variants/Chakart/class.js

   1 import ChessRules from "/base_rules.js";
   2 import GiveawayRules from "/variants/Giveaway/class.js";
   3 import { ArrayFun } from "/utils/array.js";
   4 import { Random } from "/utils/alea.js";
   5 import PiPo from "/utils/PiPo.js";
   6 import Move from "/utils/Move.js";
   7
   8 export default class ChakartRules extends ChessRules {
   9
  10   static get Options() {
  11     return {
  12       select: [
  13         {
  14           label: "Randomness",
  15           variable: "randomness",
  16           defaut: 2,
  17           options: [
  18             {label: "Deterministic", value: 0},
  19             {label: "Symmetric random", value: 1},
  20             {label: "Asymmetric random", value: 2}
  21           ]
  22         }
  23       ],
  24       styles: ["cylinder"]
  25     };
  26   }
  27
  28   get pawnPromotions() {
  29     return ['q', 'r', 'n', 'b', 'k'];
  30   }
  31
  32   get hasCastle() {
  33     return false;
  34   }
  35   get hasEnpassant() {
  36     return false;
  37   }
  38   get hasReserve() {
  39     return true;
  40   }
  41   get hasReserveFen() {
  42     return false;
  43   }
  44
  45   static get IMMOBILIZE_CODE() {
  46     return {
  47       'p': 's',
  48       'r': 'u',
  49       'n': 'o',
  50       'b': 'c',
  51       'q': 't',
  52       'k': 'l'
  53     };
  54   }
  55
  56   static get IMMOBILIZE_DECODE() {
  57     return {
  58       's': 'p',
  59       'u': 'r',
  60       'o': 'n',
  61       'c': 'b',
  62       't': 'q',
  63       'l': 'k'
  64     };
  65   }
  66
  67   // Fictive color 'a', bomb banana mushroom egg
  68   static get BOMB() {
  69     return 'w'; //"Wario"
  70   }
  71   static get BANANA() {
  72     return 'd'; //"Donkey"
  73   }
  74   static get EGG() {
  75     return 'e';
  76   }
  77   static get MUSHROOM() {
  78     return 'm';
  79   }
  80
  81   static get EGG_SURPRISE() {
  82     return [
  83       "kingboo", "bowser", "daisy", "koopa",
  84       "luigi", "waluigi", "toadette", "chomp"];
  85   }
  86
  87   canIplay(x, y) {
  88     if (
  89       this.playerColor != this.turn ||
  90       Object.keys(V.IMMOBILIZE_DECODE).includes(this.getPiece(x, y))
  91     ) {
  92       return false;
  93     }
  94     return this.egg == "kingboo" || this.getColor(x, y) == this.turn;
  95   }
  96
  97   pieces(color, x, y) {
  98     const specials = {
  99       'i': {"class": "invisible"}, //queen
 100       '?': {"class": "mystery"}, //...initial square
 101       'e': {"class": "egg"},
 102       'm': {"class": "mushroom"},
 103       'd': {"class": "banana"},
 104       'w': {"class": "bomb"},
 105       'z': {"class": "remote-capture"}
 106     };
 107     const bowsered = {
 108       's': {"class": ["immobilized", "pawn"]},
 109       'u': {"class": ["immobilized", "rook"]},
 110       'o': {"class": ["immobilized", "knight"]},
 111       'c': {"class": ["immobilized", "bishop"]},
 112       't': {"class": ["immobilized", "queen"]},
 113       'l': {"class": ["immobilized", "king"]}
 114     };
 115     return Object.assign(
 116       {
 117         'y': {
 118           // Virtual piece for "king remote shell captures"
 119           moves: [],
 120           attack: [
 121             {
 122               steps: [
 123                 [0, 1], [0, -1], [1, 0], [-1, 0],
 124                 [1, 1], [1, -1], [-1, 1], [-1, -1]
 125               ]
 126             }
 127           ]
 128         }
 129       },
 130       specials, bowsered, super.pieces(color, x, y));
 131   }
 132
 133   genRandInitFen(seed) {
 134     const options = Object.assign({mode: "suicide"}, this.options);
 135     const gr = new GiveawayRules({options: options, genFenOnly: true});
 136     const baseFen = gr.genRandInitFen(seed);
 137     const fenParts = baseFen.split(" ");
 138     let others = JSON.parse(fenParts[3]);
 139     delete others["enpassant"];
 140     others["flags"] = "1111"; //Peach + Mario flags
 141     return fenParts.slice(0, 3).join(" ") + " " + JSON.stringify(others);
 142   }
 143
 144   fen2board(f) {
 145     return (
 146       f.charCodeAt() <= 90
 147         ? "w" + f.toLowerCase()
 148         : (['w', 'd', 'e', 'm'].includes(f) ? "a" : "b") + f
 149     );
 150   }
 151
 152   setFlags(fenflags) {
 153     // King can send shell? Queen can be invisible?
