// - a "bishop" is a chameleon, capturing as its prey
// - a "queen" is a withdrawer, capturing by moving away from pieces
- getPotentialMovesFrom([x,y])
+ // Is piece on square (x,y) immobilized?
+ isImmobilized([x,y])
{
- // Pre-check: is thing on this square immobilized?
+ // Final check: is this knight immobilized?
+ let foundImmobilizer = false;
+ let neutralized = false;
+ outerLoop:
+ for (let step of steps)
+ {
+ const [i2,j2] = [i+step[0],j+step[1]];
+ if (i2>=0 && i2<sizeX && j2>=0 && j2<sizeY
+ && this.board[i2][j2] != V.EMPTY
+ && this.getColor(i2,j2) == oppCol
+ && this.getPiece(i2,j2) == V.IMMOBILIZER)
+ {
+ foundImmobilizer = true;
+ // Moving is possible only if this immobilizer is neutralized
+ for (let step2 of steps)
+ {
+ const [i3,j3] = [i2+step2[0],j2+step2[1]];
+ if (i3>=0 && i3<sizeX && j3>=0 && j3<sizeY
+ && this.board[i3][j3] != V.EMPTY && this.getColor(i3,j3) == color
+ && [V.BISHOP,V.IMMOBILIZER].includes(this.getPiece(i3,j3)))
+ {
+ neutralized = true;
+ break outerLoop;
+ }
+ }
+ }
+ }
+ if (!foundImmobilizer || neutralized)
+ return false;
+
const piece = this.getPiece(x,y);
const color = this.getColor(x,y);
const oppCol = this.getOppCol(color);
}
}
}
+ }
+
+ getPotentialMovesFrom([x,y])
+ {
+ // Pre-check: is thing on this square immobilized?
+ if (this.isImmobilized([x,y]))
+ return [];
switch (this.getPiece(x,y))
{
case VariantRules.IMMOBILIZER:
{
let moves = super.getPotentialQueenMoves([x,y])
.concat(this.getKnightCaptures([x,y],"asChameleon"));
+ // No "king capture" because king cannot remain under check
this.addPawnCaptures(moves, "asChameleon");
this.addRookCaptures(moves, "asChameleon");
this.addQueenCaptures(moves, "asChameleon");
- // Add king capture if it's within range
- const oppKp = this.kingPos[this.getOppCol(this.turn)];
- if (Math.abs(x-oppKp[0]) <= 1 && Math.abs(y-oppKp[1]) <= 1)
- moves.push(this.getBasicMove([x,y],oppKp));
// Post-processing: merge similar moves, concatenating vanish arrays
let mergedMoves = {};
const [sizeX,sizeY] = VariantRules.size;
V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
}
- atLeastOneMove()
- {
- if (this.kingPos[this.turn][0] < 0)
- return false;
- return super.atLeastOneMove();
- }
+ // isAttacked() is OK because the immobilizer doesn't take
- underCheck(move)
+ // TODO: check if any pawn can reach capturing square + !immobilized
+ isAttackedByPawn([x,y], colors)
{
- return false; //there is no check
+ // Square (x,y) must be surrounded by two enemy pieces,
+ // and one of them at least should be a pawn.
+ const dirs = [ [1,0],[0,1],[1,1],[-1,1] ];
+ const [sizeX,sizeY] = VariantRules.size;
+ for (let dir of dirs)
+ {
+ const [i1,j1] = [x-dir[0],y-dir[1]]; //"before"
+ const [i2,j2] = [x+dir[0],y+dir[1]]; //"after"
+ if (i1>=0 && i1<sizeX && i2>=0 && i2<sizeX
+ && j1>=0 && j1<sizeY && j2>=0 && j2<sizeY
+ && this.board[i1][j1]!=VariantRules.EMPTY
+ && this.board[i2][j2]!=VariantRules.EMPTY
+ && colors.includes(this.getColor(i1,j1))
+ && colors.includes(this.getColor(i2,j2))
+ && [this.getPiece(i1,j1),this.getPiece(i2,j2)].includes(VariantRules.PAWN))
+ {
+ return true;
+ }
+ }
+ return false;
}
- getCheckSquares(move)
+ // TODO: check if enemy's rook can reach capturing squares + !immobilized
+ isAttackedByRook([x,y], colors)
{
- const c = this.getOppCol(this.turn); //opponent
- const saveKingPos = this.kingPos[c]; //king might be taken
- this.play(move);
- // The only way to be "under check" is to have lost the king (thus game over)
- let res = this.kingPos[c][0] < 0
- ? [ JSON.parse(JSON.stringify(saveKingPos)) ]
- : [ ];
- this.undo(move);
- return res;
+ const [sizeX,sizeY] = VariantRules.size;
+ // King must be on same column and a rook on same row (or reverse)
+ if (x == this.kingPos[colors[0]][0]) //using colors[0], only element in this case
+ {
+ // Look for enemy rook on this column
+ for (let i=0; i<sizeY; i++)
+ {
+ if (this.board[x][i] != VariantRules.EMPTY
+ && colors.includes(this.getColor(x,i))
+ && this.getPiece(x,i) == VariantRules.ROOK)
+ {
+ return true;
+ }
+ }
+ }
+ else if (y == this.kingPos[colors[0]][1])
+ {
+ // Look for enemy rook on this row
+ for (let i=0; i<sizeX; i++)
+ {
+ if (this.board[i][y] != VariantRules.EMPTY
+ && colors.includes(this.getColor(i,y))
+ && this.getPiece(i,y) == VariantRules.ROOK)
+ {
+ return true;
+ }
+ }
+ }
+ return false;
}
- updateVariables(move)
+ isAttackedByKnight([x,y], colors)
{
- // Just update king(s) position(s)
- const piece = this.getPiece(move.start.x,move.start.y);
- const c = this.getColor(move.start.x,move.start.y);
- if (piece == VariantRules.KING && move.appear.length > 0)
+ // Square (x,y) must be on same line as a knight,
+ // and there must be empty square(s) behind.
