12 static void _trap(int line)
15 printf("Trapped from line %d, use debugger to get backtrace\n",
22 #define trap() _trap(__LINE__)
24 static int quadtree_compare_coord(const struct vector *a,
25 const struct vector *b)
41 static int quadtree_compare(const struct quadtree *a, const struct quadtree *b)
43 return quadtree_compare_coord(&a->pos, &b->pos);
46 static void validate_subtree(const struct quadtree *node)
53 printf("Attempted to validate a null pointer\n");
58 for (i = 0; i < 4; i++) {
62 if (node->child[i]->parent != node) {
63 printf("%s:%d Fatal! Tree inconsistency detected at "
64 "child %d %p in node %p, incorrent parent %p\n",
65 __func__, __LINE__, i, node->child[i], node,
66 node->child[i]->parent);
72 if (node->child[i] == node->parent) {
73 printf("%s:%d Fatal! Tree loop detected "
74 "at child %d in node %p\n",
75 __func__, __LINE__, i, node);
81 dir = quadtree_compare(node, node->child[i]);
84 printf("%s:%d Fatal! Spatial inconsistency detected "
85 "at child %d in node %p\n"
86 "parent: (%f %f), child (%f %f), "
88 __func__, __LINE__, i, node,
89 node->pos.x, node->pos.y,
90 node->child[i]->pos.x, node->child[i]->pos.y,
96 children += node->child[i]->children + 1;
98 validate_subtree(node->child[i]);
101 if (node->depth < 0) {
102 printf("%s:%d Tree statistics inconsistency detected! "
103 "Negative depth: %ld\n",
104 __func__, __LINE__, node->depth);
107 if (node->children != children) {
108 printf("%s:%d Tree statistics inconsistency detected! "
109 "child count mismatch. Expected %ld, got %ld\n",
110 __func__, __LINE__, children, node->children);
115 for (i = 0; i < 4 && node->children; i++) {
119 if (node->depth == node->child[i]->depth + 1)
122 if (node->child[i]->depth > node->depth) {
123 printf("%s:%d Tree statistics inconsistency detected! "
124 "child depth mismatch %ld > %ld\n",
125 __func__, __LINE__, node->child[i]->depth,
131 printf("%s:%d Tree statistics inconsistency detected! "
132 "child depth mismatch.",
139 static void validate_tree(const struct quadtree *node)
147 return validate_subtree(node);
149 for (i = 0; i < 4; i++)
150 if (node->parent->child[i] == node)
154 printf("%s:%d Tree inconsistency detected! "
155 "Wrong parent %p for node %p\n",
156 __func__, __LINE__, node->parent, node);
161 validate_tree(node->parent);
164 void _quadtree_validate_tree(const struct quadtree *node)
169 static struct quadtree *_quadtree_add(struct quadtree *parent,
170 struct quadtree *new)
174 ret = quadtree_compare(parent, new);
176 if (ret < 0 || ret >= 4) {
177 printf("Invalid comparison result of %d\n", ret);
181 if (parent->child[ret])
182 return _quadtree_add(parent->child[ret], new);
184 parent->child[ret] = new;
185 new->parent = parent;
186 for (i = 0; i < 4; i++)
192 static void _recalculate_node_area_stats(struct quadtree *node)
194 /* The space covered by the parent node's corner
195 * points needs be as wide as its widest child node's
198 #define CHILD_CORNER_SAFE(node, ch_idx, cor_idx, axis) \
199 ((node)->child[ch_idx] ? \
200 (node)->child[ch_idx]->corner[cor_idx].axis : \
203 node->corner[0].x = MIN(CHILD_CORNER_SAFE(node, 0, 0, x),
204 CHILD_CORNER_SAFE(node, 2, 0, x));
205 node->corner[0].y = MIN(CHILD_CORNER_SAFE(node, 0, 0, y),
206 CHILD_CORNER_SAFE(node, 1, 0, y));
207 node->corner[1].x = MAX(CHILD_CORNER_SAFE(node, 1, 1, x),
208 CHILD_CORNER_SAFE(node, 3, 1, x));
209 node->corner[1].y = MAX(CHILD_CORNER_SAFE(node, 2, 1, y),
210 CHILD_CORNER_SAFE(node, 3, 1, y));
211 #undef CHILD_CORNER_SAFE
214 static void recalculate_parent_area_stats(struct quadtree *node)
217 _recalculate_node_area_stats(node);
224 * Recursively walk through the tree and propagate changes made to the
225 * given node up until the highest parent.
