fifteen.c

   1 /*
   2  * fifteen.c: standard 15-puzzle.
   3  */
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <assert.h>
   9 #include <ctype.h>
  10 #include <math.h>
  11
  12 #include "puzzles.h"
  13
  14 #define PREFERRED_TILE_SIZE 48
  15 #define TILE_SIZE (ds->tilesize)
  16 #define BORDER    (TILE_SIZE / 2)
  17 #define HIGHLIGHT_WIDTH (TILE_SIZE / 20)
  18 #define COORD(x)  ( (x) * TILE_SIZE + BORDER )
  19 #define FROMCOORD(x)  ( ((x) - BORDER + TILE_SIZE) / TILE_SIZE - 1 )
  20
  21 #define ANIM_TIME 0.13F
  22 #define FLASH_FRAME 0.13F
  23
  24 #define X(state, i) ( (i) % (state)->w )
  25 #define Y(state, i) ( (i) / (state)->w )
  26 #define C(state, x, y) ( (y) * (state)->w + (x) )
  27
  28 enum {
  29     COL_BACKGROUND,
  30     COL_TEXT,
  31     COL_HIGHLIGHT,
  32     COL_LOWLIGHT,
  33     NCOLOURS
  34 };
  35
  36 struct game_params {
  37     int w, h;
  38 };
  39
  40 struct game_state {
  41     int w, h, n;
  42     int *tiles;
  43     int gap_pos;
  44     int completed;
  45     int used_solve;                    /* used to suppress completion flash */
  46     int movecount;
  47 };
  48
  49 static game_params *default_params(void)
  50 {
  51     game_params *ret = snew(game_params);
  52
  53     ret->w = ret->h = 4;
  54
  55     return ret;
  56 }
  57
  58 static int game_fetch_preset(int i, char **name, game_params **params)
  59 {
  60     if (i == 0) {
  61         *params = default_params();
  62         *name = dupstr("4x4");
  63         return TRUE;
  64     }
  65     return FALSE;
  66 }
  67
  68 static void free_params(game_params *params)
  69 {
  70     sfree(params);
  71 }
  72
  73 static game_params *dup_params(game_params *params)
  74 {
  75     game_params *ret = snew(game_params);
  76     *ret = *params;                    /* structure copy */
  77     return ret;
  78 }
  79
  80 static void decode_params(game_params *ret, char const *string)
  81 {
  82     ret->w = ret->h = atoi(string);
  83     while (*string && isdigit((unsigned char)*string)) string++;
  84     if (*string == 'x') {
  85         string++;
  86         ret->h = atoi(string);
  87     }
  88 }
  89
  90 static char *encode_params(game_params *params, int full)
  91 {
  92     char data[256];
  93
  94     sprintf(data, "%dx%d", params->w, params->h);
  95
  96     return dupstr(data);
  97 }
  98
  99 static config_item *game_configure(game_params *params)
 100 {
 101     config_item *ret;
 102     char buf[80];
 103
 104     ret = snewn(3, config_item);
 105
 106     ret[0].name = "Width";
 107     ret[0].type = C_STRING;
 108     sprintf(buf, "%d", params->w);
 109     ret[0].sval = dupstr(buf);
 110     ret[0].ival = 0;
 111
 112     ret[1].name = "Height";
 113     ret[1].type = C_STRING;
 114     sprintf(buf, "%d", params->h);
 115     ret[1].sval = dupstr(buf);
 116     ret[1].ival = 0;
 117
 118     ret[2].name = NULL;
 119     ret[2].type = C_END;
 120     ret[2].sval = NULL;
 121     ret[2].ival = 0;
 122
 123     return ret;
 124 }
 125
 126 static game_params *custom_params(config_item *cfg)
 127 {
 128     game_params *ret = snew(game_params);
 129
 130     ret->w = atoi(cfg[0].sval);
 131     ret->h = atoi(cfg[1].sval);
 132
 133     return ret;
 134 }
 135
 136 static char *validate_params(game_params *params, int full)
 137 {
 138     if (params->w < 2 || params->h < 2)
 139         return "Width and height must both be at least two";
 140
 141     return NULL;
 142 }
 143
 144 static int perm_parity(int *perm, int n)
 145 {
 146     int i, j, ret;
 147
 148     ret = 0;
 149
 150     for (i = 0; i < n-1; i++)
 151         for (j = i+1; j < n; j++)
 152             if (perm[i] > perm[j])
 153                 ret = !ret;
 154
 155     return ret;
 156 }
 157
 158 static char *new_game_desc(game_params *params, random_state *rs,
 159                            char **aux, int interactive)
 160 {
 161     int gap, n, i, x;
 162     int x1, x2, p1, p2, parity;
 163     int *tiles, *used;
 164     char *ret;
 165     int retlen;
 166
 167     n = params->w * params->h;
 168
 169     tiles = snewn(n, int);
 170     used = snewn(n, int);
 171
 172     for (i = 0; i < n; i++) {
 173         tiles[i] = -1;
 174         used[i] = FALSE;
 175     }
 176
 177     gap = random_upto(rs, n);
 178     tiles[gap] = 0;
 179     used[0] = TRUE;
 180
 181     /*
 182      * Place everything else except the last two tiles.
