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) {
146 break; /* found closer dot */
150 break; /* found closer dot */
154 /* Didn't find a closer dot among the neighbours of 'cur' */
160 /* 'cur' is nearest dot, so find which of the dot's edges is closest. */
163 for (i = 0; i < cur->order; i++) {
164 grid_edge *e = cur->edges[i];
165 long e2; /* squared length of edge */
166 long a2, b2; /* squared lengths of other sides */
169 /* See if edge e is eligible - the triangle must have acute angles
170 * at the edge's dots.
171 * Pythagoras formula h^2 = a^2 + b^2 detects right-angles,
172 * so detect acute angles by testing for h^2 < a^2 + b^2 */
173 e2 = SQ((long)e->dot1->x - (long)e->dot2->x) + SQ((long)e->dot1->y - (long)e->dot2->y);
174 a2 = SQ((long)e->dot1->x - (long)x) + SQ((long)e->dot1->y - (long)y);
175 b2 = SQ((long)e->dot2->x - (long)x) + SQ((long)e->dot2->y - (long)y);
176 if (a2 >= e2 + b2) continue;
177 if (b2 >= e2 + a2) continue;
179 /* e is eligible so far. Now check the edge is reasonably close
180 * to where the user clicked. Don't want to toggle an edge if the
181 * click was way off the grid.
182 * There is room for experimentation here. We could check the
183 * perpendicular distance is within a certain fraction of the length
184 * of the edge. That amounts to testing a rectangular region around
186 * Alternatively, we could check that the angle at the point is obtuse.
187 * That would amount to testing a circular region with the edge as
189 dist = point_line_distance((long)x, (long)y,
190 (long)e->dot1->x, (long)e->dot1->y,
191 (long)e->dot2->x, (long)e->dot2->y);
192 /* Is dist more than half edge length ? */
193 if (4 * SQ(dist) > e2)
196 if (best_edge == NULL || dist < best_distance) {
198 best_distance = dist;
204 /* ----------------------------------------------------------------------
209 /* Show the basic grid information, before doing grid_make_consistent */
210 static void grid_print_basic(grid *g)
212 /* TODO: Maybe we should generate an SVG image of the dots and lines
213 * of the grid here, before grid_make_consistent.
214 * Would help with debugging grid generation. */
216 printf("--- Basic Grid Data ---\n");
217 for (i = 0; i < g->num_faces; i++) {
218 grid_face *f = g->faces + i;
219 printf("Face %d: dots[", i);
221 for (j = 0; j < f->order; j++) {
222 grid_dot *d = f->dots[j];
223 printf("%s%d", j ? "," : "", (int)(d - g->dots));
227 printf("Middle face: %d\n", (int)(g->middle_face - g->faces));
229 /* Show the derived grid information, computed by grid_make_consistent */
230 static void grid_print_derived(grid *g)
234 printf("--- Derived Grid Data ---\n");
235 for (i = 0; i < g->num_edges; i++) {
236 grid_edge *e = g->edges + i;
237 printf("Edge %d: dots[%d,%d] faces[%d,%d]\n",
238 i, (int)(e->dot1 - g->dots), (int)(e->dot2 - g->dots),
239 e->face1 ? (int)(e->face1 - g->faces) : -1,
240 e->face2 ? (int)(e->face2 - g->faces) : -1);
243 for (i = 0; i < g->num_faces; i++) {
244 grid_face *f = g->faces + i;
246 printf("Face %d: faces[", i);
247 for (j = 0; j < f->order; j++) {
248 grid_edge *e = f->edges[j];
249 grid_face *f2 = (e->face1 == f) ? e->face2 : e->face1;
250 printf("%s%d", j ? "," : "", f2 ? (int)(f2 - g->faces) : -1);
255 for (i = 0; i < g->num_dots; i++) {
256 grid_dot *d = g->dots + i;
258 printf("Dot %d: dots[", i);
259 for (j = 0; j < d->order; j++) {
260 grid_edge *e = d->edges[j];
261 grid_dot *d2 = (e->dot1 == d) ? e->dot2 : e->dot1;
262 printf("%s%d", j ? "," : "", (int)(d2 - g->dots));
265 for (j = 0; j < d->order; j++) {
266 grid_face *f = d->faces[j];
267 printf("%s%d", j ? "," : "", f ? (int)(f - g->faces) : -1);
272 #endif /* DEBUG_GRID */
274 /* Helper function for building incomplete-edges list in
275 * grid_make_consistent() */
276 static int grid_edge_bydots_cmpfn(void *v1, void *v2)
282 /* Pointer subtraction is valid here, because all dots point into the
283 * same dot-list (g->dots).
