'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] ]
};
}
// 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 (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 ?
{
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)
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))
{
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);
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;
}
//////////////
};
}
+ static get INFINITY() {
+ return 9999; //"checkmate" (unreachable eval)
+ }
+
+ static get THRESHOLD_MATE() {
+ // At this value or above, the game is over
+ 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()
+ getComputerMove(moves1) //moves1 might be precomputed (Magnetic chess)
{
+ this.shouldReturn = false;
+ 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++)
+ 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)
{
- 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++)
+ {
+ 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(VariantRules.SEARCH_DEPTH-1, -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); });
+ 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]; }));
+// 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++)
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>';
projects / vchess.git / blobdiff