2 * (c) Lambros Lambrou 2008
4 * Code for working with general grids, which can be any planar graph
5 * with faces, edges and vertices (dots). Includes generators for a few
6 * types of grid, including square, hexagonal, triangular and others.
20 /* Debugging options */
26 /* ----------------------------------------------------------------------
27 * Deallocate or dereference a grid
29 void grid_free(grid *g)
34 if (g->refcount == 0) {
36 for (i = 0; i < g->num_faces; i++) {
37 sfree(g->faces[i].dots);
38 sfree(g->faces[i].edges);
40 for (i = 0; i < g->num_dots; i++) {
41 sfree(g->dots[i].faces);
42 sfree(g->dots[i].edges);
51 /* Used by the other grid generators. Create a brand new grid with nothing
52 * initialised (all lists are NULL) */
53 static grid *grid_new(void)
59 g->num_faces = g->num_edges = g->num_dots = 0;
60 g->middle_face = NULL;
62 g->lowest_x = g->lowest_y = g->highest_x = g->highest_y = 0;
66 /* Helper function to calculate perpendicular distance from
67 * a point P to a line AB. A and B mustn't be equal here.
69 * Well-known formula for area A of a triangle:
71 * 2A = determinant of matrix | px ax bx |
74 * Also well-known: 2A = base * height
75 * = perpendicular distance * line-length.
77 * Combining gives: distance = determinant / line-length(a,b)
79 static double point_line_distance(long px, long py,
83 long det = ax*by - bx*ay + bx*py - px*by + px*ay - ax*py;
86 len = sqrt(SQ(ax - bx) + SQ(ay - by));
90 /* Determine nearest edge to where the user clicked.
91 * (x, y) is the clicked location, converted to grid coordinates.
92 * Returns the nearest edge, or NULL if no edge is reasonably
95 * This algorithm is nice and generic, and doesn't depend on any particular
96 * geometric layout of the grid:
97 * Start at any dot (pick one next to middle_face).
98 * Walk along a path by choosing, from all nearby dots, the one that is
99 * nearest the target (x,y). Hopefully end up at the dot which is closest
100 * to (x,y). Should work, as long as faces aren't too badly shaped.
101 * Then examine each edge around this dot, and pick whichever one is
102 * closest (perpendicular distance) to (x,y).
103 * Using perpendicular distance is not quite right - the edge might be
104 * "off to one side". So we insist that the triangle with (x,y) has
105 * acute angles at the edge's dots.
112 * | edge2 is OK, but edge1 is not, even though
113 * | edge1 is perpendicularly closer to (x,y)
117 grid_edge *grid_nearest_edge(grid *g, int x, int y)
120 grid_edge *best_edge;
121 double best_distance = 0;
124 cur = g->middle_face->dots[0];
128 long dist = SQ((long)cur->x - (long)x) + SQ((long)cur->y - (long)y);
129 /* Look for nearer dot - if found, store in 'new'. */
132 /* Search all dots in all faces touching this dot. Some shapes
133 * (such as in Cairo) don't quite work properly if we only search
134 * the dot's immediate neighbours. */
135 for (i = 0; i < cur->order; i++) {
136 grid_face *f = cur->faces[i];
139 for (j = 0; j < f->order; j++) {
141 grid_dot *d = f->dots[j];
142 if (d == cur) continue;
143 new_dist = SQ((long)d->x - (long)x) + SQ((long)d->y - (long)y);
144 if (new_dist < dist) { /* found closer dot */
152 /* Didn't find a closer dot among the neighbours of 'cur' */
158 /* 'cur' is nearest dot, so find which of the dot's edges is closest. */
161 for (i = 0; i < cur->order; i++) {
162 grid_edge *e = cur->edges[i];
163 long e2; /* squared length of edge */
164 long a2, b2; /* squared lengths of other sides */
167 /* See if edge e is eligible - the triangle must have acute angles
168 * at the edge's dots.
169 * Pythagoras formula h^2 = a^2 + b^2 detects right-angles,
170 * so detect acute angles by testing for h^2 < a^2 + b^2 */
171 e2 = SQ((long)e->dot1->x - (long)e->dot2->x) + SQ((long)e->dot1->y - (long)e->dot2->y);
172 a2 = SQ((long)e->dot1->x - (long)x) + SQ((long)e->dot1->y - (long)y);
173 b2 = SQ((long)e->dot2->x - (long)x) + SQ((long)e->dot2->y - (long)y);
174 if (a2 >= e2 + b2) continue;
175 if (b2 >= e2 + a2) continue;
177 /* e is eligible so far. Now check the edge is reasonably close
178 * to where the user clicked. Don't want to toggle an edge if the
179 * click was way off the grid.
180 * There is room for experimentation here. We could check the
181 * perpendicular distance is within a certain fraction of the length
182 * of the edge. That amounts to testing a rectangular region around
184 * Alternatively, we could check that the angle at the point is obtuse.
185 * That would amount to testing a circular region with the edge as
187 dist = point_line_distance((long)x, (long)y,
188 (long)e->dot1->x, (long)e->dot1->y,
189 (long)e->dot2->x, (long)e->dot2->y);
190 /* Is dist more than half edge length ? */
191 if (4 * SQ(dist) > e2)
194 if (best_edge == NULL || dist < best_distance) {
196 best_distance = dist;
202 /* ----------------------------------------------------------------------
207 /* Show the basic grid information, before doing grid_make_consistent */
208 static void grid_print_basic(grid *g)
210 /* TODO: Maybe we should generate an SVG image of the dots and lines
211 * of the grid here, before grid_make_consistent.
