First Commit

kdtree/kdtree.c

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+/*
+This file is part of ``kdtree'', a library for working with kd-trees.
+Copyright (C) 2007-2011 John Tsiombikas <nuclear@member.fsf.org>
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+3. The name of the author may not be used to endorse or promote products
+   derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+OF SUCH DAMAGE.
+*/
+/* single nearest neighbor search written by Tamas Nepusz <tamas@cs.rhul.ac.uk> */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include "kdtree.h"
+
+#if defined(WIN32) || defined(__WIN32__) || defined(_WIN32)
+#include <malloc.h>
+#define alloca _alloca
+#endif
+
+#ifdef USE_LIST_NODE_ALLOCATOR
+
+#ifndef NO_PTHREADS
+#include <pthread.h>
+#else
+
+#ifndef I_WANT_THREAD_BUGS
+#error "You are compiling with the fast list node allocator, with pthreads disabled! This WILL break if used from multiple threads."
+#endif	/* I want thread bugs */
+
+#endif	/* pthread support */
+#endif	/* use list node allocator */
+
+struct kdhyperrect {
+	int dim;
+	double *min, *max;              /* minimum/maximum coords */
+};
+
+struct kdnode {
+	double *pos;
+	int dir;
+	void *data;
+
+	struct kdnode *left, *right;	/* negative/positive side */
+};
+
+struct res_node {
+	struct kdnode *item;
+	double dist_sq;
+	struct res_node *next;
+};
+
+struct kdtree {
+	int dim;
+	struct kdnode *root;
+	struct kdhyperrect *rect;
+	void (*destr)(void*);
+};
+
+struct kdres {
+	struct kdtree *tree;
+	struct res_node *rlist, *riter;
+	int size;
+};
+
+#define SQ(x)			((x) * (x))
+
+
+static void clear_rec(struct kdnode *node, void (*destr)(void*));
+static int insert_rec(struct kdnode **node, const double *pos, void *data, int dir, int dim);
+static int rlist_insert(struct res_node *list, struct kdnode *item, double dist_sq);
+static void clear_results(struct kdres *set);
+
+static struct kdhyperrect* hyperrect_create(int dim, const double *min, const double *max);
+static void hyperrect_free(struct kdhyperrect *rect);
+static struct kdhyperrect* hyperrect_duplicate(const struct kdhyperrect *rect);
+static void hyperrect_extend(struct kdhyperrect *rect, const double *pos);
+static double hyperrect_dist_sq(struct kdhyperrect *rect, const double *pos);
+
+#ifdef USE_LIST_NODE_ALLOCATOR
+static struct res_node *alloc_resnode(void);
+static void free_resnode(struct res_node*);
+#else
+#define alloc_resnode()		malloc(sizeof(struct res_node))
+#define free_resnode(n)		free(n)
+#endif
+
+
+
+struct kdtree *kd_create(int k)
+{
+	struct kdtree *tree;
+
+	if(!(tree = malloc(sizeof *tree))) {
+		return 0;
+	}
+
+	tree->dim = k;
+	tree->root = 0;
+	tree->destr = 0;
+	tree->rect = 0;
+
+	return tree;
+}
+
+void kd_free(struct kdtree *tree)
+{
+	if(tree) {
+		kd_clear(tree);
+		free(tree);
+	}
+}
+
+static void clear_rec(struct kdnode *node, void (*destr)(void*))
+{
+	if(!node) return;
+
+	clear_rec(node->left, destr);
+	clear_rec(node->right, destr);
+	
+	if(destr) {
+		destr(node->data);
+	}
+	free(node->pos);
+	free(node);