 154     this.powerFlags = {
 155       w: {k: false, q: false},
 156       b: {k: false, q: false}
 157     };
 158     for (let c of ['w', 'b']) {
 159       for (let p of ['k', 'q']) {
 160         this.powerFlags[c][p] =
 161           fenflags.charAt((c == "w" ? 0 : 2) + (p == 'k' ? 0 : 1)) == "1";
 162       }
 163     }
 164   }
 165
 166   aggregateFlags() {
 167     return this.powerFlags;
 168   }
 169
 170   disaggregateFlags(flags) {
 171     this.powerFlags = flags;
 172   }
 173
 174   getFlagsFen() {
 175     return ['w', 'b'].map(c => {
 176       return ['k', 'q'].map(p => this.powerFlags[c][p] ? "1" : "0").join("");
 177     }).join("");
 178   }
 179
 180   setOtherVariables(fenParsed) {
 181     super.setOtherVariables(fenParsed);
 182     this.egg = null;
 183     // Change seed (after FEN generation!!)
 184     // so that further calls differ between players:
 185     Random.setSeed(Math.floor(19840 * Math.random()));
 186   }
 187
 188   initReserves() {
 189     this.reserve = {}; //to be filled later
 190   }
 191
 192   // For Toadette bonus
 193   getDropMovesFrom([c, p]) {
 194     if (typeof c != "string" || this.reserve[c][p] == 0)
 195       return [];
 196     let moves = [];
 197     const start = (c == 'w' && p == 'p' ? 1 : 0);
 198     const end = (c == 'b' && p == 'p' ? 7 : 8);
 199     for (let i = start; i < end; i++) {
 200       for (let j = 0; j < this.size.y; j++) {
 201         const pieceIJ = this.getPiece(i, j);
 202         const colIJ = this.getColor(i, j);
 203         if (this.board[i][j] == "" || colIJ == 'a' || pieceIJ == 'i') {
 204           let m = new Move({
 205             start: {x: c, y: p},
 206             appear: [new PiPo({x: i, y: j, c: c, p: p})],
 207             vanish: []
 208           });
 209           // A drop move may remove a bonus (or hidden queen!)
 210           if (this.board[i][j] != "")
 211             m.vanish.push(new PiPo({x: i, y: j, c: colIJ, p: pieceIJ}));
 212           moves.push(m);
 213         }
 214       }
 215     }
 216     return moves;
 217   }
 218
 219   getPotentialMovesFrom([x, y]) {
 220     let moves = [];
 221     const piece = this.getPiece(x, y);
 222     if (this.egg == "toadette")
 223       moves = this.getDropMovesFrom([x, y]);
 224     else if (this.egg == "kingboo") {
 225       const color = this.turn;
 226       const oppCol = C.GetOppCol(color);
 227       // Only allow to swap (non-immobilized!) pieces
 228       for (let i=0; i<this.size.x; i++) {
 229         for (let j=0; j<this.size.y; j++) {
 230           const colIJ = this.getColor(i, j);
 231           const pieceIJ = this.getPiece(i, j);
 232           if (
 233             (i != x || j != y) &&
 234             ['w', 'b'].includes(colIJ) &&
 235             !Object.keys(V.IMMOBILIZE_DECODE).includes(pieceIJ) &&
 236             // Next conditions = no pawn on last rank
 237             (
 238               piece != 'p' ||
 239               (
 240                 (color != 'w' || i != 0) &&
 241                 (color != 'b' || i != this.size.x - 1)
 242               )
 243             )
 244             &&
 245             (
 246               pieceIJ != 'p' ||
 247               (
 248                 (colIJ != 'w' || x != 0) &&
 249                 (colIJ != 'b' || x != this.size.x - 1)
 250               )
 251             )
 252           ) {
 253             let m = this.getBasicMove([x, y], [i, j]);
 254             m.appear.push(new PiPo({x: x, y: y, p: pieceIJ, c: colIJ}));
 255             m.kingboo = true; //avoid some side effects (bananas/bombs)
 256             moves.push(m);
 257           }
 258         }
 259       }
 260     }
 261     else {
 262       // Normal case (including bonus daisy)
 263       switch (piece) {
 264         case 'p':
 265           moves = this.getPawnMovesFrom([x, y]); //apply promotions
