chess.lua

   1 -- See https://github.com/kilbith/realchess for the main repository
   2
   3 local realchess = {}
   4 screwdriver = screwdriver or {}
   5
   6 local function index_to_xy(index)
   7         index = index - 1
   8         local x = index % 8
   9         local y = (index - x) / 8
  10         return x, y
  11 end
  12
  13 local function xy_to_index(x, y)
  14         return x + y * 8 + 1
  15 end
  16
  17 function realchess.init(pos)
  18         local meta = minetest.get_meta(pos)
  19         local inv = meta:get_inventory()
  20
  21         inv:set_size("board", 64)
  22
  23         local formspec = [[ size[8,8.6;]
  24                         bgcolor[#080808BB;true]
  25                         background[0,0;8,8;chess_bg.png]
  26                         button[3.1,7.8;2,2;new;New game]
  27                         list[context;board;0,0;8,8;]
  28                         listcolors[#00000000;#00000000;#00000000;#30434C;#FFF] ]]
  29
  30         meta:set_string("formspec", formspec)
  31
  32         meta:set_string("infotext", "Chess Board")
  33         meta:set_string("playerBlack", "")
  34         meta:set_string("playerWhite", "")
  35         meta:set_string("lastMove", "")
  36         meta:set_int("lastMoveTime", 0)
  37         meta:set_string("winner", "")
  38         meta:set_int("castlingBlackL", 1)
  39         meta:set_int("castlingBlackR", 1)
  40         meta:set_int("castlingWhiteL", 1)
  41         meta:set_int("castlingWhiteR", 1)
  42
  43         inv:set_list("board", {
  44                 "realchess:rook_black_1",
  45                 "realchess:knight_black_1",
  46                 "realchess:bishop_black_1",
  47                 "realchess:queen_black",
  48                 "realchess:king_black",
  49                 "realchess:bishop_black_2",
  50                 "realchess:knight_black_2",
  51                 "realchess:rook_black_2",
  52                 "realchess:pawn_black_1",
  53                 "realchess:pawn_black_2",
  54                 "realchess:pawn_black_3",
  55                 "realchess:pawn_black_4",
  56                 "realchess:pawn_black_5",
  57                 "realchess:pawn_black_6",
  58                 "realchess:pawn_black_7",
  59                 "realchess:pawn_black_8",
  60                 "", "", "", "", "", "", "", "",
  61                 "", "", "", "", "", "", "", "",
  62                 "", "", "", "", "", "", "", "",
  63                 "", "", "", "", "", "", "", "",
  64                 "realchess:pawn_white_1",
  65                 "realchess:pawn_white_2",
  66                 "realchess:pawn_white_3",
  67                 "realchess:pawn_white_4",
  68                 "realchess:pawn_white_5",
  69                 "realchess:pawn_white_6",
  70                 "realchess:pawn_white_7",
  71                 "realchess:pawn_white_8",
  72                 "realchess:rook_white_1",
  73                 "realchess:knight_white_1",
  74                 "realchess:bishop_white_1",
  75                 "realchess:queen_white",
  76                 "realchess:king_white",
  77                 "realchess:bishop_white_2",
  78                 "realchess:knight_white_2",
  79                 "realchess:rook_white_2"
  80         })
  81 end
  82
  83 function realchess.move(pos, from_list, from_index, to_list, to_index, count, player)
  84         if from_list ~= "board" and to_list ~= "board" then
  85                 return 0
  86         end
  87
  88         local playerName = player:get_player_name()
  89         local meta = minetest.get_meta(pos)
  90
  91         if meta:get_string("winner") ~= "" then
  92                 minetest.chat_send_player(playerName, "This game is over.")
  93                 return 0
  94         end
  95
  96         local inv = meta:get_inventory()
  97         local pieceFrom = inv:get_stack(from_list, from_index):get_name()
  98         local pieceTo = inv:get_stack(to_list, to_index):get_name()
  99         local lastMove = meta:get_string("lastMove")
 100         local thisMove -- will replace lastMove when move is legal
 101         local playerWhite = meta:get_string("playerWhite")
 102         local playerBlack = meta:get_string("playerBlack")
 103
 104         if pieceFrom:find("white") then
 105                 if playerWhite ~= "" and playerWhite ~= playerName then
 106                         minetest.chat_send_player(playerName, "Someone else plays white pieces!")