+ const V = VariantRules;
+ const steps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
+ const [sizeX,sizeY] = V.size;
+ outerLoop:
+ for (let step of steps)
{
- this.kingPos[c][0] = move.appear[0].x;
- this.kingPos[c][1] = move.appear[0].y;
+ const [i0,j0] = [x+step[0],y+step[1]];
+ if (i0>=0 && i0<sizeX && j0>=0 && j0<sizeY && this.board[i0][j0] == V.EMPTY)
+ {
+ // Try in opposite direction:
+ let [i,j] = [x-step[0],y-step[1]];
+ while (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j] == V.EMPTY)
+ {
+ i -= step[0];
+ j -= step[1];
+ }
+ if (i>=0 && i<sizeX && j>=0 && j<sizeY && colors.includes(this.getColor(i,j))
+ && this.getPiece(i,j) == V.KNIGHT)
+ {
+ if (!this.isImmobilized([i,j]))
+ return true;
+ }
+ }
}
- // Does this move takes opponent's king?
- const oppCol = this.getOppCol(c);
- for (let i=1; i<move.vanish.length; i++)
+ return false;
+ }
+
+ isAttackedByBishop([x,y], colors)
+ {
+ // We cheat a little here: since this function is used exclusively for king,
+ // it's enough to check the immediate surrounding of the square.
+ const V = VariantRules;
+ const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
+ const [sizeX,sizeY] = V.size;
+ for (let step of adjacentSteps)
{
- if (move.vanish[i].p == VariantRules.KING)
+ const [i,j] = [x+step[0],y+step[1]];
+ if (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j]!=V.EMPTY
+ && colors.includes(this.getColor(i,j)) && this.getPiece(i,j) == V.BISHOP)
{
- this.kingPos[oppCol] = [-1,-1];
- break;
+ return true; //bishops are never immobilized
}
}
+ return false;
}
- unupdateVariables(move)
+ isAttackedByQueen([x,y], colors)
{
- super.unupdateVariables(move);
- const c = this.getColor(move.start.x,move.start.y);
- const oppCol = this.getOppCol(c);
- if (this.kingPos[oppCol][0] < 0)
+ // Square (x,y) must be adjacent to a queen, and the queen must have
+ // some free space in the opposite direction from (x,y)
+ const V = VariantRules;
+ const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
+ const [sizeX,sizeY] = V.size;
+ for (let step of adjacentSteps)
{
- // Last move took opponent's king
- for (let i=1; i<move.vanish.length; i++)
+ const sq2 = [x+2*step[0],y+2*step[1]];
+ if (sq2[0]>=0 && sq2[0]<sizeX && sq2[1]>=0 && sq2[1]<sizeY
+ && this.board[sq2[0]][sq2[1]] == V.EMPTY)
{
- const psq = move.vanish[i];
- if (psq.p == 'k')
+ const sq1 = [x+step[0],y+step[1]];
+ if (this.board[sq1[0]][sq1[1]] != V.EMPTY
+ && colors.includes(this.getColor(sq1[0],sq1[1]))
+ && this.getPiece(sq1[0],sq1[1]) == V.QUEEN
+ && !this.isImmobilized(sq1))
{
- this.kingPos[oppCol] = [psq.x, psq.y];
- break;
+ return true;
}
}
}
+ return false;
}
- checkGameEnd()
+ updateVariables(move)
{
- // Stalemate, or our king disappeared
- return this.turn == "w" ? "0-1" : "1-0";
+ // Just update king(s) position(s)
+ const piece = this.getPiece(move.start.x,move.start.y);
+ const c = this.getColor(move.start.x,move.start.y);
+ if (piece == VariantRules.KING && move.appear.length > 0)
+ {
+ this.kingPos[c][0] = move.appear[0].x;
+ this.kingPos[c][1] = move.appear[0].y;
+ }
}
static get VALUES() { //TODO: totally experimental!
static get SEARCH_DEPTH() { return 2; } //TODO?
- static get THRESHOLD_MATE() {
- return 500; //checkmates evals may be slightly below 1000
- }
-
static GenRandInitFen()
{
let pieces = { "w": new Array(8), "b": new Array(8) };
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