227 static void quadtree_recalculate_parent_stats(struct quadtree *node,
228 struct quadtree_ops *ops)
236 for (i = 0; i < 4; i++) {
240 node->depth = MAX(node->depth,
241 node->child[i]->depth + 1);
242 node->children += node->child[i]->children + 1;
245 _recalculate_node_area_stats(node);
247 if (ops->recalculate_stats)
248 ops->recalculate_stats(node);
255 * quadtree_add - add a node to a quadtree
256 * @parent: parent node
257 * @new: the new node to be added
259 * Add a node to a quadtree. The tree is kept in order, the new node
260 * is placed in the end of appropriate branch.
262 * The case of nodes sharing identical coordinates is not taken into
266 struct quadtree *quadtree_add(struct quadtree *parent, struct quadtree *new,
267 struct quadtree_ops *ops)
272 validate_tree(parent);
274 _quadtree_add(parent, new);
277 printf("adding node %p to parent %p\n", new, parent);
281 quadtree_recalculate_parent_stats(new, ops);
288 static int is_within(struct vector *pos, struct vector *corner)
290 if ((pos->x >= corner[1].x) && (pos->x <= corner[0].x) &&
291 (pos->y >= corner[1].y) && (pos->y <= corner[0].y))
296 static int rectangle_and_circle_overlap(struct vector *corner,
297 struct vector *pos, double radius)
299 int vertically_overlapping = 0, horizontally_overlapping = 0;
301 if ((pos->x < corner[1].x && pos->x + radius > corner[0].x) ||
302 (pos->x > corner[0].x && pos->x - radius < corner[1].x))
303 horizontally_overlapping = 1;
305 if ((pos->y < corner[1].y && pos->y + radius > corner[0].y) ||
306 (pos->y > corner[0].y && pos->y - radius < corner[1].y))
307 vertically_overlapping = 1;
309 return horizontally_overlapping && vertically_overlapping;
312 static int quadrants_to_search(struct quadtree *node, struct vector *pos,
320 if (node->child[0] &&
321 rectangle_and_circle_overlap(node->child[0]->corner, pos, dist))
322 direction |= QUADTREE_UPLEFT;
324 if (node->child[1] &&
325 rectangle_and_circle_overlap(node->child[1]->corner, pos, dist))
326 direction |= QUADTREE_UPRIGHT;
328 if (node->child[2] &&
329 rectangle_and_circle_overlap(node->child[2]->corner, pos, dist))
330 direction |= QUADTREE_DOWNLEFT;
332 if (node->child[3] &&
333 rectangle_and_circle_overlap(node->child[3]->corner, pos, dist))
334 direction |= QUADTREE_DOWNRIGHT;
339 static struct quadtree *quadtree_find_nearest(struct quadtree *tree,
341 struct vector *corner,
342 struct quadtree *nearest,
346 struct quadtree *node;
347 double distance = 0, dist;
353 vector_sub(&nearest->pos, pos, &tmp);
354 distance = vector_abs(&tmp);
356 if (tree != nearest) {
357 vector_sub(&tree->pos, pos, &tmp);
358 dist = vector_abs(&tmp);
359 if (dist < distance) {
365 if (!is_within(&nearest->pos, corner)) {
367 printf("Discarding nearest %p "
368 "as outside of search window\n", nearest);
373 directions = quadrants_to_search(tree, pos, distance);
375 printf("%d: Directions: %x\n", depth, directions);
376 for (i = 0; i < 4; i++) {
380 if (!(directions & (1 << i)))
384 node = quadtree_find_nearest(tree->child[i], pos, corner,
390 if (node != nearest) {
391 vector_sub(&node->pos, pos, &tmp);
392 dist = vector_abs(&tmp);
393 if (dist < distance || !nearest) {
398 * Update the directions where to search for