212 * Would help with debugging grid generation. */
214 printf("--- Basic Grid Data ---\n");
215 for (i = 0; i < g->num_faces; i++) {
216 grid_face *f = g->faces + i;
217 printf("Face %d: dots[", i);
219 for (j = 0; j < f->order; j++) {
220 grid_dot *d = f->dots[j];
221 printf("%s%d", j ? "," : "", (int)(d - g->dots));
225 printf("Middle face: %d\n", (int)(g->middle_face - g->faces));
227 /* Show the derived grid information, computed by grid_make_consistent */
228 static void grid_print_derived(grid *g)
232 printf("--- Derived Grid Data ---\n");
233 for (i = 0; i < g->num_edges; i++) {
234 grid_edge *e = g->edges + i;
235 printf("Edge %d: dots[%d,%d] faces[%d,%d]\n",
236 i, (int)(e->dot1 - g->dots), (int)(e->dot2 - g->dots),
237 e->face1 ? (int)(e->face1 - g->faces) : -1,
238 e->face2 ? (int)(e->face2 - g->faces) : -1);
241 for (i = 0; i < g->num_faces; i++) {
242 grid_face *f = g->faces + i;
244 printf("Face %d: faces[", i);
245 for (j = 0; j < f->order; j++) {
246 grid_edge *e = f->edges[j];
247 grid_face *f2 = (e->face1 == f) ? e->face2 : e->face1;
248 printf("%s%d", j ? "," : "", f2 ? (int)(f2 - g->faces) : -1);
253 for (i = 0; i < g->num_dots; i++) {
254 grid_dot *d = g->dots + i;
256 printf("Dot %d: dots[", i);
257 for (j = 0; j < d->order; j++) {
258 grid_edge *e = d->edges[j];
259 grid_dot *d2 = (e->dot1 == d) ? e->dot2 : e->dot1;
260 printf("%s%d", j ? "," : "", (int)(d2 - g->dots));
263 for (j = 0; j < d->order; j++) {
264 grid_face *f = d->faces[j];
265 printf("%s%d", j ? "," : "", f ? (int)(f - g->faces) : -1);
270 #endif /* DEBUG_GRID */
272 /* Helper function for building incomplete-edges list in
273 * grid_make_consistent() */
274 static int grid_edge_bydots_cmpfn(void *v1, void *v2)
280 /* Pointer subtraction is valid here, because all dots point into the
281 * same dot-list (g->dots).
282 * Edges are not "normalised" - the 2 dots could be stored in any order,
283 * so we need to take this into account when comparing edges. */
285 /* Compare first dots */
286 da = (a->dot1 < a->dot2) ? a->dot1 : a->dot2;
287 db = (b->dot1 < b->dot2) ? b->dot1 : b->dot2;
290 /* Compare last dots */
291 da = (a->dot1 < a->dot2) ? a->dot2 : a->dot1;
292 db = (b->dot1 < b->dot2) ? b->dot2 : b->dot1;
299 /* Input: grid has its dots and faces initialised:
300 * - dots have (optionally) x and y coordinates, but no edges or faces
301 * (pointers are NULL).
302 * - edges not initialised at all
303 * - faces initialised and know which dots they have (but no edges yet). The
304 * dots around each face are assumed to be clockwise.
306 * Output: grid is complete and valid with all relationships defined.
308 static void grid_make_consistent(grid *g)
311 tree234 *incomplete_edges;
312 grid_edge *next_new_edge; /* Where new edge will go into g->edges */
318 /* ====== Stage 1 ======
322 /* We know how many dots and faces there are, so we can find the exact
323 * number of edges from Euler's polyhedral formula: F + V = E + 2 .
324 * We use "-1", not "-2" here, because Euler's formula includes the
325 * infinite face, which we don't count. */
326 g->num_edges = g->num_faces + g->num_dots - 1;
327 g->edges = snewn(g->num_edges, grid_edge);
328 next_new_edge = g->edges;
330 /* Iterate over faces, and over each face's dots, generating edges as we
331 * go. As we find each new edge, we can immediately fill in the edge's
332 * dots, but only one of the edge's faces. Later on in the iteration, we
333 * will find the same edge again (unless it's on the border), but we will
334 * know the other face.
335 * For efficiency, maintain a list of the incomplete edges, sorted by
337 incomplete_edges = newtree234(grid_edge_bydots_cmpfn);
338 for (i = 0; i < g->num_faces; i++) {
339 grid_face *f = g->faces + i;
341 for (j = 0; j < f->order; j++) {
342 grid_edge e; /* fake edge for searching */
343 grid_edge *edge_found;
348 e.dot2 = f->dots[j2];
349 /* Use del234 instead of find234, because we always want to
350 * remove the edge if found */
351 edge_found = del234(incomplete_edges, &e);
353 /* This edge already added, so fill out missing face.
354 * Edge is already removed from incomplete_edges. */
355 edge_found->face2 = f;
357 assert(next_new_edge - g->edges < g->num_edges);
358 next_new_edge->dot1 = e.dot1;
359 next_new_edge->dot2 = e.dot2;
360 next_new_edge->face1 = f;
361 next_new_edge->face2 = NULL; /* potentially infinite face */
362 add234(incomplete_edges, next_new_edge);
367 freetree234(incomplete_edges);
369 /* ====== Stage 2 ======
370 * For each face, build its edge list.
373 /* Allocate space for each edge list. Can do this, because each face's
374 * edge-list is the same size as its dot-list. */
375 for (i = 0; i < g->num_faces; i++) {
376 grid_face *f = g->faces + i;
378 f->edges = snewn(f->order, grid_edge*);
379 /* Preload with NULLs, to help detect potential bugs. */
380 for (j = 0; j < f->order; j++)
384 /* Iterate over each edge, and over both its faces. Add this edge to
385 * the face's edge-list, after finding where it should go in the
387 for (i = 0; i < g->num_edges; i++) {
388 grid_edge *e = g->edges + i;
390 for (j = 0; j < 2; j++) {
391 grid_face *f = j ? e->face2 : e->face1;
393 if (f == NULL) continue;
394 /* Find one of the dots around the face */
395 for (k = 0; k < f->order; k++) {
396 if (f->dots[k] == e->dot1)
397 break; /* found dot1 */
399 assert(k != f->order); /* Must find the dot around this face */
401 /* Labelling scheme: as we walk clockwise around the face,
402 * starting at dot0 (f->dots[0]), we hit:
403 * (dot0), edge0, dot1, edge1, dot2,...