 107                         return 0
 108                 end
 109                 if lastMove ~= "" and lastMove ~= "black" then
 110                         minetest.chat_send_player(playerName, "It's not your turn, wait for your opponent to play.")
 111                         return 0
 112                 end
 113                 if pieceTo:find("white") then
 114                         -- Don't replace pieces of same color
 115                         return 0
 116                 end
 117                 playerWhite = playerName
 118                 thisMove = "white"
 119         elseif pieceFrom:find("black") then
 120                 if playerBlack ~= "" and playerBlack ~= playerName then
 121                         minetest.chat_send_player(playerName, "Someone else plays black pieces!")
 122                         return 0
 123                 end
 124                 if lastMove ~= "" and lastMove ~= "white" then
 125                         minetest.chat_send_player(playerName, "It's not your turn, wait for your opponent to play.")
 126                         return 0
 127                 end
 128                 if pieceTo:find("black") then
 129                         -- Don't replace pieces of same color
 130                         return 0
 131                 end
 132                 playerBlack = playerName
 133                 thisMove = "black"
 134         end
 135
 136         -- DETERMINISTIC MOVING
 137
 138         local from_x, from_y = index_to_xy(from_index)
 139         local to_x, to_y = index_to_xy(to_index)
 140
 141         if pieceFrom:find("pawn") then
 142                 if thisMove == "white" then
 143                         -- white pawns can go up only
 144                         if from_y - 1 == to_y then
 145                                 if from_x == to_x then
 146                                         if pieceTo ~= "" then
 147                                                 return 0
 148                                         elseif to_index >= 1 and to_index <= 8 then
 149                                                 inv:set_stack(from_list, from_index, "realchess:queen_white")
 150                                         end
 151                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 152                                         if not pieceTo:find("black") then
 153                                                 return 0
 154                                         elseif to_index >= 1 and to_index <= 8 then
 155                                                 inv:set_stack(from_list, from_index, "realchess:queen_white")
 156                                         end
 157                                 else
 158                                         return 0
 159                                 end
 160                         elseif from_y - 2 == to_y then
 161                                 if pieceTo ~= "" or from_y < 6 or inv:get_stack(from_list, xy_to_index(from_x, from_y - 1)):get_name() ~= "" then
 162                                         return 0
 163                                 end
 164                         else
 165                                 return 0
 166                         end
 167                 elseif thisMove == "black" then
 168                         -- black pawns can go down only
 169                         if from_y + 1 == to_y then
 170                                 if from_x == to_x then
 171                                         if pieceTo ~= "" then
 172                                                 return 0
 173                                         elseif to_index >= 57 and to_index <= 64 then
 174                                                 inv:set_stack(from_list, from_index, "realchess:queen_black")
 175                                         end
 176                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 177                                         if not pieceTo:find("white") then
 178                                                 return 0
 179                                         elseif to_index >= 57 and to_index <= 64 then
 180                                                 inv:set_stack(from_list, from_index, "realchess:queen_black")
 181                                         end
 182                                 else
 183                                         return 0
 184                                 end
 185                         elseif from_y + 2 == to_y then
 186                                 if pieceTo ~= "" or from_y > 1 or inv:get_stack(from_list, xy_to_index(from_x, from_y + 1)):get_name() ~= "" then
 187                                         return 0
 188                                 end
 189                         else
 190                                 return 0
 191                         end
 192
 193                         -- if x not changed,
 194                         --   ensure that destination cell is empty
 195                         -- elseif x changed one unit left or right
 196                         --   ensure the pawn is killing opponent piece
 197                         -- else
 198                         --   move is not legal - abort
 199
 200                         if from_x == to_x then
 201                                 if pieceTo ~= "" then
 202                                         return 0
 203                                 end
 204                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
 205                                 if not pieceTo:find("white") then
 206                                         return 0
 207                                 end
 208                         else
 209                                 return 0
 210                         end
 211                 else
 212                         return 0
 213                 end
 214
 215         elseif pieceFrom:find("rook") then