284 * Edges are not "normalised" - the 2 dots could be stored in any order,
285 * so we need to take this into account when comparing edges. */
287 /* Compare first dots */
288 da = (a->dot1 < a->dot2) ? a->dot1 : a->dot2;
289 db = (b->dot1 < b->dot2) ? b->dot1 : b->dot2;
292 /* Compare last dots */
293 da = (a->dot1 < a->dot2) ? a->dot2 : a->dot1;
294 db = (b->dot1 < b->dot2) ? b->dot2 : b->dot1;
301 /* Input: grid has its dots and faces initialised:
302 * - dots have (optionally) x and y coordinates, but no edges or faces
303 * (pointers are NULL).
304 * - edges not initialised at all
305 * - faces initialised and know which dots they have (but no edges yet). The
306 * dots around each face are assumed to be clockwise.
308 * Output: grid is complete and valid with all relationships defined.
310 static void grid_make_consistent(grid *g)
313 tree234 *incomplete_edges;
314 grid_edge *next_new_edge; /* Where new edge will go into g->edges */
320 /* ====== Stage 1 ======
324 /* We know how many dots and faces there are, so we can find the exact
325 * number of edges from Euler's polyhedral formula: F + V = E + 2 .
326 * We use "-1", not "-2" here, because Euler's formula includes the
327 * infinite face, which we don't count. */
328 g->num_edges = g->num_faces + g->num_dots - 1;
329 g->edges = snewn(g->num_edges, grid_edge);
330 next_new_edge = g->edges;
332 /* Iterate over faces, and over each face's dots, generating edges as we
333 * go. As we find each new edge, we can immediately fill in the edge's
334 * dots, but only one of the edge's faces. Later on in the iteration, we
335 * will find the same edge again (unless it's on the border), but we will
336 * know the other face.
337 * For efficiency, maintain a list of the incomplete edges, sorted by
339 incomplete_edges = newtree234(grid_edge_bydots_cmpfn);
340 for (i = 0; i < g->num_faces; i++) {
341 grid_face *f = g->faces + i;
343 for (j = 0; j < f->order; j++) {
344 grid_edge e; /* fake edge for searching */
345 grid_edge *edge_found;
350 e.dot2 = f->dots[j2];
351 /* Use del234 instead of find234, because we always want to
352 * remove the edge if found */
353 edge_found = del234(incomplete_edges, &e);
355 /* This edge already added, so fill out missing face.
356 * Edge is already removed from incomplete_edges. */
357 edge_found->face2 = f;
359 assert(next_new_edge - g->edges < g->num_edges);
360 next_new_edge->dot1 = e.dot1;
361 next_new_edge->dot2 = e.dot2;
362 next_new_edge->face1 = f;
363 next_new_edge->face2 = NULL; /* potentially infinite face */
364 add234(incomplete_edges, next_new_edge);
369 freetree234(incomplete_edges);
371 /* ====== Stage 2 ======
372 * For each face, build its edge list.
375 /* Allocate space for each edge list. Can do this, because each face's
376 * edge-list is the same size as its dot-list. */
377 for (i = 0; i < g->num_faces; i++) {
378 grid_face *f = g->faces + i;
380 f->edges = snewn(f->order, grid_edge*);
381 /* Preload with NULLs, to help detect potential bugs. */
382 for (j = 0; j < f->order; j++)
386 /* Iterate over each edge, and over both its faces. Add this edge to
387 * the face's edge-list, after finding where it should go in the
389 for (i = 0; i < g->num_edges; i++) {
390 grid_edge *e = g->edges + i;
392 for (j = 0; j < 2; j++) {
393 grid_face *f = j ? e->face2 : e->face1;
395 if (f == NULL) continue;
396 /* Find one of the dots around the face */
397 for (k = 0; k < f->order; k++) {
398 if (f->dots[k] == e->dot1)
399 break; /* found dot1 */
401 assert(k != f->order); /* Must find the dot around this face */
403 /* Labelling scheme: as we walk clockwise around the face,
404 * starting at dot0 (f->dots[0]), we hit:
405 * (dot0), edge0, dot1, edge1, dot2,...
415 * Therefore, edgeK joins dotK and dot{K+1}
418 /* Around this face, either the next dot or the previous dot
419 * must be e->dot2. Otherwise the edge is wrong. */
423 if (f->dots[k2] == e->dot2) {
424 /* dot1(k) and dot2(k2) go clockwise around this face, so add
425 * this edge at position k (see diagram). */
426 assert(f->edges[k] == NULL);
430 /* Try previous dot */
434 if (f->dots[k2] == e->dot2) {
435 /* dot1(k) and dot2(k2) go anticlockwise around this face. */
436 assert(f->edges[k2] == NULL);
440 assert(!"Grid broken: bad edge-face relationship");
444 /* ====== Stage 3 ======
445 * For each dot, build its edge-list and face-list.
