720a8fb7 |
1 | /* |
2 | * net.c: Net game. |
3 | */ |
4 | |
5 | #include <stdio.h> |
6 | #include <stdlib.h> |
7 | #include <string.h> |
8 | #include <assert.h> |
9 | |
10 | #include "puzzles.h" |
11 | #include "tree234.h" |
12 | |
13 | /* Direction bitfields */ |
14 | #define R 0x01 |
15 | #define U 0x02 |
16 | #define L 0x04 |
17 | #define D 0x08 |
18 | #define LOCKED 0x10 |
19 | |
20 | /* Rotations: Anticlockwise, Clockwise, Flip, general rotate */ |
21 | #define A(x) ( (((x) & 0x07) << 1) | (((x) & 0x08) >> 3) ) |
22 | #define C(x) ( (((x) & 0x0E) >> 1) | (((x) & 0x01) << 3) ) |
23 | #define F(x) ( (((x) & 0x0C) >> 2) | (((x) & 0x03) << 2) ) |
24 | #define ROT(x, n) ( ((n)&3) == 0 ? (x) : \ |
25 | ((n)&3) == 1 ? A(x) : \ |
26 | ((n)&3) == 2 ? F(x) : C(x) ) |
27 | |
28 | /* X and Y displacements */ |
29 | #define X(x) ( (x) == R ? +1 : (x) == L ? -1 : 0 ) |
30 | #define Y(x) ( (x) == D ? +1 : (x) == U ? -1 : 0 ) |
31 | |
32 | /* Bit count */ |
33 | #define COUNT(x) ( (((x) & 0x08) >> 3) + (((x) & 0x04) >> 2) + \ |
34 | (((x) & 0x02) >> 1) + ((x) & 0x01) ) |
35 | |
36 | #define TILE_SIZE 32 |
37 | #define TILE_BORDER 1 |
38 | #define WINDOW_OFFSET 16 |
39 | |
40 | struct game_params { |
41 | int width; |
42 | int height; |
43 | int wrapping; |
44 | float barrier_probability; |
45 | }; |
46 | |
47 | struct game_state { |
48 | int width, height, wrapping, completed; |
49 | unsigned char *tiles; |
50 | unsigned char *barriers; |
51 | }; |
52 | |
53 | #define OFFSET(x2,y2,x1,y1,dir,state) \ |
54 | ( (x2) = ((x1) + (state)->width + X((dir))) % (state)->width, \ |
55 | (y2) = ((y1) + (state)->height + Y((dir))) % (state)->height) |
56 | |
57 | #define index(state, a, x, y) ( a[(y) * (state)->width + (x)] ) |
58 | #define tile(state, x, y) index(state, (state)->tiles, x, y) |
59 | #define barrier(state, x, y) index(state, (state)->barriers, x, y) |
60 | |
61 | struct xyd { |
62 | int x, y, direction; |
63 | }; |
64 | |
65 | static int xyd_cmp(void *av, void *bv) { |
66 | struct xyd *a = (struct xyd *)av; |
67 | struct xyd *b = (struct xyd *)bv; |
68 | if (a->x < b->x) |
69 | return -1; |
70 | if (a->x > b->x) |
71 | return +1; |
72 | if (a->y < b->y) |
73 | return -1; |
74 | if (a->y > b->y) |
75 | return +1; |
76 | if (a->direction < b->direction) |
77 | return -1; |
78 | if (a->direction > b->direction) |
79 | return +1; |
80 | return 0; |
81 | }; |
82 | |
83 | static struct xyd *new_xyd(int x, int y, int direction) |
84 | { |
85 | struct xyd *xyd = snew(struct xyd); |
86 | xyd->x = x; |
87 | xyd->y = y; |
88 | xyd->direction = direction; |
89 | return xyd; |
90 | } |
91 | |
92 | /* ---------------------------------------------------------------------- |
93 | * Randomly select a new game seed. |
94 | */ |
95 | |
96 | char *new_game_seed(game_params *params) |
97 | { |
98 | /* |
99 | * The full description of a Net game is far too large to |
100 | * encode directly in the seed, so by default we'll have to go |
101 | * for the simple approach of providing a random-number seed. |
102 | * |
103 | * (This does not restrict me from _later on_ inventing a seed |
104 | * string syntax which can never be generated by this code - |
105 | * for example, strings beginning with a letter - allowing me |
106 | * to type in a precise game, and have new_game detect it and |