 216                 if from_x == to_x then
 217                         -- moving vertically
 218                         if from_y < to_y then
 219                                 -- moving down
 220                                 -- ensure that no piece disturbs the way
 221                                 for i = from_y + 1, to_y - 1 do
 222                                         if inv:get_stack(from_list, xy_to_index(from_x, i)):get_name() ~= "" then
 223                                                 return 0
 224                                         end
 225                                 end
 226                         else
 227                                 -- mocing up
 228                                 -- ensure that no piece disturbs the way
 229                                 for i = to_y + 1, from_y - 1 do
 230                                         if inv:get_stack(from_list, xy_to_index(from_x, i)):get_name() ~= "" then
 231                                                 return 0
 232                                         end
 233                                 end
 234                         end
 235                 elseif from_y == to_y then
 236                         -- mocing horizontally
 237                         if from_x < to_x then
 238                                 -- mocing right
 239                                 -- ensure that no piece disturbs the way
 240                                 for i = from_x + 1, to_x - 1 do
 241                                         if inv:get_stack(from_list, xy_to_index(i, from_y)):get_name() ~= "" then
 242                                                 return 0
 243                                         end
 244                                 end
 245                         else
 246                                 -- mocing left
 247                                 -- ensure that no piece disturbs the way
 248                                 for i = to_x + 1, from_x - 1 do
 249                                         if inv:get_stack(from_list, xy_to_index(i, from_y)):get_name() ~= "" then
 250                                                 return 0
 251                                         end
 252                                 end
 253                         end
 254                 else
 255                         -- attempt to move arbitrarily -> abort
 256                         return 0
 257                 end
 258
 259                 if thisMove == "white" then
 260                         if pieceFrom:find("1") then
 261                                 meta:set_int("castlingWhiteL", 0)
 262                         elseif pieceFrom:find("2") then
 263                                 meta:set_int("castlingWhiteR", 0)
 264                         end
 265                 elseif thisMove == "black" then
 266                         if pieceFrom:find("1") then
 267                                 meta:set_int("castlingWhiteL", 0)
 268                         elseif pieceFrom:find("2") then
 269                                 meta:set_int("castlingWhiteR", 0)
 270                         end
 271                 end
 272
 273         elseif pieceFrom:find("knight") then
 274                 -- get relative pos
 275                 local dx = from_x - to_x
 276                 local dy = from_y - to_y
 277
 278                 -- get absolute values
 279                 if dx < 0 then
 280                         dx = -dx
 281                 end
 282                 if dy < 0 then
 283                         dy = -dy
 284                 end
 285
 286                 -- sort x and y
 287                 if dx > dy then
 288                         dx, dy = dy, dx
 289                 end
 290
 291                 -- ensure that dx == 1 and dy == 2
 292                 if dx ~= 1 or dy ~= 2 then
 293                         return 0
 294                 end
 295                 -- just ensure that destination cell does not contain friend piece
 296                 -- ^ it was done already thus everything ok
 297
 298         elseif pieceFrom:find("bishop") then
 299                 -- get relative pos
 300                 local dx = from_x - to_x
 301                 local dy = from_y - to_y
 302
 303                 -- get absolute values
 304                 if dx < 0 then
 305                         dx = -dx
 306                 end
 307                 if dy < 0 then
 308                         dy = -dy
 309                 end
 310
 311                 -- ensure dx and dy are equal
 312                 if dx ~= dy then
 313                         return 0
 314                 end
 315
 316                 if from_x < to_x then
 317                         if from_y < to_y then
 318                                 -- moving right-down
 319                                 -- ensure that no piece disturbs the way
 320                                 for i = 1, dx - 1 do
 321                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 322                                                 return 0
 323                                         end
 324                                 end
 325                         else
 326                                 -- moving right-up
 327                                 -- ensure that no piece disturbs the way
 328                                 for i = 1, dx - 1 do
 329                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 330                                                 return 0
 331                                         end
 332                                 end
 333                         end
 334                 else
 335                         if from_y < to_y then
 336                                 -- moving left-down
 337                                 -- ensure that no piece disturbs the way
 338                                 for i = 1, dx - 1 do