413 * Therefore, edgeK joins dotK and dot{K+1}
416 /* Around this face, either the next dot or the previous dot
417 * must be e->dot2. Otherwise the edge is wrong. */
421 if (f->dots[k2] == e->dot2) {
422 /* dot1(k) and dot2(k2) go clockwise around this face, so add
423 * this edge at position k (see diagram). */
424 assert(f->edges[k] == NULL);
428 /* Try previous dot */
432 if (f->dots[k2] == e->dot2) {
433 /* dot1(k) and dot2(k2) go anticlockwise around this face. */
434 assert(f->edges[k2] == NULL);
438 assert(!"Grid broken: bad edge-face relationship");
442 /* ====== Stage 3 ======
443 * For each dot, build its edge-list and face-list.
446 /* We don't know how many edges/faces go around each dot, so we can't
447 * allocate the right space for these lists. Pre-compute the sizes by
448 * iterating over each edge and recording a tally against each dot. */
449 for (i = 0; i < g->num_dots; i++) {
450 g->dots[i].order = 0;
452 for (i = 0; i < g->num_edges; i++) {
453 grid_edge *e = g->edges + i;
457 /* Now we have the sizes, pre-allocate the edge and face lists. */
458 for (i = 0; i < g->num_dots; i++) {
459 grid_dot *d = g->dots + i;
461 assert(d->order >= 2); /* sanity check */
462 d->edges = snewn(d->order, grid_edge*);
463 d->faces = snewn(d->order, grid_face*);
464 for (j = 0; j < d->order; j++) {
469 /* For each dot, need to find a face that touches it, so we can seed
470 * the edge-face-edge-face process around each dot. */
471 for (i = 0; i < g->num_faces; i++) {
472 grid_face *f = g->faces + i;
474 for (j = 0; j < f->order; j++) {
475 grid_dot *d = f->dots[j];
479 /* Each dot now has a face in its first slot. Generate the remaining
480 * faces and edges around the dot, by searching both clockwise and
481 * anticlockwise from the first face. Need to do both directions,
482 * because of the possibility of hitting the infinite face, which
483 * blocks progress. But there's only one such face, so we will
484 * succeed in finding every edge and face this way. */
485 for (i = 0; i < g->num_dots; i++) {
486 grid_dot *d = g->dots + i;
487 int current_face1 = 0; /* ascends clockwise */
488 int current_face2 = 0; /* descends anticlockwise */
490 /* Labelling scheme: as we walk clockwise around the dot, starting
491 * at face0 (d->faces[0]), we hit:
492 * (face0), edge0, face1, edge1, face2,...
504 * So, for example, face1 should be joined to edge0 and edge1,
505 * and those edges should appear in an anticlockwise sense around
506 * that face (see diagram). */
508 /* clockwise search */
510 grid_face *f = d->faces[current_face1];
514 /* find dot around this face */
515 for (j = 0; j < f->order; j++) {
519 assert(j != f->order); /* must find dot */
521 /* Around f, required edge is anticlockwise from the dot. See
522 * the other labelling scheme higher up, for why we subtract 1
528 d->edges[current_face1] = e; /* set edge */
530 if (current_face1 == d->order)
534 d->faces[current_face1] =
535 (e->face1 == f) ? e->face2 : e->face1;
536 if (d->faces[current_face1] == NULL)
537 break; /* cannot progress beyond infinite face */
540 /* If the clockwise search made it all the way round, don't need to
541 * bother with the anticlockwise search. */
542 if (current_face1 == d->order)
543 continue; /* this dot is complete, move on to next dot */
545 /* anticlockwise search */
547 grid_face *f = d->faces[current_face2];
551 /* find dot around this face */
552 for (j = 0; j < f->order; j++) {
556 assert(j != f->order); /* must find dot */
558 /* Around f, required edge is clockwise from the dot. */
562 if (current_face2 == -1)
563 current_face2 = d->order - 1;
564 d->edges[current_face2] = e; /* set edge */
567 if (current_face2 == current_face1)
569 d->faces[current_face2] =
570 (e->face1 == f) ? e->face2 : e->face1;
571 /* There's only 1 infinite face, so we must get all the way
572 * to current_face1 before we hit it. */
573 assert(d->faces[current_face2]);
577 /* ====== Stage 4 ======
578 * Compute other grid settings
581 /* Bounding rectangle */
582 for (i = 0; i < g->num_dots; i++) {
583 grid_dot *d = g->dots + i;
585 g->lowest_x = g->highest_x = d->x;
586 g->lowest_y = g->highest_y = d->y;
588 g->lowest_x = min(g->lowest_x, d->x);
589 g->highest_x = max(g->highest_x, d->x);
590 g->lowest_y = min(g->lowest_y, d->y);
591 g->highest_y = max(g->highest_y, d->y);
596 grid_print_derived(g);
600 /* Helpers for making grid-generation easier. These functions are only
601 * intended for use during grid generation. */
603 /* Comparison function for the (tree234) sorted dot list */
604 static int grid_point_cmp_fn(void *v1, void *v2)
609 return p2->y - p1->y;
611 return p2->x - p1->x;
613 /* Add a new face to the grid, with its dot list allocated.
614 * Assumes there's enough space allocated for the new face in grid->faces */
615 static void grid_face_add_new(grid *g, int face_size)
618 grid_face *new_face = g->faces + g->num_faces;
619 new_face->order = face_size;
620 new_face->dots = snewn(face_size, grid_dot*);
621 for (i = 0; i < face_size; i++)
622 new_face->dots[i] = NULL;
623 new_face->edges = NULL;
626 /* Assumes dot list has enough space */
627 static grid_dot *grid_dot_add_new(grid *g, int x, int y)
629 grid_dot *new_dot = g->dots + g->num_dots;
631 new_dot->edges = NULL;
632 new_dot->faces = NULL;
638 /* Retrieve a dot with these (x,y) coordinates. Either return an existing dot
639 * in the dot_list, or add a new dot to the grid (and the dot_list) and
641 * Assumes g->dots has enough capacity allocated */
642 static grid_dot *grid_get_dot(grid *g, tree234 *dot_list, int x, int y)
651 ret = find234(dot_list, &test, NULL);
655 ret = grid_dot_add_new(g, x, y);
656 add234(dot_list, ret);
660 /* Sets the last face of the grid to include this dot, at this position
661 * around the face. Assumes num_faces is at least 1 (a new face has
662 * previously been added, with the required number of dots allocated) */
663 static void grid_face_set_dot(grid *g, grid_dot *d, int position)
665 grid_face *last_face = g->faces + g->num_faces - 1;
666 last_face->dots[position] = d;
669 /* ------ Generate various types of grid ------ */
671 /* General method is to generate faces, by calculating their dot coordinates.
