mdw@git.distorted.org.uk Git - sgt/puzzles/blob - sixteen.c

   1 /*
   2  * sixteen.c: `16-puzzle', a sliding-tiles jigsaw which differs
   3  * from the 15-puzzle in that you toroidally rotate a row or column
   4  * at a time.
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <assert.h>
  11 #include <ctype.h>
  12 #include <math.h>
  13
  14 #include "puzzles.h"
  15
  16 #define TILE_SIZE 48
  17 #define BORDER    TILE_SIZE            /* big border to fill with arrows */
  18 #define HIGHLIGHT_WIDTH (TILE_SIZE / 20)
  19 #define COORD(x)  ( (x) * TILE_SIZE + BORDER )
  20 #define FROMCOORD(x)  ( ((x) - BORDER + 2*TILE_SIZE) / TILE_SIZE - 2 )
  21
  22 #define ANIM_TIME 0.13F
  23 #define FLASH_FRAME 0.13F
  24
  25 #define X(state, i) ( (i) % (state)->w )
  26 #define Y(state, i) ( (i) / (state)->w )
  27 #define C(state, x, y) ( (y) * (state)->w + (x) )
  28
  29 enum {
  30     COL_BACKGROUND,
  31     COL_TEXT,
  32     COL_HIGHLIGHT,
  33     COL_LOWLIGHT,
  34     NCOLOURS
  35 };
  36
  37 struct game_params {
  38     int w, h;
  39 };
  40
  41 struct game_state {
  42     int w, h, n;
  43     int *tiles;
  44     int completed;
  45     int movecount;
  46     int last_movement_sense;
  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     game_params *ret;
  61     int w, h;
  62     char buf[80];
  63
  64     switch (i) {
  65       case 0: w = 3, h = 3; break;
  66       case 1: w = 4, h = 3; break;
  67       case 2: w = 4, h = 4; break;
  68       case 3: w = 5, h = 4; break;
  69       case 4: w = 5, h = 5; break;
  70       default: return FALSE;
  71     }
  72
  73     sprintf(buf, "%dx%d", w, h);
  74     *name = dupstr(buf);
  75     *params = ret = snew(game_params);
  76     ret->w = w;
  77     ret->h = h;
  78     return TRUE;
  79 }
  80
  81 static void free_params(game_params *params)
  82 {
  83     sfree(params);
  84 }
  85
  86 static game_params *dup_params(game_params *params)
  87 {
  88     game_params *ret = snew(game_params);
  89     *ret = *params;                    /* structure copy */
  90     return ret;
  91 }
  92
  93 static game_params *decode_params(char const *string)
  94 {
  95     game_params *ret = default_params();
  96
  97     ret->w = ret->h = atoi(string);
  98     while (*string && isdigit(*string)) string++;
  99     if (*string == 'x') {
 100         string++;
 101         ret->h = atoi(string);
 102     }
 103
 104     return ret;
 105 }
 106
 107 static char *encode_params(game_params *params)
 108 {
 109     char data[256];
 110
 111     sprintf(data, "%dx%d", params->w, params->h);
 112
 113     return dupstr(data);
 114 }
 115
 116 static config_item *game_configure(game_params *params)
 117 {
 118     config_item *ret;
 119     char buf[80];
 120
 121     ret = snewn(3, config_item);
 122
 123     ret[0].name = "Width";
 124     ret[0].type = C_STRING;
 125     sprintf(buf, "%d", params->w);
 126     ret[0].sval = dupstr(buf);
 127     ret[0].ival = 0;
 128
 129     ret[1].name = "Height";
 130     ret[1].type = C_STRING;
 131     sprintf(buf, "%d", params->h);
 132     ret[1].sval = dupstr(buf);
 133     ret[1].ival = 0;
 134
 135     ret[2].name = NULL;