448 /* We don't know how many edges/faces go around each dot, so we can't
449 * allocate the right space for these lists. Pre-compute the sizes by
450 * iterating over each edge and recording a tally against each dot. */
451 for (i = 0; i < g->num_dots; i++) {
452 g->dots[i].order = 0;
454 for (i = 0; i < g->num_edges; i++) {
455 grid_edge *e = g->edges + i;
459 /* Now we have the sizes, pre-allocate the edge and face lists. */
460 for (i = 0; i < g->num_dots; i++) {
461 grid_dot *d = g->dots + i;
463 assert(d->order >= 2); /* sanity check */
464 d->edges = snewn(d->order, grid_edge*);
465 d->faces = snewn(d->order, grid_face*);
466 for (j = 0; j < d->order; j++) {
471 /* For each dot, need to find a face that touches it, so we can seed
472 * the edge-face-edge-face process around each dot. */
473 for (i = 0; i < g->num_faces; i++) {
474 grid_face *f = g->faces + i;
476 for (j = 0; j < f->order; j++) {
477 grid_dot *d = f->dots[j];
481 /* Each dot now has a face in its first slot. Generate the remaining
482 * faces and edges around the dot, by searching both clockwise and
483 * anticlockwise from the first face. Need to do both directions,
484 * because of the possibility of hitting the infinite face, which
485 * blocks progress. But there's only one such face, so we will
486 * succeed in finding every edge and face this way. */
487 for (i = 0; i < g->num_dots; i++) {
488 grid_dot *d = g->dots + i;
489 int current_face1 = 0; /* ascends clockwise */
490 int current_face2 = 0; /* descends anticlockwise */
492 /* Labelling scheme: as we walk clockwise around the dot, starting
493 * at face0 (d->faces[0]), we hit:
494 * (face0), edge0, face1, edge1, face2,...
506 * So, for example, face1 should be joined to edge0 and edge1,
507 * and those edges should appear in an anticlockwise sense around
508 * that face (see diagram). */
510 /* clockwise search */
512 grid_face *f = d->faces[current_face1];
516 /* find dot around this face */
517 for (j = 0; j < f->order; j++) {
521 assert(j != f->order); /* must find dot */
523 /* Around f, required edge is anticlockwise from the dot. See
524 * the other labelling scheme higher up, for why we subtract 1
530 d->edges[current_face1] = e; /* set edge */
532 if (current_face1 == d->order)
536 d->faces[current_face1] =
537 (e->face1 == f) ? e->face2 : e->face1;
538 if (d->faces[current_face1] == NULL)
539 break; /* cannot progress beyond infinite face */
542 /* If the clockwise search made it all the way round, don't need to
543 * bother with the anticlockwise search. */
544 if (current_face1 == d->order)
545 continue; /* this dot is complete, move on to next dot */
547 /* anticlockwise search */
549 grid_face *f = d->faces[current_face2];
553 /* find dot around this face */
554 for (j = 0; j < f->order; j++) {
558 assert(j != f->order); /* must find dot */
560 /* Around f, required edge is clockwise from the dot. */
564 if (current_face2 == -1)
565 current_face2 = d->order - 1;
566 d->edges[current_face2] = e; /* set edge */
569 if (current_face2 == current_face1)
571 d->faces[current_face2] =
572 (e->face1 == f) ? e->face2 : e->face1;
573 /* There's only 1 infinite face, so we must get all the way
574 * to current_face1 before we hit it. */
575 assert(d->faces[current_face2]);
579 /* ====== Stage 4 ======
580 * Compute other grid settings
583 /* Bounding rectangle */
584 for (i = 0; i < g->num_dots; i++) {
585 grid_dot *d = g->dots + i;
587 g->lowest_x = g->highest_x = d->x;
588 g->lowest_y = g->highest_y = d->y;
590 g->lowest_x = min(g->lowest_x, d->x);
591 g->highest_x = max(g->highest_x, d->x);
592 g->lowest_y = min(g->lowest_y, d->y);
593 g->highest_y = max(g->highest_y, d->y);
598 grid_print_derived(g);
602 /* Helpers for making grid-generation easier. These functions are only
603 * intended for use during grid generation. */
605 /* Comparison function for the (tree234) sorted dot list */
606 static int grid_point_cmp_fn(void *v1, void *v2)
611 return p2->y - p1->y;
613 return p2->x - p1->x;
615 /* Add a new face to the grid, with its dot list allocated.
616 * Assumes there's enough space allocated for the new face in grid->faces */
617 static void grid_face_add_new(grid *g, int face_size)
620 grid_face *new_face = g->faces + g->num_faces;
621 new_face->order = face_size;
622 new_face->dots = snewn(face_size, grid_dot*);
623 for (i = 0; i < face_size; i++)
624 new_face->dots[i] = NULL;
625 new_face->edges = NULL;
628 /* Assumes dot list has enough space */
629 static grid_dot *grid_dot_add_new(grid *g, int x, int y)
631 grid_dot *new_dot = g->dots + g->num_dots;
633 new_dot->edges = NULL;
634 new_dot->faces = NULL;
640 /* Retrieve a dot with these (x,y) coordinates. Either return an existing dot
641 * in the dot_list, or add a new dot to the grid (and the dot_list) and
643 * Assumes g->dots has enough capacity allocated */
644 static grid_dot *grid_get_dot(grid *g, tree234 *dot_list, int x, int y)
646 grid_dot test = {0, NULL, NULL, x, y};
647 grid_dot *ret = find234(dot_list, &test, NULL);
651 ret = grid_dot_add_new(g, x, y);
652 add234(dot_list, ret);
656 /* Sets the last face of the grid to include this dot, at this position
657 * around the face. Assumes num_faces is at least 1 (a new face has
658 * previously been added, with the required number of dots allocated) */
659 static void grid_face_set_dot(grid *g, grid_dot *d, int position)
661 grid_face *last_face = g->faces + g->num_faces - 1;
662 last_face->dots[position] = d;
665 /* ------ Generate various types of grid ------ */
667 /* General method is to generate faces, by calculating their dot coordinates.