 183      */
 184     for (x = 0, i = n-1; i > 2; i--) {
 185         int k = random_upto(rs, i);
 186         int j;
 187
 188         for (j = 0; j < n; j++)
 189             if (!used[j] && (k-- == 0))
 190                 break;
 191
 192         assert(j < n && !used[j]);
 193         used[j] = TRUE;
 194
 195         while (tiles[x] >= 0)
 196             x++;
 197         assert(x < n);
 198         tiles[x] = j;
 199     }
 200
 201     /*
 202      * Find the last two locations, and the last two pieces.
 203      */
 204     while (tiles[x] >= 0)
 205         x++;
 206     assert(x < n);
 207     x1 = x;
 208     x++;
 209     while (tiles[x] >= 0)
 210         x++;
 211     assert(x < n);
 212     x2 = x;
 213
 214     for (i = 0; i < n; i++)
 215         if (!used[i])
 216             break;
 217     p1 = i;
 218     for (i = p1+1; i < n; i++)
 219         if (!used[i])
 220             break;
 221     p2 = i;
 222
 223     /*
 224      * Determine the required parity of the overall permutation.
 225      * This is the XOR of:
 226      *
 227      *  - The chessboard parity ((x^y)&1) of the gap square. The
 228      *    bottom right counts as even.
 229      *
 230      *  - The parity of n. (The target permutation is 1,...,n-1,0
 231      *    rather than 0,...,n-1; this is a cyclic permutation of
 232      *    the starting point and hence is odd iff n is even.)
 233      */
 234     parity = ((X(params, gap) - (params->w-1)) ^
 235               (Y(params, gap) - (params->h-1)) ^
 236               (n+1)) & 1;
 237
 238     /*
 239      * Try the last two tiles one way round. If that fails, swap
 240      * them.
 241      */
 242     tiles[x1] = p1;
 243     tiles[x2] = p2;
 244     if (perm_parity(tiles, n) != parity) {
 245         tiles[x1] = p2;
 246         tiles[x2] = p1;
 247         assert(perm_parity(tiles, n) == parity);
 248     }
 249
 250     /*
 251      * Now construct the game description, by describing the tile
 252      * array as a simple sequence of comma-separated integers.