 136     ret[2].type = C_END;
 137     ret[2].sval = NULL;
 138     ret[2].ival = 0;
 139
 140     return ret;
 141 }
 142
 143 static game_params *custom_params(config_item *cfg)
 144 {
 145     game_params *ret = snew(game_params);
 146
 147     ret->w = atoi(cfg[0].sval);
 148     ret->h = atoi(cfg[1].sval);
 149
 150     return ret;
 151 }
 152
 153 static char *validate_params(game_params *params)
 154 {
 155     if (params->w < 2 && params->h < 2)
 156         return "Width and height must both be at least two";
 157
 158     return NULL;
 159 }
 160
 161 static int perm_parity(int *perm, int n)
 162 {
 163     int i, j, ret;
 164
 165     ret = 0;
 166
 167     for (i = 0; i < n-1; i++)
 168         for (j = i+1; j < n; j++)
 169             if (perm[i] > perm[j])
 170                 ret = !ret;
 171
 172     return ret;
 173 }
 174
 175 static char *new_game_seed(game_params *params, random_state *rs,
 176                            game_aux_info **aux)
 177 {
 178     int stop, n, i, x;
 179     int x1, x2, p1, p2;
 180     int *tiles, *used;
 181     char *ret;
 182     int retlen;
 183
 184     n = params->w * params->h;
 185
 186     tiles = snewn(n, int);
 187     used = snewn(n, int);
 188
 189     for (i = 0; i < n; i++) {
 190         tiles[i] = -1;
 191         used[i] = FALSE;
 192     }
 193
 194     /*
 195      * If both dimensions are odd, there is a parity constraint.
 196      */
 197     if (params->w & params->h & 1)
 198         stop = 2;
 199     else
 200         stop = 0;
 201
 202     /*
 203      * Place everything except (possibly) the last two tiles.
 204      */
 205     for (x = 0, i = n; i > stop; i--) {
 206         int k = i > 1 ? random_upto(rs, i) : 0;
 207         int j;
 208
 209         for (j = 0; j < n; j++)
 210             if (!used[j] && (k-- == 0))
 211                 break;
 212
 213         assert(j < n && !used[j]);
 214         used[j] = TRUE;
 215
 216         while (tiles[x] >= 0)
 217             x++;
 218         assert(x < n);
 219         tiles[x] = j;
 220     }
 221
 222     if (stop) {
 223         /*
 224          * Find the last two locations, and the last two pieces.
 225          */
 226         while (tiles[x] >= 0)
 227             x++;
 228         assert(x < n);
 229         x1 = x;
 230         x++;
 231         while (tiles[x] >= 0)
 232             x++;
 233         assert(x < n);
 234         x2 = x;
 235
 236         for (i = 0; i < n; i++)
 237             if (!used[i])
 238                 break;
 239         p1 = i;
 240         for (i = p1+1; i < n; i++)
 241             if (!used[i])
 242                 break;
 243         p2 = i;
 244
 245         /*
 246          * Try the last two tiles one way round. If that fails, swap
 247          * them.
 248          */
 249         tiles[x1] = p1;
 250         tiles[x2] = p2;
 251         if (perm_parity(tiles, n) != 0) {
 252             tiles[x1] = p2;
 253             tiles[x2] = p1;
 254             assert(perm_parity(tiles, n) == 0);
 255         }
 256     }
 257
 258     /*
 259      * Now construct the game seed, by describing the tile array as
 260      * a simple sequence of comma-separated integers.
