| 1 | import { ChessRules } from "@/base_rules"; |
| 2 | |
| 3 | export class XiangqiRules extends ChessRules { |
| 4 | |
| 5 | static get Monochrome() { |
| 6 | return true; |
| 7 | } |
| 8 | |
| 9 | static get Notoodark() { |
| 10 | return true; |
| 11 | } |
| 12 | |
| 13 | static get Lines() { |
| 14 | let lines = []; |
| 15 | // Draw all inter-squares lines, shifted: |
| 16 | for (let i = 0; i < V.size.x; i++) |
| 17 | lines.push([[i+0.5, 0.5], [i+0.5, V.size.y-0.5]]); |
| 18 | for (let j = 0; j < V.size.y; j++) |
| 19 | lines.push([[0.5, j+0.5], [V.size.x-0.5, j+0.5]]); |
| 20 | // Add palaces: |
| 21 | lines.push([[0.5, 3.5], [2.5, 5.5]]); |
| 22 | lines.push([[0.5, 5.5], [2.5, 3.5]]); |
| 23 | lines.push([[9.5, 3.5], [7.5, 5.5]]); |
| 24 | lines.push([[9.5, 5.5], [7.5, 3.5]]); |
| 25 | // Show river: |
| 26 | lines.push([[4.5, 0.5], [5.5, 8.5]]); |
| 27 | lines.push([[5.5, 0.5], [4.5, 8.5]]); |
| 28 | return lines; |
| 29 | } |
| 30 | |
| 31 | static get HasFlags() { |
| 32 | return false; |
| 33 | } |
| 34 | |
| 35 | static get HasEnpassant() { |
| 36 | return false; |
| 37 | } |
| 38 | |
| 39 | static get ELEPHANT() { |
| 40 | return "e"; |
| 41 | } |
| 42 | |
| 43 | static get CANNON() { |
| 44 | return "c"; |
| 45 | } |
| 46 | |
| 47 | static get ADVISOR() { |
| 48 | return "a"; |
| 49 | } |
| 50 | |
| 51 | static get PIECES() { |
| 52 | return [V.PAWN, V.ROOK, V.KNIGHT, V.ELEPHANT, V.ADVISOR, V.KING, V.CANNON]; |
| 53 | } |
| 54 | |
| 55 | getPpath(b) { |
| 56 | return "Xiangqi/" + b; |
| 57 | } |
| 58 | |
| 59 | static get size() { |
| 60 | return { x: 10, y: 9}; |
| 61 | } |
| 62 | |
| 63 | getPotentialMovesFrom(sq) { |
| 64 | switch (this.getPiece(sq[0], sq[1])) { |
| 65 | case V.PAWN: return this.getPotentialPawnMoves(sq); |
| 66 | case V.ROOK: return super.getPotentialRookMoves(sq); |
| 67 | case V.KNIGHT: return this.getPotentialKnightMoves(sq); |
| 68 | case V.ELEPHANT: return this.getPotentialElephantMoves(sq); |
| 69 | case V.ADVISOR: return this.getPotentialAdvisorMoves(sq); |
| 70 | case V.KING: return this.getPotentialKingMoves(sq); |
| 71 | case V.CANNON: return this.getPotentialCannonMoves(sq); |
| 72 | } |
| 73 | return []; //never reached |
| 74 | } |
| 75 | |
| 76 | getPotentialPawnMoves([x, y]) { |
| 77 | const c = this.getColor(x, y); |
| 78 | const shiftX = (c == 'w' ? -1 : 1); |
| 79 | const crossedRiver = (c == 'w' && x <= 4 || c == 'b' && x >= 5); |
| 80 | const lastRank = (c == 'w' && x == 0 || c == 'b' && x == 9); |
| 81 | let steps = []; |
| 82 | if (!lastRank) steps.push([shiftX, 0]); |
| 83 | if (crossedRiver) { |
| 84 | if (y > 0) steps.push([0, -1]); |
| 85 | if (y < 9) steps.push([0, 1]); |
| 86 | } |
| 87 | return super.getSlideNJumpMoves([x, y], steps, "oneStep"); |
| 88 | } |
| 89 | |
| 90 | knightStepsFromRookStep(step) { |
| 91 | if (step[0] == 0) return [ [1, 2*step[1]], [-1, 2*step[1]] ]; |
| 92 | return [ [2*step[0], 1], [2*step[0], -1] ]; |
| 93 | } |
| 94 | |
| 95 | getPotentialKnightMoves([x, y]) { |
| 96 | let steps = []; |
| 97 | for (let rookStep of ChessRules.steps[V.ROOK]) { |
| 98 | const [i, j] = [x + rookStep[0], y + rookStep[1]]; |
| 99 | if (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 100 | Array.prototype.push.apply(steps, |