399 * since those may not be valid any more
401 directions = quadrants_to_search(tree, pos, distance);
406 if (nearest && !is_within(&nearest->pos, corner)) {
408 printf("%d: Node %p (%f %f) is not within "
409 "search window (%f %f) (%f %f)\n", depth,
410 nearest, nearest->pos.x, nearest->pos.y,
411 corner[0].x, corner[0].y,
412 corner[1].x, corner[1].y);
416 printf("%d: Node %p (%f %f) is nearest node, dist %f\n",
418 nearest ? nearest->pos.x : -1,
419 nearest ? nearest->pos.y : -1,
420 nearest ? distance : -1);
424 static struct quadtree *quadtree_find_nearest_noparent(struct quadtree *tree,
426 struct vector *corner)
428 struct quadtree *nearest = NULL;
430 struct quadtree *node;
431 double dist = 0, dist2;
434 nearest = quadtree_find_nearest(tree, pos, corner, nearest, 0);
440 printf("Avoiding parent or NULL node %p\n", nearest);
443 * oops, we don't want to pick the parent node, let's choose
447 for (i = 0; i < 4; i++) {
452 nearest = quadtree_find_nearest(tree->child[i], pos,
458 vector_sub(pos, &nearest->pos, &sub);
459 dist = vector_abs(&sub);
462 node = quadtree_find_nearest(tree->child[i], pos, corner,
468 vector_sub(pos, &node->pos, &sub);
469 dist2 = vector_abs(&sub);
481 static void get_middle_point(struct vector *corner, struct vector *middle)
483 middle->x = (corner[0].x + corner[1].x) / (double)2;
484 middle->y = (corner[0].y + corner[1].y) / (double)2;
487 static int quadtree_split_by_node(struct quadtree *node,
488 struct vector *corner, int dir)
490 if (!is_within(&node->pos, corner)) {
492 printf("Not within search rectangle\n");
497 printf("Search rectangle was before (%f %f) (%f %f), (%f %f)\n",
498 corner[0].x, corner[0].y,
499 corner[1].x, corner[1].y,
500 node->pos.x, node->pos.y);
503 case QUADTREE_UPLEFT:
504 corner[0] = node->pos;
506 case QUADTREE_UPRIGHT:
507 corner[0].y = node->pos.y;
508 corner[1].x = node->pos.x;
510 case QUADTREE_DOWNRIGHT:
511 corner[1] = node->pos;
513 case QUADTREE_DOWNLEFT:
514 corner[0].x = node->pos.x;
515 corner[1].y = node->pos.y;
522 printf("Search rectangle is now (%f %f) (%f %f), (%f %f)\n",
523 corner[0].x, corner[0].y,
524 corner[1].x, corner[1].y,
525 node->pos.x, node->pos.y);
527 if ((corner[0].x < corner[1].x) ||
528 (corner[0].y < corner[1].y))
535 * Quickly detach a node from a tree. Move all child nodes under
538 static int _quadtree_del(struct quadtree *node, struct quadtree *parent)
543 /* Detach from the tree */
545 for (i = 0; i < 4; i++) {
546 if (node->parent->child[i] == node) {
547 node->parent->child[i] = 0;
555 for (i = 0; i < 4; i++) {
560 _quadtree_del(n, parent);
561 _quadtree_add(parent, n);
562 recalculate_parent_area_stats(n);
569 * Move everything under @tree node to @parent node, everything
570 * else except the @tree node itself
572 static int optimally_move_tree(struct quadtree *tree, struct quadtree *parent,
573 struct vector *corner_orig,
574 struct quadtree_ops *ops)
576 struct vector corner[2], mid;
577 struct quadtree *t, *tmp;
580 get_middle_point(corner_orig, &mid);
581 t = quadtree_find_nearest_noparent(tree, &mid, corner_orig);
585 printf("Cannot find nearest node\n");
591 * Now we have the t node which contains the object of the
592 * spatial middle coordinates of the tree.