+}
+
+void kd_clear(struct kdtree *tree)
+{
+	clear_rec(tree->root, tree->destr);
+	tree->root = 0;
+
+	if (tree->rect) {
+		hyperrect_free(tree->rect);
+		tree->rect = 0;
+	}
+}
+
+void kd_data_destructor(struct kdtree *tree, void (*destr)(void*))
+{
+	tree->destr = destr;
+}
+
+
+static int insert_rec(struct kdnode **nptr, const double *pos, void *data, int dir, int dim)
+{
+	int new_dir;
+	struct kdnode *node;
+
+	if(!*nptr) {
+		if(!(node = malloc(sizeof *node))) {
+			return -1;
+		}
+		if(!(node->pos = malloc(dim * sizeof *node->pos))) {
+			free(node);
+			return -1;
+		}
+		memcpy(node->pos, pos, dim * sizeof *node->pos);
+		node->data = data;
+		node->dir = dir;
+		node->left = node->right = 0;
+		*nptr = node;
+		return 0;
+	}
+
+	node = *nptr;
+	new_dir = (node->dir + 1) % dim;
+	if(pos[node->dir] < node->pos[node->dir]) {
+		return insert_rec(&(*nptr)->left, pos, data, new_dir, dim);
+	}
+	return insert_rec(&(*nptr)->right, pos, data, new_dir, dim);
+}
+
+int kd_insert(struct kdtree *tree, const double *pos, void *data)
+{
+	if (insert_rec(&tree->root, pos, data, 0, tree->dim)) {
+		return -1;
+	}
+
+	if (tree->rect == 0) {
+		tree->rect = hyperrect_create(tree->dim, pos, pos);
+	} else {
+		hyperrect_extend(tree->rect, pos);
+	}
+
+	return 0;
+}
+
+int kd_insertf(struct kdtree *tree, const float *pos, void *data)
+{
+	static double sbuf[16];
+	double *bptr, *buf = 0;
+	int res, dim = tree->dim;
+
+	if(dim > 16) {
+#ifndef NO_ALLOCA
+		if(dim <= 256)
+			bptr = buf = alloca(dim * sizeof *bptr);
+		else
+#endif
+			if(!(bptr = buf = malloc(dim * sizeof *bptr))) {
+				return -1;
+			}
+	} else {
+		bptr = buf = sbuf;
+	}
+
+	while(dim-- > 0) {
+		*bptr++ = *pos++;
+	}
+
+	res = kd_insert(tree, buf, data);
+#ifndef NO_ALLOCA
+	if(tree->dim > 256)
+#else
+	if(tree->dim > 16)
+#endif
+		free(buf);
+	return res;
+}
+
+int kd_insert3(struct kdtree *tree, double x, double y, double z, void *data)
+{
+	double buf[3];
+	buf[0] = x;
+	buf[1] = y;
+	buf[2] = z;
+	return kd_insert(tree, buf, data);
+}
+
+int kd_insert3f(struct kdtree *tree, float x, float y, float z, void *data)
+{
+	double buf[3];
+	buf[0] = x;
+	buf[1] = y;
+	buf[2] = z;
+	return kd_insert(tree, buf, data);
+}
+
+static int find_nearest(struct kdnode *node, const double *pos, double range, struct res_node *list, int ordered, int dim)
+{
+	double dist_sq, dx;
+	int i, ret, added_res = 0;
+
+	if(!node) return 0;
+
+	dist_sq = 0;
+	for(i=0; i<dim; i++) {
+		dist_sq += SQ(node->pos[i] - pos[i]);
+	}
+	if(dist_sq <= SQ(range)) {
+		if(rlist_insert(list, node, ordered ? dist_sq : -1.0) == -1) {
+			return -1;
+		}
+		added_res = 1;
+	}
+
+	dx = pos[node->dir] - node->pos[node->dir];
+
+	ret = find_nearest(dx <= 0.0 ? node->left : node->right, pos, range, list, ordered, dim);
+	if(ret >= 0 && fabs(dx) < range) {
+		added_res += ret;
+		ret = find_nearest(dx <= 0.0 ? node->right : node->left, pos, range, list, ordered, dim);
+	}
+	if(ret == -1) {
+		return -1;
+	}
+	added_res += ret;
+
+	return added_res;
+}
+
+#if 0