 253      */
 254     ret = NULL;
 255     retlen = 0;
 256     for (i = 0; i < n; i++) {
 257         char buf[80];
 258         int k;
 259
 260         k = sprintf(buf, "%d,", tiles[i]);
 261
 262         ret = sresize(ret, retlen + k + 1, char);
 263         strcpy(ret + retlen, buf);
 264         retlen += k;
 265     }
 266     ret[retlen-1] = '\0';              /* delete last comma */
 267
 268     sfree(tiles);
 269     sfree(used);
 270
 271     return ret;
 272 }
 273
 274 static char *validate_desc(game_params *params, char *desc)
 275 {
 276     char *p, *err;
 277     int i, area;
 278     int *used;
 279
 280     area = params->w * params->h;
 281     p = desc;
 282     err = NULL;
 283
 284     used = snewn(area, int);
 285     for (i = 0; i < area; i++)
 286         used[i] = FALSE;
 287
 288     for (i = 0; i < area; i++) {
 289         char *q = p;
 290         int n;
 291
 292         if (*p < '0' || *p > '9') {
 293             err = "Not enough numbers in string";
 294             goto leave;
 295         }
 296         while (*p >= '0' && *p <= '9')
 297             p++;
 298         if (i < area-1 && *p != ',') {
 299             err = "Expected comma after number";
 300             goto leave;
 301         }
 302         else if (i == area-1 && *p) {
 303             err = "Excess junk at end of string";
 304             goto leave;
 305         }
 306         n = atoi(q);
 307         if (n < 0 || n >= area) {
 308             err = "Number out of range";
 309             goto leave;
 310         }
 311         if (used[n]) {
 312             err = "Number used twice";
 313             goto leave;
 314         }
 315         used[n] = TRUE;
 316
 317         if (*p) p++;                   /* eat comma */
 318     }
 319
 320     leave:
 321     sfree(used);
 322     return err;
 323 }
 324
 325 static game_state *new_game(midend *me, game_params *params, char *desc)
 326 {
 327     game_state *state = snew(game_state);
 328     int i;
 329     char *p;
 330
 331     state->w = params->w;
 332     state->h = params->h;
 333     state->n = params->w * params->h;
 334     state->tiles = snewn(state->n, int);
 335
 336     state->gap_pos = 0;
 337     p = desc;
 338     i = 0;
 339     for (i = 0; i < state->n; i++) {
 340         assert(*p);
 341         state->tiles[i] = atoi(p);
 342         if (state->tiles[i] == 0)
 343             state->gap_pos = i;
 344         while (*p && *p != ',')
 345             p++;
 346         if (*p) p++;                   /* eat comma */
 347     }
 348     assert(!*p);
 349     assert(state->tiles[state->gap_pos] == 0);
 350
 351     state->completed = state->movecount = 0;
 352     state->used_solve = FALSE;
 353
 354     return state;
 355 }
 356
 357 static game_state *dup_game(game_state *state)
 358 {
 359     game_state *ret = snew(game_state);
 360
 361     ret->w = state->w;
 362     ret->h = state->h;
 363     ret->n = state->n;
 364     ret->tiles = snewn(state->w * state->h, int);
 365     memcpy(ret->tiles, state->tiles, state->w * state->h * sizeof(int));
 366     ret->gap_pos = state->gap_pos;
 367     ret->completed = state->completed;
 368     ret->movecount = state->movecount;
 369     ret->used_solve = state->used_solve;
 370
 371     return ret;
 372 }
 373
 374 static void free_game(game_state *state)
 375 {
 376     sfree(state->tiles);
 377     sfree(state);
 378 }
 379
 380 static char *solve_game(game_state *state, game_state *currstate,
 381                         char *aux, char **error)
 382 {
 383     return dupstr("S");
 384 }
 385
 386 static int game_can_format_as_text_now(game_params *params)
 387 {
 388     return TRUE;
 389 }
 390
 391 static char *game_text_format(game_state *state)
 392 {
 393     char *ret, *p, buf[80];
 394     int x, y, col, maxlen;
 395
 396     /*
 397      * First work out how many characters we need to display each
 398      * number.
 399      */
 400     col = sprintf(buf, "%d", state->n-1);
 401
 402     /*
 403      * Now we know the exact total size of the grid we're going to
 404      * produce: it's got h rows, each containing w lots of col, w-1
 405      * spaces and a trailing newline.