596 printf("Relocating node %p (%f %f) under parent %p\n", t,
597 t->pos.x, t->pos.y, parent);
598 printf("There are %ld child nodes left\n", tree->children);
601 _quadtree_del(t, tree);
602 quadtree_add(parent, t, ops);
610 * Now split the search rectangle in quadtres and do the same
611 * with all of the quarters.
614 corner[0] = corner_orig[0];
615 corner[1] = corner_orig[1];
616 if (quadtree_split_by_node(t, corner, QUADTREE_UPLEFT))
617 moved += optimally_move_tree(tree, parent, corner, ops);
619 corner[0] = corner_orig[0];
620 corner[1] = corner_orig[1];
621 if (quadtree_split_by_node(t, corner, QUADTREE_UPRIGHT))
622 moved += optimally_move_tree(tree, parent, corner, ops);
624 corner[0] = corner_orig[0];
625 corner[1] = corner_orig[1];
626 if (quadtree_split_by_node(t, corner, QUADTREE_DOWNLEFT))
627 moved += optimally_move_tree(tree, parent, corner, ops);
629 corner[0] = corner_orig[0];
630 corner[1] = corner_orig[1];
631 if (quadtree_split_by_node(t, corner, QUADTREE_DOWNRIGHT))
632 moved += optimally_move_tree(tree, parent, corner, ops);
636 printf("Now moved %d nodes, %ld left\n", moved, tree->children);
642 * quadtree_del - Detach a node from the tree
644 * Return value: The new root node of the tree. If we are detaching
645 * anything but the root node of the entire tree, the returned root
646 * value will be the original root of the tree.
648 struct quadtree *quadtree_del(struct quadtree *node,
649 struct quadtree_ops *ops)
651 struct quadtree *parent = NULL;
652 struct vector corner[2];
653 int i, children = node->children, moved;
658 printf("Deleting node %p under parent %p\n",
660 printf("Relocating %ld children\n", node->children);
666 * We are deleting the root node. This means we have
667 * to select a new root node and reconstruct the
668 * entire tree under it again.
671 printf("Deleting root node\n");
674 for (i = 0; i < 4; i++) {
678 parent = node->child[i];
679 _quadtree_del(parent, node);
681 quadtree_recalculate_parent_stats(parent, ops);
686 * The node has a parent. Detach the node from it and
687 * relocate the children.
690 for (i = 0; i < 4; i++) {
691 if (node->parent->child[i] == node) {
692 node->parent->child[i] = 0;
699 parent = node->parent;
703 * The sub branch is now detached from the main
704 * tree. Fix the stats.