+static int find_nearest_n(struct kdnode *node, const double *pos, double range, int num, struct rheap *heap, int dim)
+{
+	double dist_sq, dx;
+	int i, ret, added_res = 0;
+
+	if(!node) return 0;
+	
+	/* if the photon is close enough, add it to the result heap */
+	dist_sq = 0;
+	for(i=0; i<dim; i++) {
+		dist_sq += SQ(node->pos[i] - pos[i]);
+	}
+	if(dist_sq <= range_sq) {
+		if(heap->size >= num) {
+			/* get furthest element */
+			struct res_node *maxelem = rheap_get_max(heap);
+
+			/* and check if the new one is closer than that */
+			if(maxelem->dist_sq > dist_sq) {
+				rheap_remove_max(heap);
+
+				if(rheap_insert(heap, node, dist_sq) == -1) {
+					return -1;
+				}
+				added_res = 1;
+
+				range_sq = dist_sq;
+			}
+		} else {
+			if(rheap_insert(heap, node, dist_sq) == -1) {
+				return =1;
+			}
+			added_res = 1;
+		}
+	}
+
+
+	/* find signed distance from the splitting plane */
+	dx = pos[node->dir] - node->pos[node->dir];
+
+	ret = find_nearest_n(dx <= 0.0 ? node->left : node->right, pos, range, num, heap, dim);
+	if(ret >= 0 && fabs(dx) < range) {
+		added_res += ret;
+		ret = find_nearest_n(dx <= 0.0 ? node->right : node->left, pos, range, num, heap, dim);
+	}
+
+}
+#endif
+
+static void kd_nearest_i(struct kdnode *node, const double *pos, struct kdnode **result, double *result_dist_sq, struct kdhyperrect* rect)
+{
+	int dir = node->dir;
+	int i;
+	double dummy, dist_sq;
+	struct kdnode *nearer_subtree, *farther_subtree;
+	double *nearer_hyperrect_coord, *farther_hyperrect_coord;
+
+	/* Decide whether to go left or right in the tree */
+	dummy = pos[dir] - node->pos[dir];
+	if (dummy <= 0) {
+		nearer_subtree = node->left;
+		farther_subtree = node->right;
+		nearer_hyperrect_coord = rect->max + dir;
+		farther_hyperrect_coord = rect->min + dir;
+	} else {
+		nearer_subtree = node->right;
+		farther_subtree = node->left;
+		nearer_hyperrect_coord = rect->min + dir;
+		farther_hyperrect_coord = rect->max + dir;
+	}
+
+	if (nearer_subtree) {
+		/* Slice the hyperrect to get the hyperrect of the nearer subtree */
+		dummy = *nearer_hyperrect_coord;
+		*nearer_hyperrect_coord = node->pos[dir];
+		/* Recurse down into nearer subtree */
+		kd_nearest_i(nearer_subtree, pos, result, result_dist_sq, rect);
+		/* Undo the slice */
+		*nearer_hyperrect_coord = dummy;
+	}
+
+	/* Check the distance of the point at the current node, compare it
+	 * with our best so far */
+	dist_sq = 0;
+	for(i=0; i < rect->dim; i++) {
+		dist_sq += SQ(node->pos[i] - pos[i]);
+	}
+	if (dist_sq < *result_dist_sq) {
+		*result = node;
+		*result_dist_sq = dist_sq;
+	}
+
+	if (farther_subtree) {
+		/* Get the hyperrect of the farther subtree */
+		dummy = *farther_hyperrect_coord;
+		*farther_hyperrect_coord = node->pos[dir];
+		/* Check if we have to recurse down by calculating the closest
+		 * point of the hyperrect and see if it's closer than our
+		 * minimum distance in result_dist_sq. */
+		if (hyperrect_dist_sq(rect, pos) < *result_dist_sq) {
+			/* Recurse down into farther subtree */
+			kd_nearest_i(farther_subtree, pos, result, result_dist_sq, rect);