107 | * understand it and do something completely different.) |
108 | */ |
109 | char buf[40]; |
110 | sprintf(buf, "%d", rand()); |
111 | return dupstr(buf); |
112 | } |
113 | |
114 | /* ---------------------------------------------------------------------- |
115 | * Construct an initial game state, given a seed and parameters. |
116 | */ |
117 | |
118 | game_state *new_game(game_params *params, char *seed) |
119 | { |
120 | random_state *rs; |
121 | game_state *state; |
122 | tree234 *possibilities, *barriers; |
123 | int w, h, x, y, nbarriers; |
124 | |
125 | assert(params->width > 2); |
126 | assert(params->height > 2); |
127 | |
128 | /* |
129 | * Create a blank game state. |
130 | */ |
131 | state = snew(game_state); |
132 | w = state->width = params->width; |
133 | h = state->height = params->height; |
134 | state->wrapping = params->wrapping; |
135 | state->completed = FALSE; |
136 | state->tiles = snewn(state->width * state->height, unsigned char); |
137 | memset(state->tiles, 0, state->width * state->height); |
138 | state->barriers = snewn(state->width * state->height, unsigned char); |
139 | memset(state->barriers, 0, state->width * state->height); |
140 | |
141 | /* |
142 | * Set up border barriers if this is a non-wrapping game. |
143 | */ |
144 | if (!state->wrapping) { |
145 | for (x = 0; x < state->width; x++) { |
146 | barrier(state, x, 0) |= U; |
147 | barrier(state, x, state->height-1) |= D; |
148 | } |
149 | for (y = 0; y < state->height; y++) { |
150 | barrier(state, y, 0) |= L; |
151 | barrier(state, y, state->width-1) |= R; |
152 | } |
153 | } |
154 | |
155 | /* |
156 | * Seed the internal random number generator. |
157 | */ |
158 | rs = random_init(seed, strlen(seed)); |
159 | |
160 | /* |
161 | * Construct the unshuffled grid. |
162 | * |
163 | * To do this, we simply start at the centre point, repeatedly |
164 | * choose a random possibility out of the available ways to |
165 | * extend a used square into an unused one, and do it. After |
166 | * extending the third line out of a square, we remove the |
167 | * fourth from the possibilities list to avoid any full-cross |
168 | * squares (which would make the game too easy because they |
169 | * only have one orientation). |
170 | * |
171 | * The slightly worrying thing is the avoidance of full-cross |
172 | * squares. Can this cause our unsophisticated construction |
173 | * algorithm to paint itself into a corner, by getting into a |
174 | * situation where there are some unreached squares and the |
175 | * only way to reach any of them is to extend a T-piece into a |
176 | * full cross? |
177 | * |
178 | * Answer: no it can't, and here's a proof. |
179 | * |
180 | * Any contiguous group of such unreachable squares must be |
181 | * surrounded on _all_ sides by T-pieces pointing away from the |
182 | * group. (If not, then there is a square which can be extended |
183 | * into one of the `unreachable' ones, and so it wasn't |
184 | * unreachable after all.) In particular, this implies that |
185 | * each contiguous group of unreachable squares must be |
186 | * rectangular in shape (any deviation from that yields a |
187 | * non-T-piece next to an `unreachable' square). |
188 | * |
189 | * So we have a rectangle of unreachable squares, with T-pieces |
190 | * forming a solid border around the rectangle. The corners of |
