if (i>=0 && i<sizeX && j>=0 && j<sizeY && this.canTake([x,y], [i,j]))
moves.push(this.getBasicMove([x,y], [i,j]));
}
return moves;
}
- // What are the pawn moves from square x,y considering color "color" ?
+ // What are the pawn moves from square x,y ?
getPotentialPawnMoves([x,y])
{
const color = this.turn;
let moves = [];
const V = VariantRules;
- const [sizeX,sizeY] = VariantRules.size;
+ const [sizeX,sizeY] = V.size;
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);
+ const firstRank = (color == 'w' ? sizeX-1 : 0);
+ const startRank = (color == "w" ? sizeX-2 : 1);
+ const lastRank = (color == "w" ? 0 : sizeX-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]));
- // Next condition because variants with pawns on 1st rank generally allow them to jump
+ // Next condition because variants with pawns on 1st rank allow them to jump
if ([startRank,firstRank].includes(x) && this.board[x+2*shift][y] == V.EMPTY)
{
// Two squares jump
}
}
// Captures
- if (y>0 && this.canTake([x,y], [x+shift,y-1]) && this.board[x+shift][y-1] != V.EMPTY)
+ if (y>0 && this.canTake([x,y], [x+shift,y-1])
+ && this.board[x+shift][y-1] != V.EMPTY)
+ {
moves.push(this.getBasicMove([x,y], [x+shift,y-1]));
- if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1]) && this.board[x+shift][y+1] != V.EMPTY)
+ }
+ if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1])
+ && this.board[x+shift][y+1] != V.EMPTY)
+ {
moves.push(this.getBasicMove([x,y], [x+shift,y+1]));
+ }
}
if (x+shift == lastRank)
if (this.board[x+shift][y] == V.EMPTY)
moves.push(this.getBasicMove([x,y], [x+shift,y], {c:color,p:p}));
// Captures
- if (y>0 && this.canTake([x,y], [x+shift,y-1]) && this.board[x+shift][y-1] != V.EMPTY)
+ if (y>0 && this.canTake([x,y], [x+shift,y-1])
+ && this.board[x+shift][y-1] != V.EMPTY)
+ {
moves.push(this.getBasicMove([x,y], [x+shift,y-1], {c:color,p:p}));
- if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1]) && this.board[x+shift][y+1] != V.EMPTY)
+ }
+ if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1])
+ && this.board[x+shift][y+1] != V.EMPTY)
+ {
moves.push(this.getBasicMove([x,y], [x+shift,y+1], {c:color,p:p}));
+ }
});
}
let step = finalSquares[castleSide][0] < y ? -1 : 1;
for (i=y; i!=finalSquares[castleSide][0]; i+=step)
{
- if (this.isAttacked([x,i], oppCol) || (this.board[x][i] != V.EMPTY &&
+ if (this.isAttacked([x,i], [oppCol]) || (this.board[x][i] != V.EMPTY &&
// NOTE: next check is enough, because of chessboard constraints
(this.getColor(x,i) != c || ![V.KING,V.ROOK].includes(this.getPiece(x,i)))))
{
const oppCol = this.getOppCol(color);
let potentialMoves = [];
const [sizeX,sizeY] = VariantRules.size;
- for (var i=0; i<sizeX; i++)
+ for (let i=0; i<sizeX; i++)
{
- for (var j=0; j<sizeY; j++)
+ for (let j=0; j<sizeY; j++)
{
// Next condition ... != oppCol is a little HACK to work with checkered variant
if (this.board[i][j] != VariantRules.EMPTY && this.getColor(i,j) != oppCol)
return false;
}
- // Check if pieces of color 'colors' are attacking square x,y
+ // Check if pieces of color in array 'colors' are attacking square x,y
isAttacked(sq, colors)
{
return (this.isAttackedByPawn(sq, colors)
|| this.isAttackedByKing(sq, colors));
}
- // Is square x,y attacked by pawns of color c ?
+ // Is square x,y attacked by 'colors' pawns ?
isAttackedByPawn([x,y], colors)
{
+ const [sizeX,sizeY] = VariantRules.size;
for (let c of colors)
{
let pawnShift = (c=="w" ? 1 : -1);
- if (x+pawnShift>=0 && x+pawnShift<8)
+ if (x+pawnShift>=0 && x+pawnShift<sizeX)
{
for (let i of [-1,1])
{
- if (y+i>=0 && y+i<8 && this.getPiece(x+pawnShift,y+i)==VariantRules.PAWN
+ if (y+i>=0 && y+i<sizeY && this.getPiece(x+pawnShift,y+i)==VariantRules.PAWN
&& this.getColor(x+pawnShift,y+i)==c)
{
return true;
return false;
}
- // Is square x,y attacked by rooks of color c ?