+		}
+		/* Undo the slice on the hyperrect */
+		*farther_hyperrect_coord = dummy;
+	}
+}
+
+struct kdres *kd_nearest(struct kdtree *kd, const double *pos)
+{
+	struct kdhyperrect *rect;
+	struct kdnode *result;
+	struct kdres *rset;
+	double dist_sq;
+	int i;
+
+	if (!kd) return 0;
+	if (!kd->rect) return 0;
+
+	/* Allocate result set */
+	if(!(rset = malloc(sizeof *rset))) {
+		return 0;
+	}
+	if(!(rset->rlist = alloc_resnode())) {
+		free(rset);
+		return 0;
+	}
+	rset->rlist->next = 0;
+	rset->tree = kd;
+
+	/* Duplicate the bounding hyperrectangle, we will work on the copy */
+	if (!(rect = hyperrect_duplicate(kd->rect))) {
+		kd_res_free(rset);
+		return 0;
+	}
+
+	/* Our first guesstimate is the root node */
+	result = kd->root;
+	dist_sq = 0;
+	for (i = 0; i < kd->dim; i++)
+		dist_sq += SQ(result->pos[i] - pos[i]);
+
+	/* Search for the nearest neighbour recursively */
+	kd_nearest_i(kd->root, pos, &result, &dist_sq, rect);
+
+	/* Free the copy of the hyperrect */
+	hyperrect_free(rect);
+
+	/* Store the result */
+	if (result) {
+		if (rlist_insert(rset->rlist, result, -1.0) == -1) {
+			kd_res_free(rset);
+			return 0;
+		}
+		rset->size = 1;
+		kd_res_rewind(rset);
+		return rset;
+	} else {
+		kd_res_free(rset);
+		return 0;
+	}
+}
+
+struct kdres *kd_nearestf(struct kdtree *tree, const float *pos)
+{
+	static double sbuf[16];
+	double *bptr, *buf = 0;
+	int dim = tree->dim;
+	struct kdres *res;
+
+	if(dim > 16) {
+#ifndef NO_ALLOCA
+		if(dim <= 256)
+			bptr = buf = alloca(dim * sizeof *bptr);
+		else
+#endif
+			if(!(bptr = buf = malloc(dim * sizeof *bptr))) {
+				return 0;
+			}
+	} else {
+		bptr = buf = sbuf;
+	}
+
+	while(dim-- > 0) {
+		*bptr++ = *pos++;
+	}
+
+	res = kd_nearest(tree, buf);
+#ifndef NO_ALLOCA
+	if(tree->dim > 256)
+#else
+	if(tree->dim > 16)
+#endif
+		free(buf);
+	return res;
+}
+
+struct kdres *kd_nearest3(struct kdtree *tree, double x, double y, double z)
+{
+	double pos[3];
+	pos[0] = x;
+	pos[1] = y;
+	pos[2] = z;
+	return kd_nearest(tree, pos);
+}
+
+struct kdres *kd_nearest3f(struct kdtree *tree, float x, float y, float z)
+{
+	double pos[3];
+	pos[0] = x;
+	pos[1] = y;
+	pos[2] = z;
+	return kd_nearest(tree, pos);
+}
+
+/* ---- nearest N search ---- */
+/*
+static kdres *kd_nearest_n(struct kdtree *kd, const double *pos, int num)
+{
+	int ret;
+	struct kdres *rset;
+
+	if(!(rset = malloc(sizeof *rset))) {
+		return 0;
+	}
+	if(!(rset->rlist = alloc_resnode())) {
+		free(rset);
+		return 0;
+	}
+	rset->rlist->next = 0;
+	rset->tree = kd;
+
+	if((ret = find_nearest_n(kd->root, pos, range, num, rset->rlist, kd->dim)) == -1) {
+		kd_res_free(rset);
+		return 0;
+	}
+	rset->size = ret;
+	kd_res_rewind(rset);
+	return rset;
+}*/
+
+struct kdres *kd_nearest_range(struct kdtree *kd, const double *pos, double range)
+{
+	int ret;
+	struct kdres *rset;
+
+	if(!(rset = malloc(sizeof *rset))) {
+		return 0;
+	}
+	if(!(rset->rlist = alloc_resnode())) {
+		free(rset);
+		return 0;
+	}
+	rset->rlist->next = 0;
+	rset->tree = kd;
+