191 | * that border must be connected (since every tile connects all |
192 | * the lines arriving in it), and therefore the border must |
193 | * form a closed loop around the rectangle. |
194 | * |
195 | * But this can't have happened in the first place, since we |
196 | * _know_ we've avoided creating closed loops! Hence, no such |
197 | * situation can ever arise, and the naive grid construction |
198 | * algorithm will guaranteeably result in a complete grid |
199 | * containing no unreached squares, no full crosses _and_ no |
200 | * closed loops. [] |
201 | */ |
202 | possibilities = newtree234(xyd_cmp); |
203 | add234(possibilities, new_xyd(w/2, h/2, R)); |
204 | add234(possibilities, new_xyd(w/2, h/2, U)); |
205 | add234(possibilities, new_xyd(w/2, h/2, L)); |
206 | add234(possibilities, new_xyd(w/2, h/2, D)); |
207 | |
208 | while (count234(possibilities) > 0) { |
209 | int i; |
210 | struct xyd *xyd; |
211 | int x1, y1, d1, x2, y2, d2, d; |
212 | |
213 | /* |
214 | * Extract a randomly chosen possibility from the list. |
215 | */ |
216 | i = random_upto(rs, count234(possibilities)); |
217 | xyd = delpos234(possibilities, i); |
218 | x1 = xyd->x; |
219 | y1 = xyd->y; |
220 | d1 = xyd->direction; |
221 | sfree(xyd); |
222 | |
223 | OFFSET(x2, y2, x1, y1, d1, state); |
224 | d2 = F(d1); |
225 | #ifdef DEBUG |
226 | printf("picked (%d,%d,%c) <-> (%d,%d,%c)\n", |
227 | x1, y1, "0RU3L567D9abcdef"[d1], x2, y2, "0RU3L567D9abcdef"[d2]); |
228 | #endif |
229 | |
230 | /* |
231 | * Make the connection. (We should be moving to an as yet |
232 | * unused tile.) |
233 | */ |
234 | tile(state, x1, y1) |= d1; |
235 | assert(tile(state, x2, y2) == 0); |
236 | tile(state, x2, y2) |= d2; |
237 | |
238 | /* |
239 | * If we have created a T-piece, remove its last |
240 | * possibility. |
241 | */ |
242 | if (COUNT(tile(state, x1, y1)) == 3) { |
243 | struct xyd xyd1, *xydp; |
244 | |
245 | xyd1.x = x1; |
246 | xyd1.y = y1; |
247 | xyd1.direction = 0x0F ^ tile(state, x1, y1); |
248 | |
249 | xydp = find234(possibilities, &xyd1, NULL); |
250 | |
251 | if (xydp) { |
252 | #ifdef DEBUG |
253 | printf("T-piece; removing (%d,%d,%c)\n", |
254 | xydp->x, xydp->y, "0RU3L567D9abcdef"[xydp->direction]); |
255 | #endif |
256 | del234(possibilities, xydp); |
257 | sfree(xydp); |
258 | } |
259 | } |
260 | |
261 | /* |
262 | * Remove all other possibilities that were pointing at the |
263 | * tile we've just moved into. |
264 | */ |
265 | for (d = 1; d < 0x10; d <<= 1) { |
266 | int x3, y3, d3; |
267 | struct xyd xyd1, *xydp; |
268 | |
269 | OFFSET(x3, y3, x2, y2, d, state); |
270 | d3 = F(d); |
271 | |
272 | xyd1.x = x3; |
273 | xyd1.y = y3; |
274 | xyd1.direction = d3; |
275 | |
276 | xydp = find234(possibilities, &xyd1, NULL); |
277 | |
278 | if (xydp) { |
279 | #ifdef DEBUG |
280 | printf("Loop avoidance; removing (%d,%d,%c)\n", |
281 | xydp->x, xydp->y, "0RU3L567D9abcdef"[xydp->direction]); |
282 | #endif |
283 | del234(possibilities, xydp); |
284 | sfree(xydp); |
285 | } |
286 | } |
287 | |
288 | /* |
289 | * Add new possibilities to the list for moving _out_ of |
290 | * the tile we have just moved into. |
291 | */ |
292 | for (d = 1; d < 0x10; d <<= 1) { |
293 | int x3, y3; |
294 | |
295 | if (d == d2) |
296 | continue; /* we've got this one already */ |
297 | |
298 | if (!state->wrapping) { |