668 * As new faces are added, we keep track of all the dots so we can tell when
669 * a new face reuses an existing dot. For example, two squares touching at an
670 * edge would generate six unique dots: four dots from the first face, then
671 * two additional dots for the second face, because we detect the other two
672 * dots have already been taken up. This list is stored in a tree234
673 * called "points". No extra memory-allocation needed here - we store the
674 * actual grid_dot* pointers, which all point into the g->dots list.
675 * For this reason, we have to calculate coordinates in such a way as to
676 * eliminate any rounding errors, so we can detect when a dot on one
677 * face precisely lands on a dot of a different face. No floating-point
681 grid *grid_new_square(int width, int height)
687 /* Upper bounds - don't have to be exact */
688 int max_faces = width * height;
689 int max_dots = (width + 1) * (height + 1);
693 grid *g = grid_new();
695 g->faces = snewn(max_faces, grid_face);
696 g->dots = snewn(max_dots, grid_dot);
698 points = newtree234(grid_point_cmp_fn);
700 /* generate square faces */
701 for (y = 0; y < height; y++) {
702 for (x = 0; x < width; x++) {
708 grid_face_add_new(g, 4);
709 d = grid_get_dot(g, points, px, py);
710 grid_face_set_dot(g, d, 0);
711 d = grid_get_dot(g, points, px + a, py);
712 grid_face_set_dot(g, d, 1);
713 d = grid_get_dot(g, points, px + a, py + a);
714 grid_face_set_dot(g, d, 2);
715 d = grid_get_dot(g, points, px, py + a);
716 grid_face_set_dot(g, d, 3);
721 assert(g->num_faces <= max_faces);
722 assert(g->num_dots <= max_dots);
723 g->middle_face = g->faces + (height/2) * width + (width/2);
725 grid_make_consistent(g);
729 grid *grid_new_honeycomb(int width, int height)
732 /* Vector for side of hexagon - ratio is close to sqrt(3) */
736 /* Upper bounds - don't have to be exact */
737 int max_faces = width * height;
738 int max_dots = 2 * (width + 1) * (height + 1);
742 grid *g = grid_new();
744 g->faces = snewn(max_faces, grid_face);
745 g->dots = snewn(max_dots, grid_dot);
747 points = newtree234(grid_point_cmp_fn);
749 /* generate hexagonal faces */
750 for (y = 0; y < height; y++) {
751 for (x = 0; x < width; x++) {
758 grid_face_add_new(g, 6);
760 d = grid_get_dot(g, points, cx - a, cy - b);
761 grid_face_set_dot(g, d, 0);
762 d = grid_get_dot(g, points, cx + a, cy - b);
763 grid_face_set_dot(g, d, 1);
764 d = grid_get_dot(g, points, cx + 2*a, cy);
765 grid_face_set_dot(g, d, 2);
766 d = grid_get_dot(g, points, cx + a, cy + b);
767 grid_face_set_dot(g, d, 3);
768 d = grid_get_dot(g, points, cx - a, cy + b);
769 grid_face_set_dot(g, d, 4);
770 d = grid_get_dot(g, points, cx - 2*a, cy);
771 grid_face_set_dot(g, d, 5);
776 assert(g->num_faces <= max_faces);
777 assert(g->num_dots <= max_dots);
778 g->middle_face = g->faces + (height/2) * width + (width/2);
780 grid_make_consistent(g);
784 /* Doesn't use the previous method of generation, it pre-dates it!