 266           break;
 267         case 'q':
 268           moves = this.getQueenMovesFrom([x, y]);
 269           break;
 270         case 'k':
 271           moves = this.getKingMovesFrom([x, y]);
 272           break;
 273         case 'n':
 274           moves = this.getKnightMovesFrom([x, y]);
 275           break;
 276         case 'b':
 277         case 'r':
 278           // Explicitely listing types to avoid moving immobilized piece
 279           moves = this.getPotentialMovesOf(piece, [x, y]);
 280           break;
 281       }
 282     }
 283     return moves;
 284   }
 285
 286   canStepOver(i, j) {
 287     return (
 288       this.board[i][j] == "" ||
 289       ['i', V.EGG, V.MUSHROOM].includes(this.getPiece(i, j))
 290     );
 291   }
 292
 293   getPawnMovesFrom([x, y]) {
 294     const color = this.turn;
 295     const oppCol = C.GetOppCol(color);
 296     const shiftX = (color == 'w' ? -1 : 1);
 297     const firstRank = (color == "w" ? this.size.x - 1 : 0);
 298     let moves = [];
 299     const frontPiece = this.getPiece(x + shiftX, y);
 300     if (
 301       this.board[x + shiftX][y] == "" ||
 302       this.getColor(x + shiftX, y) == 'a' ||
 303       frontPiece == 'i'
 304     ) {
 305       moves.push(this.getBasicMove([x, y], [x + shiftX, y]));
 306       if (
 307         [firstRank, firstRank + shiftX].includes(x) &&
 308         ![V.BANANA, V.BOMB].includes(frontPiece) &&
 309         (
 310           this.board[x + 2 * shiftX][y] == "" ||
 311           this.getColor(x + 2 * shiftX, y) == 'a' ||
 312           this.getPiece(x + 2 * shiftX, y) == 'i'
 313         )
 314       ) {
 315         moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
 316       }
 317     }
 318     for (let shiftY of [-1, 1]) {
 319       const nextY = this.getY(y + shiftY);
 320       if (
 321         nextY >= 0 &&
 322         nextY < this.size.y &&
 323         this.board[x + shiftX][nextY] != "" &&
 324         // Pawns cannot capture invisible queen this way!
 325         this.getPiece(x + shiftX, nextY) != 'i' &&
 326         ['a', oppCol].includes(this.getColor(x + shiftX, nextY))
 327       ) {
 328         moves.push(this.getBasicMove([x, y], [x + shiftX, nextY]));
 329       }
 330     }
 331     this.pawnPostProcess(moves, color, oppCol);
 332     // Add mushroom on before-last square (+ potential segments)
 333     moves.forEach(m => {
 334       let [mx, my] = [x, y];
 335       if (Math.abs(m.end.x - m.start.x) == 2)
 336         mx = (m.start.x + m.end.x) / 2;
 337       m.appear.push(new PiPo({x: mx, y: my, c: 'a', p: 'm'}));
 338       if (mx != x && this.board[mx][my] != "") {
 339         m.vanish.push(new PiPo({
 340           x: mx,
 341           y: my,
 342           c: this.getColor(mx, my),
 343           p: this.getPiece(mx, my)
 344         }));
 345       }
 346       if (Math.abs(m.end.y - m.start.y) > 1) {
 347         m.segments = [
 348           [[x, y], [x, y]],
 349           [[m.end.x, m.end.y], [m.end.x, m.end.y]]
 350         ];
 351       }
 352     });
 353     return moves;
 354   }
 355
 356   getKnightMovesFrom([x, y]) {
 357     // Add egg on initial square:
 358     return this.getPotentialMovesOf('n', [x, y]).map(m => {
 359       m.appear.push(new PiPo({p: "e", c: "a", x: x, y: y}));
 360       return m;
 361     });
 362   }
 363
 364   getQueenMovesFrom(sq) {
 365     const normalMoves = this.getPotentialMovesOf('q', sq);
 366     // If flag allows it, add 'invisible movements'
 367     let invisibleMoves = [];
 368     if (this.powerFlags[this.turn]['q']) {
 369       normalMoves.forEach(m => {
 370         if (
 371           m.appear.length == 1 &&
 372           m.vanish.length == 1 &&
 373           // Only simple non-capturing moves:
 374           m.vanish[0].c != 'a'
 375         ) {
 376           let im = JSON.parse(JSON.stringify(m));