299 | if (d == U && y2 == 0) |
300 | continue; |
301 | if (d == D && y2 == state->height-1) |
302 | continue; |
303 | if (d == L && x2 == 0) |
304 | continue; |
305 | if (d == R && x2 == state->width-1) |
306 | continue; |
307 | } |
308 | |
309 | OFFSET(x3, y3, x2, y2, d, state); |
310 | |
311 | if (tile(state, x3, y3)) |
312 | continue; /* this would create a loop */ |
313 | |
314 | #ifdef DEBUG |
315 | printf("New frontier; adding (%d,%d,%c)\n", |
316 | x2, y2, "0RU3L567D9abcdef"[d]); |
317 | #endif |
318 | add234(possibilities, new_xyd(x2, y2, d)); |
319 | } |
320 | } |
321 | /* Having done that, we should have no possibilities remaining. */ |
322 | assert(count234(possibilities) == 0); |
323 | freetree234(possibilities); |
324 | |
325 | /* |
326 | * Now compute a list of the possible barrier locations. |
327 | */ |
328 | barriers = newtree234(xyd_cmp); |
329 | for (y = 0; y < state->height - (!state->wrapping); y++) { |
330 | for (x = 0; x < state->width - (!state->wrapping); x++) { |
331 | |
332 | if (!(tile(state, x, y) & R)) |
333 | add234(barriers, new_xyd(x, y, R)); |
334 | if (!(tile(state, x, y) & D)) |
335 | add234(barriers, new_xyd(x, y, D)); |
336 | } |
337 | } |
338 | |
339 | /* |
340 | * Now shuffle the grid. |
341 | */ |
342 | for (y = 0; y < state->height - (!state->wrapping); y++) { |
343 | for (x = 0; x < state->width - (!state->wrapping); x++) { |
344 | int orig = tile(state, x, y); |
345 | int rot = random_upto(rs, 4); |
346 | tile(state, x, y) = ROT(orig, rot); |
347 | } |
348 | } |
349 | |
350 | /* |
351 | * And now choose barrier locations. (We carefully do this |
352 | * _after_ shuffling, so that changing the barrier rate in the |
353 | * params while keeping the game seed the same will give the |
354 | * same shuffled grid and _only_ change the barrier locations. |
355 | * Also the way we choose barrier locations, by repeatedly |
356 | * choosing one possibility from the list until we have enough, |
357 | * is designed to ensure that raising the barrier rate while |
358 | * keeping the seed the same will provide a superset of the |
359 | * previous barrier set - i.e. if you ask for 10 barriers, and |
360 | * then decide that's still too hard and ask for 20, you'll get |
361 | * the original 10 plus 10 more, rather than getting 20 new |
362 | * ones and the chance of remembering your first 10.) |
363 | */ |
364 | nbarriers = params->barrier_probability * count234(barriers); |
365 | assert(nbarriers >= 0 && nbarriers <= count234(barriers)); |
366 | |
367 | while (nbarriers > 0) { |
368 | int i; |
369 | struct xyd *xyd; |
370 | int x1, y1, d1, x2, y2, d2; |
371 | |
372 | /* |
373 | * Extract a randomly chosen barrier from the list. |
374 | */ |
375 | i = random_upto(rs, count234(barriers)); |
376 | xyd = delpos234(barriers, i); |
377 | |
378 | assert(xyd != NULL); |
379 | |
380 | x1 = xyd->x; |
381 | y1 = xyd->y; |
382 | d1 = xyd->direction; |
383 | sfree(xyd); |
384 | |
385 | OFFSET(x2, y2, x1, y1, d1, state); |
386 | d2 = F(d1); |
387 | |
388 | barrier(state, x1, y1) |= d1; |
389 | barrier(state, x2, y2) |= d2; |
390 | |
391 | nbarriers--; |
392 | } |
393 | |
394 | /* |
395 | * Clean up the rest of the barrier list. |
396 | */ |
397 | { |
398 | struct xyd *xyd; |
399 | |
400 | while ( (xyd = delpos234(barriers, 0)) != NULL) |