+ // Is square x,y attacked by 'colors' rooks ?
isAttackedByRook(sq, colors)
{
return this.isAttackedBySlideNJump(sq, colors,
VariantRules.ROOK, VariantRules.steps[VariantRules.ROOK]);
}
- // Is square x,y attacked by knights of color c ?
+ // Is square x,y attacked by 'colors' knights ?
isAttackedByKnight(sq, colors)
{
return this.isAttackedBySlideNJump(sq, colors,
VariantRules.KNIGHT, VariantRules.steps[VariantRules.KNIGHT], "oneStep");
}
- // Is square x,y attacked by bishops of color c ?
+ // Is square x,y attacked by 'colors' bishops ?
isAttackedByBishop(sq, colors)
{
return this.isAttackedBySlideNJump(sq, colors,
VariantRules.BISHOP, VariantRules.steps[VariantRules.BISHOP]);
}
- // Is square x,y attacked by queens of color c ?
+ // Is square x,y attacked by 'colors' queens ?
isAttackedByQueen(sq, colors)
{
const V = VariantRules;
V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
}
- // Is square x,y attacked by king of color c ?
+ // Is square x,y attacked by 'colors' king(s) ?
isAttackedByKing(sq, colors)
{
const V = VariantRules;
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 ?
+ // Generic method for non-pawn pieces ("sliding or jumping"):
+ // is x,y attacked by a piece of color in array 'colors' ?
isAttackedBySlideNJump([x,y], colors, piece, steps, oneStep)
{
+ const [sizeX,sizeY] = VariantRules.size;
for (let step of steps)
{
let rx = x+step[0], ry = y+step[1];
- while (rx>=0 && rx<8 && ry>=0 && ry<8 && this.board[rx][ry] == VariantRules.EMPTY
- && !oneStep)
+ while (rx>=0 && rx<sizeX && ry>=0 && ry<sizeY
+ && this.board[rx][ry] == VariantRules.EMPTY && !oneStep)
{
rx += step[0];
ry += step[1];
}
- if (rx>=0 && rx<8 && ry>=0 && ry<8 && this.board[rx][ry] != VariantRules.EMPTY
+ if (rx>=0 && rx<sizeX && ry>=0 && ry<sizeY
+ && this.board[rx][ry] != VariantRules.EMPTY
&& this.getPiece(rx,ry) == piece && colors.includes(this.getColor(rx,ry)))
{
return true;
return false;
}
- // Is color c under check after move ?
+ // Is current player under check after his move ?
underCheck(move)
{
const color = this.turn;
this.play(move);
- let res = this.isAttacked(this.kingPos[color], this.getOppCol(color));
+ let res = this.isAttacked(this.kingPos[color], [this.getOppCol(color)]);
this.undo(move);
return res;
}
- // On which squares is color c under check (after move) ?
+ // On which squares is opponent under check after our move ?
getCheckSquares(move)
{
this.play(move);
const color = this.turn; //opponent
- let res = this.isAttacked(this.kingPos[color], this.getOppCol(color))
+ let res = this.isAttacked(this.kingPos[color], [this.getOppCol(color)])
? [ JSON.parse(JSON.stringify(this.kingPos[color])) ] //need to duplicate!
: [ ];
this.undo(move);
}
}
+ // After move is undo-ed, un-update variables (flags are reset)
+ // TODO: more symmetry, by storing flags increment in move...
unupdateVariables(move)
{
// (Potentially) Reset king position
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);
+ move.notation = [this.getNotation(move), this.getLongNotation(move)];
move.flags = JSON.stringify(this.flags); //save flags (for undo)
this.updateVariables(move);
this.moves.pop();
this.unupdateVariables(move);
this.parseFlags(JSON.parse(move.flags));
-
- // DEBUG:
-// let state = this.states.pop();
-// if (JSON.stringify(this.board) != state)
-// debugger;
}
//////////////
// END OF GAME
+ // Basic check for 3 repetitions (in the last moves only)
checkRepetition()
{
- // Check for 3 repetitions
if (this.moves.length >= 8)
{
- // NOTE: crude detection, only moves repetition
const L = this.moves.length;
if (_.isEqual(this.moves[L-1], this.moves[L-5]) &&
_.isEqual(this.moves[L-2], this.moves[L-6]) &&
return false;
}
+ // Is game over ? And if yes, what is the score ?
checkGameOver()
{
if (this.checkRepetition())
{
const color = this.turn;
// No valid move: stalemate or checkmate?