+	if((ret = find_nearest(kd->root, pos, range, rset->rlist, 0, kd->dim)) == -1) {
+		kd_res_free(rset);
+		return 0;
+	}
+	rset->size = ret;
+	kd_res_rewind(rset);
+	return rset;
+}
+
+struct kdres *kd_nearest_rangef(struct kdtree *kd, const float *pos, float range)
+{
+	static double sbuf[16];
+	double *bptr, *buf = 0;
+	int dim = kd->dim;
+	struct kdres *res;
+
+	if(dim > 16) {
+#ifndef NO_ALLOCA
+		if(dim <= 256)
+			bptr = buf = alloca(dim * sizeof *bptr);
+		else
+#endif
+			if(!(bptr = buf = malloc(dim * sizeof *bptr))) {
+				return 0;
+			}
+	} else {
+		bptr = buf = sbuf;
+	}
+
+	while(dim-- > 0) {
+		*bptr++ = *pos++;
+	}
+
+	res = kd_nearest_range(kd, buf, range);
+#ifndef NO_ALLOCA
+	if(kd->dim > 256)
+#else
+	if(kd->dim > 16)
+#endif
+		free(buf);
+	return res;
+}
+
+struct kdres *kd_nearest_range3(struct kdtree *tree, double x, double y, double z, double range)
+{
+	double buf[3];
+	buf[0] = x;
+	buf[1] = y;
+	buf[2] = z;
+	return kd_nearest_range(tree, buf, range);
+}
+
+struct kdres *kd_nearest_range3f(struct kdtree *tree, float x, float y, float z, float range)
+{
+	double buf[3];
+	buf[0] = x;
+	buf[1] = y;
+	buf[2] = z;
+	return kd_nearest_range(tree, buf, range);
+}
+
+void kd_res_free(struct kdres *rset)
+{
+	clear_results(rset);
+	free_resnode(rset->rlist);
+	free(rset);
+}
+
+int kd_res_size(struct kdres *set)
+{
+	return (set->size);
+}
+
+void kd_res_rewind(struct kdres *rset)
+{
+	rset->riter = rset->rlist->next;
+}
+
+int kd_res_end(struct kdres *rset)
+{
+	return rset->riter == 0;
+}
+
+int kd_res_next(struct kdres *rset)
+{
+	rset->riter = rset->riter->next;
+	return rset->riter != 0;
+}
+
+void *kd_res_item(struct kdres *rset, double *pos)
+{
+	if(rset->riter) {
+		if(pos) {
+			memcpy(pos, rset->riter->item->pos, rset->tree->dim * sizeof *pos);
+		}
+		return rset->riter->item->data;
+	}
+	return 0;
+}
+
+void *kd_res_itemf(struct kdres *rset, float *pos)
+{
+	if(rset->riter) {
+		if(pos) {
+			int i;
+			for(i=0; i<rset->tree->dim; i++) {
+				pos[i] = rset->riter->item->pos[i];
+			}
+		}
+		return rset->riter->item->data;
+	}
+	return 0;
+}
+
+void *kd_res_item3(struct kdres *rset, double *x, double *y, double *z)
+{
+	if(rset->riter) {
+		if(x) *x = rset->riter->item->pos[0];
+		if(y) *y = rset->riter->item->pos[1];
+		if(z) *z = rset->riter->item->pos[2];
+		return rset->riter->item->data;
+	}
+	return 0;
+}
+
+void *kd_res_item3f(struct kdres *rset, float *x, float *y, float *z)
+{
+	if(rset->riter) {
+		if(x) *x = rset->riter->item->pos[0];
+		if(y) *y = rset->riter->item->pos[1];
+		if(z) *z = rset->riter->item->pos[2];
+		return rset->riter->item->data;
+	}
+	return 0;
+}
+
+void *kd_res_item_data(struct kdres *set)
+{
+	return kd_res_item(set, 0);
+}
+
+/* ---- hyperrectangle helpers ---- */
+static struct kdhyperrect* hyperrect_create(int dim, const double *min, const double *max)
+{
+	size_t size = dim * sizeof(double);
+	struct kdhyperrect* rect = 0;
+
+	if (!(rect = malloc(sizeof(struct kdhyperrect)))) {
+		return 0;
+	}
+
+	rect->dim = dim;
+	if (!(rect->min = malloc(size))) {
+		free(rect);