401 | sfree(xyd); |
402 | |
403 | freetree234(barriers); |
404 | } |
405 | |
406 | random_free(rs); |
407 | |
408 | return state; |
409 | } |
410 | |
411 | game_state *dup_game(game_state *state) |
412 | { |
413 | game_state *ret; |
414 | |
415 | ret = snew(game_state); |
416 | ret->width = state->width; |
417 | ret->height = state->height; |
418 | ret->wrapping = state->wrapping; |
419 | ret->completed = state->completed; |
420 | ret->tiles = snewn(state->width * state->height, unsigned char); |
421 | memcpy(ret->tiles, state->tiles, state->width * state->height); |
422 | ret->barriers = snewn(state->width * state->height, unsigned char); |
423 | memcpy(ret->barriers, state->barriers, state->width * state->height); |
424 | |
425 | return ret; |
426 | } |
427 | |
428 | void free_game(game_state *state) |
429 | { |
430 | sfree(state->tiles); |
431 | sfree(state->barriers); |
432 | sfree(state); |
433 | } |
434 | |
435 | /* ---------------------------------------------------------------------- |
436 | * Utility routine. |
437 | */ |
438 | |
439 | /* |
440 | * Compute which squares are reachable from the centre square, as a |
441 | * quick visual aid to determining how close the game is to |
442 | * completion. This is also a simple way to tell if the game _is_ |
443 | * completed - just call this function and see whether every square |
444 | * is marked active. |
445 | */ |
446 | static unsigned char *compute_active(game_state *state) |
447 | { |
448 | unsigned char *active; |
449 | tree234 *todo; |
450 | struct xyd *xyd; |
451 | |
452 | active = snewn(state->width * state->height, unsigned char); |
453 | memset(active, 0, state->width * state->height); |
454 | |
455 | /* |
456 | * We only store (x,y) pairs in todo, but it's easier to reuse |
457 | * xyd_cmp and just store direction 0 every time. |
458 | */ |
459 | todo = newtree234(xyd_cmp); |
460 | add234(todo, new_xyd(state->width / 2, state->height / 2, 0)); |
461 | |
462 | while ( (xyd = delpos234(todo, 0)) != NULL) { |
463 | int x1, y1, d1, x2, y2, d2; |
464 | |
465 | x1 = xyd->x; |
466 | y1 = xyd->y; |
467 | sfree(xyd); |
468 | |
469 | for (d1 = 1; d1 < 0x10; d1 <<= 1) { |
470 | OFFSET(x2, y2, x1, y1, d1, state); |
471 | d2 = F(d1); |
472 | |
473 | /* |
474 | * If the next tile in this direction is connected to |
475 | * us, and there isn't a barrier in the way, and it |
476 | * isn't already marked active, then mark it active and |
477 | * add it to the to-examine list. |
478 | */ |
479 | if ((tile(state, x1, y1) & d1) && |
480 | (tile(state, x2, y2) & d2) && |
481 | !(barrier(state, x1, y1) & d1) && |
482 | !index(state, active, x2, y2)) { |
483 | index(state, active, x2, y2) = 1; |
484 | add234(todo, new_xyd(x2, y2, 0)); |
485 | } |
486 | } |
487 | } |
488 | /* Now we expect the todo list to have shrunk to zero size. */ |
489 | assert(count234(todo) == 0); |
490 | freetree234(todo); |
491 | |
492 | return active; |
493 | } |
494 | |
495 | /* ---------------------------------------------------------------------- |
496 | * Process a move. |
497 | */ |
498 | game_state *make_move(game_state *state, int x, int y, int button) |
499 | { |
500 | game_state *ret; |
501 | int tx, ty, orig; |
502 | |
503 | /* |
504 | * All moves in Net are made with the mouse. |
505 | */ |
506 | if (button != LEFT_BUTTON && |
507 | button != MIDDLE_BUTTON && |