785 * A triangular grid is just about simple enough to do by "brute force" */
786 grid *grid_new_triangular(int width, int height)
790 /* Vector for side of triangle - ratio is close to sqrt(3) */
796 /* convenient alias */
799 grid *g = grid_new();
800 g->tilesize = 18; /* adjust to your taste */
802 g->num_faces = width * height * 2;
803 g->num_dots = (width + 1) * (height + 1);
804 g->faces = snewn(g->num_faces, grid_face);
805 g->dots = snewn(g->num_dots, grid_dot);
809 for (y = 0; y <= height; y++) {
810 for (x = 0; x <= width; x++) {
811 grid_dot *d = g->dots + index;
812 /* odd rows are offset to the right */
816 d->x = x * 2 * vec_x + ((y % 2) ? vec_x : 0);
824 for (y = 0; y < height; y++) {
825 for (x = 0; x < width; x++) {
826 /* initialise two faces for this (x,y) */
827 grid_face *f1 = g->faces + index;
828 grid_face *f2 = f1 + 1;
831 f1->dots = snewn(f1->order, grid_dot*);
834 f2->dots = snewn(f2->order, grid_dot*);
836 /* face descriptions depend on whether the row-number is
839 f1->dots[0] = g->dots + y * w + x;
840 f1->dots[1] = g->dots + (y + 1) * w + x + 1;
841 f1->dots[2] = g->dots + (y + 1) * w + x;
842 f2->dots[0] = g->dots + y * w + x;
843 f2->dots[1] = g->dots + y * w + x + 1;
844 f2->dots[2] = g->dots + (y + 1) * w + x + 1;
846 f1->dots[0] = g->dots + y * w + x;
847 f1->dots[1] = g->dots + y * w + x + 1;
848 f1->dots[2] = g->dots + (y + 1) * w + x;
849 f2->dots[0] = g->dots + y * w + x + 1;
850 f2->dots[1] = g->dots + (y + 1) * w + x + 1;
851 f2->dots[2] = g->dots + (y + 1) * w + x;
857 /* "+ width" takes us to the middle of the row, because each row has
858 * (2*width) faces. */
859 g->middle_face = g->faces + (height / 2) * 2 * width + width;
861 grid_make_consistent(g);
865 grid *grid_new_snubsquare(int width, int height)
868 /* Vector for side of triangle - ratio is close to sqrt(3) */
872 /* Upper bounds - don't have to be exact */
873 int max_faces = 3 * width * height;
874 int max_dots = 2 * (width + 1) * (height + 1);
878 grid *g = grid_new();
880 g->faces = snewn(max_faces, grid_face);
881 g->dots = snewn(max_dots, grid_dot);
883 points = newtree234(grid_point_cmp_fn);
885 for (y = 0; y < height; y++) {
886 for (x = 0; x < width; x++) {
889 int px = (a + b) * x;
890 int py = (a + b) * y;
892 /* generate square faces */
893 grid_face_add_new(g, 4);
895 d = grid_get_dot(g, points, px + a, py);
896 grid_face_set_dot(g, d, 0);
897 d = grid_get_dot(g, points, px + a + b, py + a);
898 grid_face_set_dot(g, d, 1);
899 d = grid_get_dot(g, points, px + b, py + a + b);
900 grid_face_set_dot(g, d, 2);
901 d = grid_get_dot(g, points, px, py + b);
902 grid_face_set_dot(g, d, 3);
904 d = grid_get_dot(g, points, px + b, py);
905 grid_face_set_dot(g, d, 0);
906 d = grid_get_dot(g, points, px + a + b, py + b);
907 grid_face_set_dot(g, d, 1);
908 d = grid_get_dot(g, points, px + a, py + a + b);
909 grid_face_set_dot(g, d, 2);
910 d = grid_get_dot(g, points, px, py + a);
911 grid_face_set_dot(g, d, 3);
914 /* generate up/down triangles */
916 grid_face_add_new(g, 3);
918 d = grid_get_dot(g, points, px + a, py);
919 grid_face_set_dot(g, d, 0);
920 d = grid_get_dot(g, points, px, py + b);
921 grid_face_set_dot(g, d, 1);
922 d = grid_get_dot(g, points, px - a, py);
923 grid_face_set_dot(g, d, 2);
925 d = grid_get_dot(g, points, px, py + a);
926 grid_face_set_dot(g, d, 0);
927 d = grid_get_dot(g, points, px + a, py + a + b);
928 grid_face_set_dot(g, d, 1);
929 d = grid_get_dot(g, points, px - a, py + a + b);
930 grid_face_set_dot(g, d, 2);
934 /* generate left/right triangles */
936 grid_face_add_new(g, 3);
938 d = grid_get_dot(g, points, px + a, py);
939 grid_face_set_dot(g, d, 0);
940 d = grid_get_dot(g, points, px + a + b, py - a);
941 grid_face_set_dot(g, d, 1);