672 * As new faces are added, we keep track of all the dots so we can tell when
673 * a new face reuses an existing dot. For example, two squares touching at an
674 * edge would generate six unique dots: four dots from the first face, then
675 * two additional dots for the second face, because we detect the other two
676 * dots have already been taken up. This list is stored in a tree234
677 * called "points". No extra memory-allocation needed here - we store the
678 * actual grid_dot* pointers, which all point into the g->dots list.
679 * For this reason, we have to calculate coordinates in such a way as to
680 * eliminate any rounding errors, so we can detect when a dot on one
681 * face precisely lands on a dot of a different face. No floating-point
685 grid *grid_new_square(int width, int height)
691 /* Upper bounds - don't have to be exact */
692 int max_faces = width * height;
693 int max_dots = (width + 1) * (height + 1);
697 grid *g = grid_new();
699 g->faces = snewn(max_faces, grid_face);
700 g->dots = snewn(max_dots, grid_dot);
702 points = newtree234(grid_point_cmp_fn);
704 /* generate square faces */
705 for (y = 0; y < height; y++) {
706 for (x = 0; x < width; x++) {
712 grid_face_add_new(g, 4);
713 d = grid_get_dot(g, points, px, py);
714 grid_face_set_dot(g, d, 0);
715 d = grid_get_dot(g, points, px + a, py);
716 grid_face_set_dot(g, d, 1);
717 d = grid_get_dot(g, points, px + a, py + a);
718 grid_face_set_dot(g, d, 2);
719 d = grid_get_dot(g, points, px, py + a);
720 grid_face_set_dot(g, d, 3);
725 assert(g->num_faces <= max_faces);
726 assert(g->num_dots <= max_dots);
727 g->middle_face = g->faces + (height/2) * width + (width/2);
729 grid_make_consistent(g);
733 grid *grid_new_honeycomb(int width, int height)
736 /* Vector for side of hexagon - ratio is close to sqrt(3) */
740 /* Upper bounds - don't have to be exact */
741 int max_faces = width * height;
742 int max_dots = 2 * (width + 1) * (height + 1);
746 grid *g = grid_new();
748 g->faces = snewn(max_faces, grid_face);
749 g->dots = snewn(max_dots, grid_dot);
751 points = newtree234(grid_point_cmp_fn);
753 /* generate hexagonal faces */
754 for (y = 0; y < height; y++) {
755 for (x = 0; x < width; x++) {
762 grid_face_add_new(g, 6);
764 d = grid_get_dot(g, points, cx - a, cy - b);
765 grid_face_set_dot(g, d, 0);
766 d = grid_get_dot(g, points, cx + a, cy - b);
767 grid_face_set_dot(g, d, 1);
768 d = grid_get_dot(g, points, cx + 2*a, cy);
769 grid_face_set_dot(g, d, 2);
770 d = grid_get_dot(g, points, cx + a, cy + b);
771 grid_face_set_dot(g, d, 3);
772 d = grid_get_dot(g, points, cx - a, cy + b);
773 grid_face_set_dot(g, d, 4);
774 d = grid_get_dot(g, points, cx - 2*a, cy);
775 grid_face_set_dot(g, d, 5);
780 assert(g->num_faces <= max_faces);
781 assert(g->num_dots <= max_dots);
782 g->middle_face = g->faces + (height/2) * width + (width/2);
784 grid_make_consistent(g);
788 /* Doesn't use the previous method of generation, it pre-dates it!
789 * A triangular grid is just about simple enough to do by "brute force" */
790 grid *grid_new_triangular(int width, int height)
794 /* Vector for side of triangle - ratio is close to sqrt(3) */
800 /* convenient alias */
803 grid *g = grid_new();
804 g->tilesize = 18; /* adjust to your taste */
806 g->num_faces = width * height * 2;
807 g->num_dots = (width + 1) * (height + 1);
808 g->faces = snewn(g->num_faces, grid_face);
809 g->dots = snewn(g->num_dots, grid_dot);
813 for (y = 0; y <= height; y++) {
814 for (x = 0; x <= width; x++) {
815 grid_dot *d = g->dots + index;
816 /* odd rows are offset to the right */
820 d->x = x * 2 * vec_x + ((y % 2) ? vec_x : 0);
828 for (y = 0; y < height; y++) {
829 for (x = 0; x < width; x++) {
830 /* initialise two faces for this (x,y) */
831 grid_face *f1 = g->faces + index;
832 grid_face *f2 = f1 + 1;
835 f1->dots = snewn(f1->order, grid_dot*);
838 f2->dots = snewn(f2->order, grid_dot*);
840 /* face descriptions depend on whether the row-number is
843 f1->dots[0] = g->dots + y * w + x;
844 f1->dots[1] = g->dots + (y + 1) * w + x + 1;
845 f1->dots[2] = g->dots + (y + 1) * w + x;
846 f2->dots[0] = g->dots + y * w + x;
847 f2->dots[1] = g->dots + y * w + x + 1;
848 f2->dots[2] = g->dots + (y + 1) * w + x + 1;
850 f1->dots[0] = g->dots + y * w + x;
851 f1->dots[1] = g->dots + y * w + x + 1;
852 f1->dots[2] = g->dots + (y + 1) * w + x;