 261      */
 262     ret = NULL;
 263     retlen = 0;
 264     for (i = 0; i < n; i++) {
 265         char buf[80];
 266         int k;
 267
 268         k = sprintf(buf, "%d,", tiles[i]+1);
 269
 270         ret = sresize(ret, retlen + k + 1, char);
 271         strcpy(ret + retlen, buf);
 272         retlen += k;
 273     }
 274     ret[retlen-1] = '\0';              /* delete last comma */
 275
 276     sfree(tiles);
 277     sfree(used);
 278
 279     return ret;
 280 }
 281
 282 void game_free_aux_info(game_aux_info *aux)
 283 {
 284     assert(!"Shouldn't happen");
 285 }
 286
 287
 288 static char *validate_seed(game_params *params, char *seed)
 289 {
 290     char *p, *err;
 291     int i, area;
 292     int *used;
 293
 294     area = params->w * params->h;
 295     p = seed;
 296     err = NULL;
 297
 298     used = snewn(area, int);
 299     for (i = 0; i < area; i++)
 300         used[i] = FALSE;
 301
 302     for (i = 0; i < area; i++) {
 303         char *q = p;
 304         int n;
 305
 306         if (*p < '0' || *p > '9') {
 307             err = "Not enough numbers in string";
 308             goto leave;
 309         }
 310         while (*p >= '0' && *p <= '9')
 311             p++;
 312         if (i < area-1 && *p != ',') {
 313             err = "Expected comma after number";
 314             goto leave;
 315         }
 316         else if (i == area-1 && *p) {
 317             err = "Excess junk at end of string";
 318             goto leave;
 319         }
 320         n = atoi(q);
 321         if (n < 1 || n > area) {
 322             err = "Number out of range";
 323             goto leave;
 324         }
 325         if (used[n-1]) {
 326             err = "Number used twice";
 327             goto leave;
 328         }
 329         used[n-1] = TRUE;
 330
 331         if (*p) p++;                   /* eat comma */
 332     }
 333
 334     leave:
 335     sfree(used);
 336     return err;
 337 }
 338
 339 static game_state *new_game(game_params *params, char *seed)
 340 {
 341     game_state *state = snew(game_state);
 342     int i;
 343     char *p;
 344
 345     state->w = params->w;
 346     state->h = params->h;
 347     state->n = params->w * params->h;
 348     state->tiles = snewn(state->n, int);
 349
 350     p = seed;
 351     i = 0;
 352     for (i = 0; i < state->n; i++) {
 353         assert(*p);
 354         state->tiles[i] = atoi(p);
 355         while (*p && *p != ',')
 356             p++;
 357         if (*p) p++;                   /* eat comma */
 358     }
 359     assert(!*p);
 360
 361     state->completed = state->movecount = 0;
 362     state->last_movement_sense = 0;
 363
 364     return state;
 365 }
 366
 367 static game_state *dup_game(game_state *state)
 368 {
 369     game_state *ret = snew(game_state);
 370
 371     ret->w = state->w;
 372     ret->h = state->h;
 373     ret->n = state->n;
 374     ret->tiles = snewn(state->w * state->h, int);
 375     memcpy(ret->tiles, state->tiles, state->w * state->h * sizeof(int));
 376     ret->completed = state->completed;
 377     ret->movecount = state->movecount;
 378     ret->last_movement_sense = state->last_movement_sense;
 379
 380     return ret;
 381 }
 382
 383 static void free_game(game_state *state)
 384 {
 385     sfree(state);
 386 }
 387
 388 static char *game_text_format(game_state *state)
 389 {
 390     char *ret, *p, buf[80];
 391     int x, y, col, maxlen;
 392
 393     /*
 394      * First work out how many characters we need to display each
 395      * number.
 396      */
 397     col = sprintf(buf, "%d", state->n);
 398
 399     /*
 400      * Now we know the exact total size of the grid we're going to
 401      * produce: it's got h rows, each containing w lots of col, w-1
 402      * spaces and a trailing newline.