+		return 0;
+	}
+	if (!(rect->max = malloc(size))) {
+		free(rect->min);
+		free(rect);
+		return 0;
+	}
+	memcpy(rect->min, min, size);
+	memcpy(rect->max, max, size);
+
+	return rect;
+}
+
+static void hyperrect_free(struct kdhyperrect *rect)
+{
+	free(rect->min);
+	free(rect->max);
+	free(rect);
+}
+
+static struct kdhyperrect* hyperrect_duplicate(const struct kdhyperrect *rect)
+{
+	return hyperrect_create(rect->dim, rect->min, rect->max);
+}
+
+static void hyperrect_extend(struct kdhyperrect *rect, const double *pos)
+{
+	int i;
+
+	for (i=0; i < rect->dim; i++) {
+		if (pos[i] < rect->min[i]) {
+			rect->min[i] = pos[i];
+		}
+		if (pos[i] > rect->max[i]) {
+			rect->max[i] = pos[i];
+		}
+	}
+}
+
+static double hyperrect_dist_sq(struct kdhyperrect *rect, const double *pos)
+{
+	int i;
+	double result = 0;
+
+	for (i=0; i < rect->dim; i++) {
+		if (pos[i] < rect->min[i]) {
+			result += SQ(rect->min[i] - pos[i]);
+		} else if (pos[i] > rect->max[i]) {
+			result += SQ(rect->max[i] - pos[i]);
+		}
+	}
+
+	return result;
+}
+
+/* ---- static helpers ---- */
+
+#ifdef USE_LIST_NODE_ALLOCATOR
+/* special list node allocators. */
+static struct res_node *free_nodes;
+
+#ifndef NO_PTHREADS
+static pthread_mutex_t alloc_mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
+static struct res_node *alloc_resnode(void)
+{
+	struct res_node *node;
+
+#ifndef NO_PTHREADS
+	pthread_mutex_lock(&alloc_mutex);
+#endif
+
+	if(!free_nodes) {
+		node = malloc(sizeof *node);
+	} else {
+		node = free_nodes;
+		free_nodes = free_nodes->next;
+		node->next = 0;
+	}
+
+#ifndef NO_PTHREADS
+	pthread_mutex_unlock(&alloc_mutex);
+#endif
+
+	return node;
+}
+
+static void free_resnode(struct res_node *node)
+{
+#ifndef NO_PTHREADS
+	pthread_mutex_lock(&alloc_mutex);
+#endif
+
+	node->next = free_nodes;
+	free_nodes = node;
+
+#ifndef NO_PTHREADS
+	pthread_mutex_unlock(&alloc_mutex);
+#endif
+}
+#endif	/* list node allocator or not */
+
+
+/* inserts the item. if dist_sq is >= 0, then do an ordered insert */
+/* TODO make the ordering code use heapsort */
+static int rlist_insert(struct res_node *list, struct kdnode *item, double dist_sq)
+{
+	struct res_node *rnode;
+
+	if(!(rnode = alloc_resnode())) {
+		return -1;
+	}
+	rnode->item = item;
+	rnode->dist_sq = dist_sq;
+
+	if(dist_sq >= 0.0) {
+		while(list->next && list->next->dist_sq < dist_sq) {
+			list = list->next;
+		}
+	}
+	rnode->next = list->next;
+	list->next = rnode;
+	return 0;
+}
+
+static void clear_results(struct kdres *rset)
+{
+	struct res_node *tmp, *node = rset->rlist->next;
+
+	while(node) {
+		tmp = node;
+		node = node->next;
+		free_resnode(tmp);
+	}
+
+	rset->rlist->next = 0;
+}

kdtree/kdtree.h

@@ -0,0 +1,129 @@
+/*
+This file is part of ``kdtree'', a library for working with kd-trees.
+Copyright (C) 2007-2011 John Tsiombikas <nuclear@member.fsf.org>
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+3. The name of the author may not be used to endorse or promote products
+   derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+OF SUCH DAMAGE.
