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