853 f2->dots[0] = g->dots + y * w + x + 1;
854 f2->dots[1] = g->dots + (y + 1) * w + x + 1;
855 f2->dots[2] = g->dots + (y + 1) * w + x;
861 /* "+ width" takes us to the middle of the row, because each row has
862 * (2*width) faces. */
863 g->middle_face = g->faces + (height / 2) * 2 * width + width;
865 grid_make_consistent(g);
869 grid *grid_new_snubsquare(int width, int height)
872 /* Vector for side of triangle - ratio is close to sqrt(3) */
876 /* Upper bounds - don't have to be exact */
877 int max_faces = 3 * width * height;
878 int max_dots = 2 * (width + 1) * (height + 1);
882 grid *g = grid_new();
884 g->faces = snewn(max_faces, grid_face);
885 g->dots = snewn(max_dots, grid_dot);
887 points = newtree234(grid_point_cmp_fn);
889 for (y = 0; y < height; y++) {
890 for (x = 0; x < width; x++) {
893 int px = (a + b) * x;
894 int py = (a + b) * y;
896 /* generate square faces */
897 grid_face_add_new(g, 4);
899 d = grid_get_dot(g, points, px + a, py);
900 grid_face_set_dot(g, d, 0);
901 d = grid_get_dot(g, points, px + a + b, py + a);
902 grid_face_set_dot(g, d, 1);
903 d = grid_get_dot(g, points, px + b, py + a + b);
904 grid_face_set_dot(g, d, 2);
905 d = grid_get_dot(g, points, px, py + b);
906 grid_face_set_dot(g, d, 3);
908 d = grid_get_dot(g, points, px + b, py);
909 grid_face_set_dot(g, d, 0);
910 d = grid_get_dot(g, points, px + a + b, py + b);
911 grid_face_set_dot(g, d, 1);
912 d = grid_get_dot(g, points, px + a, py + a + b);
913 grid_face_set_dot(g, d, 2);
914 d = grid_get_dot(g, points, px, py + a);
915 grid_face_set_dot(g, d, 3);
918 /* generate up/down triangles */
920 grid_face_add_new(g, 3);
922 d = grid_get_dot(g, points, px + a, py);
923 grid_face_set_dot(g, d, 0);
924 d = grid_get_dot(g, points, px, py + b);
925 grid_face_set_dot(g, d, 1);
926 d = grid_get_dot(g, points, px - a, py);
927 grid_face_set_dot(g, d, 2);
929 d = grid_get_dot(g, points, px, py + a);
930 grid_face_set_dot(g, d, 0);
931 d = grid_get_dot(g, points, px + a, py + a + b);
932 grid_face_set_dot(g, d, 1);
933 d = grid_get_dot(g, points, px - a, py + a + b);
934 grid_face_set_dot(g, d, 2);
938 /* generate left/right triangles */
940 grid_face_add_new(g, 3);
942 d = grid_get_dot(g, points, px + a, py);
943 grid_face_set_dot(g, d, 0);
944 d = grid_get_dot(g, points, px + a + b, py - a);
945 grid_face_set_dot(g, d, 1);
946 d = grid_get_dot(g, points, px + a + b, py + a);
947 grid_face_set_dot(g, d, 2);
949 d = grid_get_dot(g, points, px, py - a);
950 grid_face_set_dot(g, d, 0);
951 d = grid_get_dot(g, points, px + b, py);
952 grid_face_set_dot(g, d, 1);
953 d = grid_get_dot(g, points, px, py + a);
954 grid_face_set_dot(g, d, 2);
961 assert(g->num_faces <= max_faces);
962 assert(g->num_dots <= max_dots);
963 g->middle_face = g->faces + (height/2) * width + (width/2);
965 grid_make_consistent(g);
969 grid *grid_new_cairo(int width, int height)
972 /* Vector for side of pentagon - ratio is close to (4+sqrt(7))/3 */
976 /* Upper bounds - don't have to be exact */
977 int max_faces = 2 * width * height;
978 int max_dots = 3 * (width + 1) * (height + 1);
982 grid *g = grid_new();
984 g->faces = snewn(max_faces, grid_face);
985 g->dots = snewn(max_dots, grid_dot);
987 points = newtree234(grid_point_cmp_fn);
989 for (y = 0; y < height; y++) {
990 for (x = 0; x < width; x++) {
996 /* horizontal pentagons */
998 grid_face_add_new(g, 5);
1000 d = grid_get_dot(g, points, px + a, py - b);
1001 grid_face_set_dot(g, d, 0);
1002 d = grid_get_dot(g, points, px + 2*b - a, py - b);
1003 grid_face_set_dot(g, d, 1);
1004 d = grid_get_dot(g, points, px + 2*b, py);
1005 grid_face_set_dot(g, d, 2);
1006 d = grid_get_dot(g, points, px + b, py + a);
1007 grid_face_set_dot(g, d, 3);
1008 d = grid_get_dot(g, points, px, py);
1009 grid_face_set_dot(g, d, 4);
1011 d = grid_get_dot(g, points, px, py);
1012 grid_face_set_dot(g, d, 0);
1013 d = grid_get_dot(g, points, px + b, py - a);
1014 grid_face_set_dot(g, d, 1);
1015 d = grid_get_dot(g, points, px + 2*b, py);
1016 grid_face_set_dot(g, d, 2);
1017 d = grid_get_dot(g, points, px + 2*b - a, py + b);
1018 grid_face_set_dot(g, d, 3);
1019 d = grid_get_dot(g, points, px + a, py + b);
1020 grid_face_set_dot(g, d, 4);
1023 /* vertical pentagons */
1025 grid_face_add_new(g, 5);
1027 d = grid_get_dot(g, points, px, py);
1028 grid_face_set_dot(g, d, 0);
1029 d = grid_get_dot(g, points, px + b, py + a);