 406      */
 407     maxlen = state->h * state->w * (col+1);
 408
 409     ret = snewn(maxlen+1, char);
 410     p = ret;
 411
 412     for (y = 0; y < state->h; y++) {
 413         for (x = 0; x < state->w; x++) {
 414             int v = state->tiles[state->w*y+x];
 415             if (v == 0)
 416                 sprintf(buf, "%*s", col, "");
 417             else
 418                 sprintf(buf, "%*d", col, v);
 419             memcpy(p, buf, col);
 420             p += col;
 421             if (x+1 == state->w)
 422                 *p++ = '\n';
 423             else
 424                 *p++ = ' ';
 425         }
 426     }
 427
 428     assert(p - ret == maxlen);
 429     *p = '\0';
 430     return ret;
 431 }
 432
 433 static game_ui *new_ui(game_state *state)
 434 {
 435     return NULL;
 436 }
 437
 438 static void free_ui(game_ui *ui)
 439 {
 440 }
 441
 442 static char *encode_ui(game_ui *ui)
 443 {
 444     return NULL;
 445 }
 446
 447 static void decode_ui(game_ui *ui, char *encoding)
 448 {
 449 }
 450
 451 static void game_changed_state(game_ui *ui, game_state *oldstate,
 452                                game_state *newstate)
 453 {
 454 }
 455
 456 struct game_drawstate {
 457     int started;
 458     int w, h, bgcolour;
 459     int *tiles;
 460     int tilesize;
 461 };
 462
 463 static char *interpret_move(game_state *state, game_ui *ui, game_drawstate *ds,
 464                             int x, int y, int button)
 465 {
 466     int gx, gy, dx, dy;
 467     char buf[80];
 468
 469     button &= ~MOD_MASK;
 470
 471     gx = X(state, state->gap_pos);
 472     gy = Y(state, state->gap_pos);
 473
 474     if (button == CURSOR_RIGHT && gx > 0)
 475         dx = gx - 1, dy = gy;
 476     else if (button == CURSOR_LEFT && gx < state->w-1)
 477         dx = gx + 1, dy = gy;
 478     else if (button == CURSOR_DOWN && gy > 0)
 479         dy = gy - 1, dx = gx;
 480     else if (button == CURSOR_UP && gy < state->h-1)
 481         dy = gy + 1, dx = gx;
 482     else if (button == LEFT_BUTTON) {
 483         dx = FROMCOORD(x);
 484         dy = FROMCOORD(y);
 485         if (dx < 0 || dx >= state->w || dy < 0 || dy >= state->h)
 486             return NULL;               /* out of bounds */
 487         /*
 488          * Any click location should be equal to the gap location
 489          * in _precisely_ one coordinate.
 490          */
 491         if ((dx == gx && dy == gy) || (dx != gx && dy != gy))
 492             return NULL;
 493     } else
 494         return NULL;                   /* no move */
 495
 496     sprintf(buf, "M%d,%d", dx, dy);
 497     return dupstr(buf);
 498 }
 499
 500 static game_state *execute_move(game_state *from, char *move)
 501 {
 502     int gx, gy, dx, dy, ux, uy, up, p;
 503     game_state *ret;
 504
 505     if (!strcmp(move, "S")) {
 506         int i;
 507
 508         ret = dup_game(from);
 509
 510         /*
 511          * Simply replace the grid with a solved one. For this game,
 512          * this isn't a useful operation for actually telling the user
 513          * what they should have done, but it is useful for
 514          * conveniently being able to get hold of a clean state from
 515          * which to practise manoeuvres.
 516          */
 517         for (i = 0; i < ret->n; i++)
 518             ret->tiles[i] = (i+1) % ret->n;
 519         ret->gap_pos = ret->n-1;
 520         ret->used_solve = TRUE;
 521         ret->completed = ret->movecount = 1;
 522
 523         return ret;
 524     }
 525
 526     gx = X(from, from->gap_pos);
 527     gy = Y(from, from->gap_pos);
 528
 529     if (move[0] != 'M' ||
 530         sscanf(move+1, "%d,%d", &dx, &dy) != 2 ||
 531         (dx == gx && dy == gy) || (dx != gx && dy != gy) ||
 532         dx < 0 || dx >= from->w || dy < 0 || dy >= from->h)
 533         return NULL;
 534
 535     /*
 536      * Find the unit displacement from the original gap
 537      * position towards this one.