 339                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 340                                                 return 0
 341                                         end
 342                                 end
 343                         else
 344                                 -- moving left-up
 345                                 -- ensure that no piece disturbs the way
 346                                 for i = 1, dx - 1 do
 347                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 348                                                 return 0
 349                                         end
 350                                 end
 351                         end
 352                 end
 353
 354         elseif pieceFrom:find("queen") then
 355                 local dx = from_x - to_x
 356                 local dy = from_y - to_y
 357
 358                 -- get absolute values
 359                 if dx < 0 then
 360                         dx = -dx
 361                 end
 362                 if dy < 0 then
 363                         dy = -dy
 364                 end
 365
 366                 -- ensure valid relative move
 367                 if dx ~= 0 and dy ~= 0 and dx ~= dy then
 368                         return 0
 369                 end
 370
 371                 if from_x == to_x then
 372                         if from_y < to_y then
 373                                 -- goes down
 374                                 -- ensure that no piece disturbs the way
 375                                 for i = 1, dx - 1 do
 376                                         if inv:get_stack(from_list, xy_to_index(from_x, from_y + i)):get_name() ~= "" then
 377                                                 return 0
 378                                         end
 379                                 end
 380                         else
 381                                 -- goes up
 382                                 -- ensure that no piece disturbs the way
 383                                 for i = 1, dx - 1 do
 384                                         if inv:get_stack(from_list, xy_to_index(from_x, from_y - i)):get_name() ~= "" then
 385                                                 return 0
 386                                         end
 387                                 end
 388                         end
 389                 elseif from_x < to_x then
 390                         if from_y == to_y then
 391                                 -- goes right
 392                                 -- ensure that no piece disturbs the way
 393                                 for i = 1, dx - 1 do
 394                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y)):get_name() ~= "" then
 395                                                 return 0
 396                                         end
 397                                 end
 398                         elseif from_y < to_y then
 399                                 -- goes right-down
 400                                 -- ensure that no piece disturbs the way
 401                                 for i = 1, dx - 1 do
 402                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 403                                                 return 0
 404                                         end
 405                                 end
 406                         else
 407                                 -- goes right-up
 408                                 -- ensure that no piece disturbs the way
 409                                 for i = 1, dx - 1 do
 410                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 411                                                 return 0
 412                                         end
 413                                 end
 414                         end
 415                 else
 416                         if from_y == to_y then
 417                                 -- goes left
 418                                 -- ensure that no piece disturbs the way and destination cell does
 419                                 for i = 1, dx - 1 do
 420                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y)):get_name() ~= "" then
 421                                                 return 0
 422                                         end
 423                                 end
 424                         elseif from_y < to_y then
 425                                 -- goes left-down
 426                                 -- ensure that no piece disturbs the way
 427                                 for i = 1, dx - 1 do
 428                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 429                                                 return 0
 430                                         end
 431                                 end
 432                         else
 433                                 -- goes left-up
 434                                 -- ensure that no piece disturbs the way
 435                                 for i = 1, dx - 1 do
 436                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 437                                                 return 0
 438                                         end
 439                                 end
 440                         end
 441                 end
 442
 443         elseif pieceFrom:find("king") then
 444                 local dx = from_x - to_x
 445                 local dy = from_y - to_y
 446                 local check = true
 447
 448                 if thisMove == "white" then
 449                         if from_y == 7 and to_y == 7 then
 450                                 if to_x == 1 then
 451                                         if meta:get_int("castlingWhiteL") == 1 and inv:get_stack(from_list, 57):get_name() == "realchess:rook_white_1" then