 403      */
 404     maxlen = state->h * state->w * (col+1);
 405
 406     ret = snewn(maxlen, char);
 407     p = ret;
 408
 409     for (y = 0; y < state->h; y++) {
 410         for (x = 0; x < state->w; x++) {
 411             int v = state->tiles[state->w*y+x];
 412             sprintf(buf, "%*d", col, v);
 413             memcpy(p, buf, col);
 414             p += col;
 415             if (x+1 == state->w)
 416                 *p++ = '\n';
 417             else
 418                 *p++ = ' ';
 419         }
 420     }
 421
 422     assert(p - ret == maxlen);
 423     *p = '\0';
 424     return ret;
 425 }
 426
 427 static game_ui *new_ui(game_state *state)
 428 {
 429     return NULL;
 430 }
 431
 432 static void free_ui(game_ui *ui)
 433 {
 434 }
 435
 436 static game_state *make_move(game_state *from, game_ui *ui,
 437                              int x, int y, int button)
 438 {
 439     int cx, cy;
 440     int dx, dy, tx, ty, n;
 441     game_state *ret;
 442
 443     if (button != LEFT_BUTTON && button != RIGHT_BUTTON)
 444         return NULL;
 445
 446     cx = FROMCOORD(x);
 447     cy = FROMCOORD(y);
 448     if (cx == -1 && cy >= 0 && cy < from->h)
 449         n = from->w, dx = +1, dy = 0;
 450     else if (cx == from->w && cy >= 0 && cy < from->h)
 451         n = from->w, dx = -1, dy = 0;
 452     else if (cy == -1 && cx >= 0 && cx < from->w)
 453         n = from->h, dy = +1, dx = 0;
 454     else if (cy == from->h && cx >= 0 && cx < from->w)
 455         n = from->h, dy = -1, dx = 0;
 456     else
 457         return NULL;                   /* invalid click location */
 458
 459     /* reverse direction if right hand button is pressed */
 460     if (button == RIGHT_BUTTON)
 461     {
 462         dx = -dx; if (dx) cx = from->w - 1 - cx;
 463         dy = -dy; if (dy) cy = from->h - 1 - cy;
 464     }
 465
 466     ret = dup_game(from);
 467
 468     do {
 469         cx += dx;
 470         cy += dy;
 471         tx = (cx + dx + from->w) % from->w;
 472         ty = (cy + dy + from->h) % from->h;
 473         ret->tiles[C(ret, cx, cy)] = from->tiles[C(from, tx, ty)];
 474     } while (--n > 0);
 475
 476     ret->movecount++;
 477
 478     ret->last_movement_sense = -(dx+dy);
 479
 480     /*
 481      * See if the game has been completed.
 482      */
 483     if (!ret->completed) {
 484         ret->completed = ret->movecount;
 485         for (n = 0; n < ret->n; n++)
 486             if (ret->tiles[n] != n+1)
 487                 ret->completed = FALSE;
 488     }
 489
 490     return ret;
 491 }
 492
 493 /* ----------------------------------------------------------------------
 494  * Drawing routines.
 495  */
 496
 497 struct game_drawstate {
 498     int started;
 499     int w, h, bgcolour;
 500     int *tiles;
 501 };
 502
 503 static void game_size(game_params *params, int *x, int *y)
 504 {
 505     *x = TILE_SIZE * params->w + 2 * BORDER;
 506     *y = TILE_SIZE * params->h + 2 * BORDER;
 507 }
 508
 509 static float *game_colours(frontend *fe, game_state *state, int *ncolours)
 510 {
 511     float *ret = snewn(3 * NCOLOURS, float);
 512     int i;
 513     float max;
 514
 515     frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
 516
 517     /*
 518      * Drop the background colour so that the highlight is
 519      * noticeably brighter than it while still being under 1.
