}
filterValid(moves) {
+ // Sub-function to check a path (between kings)
+ const scanPath = (start, end, justOne) => {
+ let s = [end[0] - start[0], end[1] - start[1]];
+ for (const i in [0, 1]) {
+ if (s[i] != 0)
+ s[i] = s[i] / Math.abs(s[i]);
+ }
+ let onPath = {};
+ let [i, j] = [start[0] + s[0], start[1] + s[1]];
+ while (i != end[0] || j != end[1]) {
+ if (this.board[i][j] != "") {
+ onPath[i + "." + j] = true;
+ if (justOne)
+ return true;
+ }
+ [i, j] = [i + s[0], j + s[1]];
+ }
+ return (justOne ? false : onPath);
+ };
const kp = {
'w': super.searchKingPos('w')[0],
'b': super.searchKingPos('b')[0]
// Filter out moves letting kings facing each other
if (
!pf &&
- [m.start, m.end].every(xy => {
- return ['w','b'].every(c => xy.x != kp[c][0] || xy.y != kp[c][1]);
- })
+ ['w','b'].every(c => m.start.x != kp[c][0] || m.start.y != kp[c][1])
) {
- // King don't face each other and don't move
+ // Kings don't face each other and don't move
return true;
}
if (pf) {
// Check that current move doesn't clear the path between kings
- // TODO: apply vanish / appear on the path (horizontal or vertical)
- return true;
+ const onPath = scanPath(kp['b'], kp['w']);
+ m.vanish.forEach(v => {
+ const key = v.x + "." + v.y;
+ if (onPath[key])
+ onPath[key] = false;
+ });
+ if (Object.values(onPath).some(z => z))
+ return true;
+ for (const a of m.appear) {
+ const key = a.x + "." + a.y;
+ if (Object.keys(onPath).includes(key))
+ return true;
+ }
+ return false;
}
- // Situation: a king moves. Does it lead to a forbidden configuration ?
- // TODO: check alignment, then check path (same as above).
- return true;
+ // A king moves. Does it lead to a forbidden configuration ?
+ const kc =
+ ['w','b'].filter(c => m.start.x == kp[c][0] && m.start.y == kp[c][1]);
+ const oppCol = C.GetOppTurn(kc);
+ if (kp[oppCol][0] != m.end.x && kp[oppCol][1] != m.end.y)
+ return true;
+ // Potentially yes:
+ this.playOnBoard(m);
+ const valid = scanPath(kp[oppCol], [m.end.x, m.end.y], true);
+ this.undoOnBoard(m);
+ return valid;
});
}
--- /dev/null
+<html>
+<head>
+ <title>Empire Rules</title>
+ <link href="/css/common.css" rel="stylesheet"/>
+ <link href="/variants/Empire/style.css" rel="stylesheet"/>
+</head>
+<body>
+<div class="full-rules">
+<h1>Empire Rules</h1>
+
+<div>
+ <p>
+ The player in first has a different set of pieces,
+ moving generally like a queen but capturing (almost) as usual.
+ </p>
+ <figure>
+ <img src="/extras/Empire/Board.png"/>
+ <figcaption>Initial deterministic setup.</figcaption>
+ </figure>
+ <p>
+ Empire Chess is a chess variant designed in 2020 by Couch Tomato, the
+ third asymmetric game. This game pits the army of the "Empire" (gold)
+ against the original chess army (the "Kingdom", black). The Empire's
+ unique feature is that its pieces move like queens but attack differently.
+ </p>
+</div>
+
+<h3>General Rules</h3>
+<ol>
+ <li>The Empire (gold) always moves first.</li>
+ <li>The Empire cannot castle.</li>
+ <li>
+ As the Empire's pawns start on the third rank, they do not have the
+ option to move two spaces or be captured by en passant.
+ </li>
+ <li>Pawns on either side can only promote to a queen.</li>
+ <li>
+ One can win by bringing the king into the final rank without being
+ check. This situation is called "campmate".
+ </li>
+ <li>Stalemate and repetition are both losses.</li>
+ <li>
+ The King and Kaiser (Imperial King) may not face
+ each other on a file or rank.
+ </li>
+</ol>
+
+<h3>Imperial Pieces</h3>
+<div>
+ <p>
+ There are five new units unique to the Empire: Siege Towers, Eagles,
+ Cardinals, Duke, and Soldiers. The bottom rank pieces are all stronger
+ than their Kingdom counterparts with the exception of the Duke.
+ </p>
+ <ul>
+ <li>
+ Kaiser (K) — The Imperial king is called the Kaiser and has a
+ different symbol, but the change is purely aesthetic and thematic:
+ it behave like an orthodox king.
+ </li>
+ <li>
+ Soldier (S) — The Soldiers are the two pawn-like pieces replacing
+ the two middle pawns. They can move one square orthogonally forward,
+ or lateraly.
+ </li>
+ </ul>
+ <p>
+ The remaining pieces are "divergent" pieces: they move differently
+ than they attack (such as pawns). Imperial pieces all move as queens,
+ but attack like their Kingdom counterpart except for the Duke.
+ </p>
+ <ul>
+ <li>
+ Siege Tower (T) — The Siege Tower, or Tower for short,
+ attacks like a Rook.
+ </li>
+ <li>Eagle (E) — The Eagle attacks like a Knight.</li>
+ <li>Cardinal (C) — The Cardinal attacks like a Bishop.</li>
+ <li>Duke (D) — The Duke attacks like a King.</li>
+ </ul>
+ <figure>
+ <img src="/extras/Empire/EagleMoves.png"/>
+ <figcaption>Eagle's moves (green) & captures (red).</figcaption>
+ </figure>
+</div>
+
+<h3>Pieces valuation</h3>
+<div>
+ <p>The following simplified values can be used:</p>
+ <table>
+ <tr>
+ <th>Kingdom piece</th>
+ <th>Values</th>
+ <th>Imperial piece</th>
+ </tr>
+ <tr>
+ <td>Pawn</td>
+ <td>1 / 1</td>
+ <td>Pawn</td>
+ </tr>
+ <tr>
+ <td>Queen</td>
+ <td>9 / 4</td>
+ <td>Duke</td>
+ </tr>
+ <tr>
+ <td>Bishop</td>
+ <td>3 / 4</td>
+ <td>Cardinal</td>
+ </tr>
+ <tr>
+ <td>Knight</td>
+ <td>3 / 7</td>
+ <td>Eagle</td>
+ </tr>
+ <tr>
+ <td>Rook</td>
+ <td>5 / 7</td>
+ <td>Siege Tower</td>
+ </tr>
+ <tr>
+ <td> - </td>
+ <td> - / 2</td>
+ <td>Soldier</td>
+ </tr>
+ </table>
+</div>
+
+<h3>More information</h3>
+<p>
+ See
+ <a href="https://www.pychess.org/variants/empire">Empire Chess</a>
+ on pychess.org, where you can also play this variant (among many others !).
+</p>
-<p>TODO</p>
+<p>
+ Two different armies: yellow pieces ("kingdom") generally move and
+ capture in two different ways. Tower, Eagle, Cardinal and Duke, initially
+ from square a1 to d1, all move like a queen, but capture respectively
+ like a rook, knight, bishop and king.
+</p>
+<p>
+ The two "big pawns" in the middle are soldiers, they move and capture in
+ the same way, forward one square or laterally.
+</p>
+<p>Win by checkmate or by crossing the board with your king.</p>
+
+<p>
+ <a target="_blank" href="/variants/Empire/complete_rules.html">
+ Full rules description.
+ </a>
+</p>
+
+<p class="author">Couch Tomato (2020).</p>
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