942 d = grid_get_dot(g, points, px + a + b, py + a);
943 grid_face_set_dot(g, d, 2);
945 d = grid_get_dot(g, points, px, py - a);
946 grid_face_set_dot(g, d, 0);
947 d = grid_get_dot(g, points, px + b, py);
948 grid_face_set_dot(g, d, 1);
949 d = grid_get_dot(g, points, px, py + a);
950 grid_face_set_dot(g, d, 2);
957 assert(g->num_faces <= max_faces);
958 assert(g->num_dots <= max_dots);
959 g->middle_face = g->faces + (height/2) * width + (width/2);
961 grid_make_consistent(g);
965 grid *grid_new_cairo(int width, int height)
968 /* Vector for side of pentagon - ratio is close to (4+sqrt(7))/3 */
972 /* Upper bounds - don't have to be exact */
973 int max_faces = 2 * width * height;
974 int max_dots = 3 * (width + 1) * (height + 1);
978 grid *g = grid_new();
980 g->faces = snewn(max_faces, grid_face);
981 g->dots = snewn(max_dots, grid_dot);
983 points = newtree234(grid_point_cmp_fn);
985 for (y = 0; y < height; y++) {
986 for (x = 0; x < width; x++) {
992 /* horizontal pentagons */
994 grid_face_add_new(g, 5);
996 d = grid_get_dot(g, points, px + a, py - b);
997 grid_face_set_dot(g, d, 0);
998 d = grid_get_dot(g, points, px + 2*b - a, py - b);
999 grid_face_set_dot(g, d, 1);
1000 d = grid_get_dot(g, points, px + 2*b, py);
1001 grid_face_set_dot(g, d, 2);
1002 d = grid_get_dot(g, points, px + b, py + a);
1003 grid_face_set_dot(g, d, 3);
1004 d = grid_get_dot(g, points, px, py);
1005 grid_face_set_dot(g, d, 4);
1007 d = grid_get_dot(g, points, px, py);
1008 grid_face_set_dot(g, d, 0);
1009 d = grid_get_dot(g, points, px + b, py - a);
1010 grid_face_set_dot(g, d, 1);
1011 d = grid_get_dot(g, points, px + 2*b, py);
1012 grid_face_set_dot(g, d, 2);
1013 d = grid_get_dot(g, points, px + 2*b - a, py + b);
1014 grid_face_set_dot(g, d, 3);
1015 d = grid_get_dot(g, points, px + a, py + b);
1016 grid_face_set_dot(g, d, 4);
1019 /* vertical pentagons */
1021 grid_face_add_new(g, 5);
1023 d = grid_get_dot(g, points, px, py);
1024 grid_face_set_dot(g, d, 0);
1025 d = grid_get_dot(g, points, px + b, py + a);
1026 grid_face_set_dot(g, d, 1);
1027 d = grid_get_dot(g, points, px + b, py + 2*b - a);
1028 grid_face_set_dot(g, d, 2);
1029 d = grid_get_dot(g, points, px, py + 2*b);
1030 grid_face_set_dot(g, d, 3);
1031 d = grid_get_dot(g, points, px - a, py + b);
1032 grid_face_set_dot(g, d, 4);
1034 d = grid_get_dot(g, points, px, py);
1035 grid_face_set_dot(g, d, 0);
1036 d = grid_get_dot(g, points, px + a, py + b);
1037 grid_face_set_dot(g, d, 1);
1038 d = grid_get_dot(g, points, px, py + 2*b);
1039 grid_face_set_dot(g, d, 2);
1040 d = grid_get_dot(g, points, px - b, py + 2*b - a);
1041 grid_face_set_dot(g, d, 3);
1042 d = grid_get_dot(g, points, px - b, py + a);
1043 grid_face_set_dot(g, d, 4);
1049 freetree234(points);
1050 assert(g->num_faces <= max_faces);
1051 assert(g->num_dots <= max_dots);
1052 g->middle_face = g->faces + (height/2) * width + (width/2);
1054 grid_make_consistent(g);
1058 grid *grid_new_greathexagonal(int width, int height)
1061 /* Vector for side of triangle - ratio is close to sqrt(3) */
1065 /* Upper bounds - don't have to be exact */
1066 int max_faces = 6 * (width + 1) * (height + 1);
1067 int max_dots = 6 * width * height;
1071 grid *g = grid_new();
1073 g->faces = snewn(max_faces, grid_face);
1074 g->dots = snewn(max_dots, grid_dot);
1076 points = newtree234(grid_point_cmp_fn);
1078 for (y = 0; y < height; y++) {
1079 for (x = 0; x < width; x++) {
1081 /* centre of hexagon */
1082 int px = (3*a + b) * x;
1083 int py = (2*a + 2*b) * y;
1088 grid_face_add_new(g, 6);
1089 d = grid_get_dot(g, points, px - a, py - b);
1090 grid_face_set_dot(g, d, 0);
1091 d = grid_get_dot(g, points, px + a, py - b);
1092 grid_face_set_dot(g, d, 1);
1093 d = grid_get_dot(g, points, px + 2*a, py);