508 | button != RIGHT_BUTTON) |
509 | return NULL; |
510 | |
511 | /* |
512 | * The button must have been clicked on a valid tile. |
513 | */ |
514 | x -= WINDOW_OFFSET; |
515 | y -= WINDOW_OFFSET; |
516 | if (x < 0 || y < 0) |
517 | return NULL; |
518 | tx = x / TILE_SIZE; |
519 | ty = y / TILE_SIZE; |
520 | if (tx >= state->width || ty >= state->height) |
521 | return NULL; |
522 | if (tx % TILE_SIZE >= TILE_SIZE - TILE_BORDER || |
523 | ty % TILE_SIZE >= TILE_SIZE - TILE_BORDER) |
524 | return NULL; |
525 | |
526 | /* |
527 | * The middle button locks or unlocks a tile. (A locked tile |
528 | * cannot be turned, and is visually marked as being locked. |
529 | * This is a convenience for the player, so that once they are |
530 | * sure which way round a tile goes, they can lock it and thus |
531 | * avoid forgetting later on that they'd already done that one; |
532 | * and the locking also prevents them turning the tile by |
533 | * accident. If they change their mind, another middle click |
534 | * unlocks it.) |
535 | */ |
536 | if (button == MIDDLE_BUTTON) { |
537 | ret = dup_game(state); |
538 | tile(ret, tx, ty) ^= LOCKED; |
539 | return ret; |
540 | } |
541 | |
542 | /* |
543 | * The left and right buttons have no effect if clicked on a |
544 | * locked tile. |
545 | */ |
546 | if (tile(state, tx, ty) & LOCKED) |
547 | return NULL; |
548 | |
549 | /* |
550 | * Otherwise, turn the tile one way or the other. Left button |
551 | * turns anticlockwise; right button turns clockwise. |
552 | */ |
553 | ret = dup_game(state); |
554 | orig = tile(ret, tx, ty); |
555 | if (button == LEFT_BUTTON) |
556 | tile(ret, tx, ty) = A(orig); |
557 | else |
558 | tile(ret, tx, ty) = C(orig); |
559 | |
560 | /* |
561 | * Check whether the game has been completed. |
562 | */ |
563 | { |
564 | unsigned char *active = compute_active(ret); |
565 | int x1, y1; |
566 | int complete = TRUE; |
567 | |
568 | for (x1 = 0; x1 < ret->width; x1++) |
569 | for (y1 = 0; y1 < ret->height; y1++) |
570 | if (!index(ret, active, x1, y1)) { |
571 | complete = FALSE; |
572 | goto break_label; /* break out of two loops at once */ |
573 | } |
574 | break_label: |
575 | |
576 | sfree(active); |
577 | |
578 | if (complete) |
579 | ret->completed = TRUE; |
580 | } |
581 | |
582 | return ret; |
583 | } |
584 | |
585 | /* ---------------------------------------------------------------------- |
586 | * Routines for drawing the game position on the screen. |
587 | */ |
588 | |
589 | #ifndef TESTMODE /* FIXME: should be #ifdef */ |
590 | |
591 | int main(void) |
592 | { |
593 | game_params params = { 13, 11, TRUE, 0.1 }; |
594 | char *seed; |
595 | game_state *state; |
596 | unsigned char *active; |
597 | |
598 | seed = "123"; |
599 | state = new_game(¶ms, seed); |
600 | active = compute_active(state); |
601 | |
602 | { |
603 | int x, y; |
604 | |
605 | printf("\033)0\016"); |
606 | for (y = 0; y < state->height; y++) { |
607 | for (x = 0; x < state->width; x++) { |
608 | if (index(state, active, x, y)) |
609 | printf("\033[1;32m"); |
610 | else |
611 | printf("\033[0;31m"); |
612 | putchar("~``m`qjv`lxtkwua"[tile(state, x, y)]); |
613 | } |
614 | printf("\033[m\n"); |
615 | } |
616 | printf("\017"); |
617 | } |
618 | |
619 | free_game(state); |
620 | |
621 | return 0; |
622 | } |
623 | |
624 | #endif |