1030 grid_face_set_dot(g, d, 1);
1031 d = grid_get_dot(g, points, px + b, py + 2*b - a);
1032 grid_face_set_dot(g, d, 2);
1033 d = grid_get_dot(g, points, px, py + 2*b);
1034 grid_face_set_dot(g, d, 3);
1035 d = grid_get_dot(g, points, px - a, py + b);
1036 grid_face_set_dot(g, d, 4);
1038 d = grid_get_dot(g, points, px, py);
1039 grid_face_set_dot(g, d, 0);
1040 d = grid_get_dot(g, points, px + a, py + b);
1041 grid_face_set_dot(g, d, 1);
1042 d = grid_get_dot(g, points, px, py + 2*b);
1043 grid_face_set_dot(g, d, 2);
1044 d = grid_get_dot(g, points, px - b, py + 2*b - a);
1045 grid_face_set_dot(g, d, 3);
1046 d = grid_get_dot(g, points, px - b, py + a);
1047 grid_face_set_dot(g, d, 4);
1053 freetree234(points);
1054 assert(g->num_faces <= max_faces);
1055 assert(g->num_dots <= max_dots);
1056 g->middle_face = g->faces + (height/2) * width + (width/2);
1058 grid_make_consistent(g);
1062 grid *grid_new_greathexagonal(int width, int height)
1065 /* Vector for side of triangle - ratio is close to sqrt(3) */
1069 /* Upper bounds - don't have to be exact */
1070 int max_faces = 6 * (width + 1) * (height + 1);
1071 int max_dots = 6 * width * height;
1075 grid *g = grid_new();
1077 g->faces = snewn(max_faces, grid_face);
1078 g->dots = snewn(max_dots, grid_dot);
1080 points = newtree234(grid_point_cmp_fn);
1082 for (y = 0; y < height; y++) {
1083 for (x = 0; x < width; x++) {
1085 /* centre of hexagon */
1086 int px = (3*a + b) * x;
1087 int py = (2*a + 2*b) * y;
1092 grid_face_add_new(g, 6);
1093 d = grid_get_dot(g, points, px - a, py - b);
1094 grid_face_set_dot(g, d, 0);
1095 d = grid_get_dot(g, points, px + a, py - b);
1096 grid_face_set_dot(g, d, 1);
1097 d = grid_get_dot(g, points, px + 2*a, py);
1098 grid_face_set_dot(g, d, 2);
1099 d = grid_get_dot(g, points, px + a, py + b);
1100 grid_face_set_dot(g, d, 3);
1101 d = grid_get_dot(g, points, px - a, py + b);
1102 grid_face_set_dot(g, d, 4);
1103 d = grid_get_dot(g, points, px - 2*a, py);
1104 grid_face_set_dot(g, d, 5);
1106 /* square below hexagon */
1107 if (y < height - 1) {
1108 grid_face_add_new(g, 4);
1109 d = grid_get_dot(g, points, px - a, py + b);
1110 grid_face_set_dot(g, d, 0);
1111 d = grid_get_dot(g, points, px + a, py + b);
1112 grid_face_set_dot(g, d, 1);
1113 d = grid_get_dot(g, points, px + a, py + 2*a + b);
1114 grid_face_set_dot(g, d, 2);
1115 d = grid_get_dot(g, points, px - a, py + 2*a + b);
1116 grid_face_set_dot(g, d, 3);
1119 /* square below right */
1120 if ((x < width - 1) && (((x % 2) == 0) || (y < height - 1))) {
1121 grid_face_add_new(g, 4);
1122 d = grid_get_dot(g, points, px + 2*a, py);
1123 grid_face_set_dot(g, d, 0);
1124 d = grid_get_dot(g, points, px + 2*a + b, py + a);
1125 grid_face_set_dot(g, d, 1);
1126 d = grid_get_dot(g, points, px + a + b, py + a + b);
1127 grid_face_set_dot(g, d, 2);
1128 d = grid_get_dot(g, points, px + a, py + b);
1129 grid_face_set_dot(g, d, 3);
1132 /* square below left */
1133 if ((x > 0) && (((x % 2) == 0) || (y < height - 1))) {
1134 grid_face_add_new(g, 4);
1135 d = grid_get_dot(g, points, px - 2*a, py);
1136 grid_face_set_dot(g, d, 0);
1137 d = grid_get_dot(g, points, px - a, py + b);
1138 grid_face_set_dot(g, d, 1);
1139 d = grid_get_dot(g, points, px - a - b, py + a + b);
1140 grid_face_set_dot(g, d, 2);
1141 d = grid_get_dot(g, points, px - 2*a - b, py + a);
1142 grid_face_set_dot(g, d, 3);
1145 /* Triangle below right */
1146 if ((x < width - 1) && (y < height - 1)) {
1147 grid_face_add_new(g, 3);
1148 d = grid_get_dot(g, points, px + a, py + b);
1149 grid_face_set_dot(g, d, 0);
1150 d = grid_get_dot(g, points, px + a + b, py + a + b);
1151 grid_face_set_dot(g, d, 1);
1152 d = grid_get_dot(g, points, px + a, py + 2*a + b);
1153 grid_face_set_dot(g, d, 2);
1156 /* Triangle below left */
1157 if ((x > 0) && (y < height - 1)) {
1158 grid_face_add_new(g, 3);
1159 d = grid_get_dot(g, points, px - a, py + b);
1160 grid_face_set_dot(g, d, 0);
1161 d = grid_get_dot(g, points, px - a, py + 2*a + b);
1162 grid_face_set_dot(g, d, 1);
1163 d = grid_get_dot(g, points, px - a - b, py + a + b);
1164 grid_face_set_dot(g, d, 2);
1169 freetree234(points);
1170 assert(g->num_faces <= max_faces);
1171 assert(g->num_dots <= max_dots);
1172 g->middle_face = g->faces + (height/2) * width + (width/2);
1174 grid_make_consistent(g);
1178 grid *grid_new_octagonal(int width, int height)