 538      */
 539     ux = (dx < gx ? -1 : dx > gx ? +1 : 0);
 540     uy = (dy < gy ? -1 : dy > gy ? +1 : 0);
 541     up = C(from, ux, uy);
 542
 543     ret = dup_game(from);
 544
 545     ret->gap_pos = C(from, dx, dy);
 546     assert(ret->gap_pos >= 0 && ret->gap_pos < ret->n);
 547
 548     ret->tiles[ret->gap_pos] = 0;
 549
 550     for (p = from->gap_pos; p != ret->gap_pos; p += up) {
 551         assert(p >= 0 && p < from->n);
 552         ret->tiles[p] = from->tiles[p + up];
 553         ret->movecount++;
 554     }
 555
 556     /*
 557      * See if the game has been completed.
 558      */
 559     if (!ret->completed) {
 560         ret->completed = ret->movecount;
 561         for (p = 0; p < ret->n; p++)
 562             if (ret->tiles[p] != (p < ret->n-1 ? p+1 : 0))
 563                 ret->completed = 0;
 564     }
 565
 566     return ret;
 567 }
 568
 569 /* ----------------------------------------------------------------------
 570  * Drawing routines.
 571  */
 572
 573 static void game_compute_size(game_params *params, int tilesize,
 574                               int *x, int *y)
 575 {
 576     /* Ick: fake up `ds->tilesize' for macro expansion purposes */
 577     struct { int tilesize; } ads, *ds = &ads;
 578     ads.tilesize = tilesize;
 579
 580     *x = TILE_SIZE * params->w + 2 * BORDER;
 581     *y = TILE_SIZE * params->h + 2 * BORDER;
 582 }
 583
 584 static void game_set_size(drawing *dr, game_drawstate *ds,
 585                           game_params *params, int tilesize)
 586 {
 587     ds->tilesize = tilesize;
 588 }
 589
 590 static float *game_colours(frontend *fe, int *ncolours)
 591 {
 592     float *ret = snewn(3 * NCOLOURS, float);
 593     int i;
 594
 595     game_mkhighlight(fe, ret, COL_BACKGROUND, COL_HIGHLIGHT, COL_LOWLIGHT);
 596
 597     for (i = 0; i < 3; i++)
 598         ret[COL_TEXT * 3 + i] = 0.0;
 599
 600     *ncolours = NCOLOURS;
 601     return ret;
 602 }
 603
 604 static game_drawstate *game_new_drawstate(drawing *dr, game_state *state)
 605 {
 606     struct game_drawstate *ds = snew(struct game_drawstate);
 607     int i;
 608
 609     ds->started = FALSE;
 610     ds->w = state->w;
 611     ds->h = state->h;
 612     ds->bgcolour = COL_BACKGROUND;
 613     ds->tiles = snewn(ds->w*ds->h, int);
 614     ds->tilesize = 0;                  /* haven't decided yet */
 615     for (i = 0; i < ds->w*ds->h; i++)
 616         ds->tiles[i] = -1;
 617
 618     return ds;
 619 }
 620
 621 static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 622 {
 623     sfree(ds->tiles);
 624     sfree(ds);
 625 }
 626
 627 static void draw_tile(drawing *dr, game_drawstate *ds, game_state *state,
 628                       int x, int y, int tile, int flash_colour)
 629 {
 630     if (tile == 0) {
 631         draw_rect(dr, x, y, TILE_SIZE, TILE_SIZE,
 632                   flash_colour);
 633     } else {
 634         int coords[6];
 635         char str[40];
 636
 637         coords[0] = x + TILE_SIZE - 1;
 638         coords[1] = y + TILE_SIZE - 1;
 639         coords[2] = x + TILE_SIZE - 1;
 640         coords[3] = y;
 641         coords[4] = x;
 642         coords[5] = y + TILE_SIZE - 1;
 643         draw_polygon(dr, coords, 3, COL_LOWLIGHT, COL_LOWLIGHT);
 644
 645         coords[0] = x;
 646         coords[1] = y;
 647         draw_polygon(dr, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
 648
 649         draw_rect(dr, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
 650                   TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
 651                   flash_colour);
 652
 653         sprintf(str, "%d", tile);
 654         draw_text(dr, x + TILE_SIZE/2, y + TILE_SIZE/2,
 655                   FONT_VARIABLE, TILE_SIZE/3, ALIGN_VCENTRE | ALIGN_HCENTRE,
 656                   COL_TEXT, str);
 657     }
 658     draw_update(dr, x, y, TILE_SIZE, TILE_SIZE);
 659 }
 660