| 101 | // These moves might be impossible, but need to be checked: |
| 102 | this.knightStepsFromRookStep(rookStep)); |
| 103 | } |
| 104 | } |
| 105 | return super.getSlideNJumpMoves([x, y], steps, "oneStep"); |
| 106 | } |
| 107 | |
| 108 | getPotentialElephantMoves([x, y]) { |
| 109 | let steps = []; |
| 110 | const c = this.getColor(x, y); |
| 111 | for (let bishopStep of ChessRules.steps[V.BISHOP]) { |
| 112 | const [i, j] = [x + bishopStep[0], y + bishopStep[1]]; |
| 113 | if (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 114 | const [newX, newY] = [x + 2*bishopStep[0], y + 2*bishopStep[1]]; |
| 115 | if ((c == 'w' && newX >= 5) || (c == 'b' && newX <= 4)) |
| 116 | // A priori valid (elephant don't cross the river) |
| 117 | steps.push(bishopStep.map(s => 2*s)); |
| 118 | // "out of board" checks delayed to next method |
| 119 | } |
| 120 | } |
| 121 | return super.getSlideNJumpMoves([x, y], steps, "oneStep"); |
| 122 | } |
| 123 | |
| 124 | insidePalace(x, y, c) { |
| 125 | return ( |
| 126 | (y >= 3 && y <= 5) && |
| 127 | ( |
| 128 | (c == 'w' && x >= 7) || |
| 129 | (c == 'b' && x <= 2) |
| 130 | ) |
| 131 | ); |
| 132 | } |
| 133 | |
| 134 | getPotentialAdvisorMoves([x, y]) { |
| 135 | // Diagonal steps inside palace |
| 136 | let steps = []; |
| 137 | const c = this.getColor(x, y); |
| 138 | for (let s of ChessRules.steps[V.BISHOP]) { |
| 139 | if (this.insidePalace(x + s[0], y + s[1], c)) steps.push(s); |
| 140 | } |
| 141 | return super.getSlideNJumpMoves([x, y], steps, "oneStep"); |
| 142 | } |
| 143 | |
| 144 | getPotentialKingMoves([x, y]) { |
| 145 | // Orthogonal steps inside palace |
| 146 | let steps = []; |
| 147 | const c = this.getColor(x, y); |
| 148 | for (let s of ChessRules.steps[V.ROOK]) { |
| 149 | if (this.insidePalace(x + s[0], y + s[1], c)) steps.push(s); |
| 150 | } |
| 151 | return super.getSlideNJumpMoves([x, y], steps, "oneStep"); |
| 152 | } |
| 153 | |
| 154 | // NOTE: duplicated from Shako (TODO?) |
| 155 | getPotentialCannonMoves([x, y]) { |
| 156 | const oppCol = V.GetOppCol(this.turn); |
| 157 | let moves = []; |
| 158 | // Look in every direction until an obstacle (to jump) is met |
| 159 | for (const step of V.steps[V.ROOK]) { |
| 160 | let i = x + step[0]; |
| 161 | let j = y + step[1]; |
| 162 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 163 | moves.push(this.getBasicMove([x, y], [i, j])); |
| 164 | i += step[0]; |
| 165 | j += step[1]; |
| 166 | } |
| 167 | // Then, search for an enemy |
| 168 | i += step[0]; |
| 169 | j += step[1]; |
| 170 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 171 | i += step[0]; |
| 172 | j += step[1]; |
| 173 | } |
| 174 | if (V.OnBoard(i, j) && this.getColor(i, j) == oppCol) |
| 175 | moves.push(this.getBasicMove([x, y], [i, j])); |
| 176 | } |
| 177 | return moves; |
| 178 | } |
| 179 | |
| 180 | // (King) Never attacked by advisor, since it stays in the palace |
| 181 | // Also, never attacked by elephants since they don't cross the river. |
| 182 | isAttacked(sq, color) { |
| 183 | return ( |
| 184 | this.isAttackedByPawn(sq, color) || |
| 185 | super.isAttackedByRook(sq, color) || |
| 186 | this.isAttackedByKnight(sq, color) || |
| 187 | this.isAttackedByCannon(sq, color) |
| 188 | ); |
| 189 | } |
| 190 | |
