+class BerolinaRules extends ChessRules
+{
+ // En-passant after 2-sq jump
+ getEpSquare(moveOrSquare)
+ {
+ if (!moveOrSquare)
+ return undefined;
+ if (typeof moveOrSquare === "string")
+ {
+ const square = moveOrSquare;
+ if (square == "-")
+ return undefined;
+ return V.SquareToCoords(square);
+ }
+ // Argument is a move:
+ const move = moveOrSquare;
+ const [sx,ex,sy] = [move.start.x,move.end.x,move.start.y];
+ if (this.getPiece(sx,sy) == V.PAWN && Math.abs(sx - ex) == 2)
+ {
+ return {
+ x: ex,
+ y: (move.end.y + sy)/2
+ };
+ }
+ return undefined; //default
+ }
+
+ // Special pawn rules: promotions to captured friendly pieces,
+ // optional on ranks 8-9 and mandatory on rank 10.
+ getPotentialPawnMoves([x,y])
+ {
+ const color = this.turn;
+ let moves = [];
+ const [sizeX,sizeY] = [V.size.x,V.size.y];
+ const shiftX = (color == "w" ? -1 : 1);
+ const firstRank = (color == 'w' ? sizeX-1 : 0);
+ const startRank = (color == "w" ? sizeX-2 : 1);
+ const lastRank = (color == "w" ? 0 : sizeX-1);
+
+ if (x+shiftX >= 0 && x+shiftX < sizeX) //TODO: always true
+ {
+ const finalPieces = x + shiftX == lastRank
+ ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]
+ : [V.PAWN]
+ // One square diagonally
+ for (let shiftY of [-1,1])
+ {
+ if (this.board[x+shiftX][y+shiftY] == V.EMPTY)
+ {
+ for (let piece of finalPieces)
+ {
+ moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
+ {c:pawnColor,p:piece}));
+ }
+ if (x == startRank && this.board[x+2*shiftX][y] == V.EMPTY)
+ {
+ // Two squares jump
+ moves.push(this.getBasicMove([x,y], [x+2*shiftX,y+2*shiftY]);
+ }
+ }
+ }
+ // Capture
+ if (this.board[x+shiftX][y] != V.EMPTY
+ && this.canTake([x,y], [x+shiftX,y]))
+ {
+ for (let piece of finalPieces)
+ {
+ moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
+ {c:pawnColor,p:piece}));
+ }
+ }
+ }
+
+ // En passant
+ const Lep = this.epSquares.length;
+ const epSquare = this.epSquares[Lep-1]; //always at least one element
+ if (!!epSquare && epSquare.x == x+shiftX && epSquare.y == y)
+ {
+ let enpassantMove = this.getBasicMove([x,y], [x+shift,y]);
+ enpassantMove.vanish.push({
+ x: epSquare.x,
+ y: y,
+ p: 'p',
+ c: this.getColor(epSquare.x,y)
+ });
+ moves.push(enpassantMove);
+ }
+
+ return moves;
+ }
+}
+
+const VariantRules = BerolinaRules;
projects / vchess.git / commitdiff