 452                                                 for i = 58, from_index - 1 do
 453                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 454                                                                 return 0
 455                                                         end
 456                                                 end
 457                                                 inv:set_stack(from_list, 57, "")
 458                                                 inv:set_stack(from_list, 59, "realchess:rook_white_1")
 459                                                 check = false
 460                                         end
 461                                 elseif to_x == 6 then
 462                                         if meta:get_int("castlingWhiteR") == 1 and inv:get_stack(from_list, 64):get_name() == "realchess:rook_white_2" then
 463                                                 for i = from_index + 1, 63 do
 464                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 465                                                                 return 0
 466                                                         end
 467                                                 end
 468                                                 inv:set_stack(from_list, 62, "realchess:rook_white_2")
 469                                                 inv:set_stack(from_list, 64, "")
 470                                                 check = false
 471                                         end
 472                                 end
 473                         end
 474                 elseif thisMove == "black" then
 475                         if from_y == 0 and to_y == 0 then
 476                                 if to_x == 1 then
 477                                         if meta:get_int("castlingBlackL") == 1 and inv:get_stack(from_list, 1):get_name() == "realchess:rook_black_1" then
 478                                                 for i = 2, from_index - 1 do
 479                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 480                                                                 return 0
 481                                                         end
 482                                                 end
 483                                                 inv:set_stack(from_list, 1, "")
 484                                                 inv:set_stack(from_list, 3, "realchess:rook_black_1")
 485                                                 check = false
 486                                         end
 487                                 elseif to_x == 6 then
 488                                         if meta:get_int("castlingBlackR") == 1 and inv:get_stack(from_list, 8):get_name() == "realchess:rook_black_2" then
 489                                                 for i = from_index + 1, 7 do
 490                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 491                                                                 return 0
 492                                                         end
 493                                                 end
 494                                                 inv:set_stack(from_list, 6, "realchess:rook_black_2")
 495                                                 inv:set_stack(from_list, 8, "")
 496                                                 check = false
 497                                         end
 498                                 end
 499                         end
 500                 end
 501
 502                 if check then
 503                         if dx < 0 then
 504                                 dx = -dx
 505                         end
 506                         if dy < 0 then
 507                                 dy = -dy
 508                         end
 509
 510                         if dx > 1 or dy > 1 then
 511                                 return 0
 512                         end
 513                 end
 514
 515                 if thisMove == "white" then
 516                         meta:set_int("castlingWhiteL", 0)
 517                         meta:set_int("castlingWhiteR", 0)
 518                 elseif thisMove == "black" then
 519                         meta:set_int("castlingBlackL", 0)
 520                         meta:set_int("castlingBlackR", 0)
 521                 end
 522         end
 523
 524         meta:set_string("playerWhite", playerWhite)
 525         meta:set_string("playerBlack", playerBlack)
 526         meta:set_string("lastMove", thisMove)
 527         meta:set_int("lastMoveTime", minetest.get_gametime())
 528
 529         if meta:get_string("lastMove") == "black" then
 530                 minetest.chat_send_player(playerWhite, "["..os.date("%H:%M:%S").."] "..
 531                                 playerName.." has moved a "..pieceFrom:match("%a+:(%a+)")..", it's now your turn.")
 532         elseif meta:get_string("lastMove") == "white" then
 533                 minetest.chat_send_player(playerBlack, "["..os.date("%H:%M:%S").."] "..
 534                                 playerName.." has moved a "..pieceFrom:match("%a+:(%a+)")..", it's now your turn.")
 535         end
 536
 537         if pieceTo:find("king") then
 538                 minetest.chat_send_player(playerBlack, playerName.." won the game.")
 539                 minetest.chat_send_player(playerWhite, playerName.." won the game.")
 540                 meta:set_string("winner", thisMove)
 541         end
 542
 543         return 1
 544 end
 545
 546 local function timeout_format(timeout_limit)
 547         local time_remaining = timeout_limit - minetest.get_gametime()
 548         local minutes = math.floor(time_remaining / 60)
 549         local seconds = time_remaining % 60
 550
 551         if minutes == 0 then return seconds.." sec." end
 552         return minutes.." min. "..seconds.." sec."