| 191 | isAttackedByPawn([x, y], color) { |
| 192 | // The pawn necessarily crossed the river (attack on king) |
| 193 | const shiftX = (color == 'w' ? 1 : -1); //shift from king |
| 194 | for (let s of [[shiftX, 0], [0, 1], [0, -1]]) { |
| 195 | const [i, j] = [x + s[0], y + s[1]]; |
| 196 | if ( |
| 197 | this.board[i][j] != V.EMPTY && |
| 198 | this.getColor(i, j) == color && |
| 199 | this.getPiece(i, j) == V.PAWN |
| 200 | ) { |
| 201 | return true; |
| 202 | } |
| 203 | } |
| 204 | return false; |
| 205 | } |
| 206 | |
| 207 | knightStepsFromBishopStep(step) { |
| 208 | return [ [2*step[0], step[1]], [step[0], 2*step[1]] ]; |
| 209 | } |
| 210 | |
| 211 | isAttackedByKnight([x, y], color) { |
| 212 | // Check bishop steps: if empty, look continuation knight step |
| 213 | let steps = []; |
| 214 | for (let s of ChessRules.steps[V.BISHOP]) { |
| 215 | const [i, j] = [x + s[0], y + s[1]]; |
| 216 | if ( |
| 217 | V.OnBoard(i, j) && |
| 218 | this.board[i][j] == V.EMPTY |
| 219 | ) { |
| 220 | Array.prototype.push.apply(steps, this.knightStepsFromBishopStep(s)); |
| 221 | } |
| 222 | } |
| 223 | return ( |
| 224 | super.isAttackedBySlideNJump([x, y], color, V.KNIGHT, steps, "oneStep") |
| 225 | ); |
| 226 | } |
| 227 | |
| 228 | // NOTE: duplicated from Shako (TODO?) |
| 229 | isAttackedByCannon([x, y], color) { |
| 230 | // Reversed process: is there an obstacle in line, |
| 231 | // and a cannon next in the same line? |
| 232 | for (const step of V.steps[V.ROOK]) { |
| 233 | let [i, j] = [x+step[0], y+step[1]]; |
| 234 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 235 | i += step[0]; |
| 236 | j += step[1]; |
| 237 | } |
| 238 | if (V.OnBoard(i, j)) { |
| 239 | // Keep looking in this direction |
| 240 | i += step[0]; |
| 241 | j += step[1]; |
| 242 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 243 | i += step[0]; |
| 244 | j += step[1]; |
| 245 | } |
| 246 | if ( |
| 247 | V.OnBoard(i, j) && |
| 248 | this.getPiece(i, j) == V.CANNON && |
| 249 | this.getColor(i, j) == color |
| 250 | ) { |
| 251 | return true; |
| 252 | } |
| 253 | } |
| 254 | } |
| 255 | return false; |
| 256 | } |
| 257 | |
| 258 | static get VALUES() { |
| 259 | return { |
| 260 | p: 1, |
| 261 | r: 9, |
| 262 | n: 4, |
| 263 | e: 2.5, |
| 264 | a: 2, |
| 265 | c: 4.5, |
| 266 | k: 1000 |
| 267 | }; |
| 268 | } |
| 269 | |
| 270 | evalPosition() { |
| 271 | let evaluation = 0; |
| 272 | for (let i = 0; i < V.size.x; i++) { |
| 273 | for (let j = 0; j < V.size.y; j++) { |
| 274 | if (this.board[i][j] != V.EMPTY) { |
| 275 | const c = this.getColor(i, j); |
| 276 | const sign = (c == 'w' ? 1 : -1); |
| 277 | const piece = this.getPiece(i, j); |
| 278 | let pieceEval = V.VALUES[this.getPiece(i, j)]; |
| 279 | if ( |
| 280 | piece == V.PAWN && |
| 281 | ( |
| 282 | (c == 'w' && i <= 4) || |
| 283 | (c == 'b' && i >= 5) |
| 284 | ) |
| 285 | ) { |
| 286 | // Pawn crossed the river: higher value |
| 287 | pieceEval++; |
| 288 | } |
| 289 | evaluation += sign * pieceEval; |
| 290 | } |
| 291 | } |
| 292 | } |
| 293 | return evaluation; |
| 294 | } |
| 295 | |
| 296 | static GenRandInitFen() { |
| 297 | // No randomization here (TODO?) |
| 298 | return "rneakaenr/9/1c5c1/p1p1p1p1p/9/9/P1P1P1P1P/1C5C1/9/RNEAKAENR w 0"; |
| 299 | } |
| 300 | |
| 301 | }; |