+*/
+#ifndef _KDTREE_H_
+#define _KDTREE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct kdtree;
+struct kdres;
+
+
+/* create a kd-tree for "k"-dimensional data */
+struct kdtree *kd_create(int k);
+
+/* free the struct kdtree */
+void kd_free(struct kdtree *tree);
+
+/* remove all the elements from the tree */
+void kd_clear(struct kdtree *tree);
+
+/* if called with non-null 2nd argument, the function provided
+ * will be called on data pointers (see kd_insert) when nodes
+ * are to be removed from the tree.
+ */
+void kd_data_destructor(struct kdtree *tree, void (*destr)(void*));
+
+/* insert a node, specifying its position, and optional data */
+int kd_insert(struct kdtree *tree, const double *pos, void *data);
+int kd_insertf(struct kdtree *tree, const float *pos, void *data);
+int kd_insert3(struct kdtree *tree, double x, double y, double z, void *data);
+int kd_insert3f(struct kdtree *tree, float x, float y, float z, void *data);
+
+/* Find the nearest node from a given point.
+ *
+ * This function returns a pointer to a result set with at most one element.
+ */
+struct kdres *kd_nearest(struct kdtree *tree, const double *pos);
+struct kdres *kd_nearestf(struct kdtree *tree, const float *pos);
+struct kdres *kd_nearest3(struct kdtree *tree, double x, double y, double z);
+struct kdres *kd_nearest3f(struct kdtree *tree, float x, float y, float z);
+
+/* Find the N nearest nodes from a given point.
+ *
+ * This function returns a pointer to a result set, with at most N elements,
+ * which can be manipulated with the kd_res_* functions.
+ * The returned pointer can be null as an indication of an error. Otherwise
+ * a valid result set is always returned which may contain 0 or more elements.
+ * The result set must be deallocated with kd_res_free after use.
+ */
+/*
+struct kdres *kd_nearest_n(struct kdtree *tree, const double *pos, int num);
+struct kdres *kd_nearest_nf(struct kdtree *tree, const float *pos, int num);
+struct kdres *kd_nearest_n3(struct kdtree *tree, double x, double y, double z);
+struct kdres *kd_nearest_n3f(struct kdtree *tree, float x, float y, float z);
+*/
+
+/* Find any nearest nodes from a given point within a range.
+ *
+ * This function returns a pointer to a result set, which can be manipulated
+ * by the kd_res_* functions.
+ * The returned pointer can be null as an indication of an error. Otherwise
+ * a valid result set is always returned which may contain 0 or more elements.
+ * The result set must be deallocated with kd_res_free after use.
+ */
+struct kdres *kd_nearest_range(struct kdtree *tree, const double *pos, double range);
+struct kdres *kd_nearest_rangef(struct kdtree *tree, const float *pos, float range);
+struct kdres *kd_nearest_range3(struct kdtree *tree, double x, double y, double z, double range);
+struct kdres *kd_nearest_range3f(struct kdtree *tree, float x, float y, float z, float range);
+
+/* frees a result set returned by kd_nearest_range() */
+void kd_res_free(struct kdres *set);
+
+/* returns the size of the result set (in elements) */
+int kd_res_size(struct kdres *set);
+
+/* rewinds the result set iterator */
+void kd_res_rewind(struct kdres *set);
+
+/* returns non-zero if the set iterator reached the end after the last element */
+int kd_res_end(struct kdres *set);
+
+/* advances the result set iterator, returns non-zero on success, zero if
+ * there are no more elements in the result set.
+ */
+int kd_res_next(struct kdres *set);
+
+/* returns the data pointer (can be null) of the current result set item
+ * and optionally sets its position to the pointers(s) if not null.
+ */
+void *kd_res_item(struct kdres *set, double *pos);
+void *kd_res_itemf(struct kdres *set, float *pos);
+void *kd_res_item3(struct kdres *set, double *x, double *y, double *z);
+void *kd_res_item3f(struct kdres *set, float *x, float *y, float *z);
+
+/* equivalent to kd_res_item(set, 0) */
+void *kd_res_item_data(struct kdres *set);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* _KDTREE_H_ */