 661 static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
 662                  game_state *state, int dir, game_ui *ui,
 663                  float animtime, float flashtime)
 664 {
 665     int i, pass, bgcolour;
 666
 667     if (flashtime > 0) {
 668         int frame = (int)(flashtime / FLASH_FRAME);
 669         bgcolour = (frame % 2 ? COL_LOWLIGHT : COL_HIGHLIGHT);
 670     } else
 671         bgcolour = COL_BACKGROUND;
 672
 673     if (!ds->started) {
 674         int coords[10];
 675
 676         draw_rect(dr, 0, 0,
 677                   TILE_SIZE * state->w + 2 * BORDER,
 678                   TILE_SIZE * state->h + 2 * BORDER, COL_BACKGROUND);
 679         draw_update(dr, 0, 0,
 680                     TILE_SIZE * state->w + 2 * BORDER,
 681                     TILE_SIZE * state->h + 2 * BORDER);
 682
 683         /*
 684          * Recessed area containing the whole puzzle.
 685          */
 686         coords[0] = COORD(state->w) + HIGHLIGHT_WIDTH - 1;
 687         coords[1] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
 688         coords[2] = COORD(state->w) + HIGHLIGHT_WIDTH - 1;
 689         coords[3] = COORD(0) - HIGHLIGHT_WIDTH;
 690         coords[4] = coords[2] - TILE_SIZE;
 691         coords[5] = coords[3] + TILE_SIZE;
 692         coords[8] = COORD(0) - HIGHLIGHT_WIDTH;
 693         coords[9] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
 694         coords[6] = coords[8] + TILE_SIZE;
 695         coords[7] = coords[9] - TILE_SIZE;
 696         draw_polygon(dr, coords, 5, COL_HIGHLIGHT, COL_HIGHLIGHT);
 697
 698         coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
 699         coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
 700         draw_polygon(dr, coords, 5, COL_LOWLIGHT, COL_LOWLIGHT);
 701
 702         ds->started = TRUE;
 703     }
 704
 705     /*
 706      * Now draw each tile. We do this in two passes to make
 707      * animation easy.
 708      */
 709     for (pass = 0; pass < 2; pass++) {
 710         for (i = 0; i < state->n; i++) {
 711             int t, t0;
 712             /*
 713              * Figure out what should be displayed at this
 714              * location. It's either a simple tile, or it's a
 715              * transition between two tiles (in which case we say
 716              * -1 because it must always be drawn).
 717              */
 718
 719             if (oldstate && oldstate->tiles[i] != state->tiles[i])
 720                 t = -1;
 721             else
 722                 t = state->tiles[i];
 723
 724             t0 = t;
 725
 726             if (ds->bgcolour != bgcolour ||   /* always redraw when flashing */
 727                 ds->tiles[i] != t || ds->tiles[i] == -1 || t == -1) {
 728                 int x, y;
 729
 730                 /*
 731                  * Figure out what to _actually_ draw, and where to
 732                  * draw it.
 733                  */
 734                 if (t == -1) {
 735                     int x0, y0, x1, y1;
 736                     int j;
 737
 738                     /*
 739                      * On the first pass, just blank the tile.
 740                      */
 741                     if (pass == 0) {
 742                         x = COORD(X(state, i));
 743                         y = COORD(Y(state, i));
 744                         t = 0;
 745                     } else {
 746                         float c;
 747
 748                         t = state->tiles[i];
 749
 750                         /*
 751                          * Don't bother moving the gap; just don't
 752                          * draw it.
 753                          */
 754                         if (t == 0)
 755                             continue;
 756
 757                         /*
 758                          * Find the coordinates of this tile in the old and
 759                          * new states.