1181 /* b/a approx sqrt(2) */
1185 /* Upper bounds - don't have to be exact */
1186 int max_faces = 2 * width * height;
1187 int max_dots = 4 * (width + 1) * (height + 1);
1191 grid *g = grid_new();
1193 g->faces = snewn(max_faces, grid_face);
1194 g->dots = snewn(max_dots, grid_dot);
1196 points = newtree234(grid_point_cmp_fn);
1198 for (y = 0; y < height; y++) {
1199 for (x = 0; x < width; x++) {
1202 int px = (2*a + b) * x;
1203 int py = (2*a + b) * y;
1205 grid_face_add_new(g, 8);
1206 d = grid_get_dot(g, points, px + a, py);
1207 grid_face_set_dot(g, d, 0);
1208 d = grid_get_dot(g, points, px + a + b, py);
1209 grid_face_set_dot(g, d, 1);
1210 d = grid_get_dot(g, points, px + 2*a + b, py + a);
1211 grid_face_set_dot(g, d, 2);
1212 d = grid_get_dot(g, points, px + 2*a + b, py + a + b);
1213 grid_face_set_dot(g, d, 3);
1214 d = grid_get_dot(g, points, px + a + b, py + 2*a + b);
1215 grid_face_set_dot(g, d, 4);
1216 d = grid_get_dot(g, points, px + a, py + 2*a + b);
1217 grid_face_set_dot(g, d, 5);
1218 d = grid_get_dot(g, points, px, py + a + b);
1219 grid_face_set_dot(g, d, 6);
1220 d = grid_get_dot(g, points, px, py + a);
1221 grid_face_set_dot(g, d, 7);
1224 if ((x > 0) && (y > 0)) {
1225 grid_face_add_new(g, 4);
1226 d = grid_get_dot(g, points, px, py - a);
1227 grid_face_set_dot(g, d, 0);
1228 d = grid_get_dot(g, points, px + a, py);
1229 grid_face_set_dot(g, d, 1);
1230 d = grid_get_dot(g, points, px, py + a);
1231 grid_face_set_dot(g, d, 2);
1232 d = grid_get_dot(g, points, px - a, py);
1233 grid_face_set_dot(g, d, 3);
1238 freetree234(points);
1239 assert(g->num_faces <= max_faces);
1240 assert(g->num_dots <= max_dots);
1241 g->middle_face = g->faces + (height/2) * width + (width/2);
1243 grid_make_consistent(g);
1247 grid *grid_new_kites(int width, int height)
1250 /* b/a approx sqrt(3) */
1254 /* Upper bounds - don't have to be exact */
1255 int max_faces = 6 * width * height;
1256 int max_dots = 6 * (width + 1) * (height + 1);
1260 grid *g = grid_new();
1262 g->faces = snewn(max_faces, grid_face);
1263 g->dots = snewn(max_dots, grid_dot);
1265 points = newtree234(grid_point_cmp_fn);
1267 for (y = 0; y < height; y++) {
1268 for (x = 0; x < width; x++) {
1270 /* position of order-6 dot */
1276 /* kite pointing up-left */
1277 grid_face_add_new(g, 4);
1278 d = grid_get_dot(g, points, px, py);
1279 grid_face_set_dot(g, d, 0);
1280 d = grid_get_dot(g, points, px + 2*b, py);
1281 grid_face_set_dot(g, d, 1);
1282 d = grid_get_dot(g, points, px + 2*b, py + 2*a);
1283 grid_face_set_dot(g, d, 2);
1284 d = grid_get_dot(g, points, px + b, py + 3*a);
1285 grid_face_set_dot(g, d, 3);
1287 /* kite pointing up */
1288 grid_face_add_new(g, 4);
1289 d = grid_get_dot(g, points, px, py);
1290 grid_face_set_dot(g, d, 0);
1291 d = grid_get_dot(g, points, px + b, py + 3*a);
1292 grid_face_set_dot(g, d, 1);
1293 d = grid_get_dot(g, points, px, py + 4*a);
1294 grid_face_set_dot(g, d, 2);
1295 d = grid_get_dot(g, points, px - b, py + 3*a);
1296 grid_face_set_dot(g, d, 3);
1298 /* kite pointing up-right */
1299 grid_face_add_new(g, 4);
1300 d = grid_get_dot(g, points, px, py);
1301 grid_face_set_dot(g, d, 0);
1302 d = grid_get_dot(g, points, px - b, py + 3*a);
1303 grid_face_set_dot(g, d, 1);
1304 d = grid_get_dot(g, points, px - 2*b, py + 2*a);
1305 grid_face_set_dot(g, d, 2);
1306 d = grid_get_dot(g, points, px - 2*b, py);
1307 grid_face_set_dot(g, d, 3);
1309 /* kite pointing down-right */
1310 grid_face_add_new(g, 4);
1311 d = grid_get_dot(g, points, px, py);
1312 grid_face_set_dot(g, d, 0);
1313 d = grid_get_dot(g, points, px - 2*b, py);
1314 grid_face_set_dot(g, d, 1);
1315 d = grid_get_dot(g, points, px - 2*b, py - 2*a);
1316 grid_face_set_dot(g, d, 2);
1317 d = grid_get_dot(g, points, px - b, py - 3*a);
1318 grid_face_set_dot(g, d, 3);
1320 /* kite pointing down */
1321 grid_face_add_new(g, 4);
1322 d = grid_get_dot(g, points, px, py);
1323 grid_face_set_dot(g, d, 0);
1324 d = grid_get_dot(g, points, px - b, py - 3*a);
1325 grid_face_set_dot(g, d, 1);
1326 d = grid_get_dot(g, points, px, py - 4*a);
1327 grid_face_set_dot(g, d, 2);
1328 d = grid_get_dot(g, points, px + b, py - 3*a);
1329 grid_face_set_dot(g, d, 3);
1331 /* kite pointing down-left */
1332 grid_face_add_new(g, 4);
1333 d = grid_get_dot(g, points, px, py);
1334 grid_face_set_dot(g, d, 0);
1335 d = grid_get_dot(g, points, px + b, py - 3*a);