 520      */
 521     max = ret[COL_BACKGROUND*3];
 522     for (i = 1; i < 3; i++)
 523         if (ret[COL_BACKGROUND*3+i] > max)
 524             max = ret[COL_BACKGROUND*3+i];
 525     if (max * 1.2F > 1.0F) {
 526         for (i = 0; i < 3; i++)
 527             ret[COL_BACKGROUND*3+i] /= (max * 1.2F);
 528     }
 529
 530     for (i = 0; i < 3; i++) {
 531         ret[COL_HIGHLIGHT * 3 + i] = ret[COL_BACKGROUND * 3 + i] * 1.2F;
 532         ret[COL_LOWLIGHT * 3 + i] = ret[COL_BACKGROUND * 3 + i] * 0.8F;
 533         ret[COL_TEXT * 3 + i] = 0.0;
 534     }
 535
 536     *ncolours = NCOLOURS;
 537     return ret;
 538 }
 539
 540 static game_drawstate *game_new_drawstate(game_state *state)
 541 {
 542     struct game_drawstate *ds = snew(struct game_drawstate);
 543     int i;
 544
 545     ds->started = FALSE;
 546     ds->w = state->w;
 547     ds->h = state->h;
 548     ds->bgcolour = COL_BACKGROUND;
 549     ds->tiles = snewn(ds->w*ds->h, int);
 550     for (i = 0; i < ds->w*ds->h; i++)
 551         ds->tiles[i] = -1;
 552
 553     return ds;
 554 }
 555
 556 static void game_free_drawstate(game_drawstate *ds)
 557 {
 558     sfree(ds->tiles);
 559     sfree(ds);
 560 }
 561
 562 static void draw_tile(frontend *fe, game_state *state, int x, int y,
 563                       int tile, int flash_colour)
 564 {
 565     if (tile == 0) {
 566         draw_rect(fe, x, y, TILE_SIZE, TILE_SIZE,
 567                   flash_colour);
 568     } else {
 569         int coords[6];
 570         char str[40];
 571
 572         coords[0] = x + TILE_SIZE - 1;
 573         coords[1] = y + TILE_SIZE - 1;
 574         coords[2] = x + TILE_SIZE - 1;
 575         coords[3] = y;
 576         coords[4] = x;
 577         coords[5] = y + TILE_SIZE - 1;
 578         draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT);
 579         draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT);
 580
 581         coords[0] = x;
 582         coords[1] = y;
 583         draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
 584         draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT);
 585
 586         draw_rect(fe, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
 587                   TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
 588                   flash_colour);
 589
 590         sprintf(str, "%d", tile);
 591         draw_text(fe, x + TILE_SIZE/2, y + TILE_SIZE/2,
 592                   FONT_VARIABLE, TILE_SIZE/3, ALIGN_VCENTRE | ALIGN_HCENTRE,
 593                   COL_TEXT, str);
 594     }
 595     draw_update(fe, x, y, TILE_SIZE, TILE_SIZE);
 596 }
 597
 598 static void draw_arrow(frontend *fe, int x, int y, int xdx, int xdy)
 599 {
 600     int coords[14];
 601     int ydy = -xdx, ydx = xdy;
 602
 603 #define POINT(n, xx, yy) ( \
 604     coords[2*(n)+0] = x + (xx)*xdx + (yy)*ydx, \
 605     coords[2*(n)+1] = y + (xx)*xdy + (yy)*ydy)
 606
 607     POINT(0, TILE_SIZE / 2, 3 * TILE_SIZE / 4);   /* top of arrow */
 608     POINT(1, 3 * TILE_SIZE / 4, TILE_SIZE / 2);   /* right corner */
 609     POINT(2, 5 * TILE_SIZE / 8, TILE_SIZE / 2);   /* right concave */
 610     POINT(3, 5 * TILE_SIZE / 8, TILE_SIZE / 4);   /* bottom right */
 611     POINT(4, 3 * TILE_SIZE / 8, TILE_SIZE / 4);   /* bottom left */
 612     POINT(5, 3 * TILE_SIZE / 8, TILE_SIZE / 2);   /* left concave */
 613     POINT(6,     TILE_SIZE / 4, TILE_SIZE / 2);   /* left corner */
 614
 615     draw_polygon(fe, coords, 7, TRUE, COL_LOWLIGHT);
 616     draw_polygon(fe, coords, 7, FALSE, COL_TEXT);
 617 }
 618
 619 static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 620                  game_state *state, int dir, game_ui *ui,
 621                  float animtime, float flashtime)
 622 {
 623     int i, bgcolour;
 624
 625     if (flashtime > 0) {
 626         int frame = (int)(flashtime / FLASH_FRAME);
 627         bgcolour = (frame % 2 ? COL_LOWLIGHT : COL_HIGHLIGHT);
 628     } else
 629         bgcolour = COL_BACKGROUND;
 630
 631     if (!ds->started) {
 632         int coords[6];
 633
 634         draw_rect(fe, 0, 0,
 635                   TILE_SIZE * state->w + 2 * BORDER,
 636                   TILE_SIZE * state->h + 2 * BORDER, COL_BACKGROUND);
 637         draw_update(fe, 0, 0,
 638                     TILE_SIZE * state->w + 2 * BORDER,
 639                     TILE_SIZE * state->h + 2 * BORDER);
 640
 641         /*
 642          * Recessed area containing the whole puzzle.