1094 grid_face_set_dot(g, d, 2);
1095 d = grid_get_dot(g, points, px + a, py + b);
1096 grid_face_set_dot(g, d, 3);
1097 d = grid_get_dot(g, points, px - a, py + b);
1098 grid_face_set_dot(g, d, 4);
1099 d = grid_get_dot(g, points, px - 2*a, py);
1100 grid_face_set_dot(g, d, 5);
1102 /* square below hexagon */
1103 if (y < height - 1) {
1104 grid_face_add_new(g, 4);
1105 d = grid_get_dot(g, points, px - a, py + b);
1106 grid_face_set_dot(g, d, 0);
1107 d = grid_get_dot(g, points, px + a, py + b);
1108 grid_face_set_dot(g, d, 1);
1109 d = grid_get_dot(g, points, px + a, py + 2*a + b);
1110 grid_face_set_dot(g, d, 2);
1111 d = grid_get_dot(g, points, px - a, py + 2*a + b);
1112 grid_face_set_dot(g, d, 3);
1115 /* square below right */
1116 if ((x < width - 1) && (((x % 2) == 0) || (y < height - 1))) {
1117 grid_face_add_new(g, 4);
1118 d = grid_get_dot(g, points, px + 2*a, py);
1119 grid_face_set_dot(g, d, 0);
1120 d = grid_get_dot(g, points, px + 2*a + b, py + a);
1121 grid_face_set_dot(g, d, 1);
1122 d = grid_get_dot(g, points, px + a + b, py + a + b);
1123 grid_face_set_dot(g, d, 2);
1124 d = grid_get_dot(g, points, px + a, py + b);
1125 grid_face_set_dot(g, d, 3);
1128 /* square below left */
1129 if ((x > 0) && (((x % 2) == 0) || (y < height - 1))) {
1130 grid_face_add_new(g, 4);
1131 d = grid_get_dot(g, points, px - 2*a, py);
1132 grid_face_set_dot(g, d, 0);
1133 d = grid_get_dot(g, points, px - a, py + b);
1134 grid_face_set_dot(g, d, 1);
1135 d = grid_get_dot(g, points, px - a - b, py + a + b);
1136 grid_face_set_dot(g, d, 2);
1137 d = grid_get_dot(g, points, px - 2*a - b, py + a);
1138 grid_face_set_dot(g, d, 3);
1141 /* Triangle below right */
1142 if ((x < width - 1) && (y < height - 1)) {
1143 grid_face_add_new(g, 3);
1144 d = grid_get_dot(g, points, px + a, py + b);
1145 grid_face_set_dot(g, d, 0);
1146 d = grid_get_dot(g, points, px + a + b, py + a + b);
1147 grid_face_set_dot(g, d, 1);
1148 d = grid_get_dot(g, points, px + a, py + 2*a + b);
1149 grid_face_set_dot(g, d, 2);
1152 /* Triangle below left */
1153 if ((x > 0) && (y < height - 1)) {
1154 grid_face_add_new(g, 3);
1155 d = grid_get_dot(g, points, px - a, py + b);
1156 grid_face_set_dot(g, d, 0);
1157 d = grid_get_dot(g, points, px - a, py + 2*a + b);
1158 grid_face_set_dot(g, d, 1);
1159 d = grid_get_dot(g, points, px - a - b, py + a + b);
1160 grid_face_set_dot(g, d, 2);
1165 freetree234(points);
1166 assert(g->num_faces <= max_faces);
1167 assert(g->num_dots <= max_dots);
1168 g->middle_face = g->faces + (height/2) * width + (width/2);
1170 grid_make_consistent(g);
1174 grid *grid_new_octagonal(int width, int height)
1177 /* b/a approx sqrt(2) */
1181 /* Upper bounds - don't have to be exact */
1182 int max_faces = 2 * width * height;
1183 int max_dots = 4 * (width + 1) * (height + 1);
1187 grid *g = grid_new();
1189 g->faces = snewn(max_faces, grid_face);
1190 g->dots = snewn(max_dots, grid_dot);
1192 points = newtree234(grid_point_cmp_fn);
1194 for (y = 0; y < height; y++) {
1195 for (x = 0; x < width; x++) {
1198 int px = (2*a + b) * x;
1199 int py = (2*a + b) * y;
1201 grid_face_add_new(g, 8);
1202 d = grid_get_dot(g, points, px + a, py);
1203 grid_face_set_dot(g, d, 0);
1204 d = grid_get_dot(g, points, px + a + b, py);
1205 grid_face_set_dot(g, d, 1);
1206 d = grid_get_dot(g, points, px + 2*a + b, py + a);
1207 grid_face_set_dot(g, d, 2);
1208 d = grid_get_dot(g, points, px + 2*a + b, py + a + b);
1209 grid_face_set_dot(g, d, 3);
1210 d = grid_get_dot(g, points, px + a + b, py + 2*a + b);
1211 grid_face_set_dot(g, d, 4);
1212 d = grid_get_dot(g, points, px + a, py + 2*a + b);
1213 grid_face_set_dot(g, d, 5);
1214 d = grid_get_dot(g, points, px, py + a + b);
1215 grid_face_set_dot(g, d, 6);