 377           im.appear[0].p = 'i';
 378           im.noAnimate = true;
 379           invisibleMoves.push(im);
 380         }
 381       });
 382     }
 383     return normalMoves.concat(invisibleMoves);
 384   }
 385
 386   getKingMovesFrom([x, y]) {
 387     let moves = this.getPotentialMovesOf('k', [x, y]);
 388     // If flag allows it, add 'remote shell captures'
 389     if (this.powerFlags[this.turn]['k']) {
 390       let shellCaptures = this.getPotentialMovesOf('y', [x, y]);
 391       shellCaptures.forEach(sc => {
 392         sc.shell = true; //easier play()
 393         sc.choice = 'z'; //to display in showChoices()
 394         // Fix move (Rifle style):
 395         sc.vanish.shift();
 396         sc.appear.shift();
 397       });
 398       Array.prototype.push.apply(moves, shellCaptures);
 399     }
 400     return moves;
 401   }
 402
 403   play(move) {
 404     const color = this.turn;
 405     const oppCol = C.GetOppCol(color);
 406     if (
 407       move.appear.length > 0 &&
 408       move.appear[0].p == 'p' &&
 409       (
 410         (color == 'w' && move.end.x == 0) ||
 411         (color == 'b' && move.end.x == this.size.x - 1)
 412       )
 413     ) {
 414       // "Forgotten" promotion, which occurred after some effect
 415       let moves = [move];
 416       super.pawnPostProcess(moves, color, oppCol);
 417       super.showChoices(moves);
 418       return false;
 419     }
 420     this.postPlay(move, color, oppCol);
 421     return true;
 422   }
 423
 424   postPlay(move, color, oppCol) {
 425     this.egg = move.egg;
 426     if (move.egg == "toadette") {
 427       this.reserve = { w: {}, b: {} };
 428       // Randomly select a piece in pawnPromotions
 429       if (!move.toadette)
 430         move.toadette = Random.sample(this.pawnPromotions);
 431       this.reserve[color][move.toadette] = 1;
 432       this.re_drawReserve([color]);
 433     }
 434     else if (Object.keys(this.reserve).length > 0) {
 435       this.reserve = {};
 436       this.re_drawReserve([color]);
 437     }
 438     if (move.shell)
 439       this.powerFlags[color]['k'] = false;
 440     else if (move.appear.length > 0 && move.appear[0].p == 'i') {
 441       this.powerFlags[move.appear[0].c]['q'] = false;
 442       if (color == this.playerColor) {
 443         move.appear.push(
 444           new PiPo({x: move.start.x, y: move.start.y, c: color, p: '?'}));
 445       }
 446     }
 447     if (color == this.playerColor) {
 448       // Look for an immobilized piece of my color: it can now move
 449       for (let i=0; i<8; i++) {
 450         for (let j=0; j<8; j++) {
 451           if ((i != move.end.x || j != move.end.y) && this.board[i][j] != "") {
 452             const piece = this.getPiece(i, j);
 453             if (
 454               this.getColor(i, j) == color &&
 455               Object.keys(V.IMMOBILIZE_DECODE).includes(piece)
 456             ) {
 457               move.vanish.push(new PiPo({
 458                 x: i, y: j, c: color, p: piece
 459               }));
 460               move.appear.push(new PiPo({
 461                 x: i, y: j, c: color, p: V.IMMOBILIZE_DECODE[piece]
 462               }));
 463             }
 464           }
 465         }
 466       }
 467       // Also make opponent invisible queen visible again, if any
 468       for (let i=0; i<8; i++) {
 469         for (let j=0; j<8; j++) {
 470           if (
 471             this.board[i][j] != "" &&
 472             this.getColor(i, j) == oppCol
 473           ) {
 474             const pieceIJ = this.getPiece(i, j);
 475             if (pieceIJ == 'i') {
 476               move.vanish.push(new PiPo({x: i, y: j, c: oppCol, p: 'i'}));
 477               move.appear.push(new PiPo({x: i, y: j, c: oppCol, p: 'q'}));
 478             }
 479             else if (pieceIJ == '?')