 643          */
 644         coords[0] = COORD(state->w) + HIGHLIGHT_WIDTH - 1;
 645         coords[1] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
 646         coords[2] = COORD(state->w) + HIGHLIGHT_WIDTH - 1;
 647         coords[3] = COORD(0) - HIGHLIGHT_WIDTH;
 648         coords[4] = COORD(0) - HIGHLIGHT_WIDTH;
 649         coords[5] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
 650         draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
 651         draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT);
 652
 653         coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
 654         coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
 655         draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT);
 656         draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT);
 657
 658         /*
 659          * Arrows for making moves.
 660          */
 661         for (i = 0; i < state->w; i++) {
 662             draw_arrow(fe, COORD(i), COORD(0), +1, 0);
 663             draw_arrow(fe, COORD(i+1), COORD(state->h), -1, 0);
 664         }
 665         for (i = 0; i < state->h; i++) {
 666             draw_arrow(fe, COORD(state->w), COORD(i), 0, +1);
 667             draw_arrow(fe, COORD(0), COORD(i+1), 0, -1);
 668         }
 669
 670         ds->started = TRUE;
 671     }
 672
 673     /*
 674      * Now draw each tile.
 675      */
 676
 677     clip(fe, COORD(0), COORD(0), TILE_SIZE*state->w, TILE_SIZE*state->h);
 678
 679     for (i = 0; i < state->n; i++) {
 680         int t, t0;
 681         /*
 682          * Figure out what should be displayed at this
 683          * location. It's either a simple tile, or it's a
 684          * transition between two tiles (in which case we say
 685          * -1 because it must always be drawn).
 686          */
 687
 688         if (oldstate && oldstate->tiles[i] != state->tiles[i])
 689             t = -1;
 690         else
 691             t = state->tiles[i];
 692
 693         t0 = t;
 694
 695         if (ds->bgcolour != bgcolour ||   /* always redraw when flashing */
 696             ds->tiles[i] != t || ds->tiles[i] == -1 || t == -1) {
 697             int x, y, x2, y2;
 698
 699             /*
 700              * Figure out what to _actually_ draw, and where to
 701              * draw it.
 702              */
 703             if (t == -1) {
 704                 int x0, y0, x1, y1, dx, dy;
 705                 int j;
 706                 float c;
 707                 int sense;
 708
 709                 if (dir < 0) {
 710                     assert(oldstate);
 711                     sense = -oldstate->last_movement_sense;
 712                 } else {
 713                     sense = state->last_movement_sense;
 714                 }
 715
 716                 t = state->tiles[i];
 717
 718                 /*
 719                  * FIXME: must be prepared to draw a double
 720                  * tile in some situations.
 721                  */
 722
 723                 /*
 724                  * Find the coordinates of this tile in the old and
 725                  * new states.