1336 grid_face_set_dot(g, d, 1);
1337 d = grid_get_dot(g, points, px + 2*b, py - 2*a);
1338 grid_face_set_dot(g, d, 2);
1339 d = grid_get_dot(g, points, px + 2*b, py);
1340 grid_face_set_dot(g, d, 3);
1344 freetree234(points);
1345 assert(g->num_faces <= max_faces);
1346 assert(g->num_dots <= max_dots);
1347 g->middle_face = g->faces + 6 * ((height/2) * width + (width/2));
1349 grid_make_consistent(g);
1353 grid *grid_new_floret(int width, int height)
1356 /* Vectors for sides; weird numbers needed to keep puzzle aligned with window
1357 * -py/px is close to tan(30 - atan(sqrt(3)/9))
1358 * using py=26 makes everything lean to the left, rather than right
1360 int px = 75, py = -26; /* |( 75, -26)| = 79.43 */
1361 int qx = 4*px/5, qy = -py*2; /* |( 60, 52)| = 79.40 */
1362 int rx = qx-px, ry = qy-py; /* |(-15, 78)| = 79.38 */
1364 /* Upper bounds - don't have to be exact */
1365 int max_faces = 6 * width * height;
1366 int max_dots = 9 * (width + 1) * (height + 1);
1370 grid *g = grid_new();
1371 g->tilesize = 2 * px;
1372 g->faces = snewn(max_faces, grid_face);
1373 g->dots = snewn(max_dots, grid_dot);
1375 points = newtree234(grid_point_cmp_fn);
1377 /* generate pentagonal faces */
1378 for (y = 0; y < height; y++) {
1379 for (x = 0; x < width; x++) {
1382 int cx = (6*px+3*qx)/2 * x;
1383 int cy = (4*py-5*qy) * y;
1385 cy -= (4*py-5*qy)/2;
1386 else if (y && y == height-1)
1387 continue; /* make better looking grids? try 3x3 for instance */
1389 grid_face_add_new(g, 5);
1390 d = grid_get_dot(g, points, cx , cy ); grid_face_set_dot(g, d, 0);
1391 d = grid_get_dot(g, points, cx+2*rx , cy+2*ry ); grid_face_set_dot(g, d, 1);
1392 d = grid_get_dot(g, points, cx+2*rx+qx, cy+2*ry+qy); grid_face_set_dot(g, d, 2);
1393 d = grid_get_dot(g, points, cx+2*qx+rx, cy+2*qy+ry); grid_face_set_dot(g, d, 3);
1394 d = grid_get_dot(g, points, cx+2*qx , cy+2*qy ); grid_face_set_dot(g, d, 4);
1396 grid_face_add_new(g, 5);
1397 d = grid_get_dot(g, points, cx , cy ); grid_face_set_dot(g, d, 0);
1398 d = grid_get_dot(g, points, cx+2*qx , cy+2*qy ); grid_face_set_dot(g, d, 1);
1399 d = grid_get_dot(g, points, cx+2*qx+px, cy+2*qy+py); grid_face_set_dot(g, d, 2);
1400 d = grid_get_dot(g, points, cx+2*px+qx, cy+2*py+qy); grid_face_set_dot(g, d, 3);
1401 d = grid_get_dot(g, points, cx+2*px , cy+2*py ); grid_face_set_dot(g, d, 4);
1403 grid_face_add_new(g, 5);
1404 d = grid_get_dot(g, points, cx , cy ); grid_face_set_dot(g, d, 0);
1405 d = grid_get_dot(g, points, cx+2*px , cy+2*py ); grid_face_set_dot(g, d, 1);
1406 d = grid_get_dot(g, points, cx+2*px-rx, cy+2*py-ry); grid_face_set_dot(g, d, 2);
1407 d = grid_get_dot(g, points, cx-2*rx+px, cy-2*ry+py); grid_face_set_dot(g, d, 3);
1408 d = grid_get_dot(g, points, cx-2*rx , cy-2*ry ); grid_face_set_dot(g, d, 4);
1410 grid_face_add_new(g, 5);
1411 d = grid_get_dot(g, points, cx , cy ); grid_face_set_dot(g, d, 0);
1412 d = grid_get_dot(g, points, cx-2*rx , cy-2*ry ); grid_face_set_dot(g, d, 1);
1413 d = grid_get_dot(g, points, cx-2*rx-qx, cy-2*ry-qy); grid_face_set_dot(g, d, 2);
1414 d = grid_get_dot(g, points, cx-2*qx-rx, cy-2*qy-ry); grid_face_set_dot(g, d, 3);
1415 d = grid_get_dot(g, points, cx-2*qx , cy-2*qy ); grid_face_set_dot(g, d, 4);
1417 grid_face_add_new(g, 5);
1418 d = grid_get_dot(g, points, cx , cy ); grid_face_set_dot(g, d, 0);
1419 d = grid_get_dot(g, points, cx-2*qx , cy-2*qy ); grid_face_set_dot(g, d, 1);
1420 d = grid_get_dot(g, points, cx-2*qx-px, cy-2*qy-py); grid_face_set_dot(g, d, 2);
1421 d = grid_get_dot(g, points, cx-2*px-qx, cy-2*py-qy); grid_face_set_dot(g, d, 3);
1422 d = grid_get_dot(g, points, cx-2*px , cy-2*py ); grid_face_set_dot(g, d, 4);
1424 grid_face_add_new(g, 5);
1425 d = grid_get_dot(g, points, cx , cy ); grid_face_set_dot(g, d, 0);
1426 d = grid_get_dot(g, points, cx-2*px , cy-2*py ); grid_face_set_dot(g, d, 1);
1427 d = grid_get_dot(g, points, cx-2*px+rx, cy-2*py+ry); grid_face_set_dot(g, d, 2);
1428 d = grid_get_dot(g, points, cx+2*rx-px, cy+2*ry-py); grid_face_set_dot(g, d, 3);
1429 d = grid_get_dot(g, points, cx+2*rx , cy+2*ry ); grid_face_set_dot(g, d, 4);
1433 freetree234(points);
1434 assert(g->num_faces <= max_faces);
1435 assert(g->num_dots <= max_dots);
1436 g->middle_face = g->faces + 6 * ((height/2) * width + (width/2));
1438 grid_make_consistent(g);
1442 /* ----------- End of grid generators ------------- */