- if (!this.isAttacked(this.kingPos[color], this.getOppCol(color)))
+ if (!this.isAttacked(this.kingPos[color], [this.getOppCol(color)]))
return "1/2";
// OK, checkmate
return color == "w" ? "0-1" : "1-0";
return VariantRules.INFINITY;
}
+ static get SEARCH_DEPTH() {
+ return 3; //2 for high branching factor, 4 for small (Loser chess)
+ }
+
// Assumption: at least one legal move
- getComputerMove(moves1) //moves1 might be precomputed (Magnetic chess)
+ // NOTE: works also for extinction chess because depth is 3...
+ getComputerMove()
{
+ this.shouldReturn = false;
const maxeval = VariantRules.INFINITY;
const color = this.turn;
- if (!moves1)
- moves1 = this.getAllValidMoves();
+ let moves1 = this.getAllValidMoves();
+
+ // Can I mate in 1 ? (for Magnetic & Extinction)
+ for (let i of _.shuffle(_.range(moves1.length)))
+ {
+ this.play(moves1[i]);
+ const finish = (Math.abs(this.evalPosition()) >= VariantRules.THRESHOLD_MATE);
+ this.undo(moves1[i]);
+ if (finish)
+ return moves1[i];
+ }
// Rank moves using a min-max at depth 2
for (let i=0; i<moves1.length; i++)
}
moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
- // Skip depth 3 if we found a checkmate (or if we are checkmated in 1...)
- if (Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
+ let candidates = [0]; //indices of candidates moves
+ for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
+ candidates.push(j);
+ let currentBest = moves1[_.sample(candidates, 1)];
+
+ // Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...)
+ if (VariantRules.SEARCH_DEPTH >= 3
+ && Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
{
- // TODO: show current analyzed move for depth 3, allow stopping eval (return moves1[0])
for (let i=0; i<moves1.length; i++)
{
+ if (this.shouldReturn)
+ return currentBest; //depth-2, minimum
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);
+ moves1[i].eval = 0.1*moves1[i].eval +
+ this.alphabeta(VariantRules.SEARCH_DEPTH-1, -maxeval, maxeval);
this.undo(moves1[i]);
}
moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
}
+ else
+ return currentBest;
- let candidates = [0]; //indices of candidates moves
+ candidates = [0];
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]; }));
return moves1[_.sample(candidates, 1)];
}
+ // TODO: some optimisations, understand why CH get mated in 2
alphabeta(depth, alpha, beta)
{
const maxeval = VariantRules.INFINITY;
{
const [sizeX,sizeY] = VariantRules.size;
let evaluation = 0;
- //Just count material for now
+ // Just count material for now
for (let i=0; i<sizeX; i++)
{
for (let j=0; j<sizeY; j++)
////////////
// FEN utils
- // Overridable..
+ // Setup the initial random (assymetric) position
static GenRandInitFen()
{
let pieces = [new Array(8), new Array(8)];
return this.getBaseFen() + " " + this.getFlagsFen();
}
+ // Position part of the FEN string
getBaseFen()
{
let fen = "";
return fen;
}
- // Overridable..
+ // Flags part of the FEN string
getFlagsFen()
{
let fen = "";
}
}
+ // Complete the usual notation, may be required for de-ambiguification
+ getLongNotation(move)
+ {
+ const startSquare =
+ String.fromCharCode(97 + move.start.y) + (VariantRules.size[0]-move.start.x);
+ const finalSquare =
+ String.fromCharCode(97 + move.end.y) + (VariantRules.size[0]-move.end.x);
+ return startSquare + finalSquare; //not encoding move. But short+long is enough
+ }
+
// The score is already computed when calling this function
getPGN(mycolor, score, fenStart, mode)
{
pgn += '[Fen "' + fenStart + '"]<br>';
pgn += '[Result "' + score + '"]<br><br>';
+ // Standard PGN
for (let i=0; i<this.moves.length; i++)
{
if (i % 2 == 0)
pgn += ((i/2)+1) + ".";
- pgn += this.moves[i].notation + " ";
+ pgn += this.moves[i].notation[0] + " ";
}
+ pgn += score + "<br><br>";
+ // "Complete moves" PGN (helping in ambiguous cases)
+ for (let i=0; i<this.moves.length; i++)
+ {
+ if (i % 2 == 0)
+ pgn += ((i/2)+1) + ".";
+ pgn += this.moves[i].notation[1] + " ";
+ }
pgn += score;
+
return pgn;
}
}
projects / vchess.git / blobdiff