 726                  */
 727                 x1 = COORD(X(state, i));
 728                 y1 = COORD(Y(state, i));
 729                 for (j = 0; j < oldstate->n; j++)
 730                     if (oldstate->tiles[j] == state->tiles[i])
 731                         break;
 732                 assert(j < oldstate->n);
 733                 x0 = COORD(X(state, j));
 734                 y0 = COORD(Y(state, j));
 735
 736                 dx = (x1 - x0);
 737                 if (dx != 0 &&
 738                     dx != TILE_SIZE * sense) {
 739                     dx = (dx < 0 ? dx + TILE_SIZE * state->w :
 740                           dx - TILE_SIZE * state->w);
 741                     assert(abs(dx) == TILE_SIZE);
 742                 }
 743                 dy = (y1 - y0);
 744                 if (dy != 0 &&
 745                     dy != TILE_SIZE * sense) {
 746                     dy = (dy < 0 ? dy + TILE_SIZE * state->h :
 747                           dy - TILE_SIZE * state->h);
 748                     assert(abs(dy) == TILE_SIZE);
 749                 }
 750
 751                 c = (animtime / ANIM_TIME);
 752                 if (c < 0.0F) c = 0.0F;
 753                 if (c > 1.0F) c = 1.0F;
 754
 755                 x = x0 + (int)(c * dx);
 756                 y = y0 + (int)(c * dy);
 757                 x2 = x1 - dx + (int)(c * dx);
 758                 y2 = y1 - dy + (int)(c * dy);
 759             } else {
 760                 x = COORD(X(state, i));
 761                 y = COORD(Y(state, i));
 762                 x2 = y2 = -1;
 763             }
 764
 765             draw_tile(fe, state, x, y, t, bgcolour);
 766             if (x2 != -1 || y2 != -1)
 767                 draw_tile(fe, state, x2, y2, t, bgcolour);
 768         }
 769         ds->tiles[i] = t0;
 770     }
 771
 772     unclip(fe);
 773
 774     ds->bgcolour = bgcolour;
 775
 776     /*
 777      * Update the status bar.
 778      */
 779     {
 780         char statusbuf[256];
 781
 782         /*
 783          * Don't show the new status until we're also showing the
 784          * new _state_ - after the game animation is complete.
 785          */
 786         if (oldstate)
 787             state = oldstate;
 788
 789         sprintf(statusbuf, "%sMoves: %d",
 790                 (state->completed ? "COMPLETED! " : ""),
 791                 (state->completed ? state->completed : state->movecount));
 792
 793         status_bar(fe, statusbuf);
 794     }
 795 }
 796
 797 static float game_anim_length(game_state *oldstate,
 798                               game_state *newstate, int dir)
 799 {
 800     return ANIM_TIME;
 801 }
 802
 803 static float game_flash_length(game_state *oldstate,
 804                                game_state *newstate, int dir)
 805 {
 806     if (!oldstate->completed && newstate->completed)
 807         return 2 * FLASH_FRAME;
 808     else
 809         return 0.0F;
 810 }
 811
 812 static int game_wants_statusbar(void)
 813 {
 814     return TRUE;
 815 }
 816
 817 #ifdef COMBINED
 818 #define thegame sixteen
 819 #endif
 820
 821 const struct game thegame = {
 822     "Sixteen", "games.sixteen",
 823     default_params,
 824     game_fetch_preset,
 825     decode_params,
 826     encode_params,
 827     free_params,
 828     dup_params,
 829     TRUE, game_configure, custom_params,
 830     validate_params,
 831     new_game_seed,
 832     game_free_aux_info,
 833     validate_seed,
 834     new_game,
 835     dup_game,
 836     free_game,
 837     TRUE, game_text_format,
 838     new_ui,
 839     free_ui,
 840     make_move,
 841     game_size,
 842     game_colours,
 843     game_new_drawstate,
 844     game_free_drawstate,
 845     game_redraw,
 846     game_anim_length,
 847     game_flash_length,
 848     game_wants_statusbar,
 849 };