 480               move.vanish.push(new PiPo({x: i, y: j, c: oppCol, p: '?'}));
 481           }
 482         }
 483       }
 484     }
 485     this.playOnBoard(move);
 486     super.postPlay(move);
 487   }
 488
 489   playVisual(move, r) {
 490     super.playVisual(move, r);
 491     if (move.egg)
 492       this.displayBonus(move);
 493   }
 494
 495   computeNextMove(move) {
 496     // Set potential random effects, so that play() is deterministic
 497     // from opponent viewpoint:
 498     const endPiece = this.getPiece(move.end.x, move.end.y);
 499     switch (endPiece) {
 500       case V.EGG:
 501         move.egg = Random.sample(V.EGG_SURPRISE);
 502         move.next = this.getEggEffect(move);
 503         break;
 504       case V.MUSHROOM:
 505         move.next = this.getMushroomEffect(move);
 506         break;
 507       case V.BANANA:
 508       case V.BOMB:
 509         move.next = this.getBombBananaEffect(move, endPiece);
 510         break;
 511     }
 512     // NOTE: Chakart has also some side-effects:
 513     if (
 514       !move.next && move.appear.length > 0 &&
 515       !move.kingboo && !move.luigiEffect
 516     ) {
 517       const movingPiece = move.appear[0].p;
 518       if (['b', 'r'].includes(movingPiece)) {
 519         // Drop a banana or bomb:
 520         const bs =
 521           this.getRandomSquare([move.end.x, move.end.y],
 522             movingPiece == 'r'
 523               ? [[1, 1], [1, -1], [-1, 1], [-1, -1]]
 524               : [[1, 0], [-1, 0], [0, 1], [0, -1]],
 525             "freeSquare");
 526         if (bs) {
 527           move.appear.push(
 528             new PiPo({
 529               x: bs[0],
 530               y: bs[1],
 531               c: 'a',
 532               p: movingPiece == 'r' ? 'd' : 'w'
 533             })
 534           );
 535           if (this.board[bs[0]][bs[1]] != "") {
 536             move.vanish.push(
 537               new PiPo({
 538                 x: bs[0],
 539                 y: bs[1],
 540                 c: this.getColor(bs[0], bs[1]),
 541                 p: this.getPiece(bs[0], bs[1])
 542               })
 543             );
 544           }
 545         }
 546       }
 547     }
 548   }
 549
 550   isLastMove(move) {
 551     return !move.next && !["daisy", "toadette", "kingboo"].includes(move.egg);
 552   }
 553
 554   // Helper to set and apply banana/bomb effect
 555   getRandomSquare([x, y], steps, freeSquare) {
 556     let validSteps = steps.filter(s => this.onBoard(x + s[0], y + s[1]));
 557     if (freeSquare) {
 558       // Square to put banana/bomb cannot be occupied by a piece
 559       validSteps = validSteps.filter(s => {
 560         return ["", 'a'].includes(this.getColor(x + s[0], y + s[1]))
 561       });
 562     }
 563     if (validSteps.length == 0)
 564       return null;
 565     const step = validSteps[Random.randInt(validSteps.length)];
 566     return [x + step[0], y + step[1]];
 567   }
 568
 569   getEggEffect(move) {
 570     const getRandomPiece = (c) => {
 571       let bagOfPieces = [];
 572       for (let i=0; i<this.size.x; i++) {
 573         for (let j=0; j<this.size.y; j++) {
 574           if (this.getColor(i, j) == c && this.getPiece(i, j) != 'k')
 575             bagOfPieces.push([i, j]);
 576         }
 577       }
 578       if (bagOfPieces.length >= 1)
 579         return Random.sample(bagOfPieces);
 580       return null;
 581     };
 582     const color = this.turn;
 583     let em = null;
 584     switch (move.egg) {
 585       case "luigi":
 586       case "waluigi":
 587         // Change color of friendly or enemy piece, king excepted
 588         const oldColor = (move.egg == "waluigi" ? color : C.GetOppCol(color));
 589         const newColor = C.GetOppCol(oldColor);
 590         const coords = getRandomPiece(oldColor);
 591         if (coords) {
 592           const piece = this.getPiece(coords[0], coords[1]);
 593           em = new Move({
 594             appear: [
 595               new PiPo({x: coords[0], y: coords[1], c: newColor, p: piece})
 596             ],
 597             vanish: [
 598               new PiPo({x: coords[0], y: coords[1], c: oldColor, p: piece})
 599             ]
 600           });