706 quadtree_recalculate_parent_stats(parent, ops);
709 validate_tree(parent);
714 * Now we are ready to prepare for relocating the nodes under
718 corner[0] = node->corner[1];
719 corner[1] = node->corner[0];
721 printf("\nInitial Search rectangle (%f %f) (%f %f), (%f %f)\n",
722 corner[0].x, corner[0].y,
723 corner[1].x, corner[1].y,
724 node->pos.x, node->pos.y);
727 moved = optimally_move_tree(node, parent, corner, ops);
730 if (moved != children) {
731 printf("Got %d children but %d were moved\n",
733 printf("nearest children left:\n");
734 for (i = 0 ; i < 4; i++)
736 printf(" node %d %p, (%f %f)\n",
738 node->child[i]->pos.x,
739 node->child[i]->pos.y);
743 printf("Delete done, returning parent %p\n", parent);
748 validate_tree(parent);
749 return quadtree_find_parent(parent);
752 static void check_for_crossed_subnodes(struct quadtree *node,
753 struct vector *limit, struct quadtree_ops *ops)
755 int direction = 0, i;
756 int up = 0, left = 0, right = 0, down = 0;
758 for (i = 0; i < 2; i++) {
759 if (limit[i].x < node->pos.x)
763 if (limit[i].y < node->pos.y)
770 direction |= QUADTREE_UPLEFT;
772 direction |= QUADTREE_UPRIGHT;
774 direction |= QUADTREE_DOWNLEFT;
776 direction |= QUADTREE_DOWNRIGHT;
777 if ((left && right) || (up && down))
778 direction |= QUADTREE_SELF;
780 if ((direction & QUADTREE_UPLEFT) && node->child[0])
781 check_for_crossed_subnodes(node->child[0], limit, ops);
783 if ((direction & QUADTREE_UPRIGHT) && node->child[1])
784 check_for_crossed_subnodes(node->child[0], limit, ops);
786 if ((direction & QUADTREE_DOWNLEFT) && node->child[2])
787 check_for_crossed_subnodes(node->child[0], limit, ops);
789 if ((direction & QUADTREE_DOWNRIGHT) && node->child[3])
790 check_for_crossed_subnodes(node->child[0], limit, ops);
792 if (direction & QUADTREE_SELF) {
793 struct quadtree *parent;
795 parent = quadtree_del(node, ops);
796 quadtree_add(parent, node, ops);
800 struct quadtree *quadtree_move(struct quadtree *node, struct vector new_pos,
801 struct quadtree_ops *ops)
803 struct quadtree *parent, *tree_parent;
806 /* Check if we have crossed any of the parents */
807 parent = node->parent;
809 if (node->pos.x < parent->pos.x && new_pos.x > parent->pos.x)
811 if (node->pos.x > parent->pos.x && new_pos.x < parent->pos.x)
813 if (node->pos.y < parent->pos.y && new_pos.y > parent->pos.y)
815 if (node->pos.y > parent->pos.y && new_pos.y < parent->pos.y)
819 parent = parent->parent;
824 * If the node has crossed the boundaries, remove it
825 * from the tree and add it again to it. It is then
826 * guaranteed to be in the correct position of the
829 tree_parent = quadtree_del(node, ops);
831 quadtree_add(tree_parent, node, ops);
835 /* Move the node into its new location */
837 recalculate_parent_area_stats(node);
839 if (node->children) {
841 * Now, search the subtree for any children that are
842 * located in wrong place and move them into correct
843 * place within the tree.
845 struct vector limit[2];
847 limit[0] = node->pos;
849 check_for_crossed_subnodes(node, limit, ops);
852 return quadtree_find_parent(node);
856 static int _walk_tree(struct quadtree *head, const struct quadtree_iterator *it)
858 int direction, count = 0;
860 direction = it->direction(head, (struct quadtree_iterator *)it);
862 if ((direction & QUADTREE_UPLEFT) && head->child[0])
863 count += _walk_tree(head->child[0], it);
865 if ((direction & QUADTREE_UPRIGHT) && head->child[1])
866 count += _walk_tree(head->child[1], it);
868 if ((direction & QUADTREE_DOWNLEFT) && head->child[2])
869 count += _walk_tree(head->child[2], it);
871 if ((direction & QUADTREE_DOWNRIGHT) && head->child[3])
872 count += _walk_tree(head->child[3], it);
874 if ((direction & QUADTREE_SELF) && it->callback) {
875 it->callback(head, (struct quadtree_iterator *)it);
882 int walk_quadtree(const struct quadtree_iterator *it)
884 return _walk_tree(it->head, it);