 760                          */
 761                         x1 = COORD(X(state, i));
 762                         y1 = COORD(Y(state, i));
 763                         for (j = 0; j < oldstate->n; j++)
 764                             if (oldstate->tiles[j] == state->tiles[i])
 765                                 break;
 766                         assert(j < oldstate->n);
 767                         x0 = COORD(X(state, j));
 768                         y0 = COORD(Y(state, j));
 769
 770                         c = (animtime / ANIM_TIME);
 771                         if (c < 0.0F) c = 0.0F;
 772                         if (c > 1.0F) c = 1.0F;
 773
 774                         x = x0 + (int)(c * (x1 - x0));
 775                         y = y0 + (int)(c * (y1 - y0));
 776                     }
 777
 778                 } else {
 779                     if (pass == 0)
 780                         continue;
 781                     x = COORD(X(state, i));
 782                     y = COORD(Y(state, i));
 783                 }
 784
 785                 draw_tile(dr, ds, state, x, y, t, bgcolour);
 786             }
 787             ds->tiles[i] = t0;
 788         }
 789     }
 790     ds->bgcolour = bgcolour;
 791
 792     /*
 793      * Update the status bar.
 794      */
 795     {
 796         char statusbuf[256];
 797
 798         /*
 799          * Don't show the new status until we're also showing the
 800          * new _state_ - after the game animation is complete.
 801          */
 802         if (oldstate)
 803             state = oldstate;
 804
 805         if (state->used_solve)
 806             sprintf(statusbuf, "Moves since auto-solve: %d",
 807                     state->movecount - state->completed);
 808         else
 809             sprintf(statusbuf, "%sMoves: %d",
 810                     (state->completed ? "COMPLETED! " : ""),
 811                     (state->completed ? state->completed : state->movecount));
 812
 813         status_bar(dr, statusbuf);
 814     }
 815 }
 816
 817 static float game_anim_length(game_state *oldstate,
 818                               game_state *newstate, int dir, game_ui *ui)
 819 {
 820     return ANIM_TIME;
 821 }
 822
 823 static float game_flash_length(game_state *oldstate,
 824                                game_state *newstate, int dir, game_ui *ui)
 825 {
 826     if (!oldstate->completed && newstate->completed &&
 827         !oldstate->used_solve && !newstate->used_solve)
 828         return 2 * FLASH_FRAME;
 829     else
 830         return 0.0F;
 831 }
 832
 833 static int game_status(game_state *state)
 834 {
 835     return state->completed ? +1 : 0;
 836 }
 837
 838 static int game_timing_state(game_state *state, game_ui *ui)
 839 {
 840     return TRUE;
 841 }
 842
 843 static void game_print_size(game_params *params, float *x, float *y)
 844 {
 845 }
 846
 847 static void game_print(drawing *dr, game_state *state, int tilesize)
 848 {
 849 }
 850
 851 #ifdef COMBINED
 852 #define thegame fifteen
 853 #endif
 854
 855 const struct game thegame = {
 856     "Fifteen", "games.fifteen", "fifteen",
 857     default_params,
 858     game_fetch_preset,
 859     decode_params,
 860     encode_params,
 861     free_params,
 862     dup_params,
 863     TRUE, game_configure, custom_params,
 864     validate_params,
 865     new_game_desc,
 866     validate_desc,
 867     new_game,
 868     dup_game,
 869     free_game,
 870     TRUE, solve_game,
 871     TRUE, game_can_format_as_text_now, game_text_format,
 872     new_ui,
 873     free_ui,
 874     encode_ui,
 875     decode_ui,
 876     game_changed_state,
 877     interpret_move,
 878     execute_move,
 879     PREFERRED_TILE_SIZE, game_compute_size, game_set_size,
 880     game_colours,
 881     game_new_drawstate,
 882     game_free_drawstate,
 883     game_redraw,
 884     game_anim_length,
 885     game_flash_length,
 886     game_status,
 887     FALSE, FALSE, game_print_size, game_print,
 888     TRUE,                              /* wants_statusbar */
 889     FALSE, game_timing_state,
 890     0,                                 /* flags */
 891 };