 601           em.luigiEffect = true; //avoid dropping bomb/banana by mistake
 602         }
 603         break;
 604       case "bowser":
 605         em = new Move({
 606           appear: [
 607             new PiPo({
 608               x: move.end.x,
 609               y: move.end.y,
 610               c: color,
 611               p: V.IMMOBILIZE_CODE[move.appear[0].p]
 612             })
 613           ],
 614           vanish: [
 615             new PiPo({
 616               x: move.end.x,
 617               y: move.end.y,
 618               c: color,
 619               p: move.appear[0].p
 620             })
 621           ]
 622         });
 623         break;
 624       case "koopa":
 625         // Reverse move
 626         em = new Move({
 627           appear: [
 628             new PiPo({
 629               x: move.start.x, y: move.start.y, c: color, p: move.appear[0].p
 630             })
 631           ],
 632           vanish: [
 633             new PiPo({
 634               x: move.end.x, y: move.end.y, c: color, p: move.appear[0].p
 635             })
 636           ]
 637         });
 638         if (this.board[move.start.x][move.start.y] != "") {
 639           // Pawn or knight let something on init square
 640           em.vanish.push(new PiPo({
 641             x: move.start.x,
 642             y: move.start.y,
 643             c: 'a',
 644             p: this.getPiece(move.start.x, move.start.y)
 645           }));
 646         }
 647         break;
 648       case "chomp":
 649         // Eat piece
 650         em = new Move({
 651           appear: [],
 652           vanish: [
 653             new PiPo({
 654               x: move.end.x, y: move.end.y, c: color, p: move.appear[0].p
 655             })
 656           ],
 657           end: {x: move.end.x, y: move.end.y}
 658         });
 659         break;
 660     }
 661     if (em && move.egg != "koopa")
 662       em.noAnimate = true; //static move
 663     return em;
 664   }
 665
 666   getMushroomEffect(move) {
 667     if (
 668       typeof move.start.x == "string" || //drop move (toadette)
 669       ['b', 'r', 'q'].includes(move.vanish[0].p) //slider
 670     ) {
 671       return null;
 672     }
 673     let step = [move.end.x - move.start.x, move.end.y - move.start.y];
 674     if (Math.abs(step[0]) == 2 && Math.abs(step[1]) == 0)
 675       // Pawn initial 2-squares move: normalize step
 676       step[0] /= 2;
 677     const nextSquare = [move.end.x + step[0], move.end.y + step[1]];
 678     let nextMove = null;
 679     if (
 680       this.onBoard(nextSquare[0], nextSquare[1]) &&
 681       (
 682         this.board[nextSquare[0]][nextSquare[1]] == "" ||
 683         this.getColor(nextSquare[0], nextSquare[1]) == 'a'
 684       )
 685     ) {
 686       this.playOnBoard(move); //HACK for getBasicMove()
 687       nextMove = this.getBasicMove([move.end.x, move.end.y], nextSquare);
 688       this.undoOnBoard(move);
 689     }
 690     return nextMove;
 691   }
 692
 693   getBombBananaEffect(move, item) {
 694     const steps = item == V.BANANA
 695       ? [[1, 0], [-1, 0], [0, 1], [0, -1]]
 696       : [[1, 1], [1, -1], [-1, 1], [-1, -1]];
 697     const nextSquare = this.getRandomSquare([move.end.x, move.end.y], steps);
 698     this.playOnBoard(move); //HACK for getBasicMove()
 699     const res = this.getBasicMove([move.end.x, move.end.y], nextSquare);
 700     this.undoOnBoard(move);
 701     return res;
 702   }
 703
 704   displayBonus(move) {
 705     let divBonus = document.createElement("div");
 706     divBonus.classList.add("bonus-text");
 707     divBonus.innerHTML = move.egg;
 708     let container = document.getElementById(this.containerId);
 709     container.appendChild(divBonus);
 710     setTimeout(() => container.removeChild(divBonus), 2000);
 711   }
 712
 713   atLeastOneMove() {
 714     return true;
 715   }
 716
 717   filterValid(moves) {
 718     return moves;
 719   }
 720
 721   // Kingboo bonus can be animated better:
 722   customAnimate(move, segments, cb) {
 723     if (!move.kingboo)
 724       return 0;
 725     super.animateMoving(move.end, move.start, null,
 726                         segments.reverse().map(s => s.reverse()), cb);
 727     return 1;
 728   }
 729
 730 };