 553 end
 554
 555 function realchess.fields(pos, formname, fields, sender)
 556         local playerName = sender:get_player_name()
 557         local meta = minetest.get_meta(pos)
 558         local timeout_limit = meta:get_int("lastMoveTime") + 300
 559         if fields.quit then return end
 560
 561         -- timeout is 5 min. by default for resetting the game (non-players only)
 562         if fields.new and (meta:get_string("playerWhite") == playerName or
 563                         meta:get_string("playerBlack") == playerName) then
 564                 realchess.init(pos)
 565         elseif fields.new and meta:get_int("lastMoveTime") ~= 0 and
 566                         minetest.get_gametime() >= timeout_limit and
 567                         (meta:get_string("playerWhite") ~= playerName or
 568                         meta:get_string("playerBlack") ~= playerName) then
 569                 realchess.init(pos)
 570         else
 571                 minetest.chat_send_player(playerName, "[!] You can't reset the chessboard, a game has been started.\n"..
 572                                 "If you are not a current player, try again in "..timeout_format(timeout_limit))
 573         end
 574 end
 575
 576 function realchess.dig(pos, player)
 577         local meta = minetest.get_meta(pos)
 578         local playerName = player:get_player_name()
 579         local timeout_limit = meta:get_int("lastMoveTime") + 300
 580
 581         -- timeout is 5 min. by default for digging the chessboard (non-players only)
 582         if meta:get_int("lastMoveTime") ~= 0 and minetest.get_gametime() <= timeout_limit then
 583                 minetest.chat_send_player(playerName, "[!] You can't dig the chessboard, a game has been started.\n"..
 584                                 "Reset it first if you're a current player, or dig again in "..timeout_format(timeout_limit))
 585                 return false
 586         end
 587
 588         return true
 589 end
 590
 591 function realchess.on_move(pos, from_list, from_index, to_list, to_index, count, player)
 592         local inv = minetest.get_meta(pos):get_inventory()
 593         inv:set_stack(from_list, from_index, '')
 594         return false
 595 end
 596
 597 minetest.register_node(":realchess:chessboard", {
 598         description = "Chess Board",
 599         drawtype = "nodebox",
 600         paramtype = "light",
 601         paramtype2 = "facedir",
 602         inventory_image = "chessboard_top.png",
 603         wield_image = "chessboard_top.png",
 604         tiles = {"chessboard_top.png", "chessboard_top.png", "chessboard_sides.png"},
 605         groups = {choppy=3, oddly_breakable_by_hand=2, flammable=3},
 606         sounds = default.node_sound_wood_defaults(),
 607         node_box = {type = "fixed", fixed = {-.375, -.5, -.375, .375, -.4375, .375}},
 608         sunlight_propagates = true,
 609         on_rotate = screwdriver.rotate_simple,
 610         can_dig = realchess.dig,
 611         on_construct = realchess.init,
 612         on_receive_fields = realchess.fields,
 613         allow_metadata_inventory_move = realchess.move,
 614         on_metadata_inventory_move = realchess.on_move,
 615         allow_metadata_inventory_take = function() return 0 end
 616 })
 617
 618 local function register_piece(name, count)
 619         for _, color in pairs({"black", "white"}) do
 620         if not count then
 621                 minetest.register_craftitem(":realchess:"..name.."_"..color, {
 622                         description = color:gsub("^%l", string.upper).." "..name:gsub("^%l", string.upper),
 623                         inventory_image = name.."_"..color..".png",
 624                         stack_max = 1,
 625                         groups = {not_in_creative_inventory=1}
 626                 })
 627         else
 628                 for i = 1, count do
 629                         minetest.register_craftitem(":realchess:"..name.."_"..color.."_"..i, {
 630                                 description = color:gsub("^%l", string.upper).." "..name:gsub("^%l", string.upper),
 631                                 inventory_image = name.."_"..color..".png",
 632                                 stack_max = 1,
 633                                 groups = {not_in_creative_inventory=1}
 634                         })
 635                 end
 636         end
 637         end
 638 end
 639
 640 register_piece("pawn", 8)
 641 register_piece("rook", 2)
 642 register_piece("knight", 2)
 643 register_piece("bishop", 2)
 644 register_piece("queen")
 645 register_piece("king")
 646