1216 d = grid_get_dot(g, points, px, py + a);
1217 grid_face_set_dot(g, d, 7);
1220 if ((x > 0) && (y > 0)) {
1221 grid_face_add_new(g, 4);
1222 d = grid_get_dot(g, points, px, py - a);
1223 grid_face_set_dot(g, d, 0);
1224 d = grid_get_dot(g, points, px + a, py);
1225 grid_face_set_dot(g, d, 1);
1226 d = grid_get_dot(g, points, px, py + a);
1227 grid_face_set_dot(g, d, 2);
1228 d = grid_get_dot(g, points, px - a, py);
1229 grid_face_set_dot(g, d, 3);
1234 freetree234(points);
1235 assert(g->num_faces <= max_faces);
1236 assert(g->num_dots <= max_dots);
1237 g->middle_face = g->faces + (height/2) * width + (width/2);
1239 grid_make_consistent(g);
1243 grid *grid_new_kites(int width, int height)
1246 /* b/a approx sqrt(3) */
1250 /* Upper bounds - don't have to be exact */
1251 int max_faces = 6 * width * height;
1252 int max_dots = 6 * (width + 1) * (height + 1);
1256 grid *g = grid_new();
1258 g->faces = snewn(max_faces, grid_face);
1259 g->dots = snewn(max_dots, grid_dot);
1261 points = newtree234(grid_point_cmp_fn);
1263 for (y = 0; y < height; y++) {
1264 for (x = 0; x < width; x++) {
1266 /* position of order-6 dot */
1272 /* kite pointing up-left */
1273 grid_face_add_new(g, 4);
1274 d = grid_get_dot(g, points, px, py);
1275 grid_face_set_dot(g, d, 0);
1276 d = grid_get_dot(g, points, px + 2*b, py);
1277 grid_face_set_dot(g, d, 1);
1278 d = grid_get_dot(g, points, px + 2*b, py + 2*a);
1279 grid_face_set_dot(g, d, 2);
1280 d = grid_get_dot(g, points, px + b, py + 3*a);
1281 grid_face_set_dot(g, d, 3);
1283 /* kite pointing up */
1284 grid_face_add_new(g, 4);
1285 d = grid_get_dot(g, points, px, py);
1286 grid_face_set_dot(g, d, 0);
1287 d = grid_get_dot(g, points, px + b, py + 3*a);
1288 grid_face_set_dot(g, d, 1);
1289 d = grid_get_dot(g, points, px, py + 4*a);
1290 grid_face_set_dot(g, d, 2);
1291 d = grid_get_dot(g, points, px - b, py + 3*a);
1292 grid_face_set_dot(g, d, 3);
1294 /* kite pointing up-right */
1295 grid_face_add_new(g, 4);
1296 d = grid_get_dot(g, points, px, py);
1297 grid_face_set_dot(g, d, 0);
1298 d = grid_get_dot(g, points, px - b, py + 3*a);
1299 grid_face_set_dot(g, d, 1);
1300 d = grid_get_dot(g, points, px - 2*b, py + 2*a);
1301 grid_face_set_dot(g, d, 2);
1302 d = grid_get_dot(g, points, px - 2*b, py);
1303 grid_face_set_dot(g, d, 3);
1305 /* kite pointing down-right */
1306 grid_face_add_new(g, 4);
1307 d = grid_get_dot(g, points, px, py);
1308 grid_face_set_dot(g, d, 0);
1309 d = grid_get_dot(g, points, px - 2*b, py);
1310 grid_face_set_dot(g, d, 1);
1311 d = grid_get_dot(g, points, px - 2*b, py - 2*a);
1312 grid_face_set_dot(g, d, 2);
1313 d = grid_get_dot(g, points, px - b, py - 3*a);
1314 grid_face_set_dot(g, d, 3);
1316 /* kite pointing down */
1317 grid_face_add_new(g, 4);
1318 d = grid_get_dot(g, points, px, py);
1319 grid_face_set_dot(g, d, 0);
1320 d = grid_get_dot(g, points, px - b, py - 3*a);
1321 grid_face_set_dot(g, d, 1);
1322 d = grid_get_dot(g, points, px, py - 4*a);
1323 grid_face_set_dot(g, d, 2);
1324 d = grid_get_dot(g, points, px + b, py - 3*a);
1325 grid_face_set_dot(g, d, 3);
1327 /* kite pointing down-left */
1328 grid_face_add_new(g, 4);
1329 d = grid_get_dot(g, points, px, py);
1330 grid_face_set_dot(g, d, 0);
1331 d = grid_get_dot(g, points, px + b, py - 3*a);
1332 grid_face_set_dot(g, d, 1);
1333 d = grid_get_dot(g, points, px + 2*b, py - 2*a);
1334 grid_face_set_dot(g, d, 2);
1335 d = grid_get_dot(g, points, px + 2*b, py);
1336 grid_face_set_dot(g, d, 3);
1340 freetree234(points);
1341 assert(g->num_faces <= max_faces);
1342 assert(g->num_dots <= max_dots);
1343 g->middle_face = g->faces + 6 * ((height/2) * width + (width/2));
1345 grid_make_consistent(g);
1349 /* ----------- End of grid generators ------------- */