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#include <stdlib.h>
#include <glib.h>
#include "quadtree.h"
#define QUADTREE_NODE_CAPACITY 10
#define MAX_DOUBLE 9999999
static double
dist_sq(double x1,double y1,double x2,double y2)
{
return (x2-x1)*(x2-x1)+(y2-y1)*(y2-y1);
}
struct quadtree_node*
quadtree_node_new(struct quadtree_node* parent, double xmin, double xmax, double ymin, double ymax ) {
struct quadtree_node*ret = g_new0(struct quadtree_node,1);
ret->xmin = xmin;
ret->xmax = xmax;
ret->ymin = ymin;
ret->ymax = ymax;
ret->is_leaf = 1;
ret->parent = parent;
return ret;
}
/*
* searches all four subnodes recursively for the list of items within a rectangle
*/
void
quadtree_find_rect_items(struct quadtree_node* this_, double dXMin, double dXMax, double dYMin, double dYMax, GList**out) {
struct quadtree_node* nodes[4] = { this_->aa, this_->ab, this_->ba, this_->bb };
if( this_->is_leaf ) {
int i;
//double distance_sq = current_max;
for(i=0;i<this_->node_num;++i) { //select only items within input rectangle
if(dXMin<=this_->items[i].longitude && this_->items[i].longitude<=dXMax &&
dYMin<=this_->items[i].latitude && this_->items[i].latitude<=dYMax
) {
*out=g_list_prepend(*out,&this_->items[i]);
}
}
}
else {
int i;
for( i=0;i<4;++i) {
if(nodes[i] ) {
//limit flooding
if(nodes[i]->xmax<dXMin || dXMax<nodes[i]->xmin ||
nodes[i]->ymax<dYMin || dYMax<nodes[i]->ymin
) {
continue;
}
//recurse into subtiles if there is at least one subtile corner within input rectangle
quadtree_find_rect_items(nodes[i],dXMin,dXMax,dYMin,dYMax,out);
}
}
}
}
/*
* searches all four subnodes recursively for the closest item
*/
struct quadtree_item*
quadtree_find_nearest_flood(struct quadtree_node* this_, struct quadtree_item* item, double current_max, struct quadtree_node* toSkip) {
struct quadtree_node* nodes[4] = { this_->aa, this_->ab, this_->ba, this_->bb };
struct quadtree_item*res = NULL;
if( this_->is_leaf ) {
int i;
double distance_sq = current_max;
for(i=0;i<this_->node_num;++i) {
double curr_dist_sq = dist_sq(item->longitude,item->latitude,this_->items[i].longitude,this_->items[i].latitude);
if(curr_dist_sq<distance_sq) {
distance_sq = curr_dist_sq;
res = &this_->items[i];
}
}
}
else {
int i;
for( i=0;i<4;++i) {
if(nodes[i] && nodes[i]!=toSkip) {
//limit flooding
struct quadtree_item*res_tmp = NULL;
if(
dist_sq(nodes[i]->xmin,nodes[i]->ymin,item->longitude,item->latitude)<current_max ||
dist_sq(nodes[i]->xmax,nodes[i]->ymin,item->longitude,item->latitude)<current_max ||
dist_sq(nodes[i]->xmax,nodes[i]->ymax,item->longitude,item->latitude)<current_max ||
dist_sq(nodes[i]->xmin,nodes[i]->ymax,item->longitude,item->latitude)<current_max
) {
res_tmp = quadtree_find_nearest_flood(nodes[i],item,current_max,NULL);
}
if(res_tmp) {
double curr_dist_sq;
res = res_tmp;
curr_dist_sq = dist_sq(item->longitude,item->latitude,res->longitude,res->latitude);
if(curr_dist_sq<current_max) {
current_max = curr_dist_sq;
}
}
}
}
}
return res;
}
/*
* tries to find an item exactly
*/
struct quadtree_item*
quadtree_find_item(struct quadtree_node* this_, struct quadtree_item* item) {
struct quadtree_item*res = NULL;
if( ! this_ ) {
return NULL;
}
if( this_->is_leaf ) {
int i;
for(i=0;i<this_->node_num;++i) {
//TODO equality check may not be correct on float values! maybe it can be replaced by range check with some tolerance
if(item->longitude==this_->items[i].longitude && item->latitude==this_->items[i].latitude) {
res = &this_->items[i];
return res;
}
}
return NULL;
}
else {
if(
this_->aa &&
this_->aa->xmin<=item->longitude && item->longitude<this_->aa->xmax &&
this_->aa->ymin<=item->latitude && item->latitude<this_->aa->ymax
) {
res = quadtree_find_item(this_->aa,item);
}
else if(
this_->ab &&
this_->ab->xmin<=item->longitude && item->longitude<this_->ab->xmax &&
this_->ab->ymin<=item->latitude && item->latitude<this_->ab->ymax
) {
res = quadtree_find_item(this_->ab,item);
}
else if(
this_->ba &&
this_->ba->xmin<=item->longitude && item->longitude<this_->ba->xmax &&
this_->ba->ymin<=item->latitude && item->latitude<this_->ba->ymax
) {
res = quadtree_find_item(this_->ba,item);
}
else if(
this_->bb &&
this_->bb->xmin<=item->longitude && item->longitude<this_->bb->xmax &&
this_->bb->ymin<=item->latitude && item->latitude<this_->bb->ymax
) {
res = quadtree_find_item(this_->bb,item);
}
else {
return NULL;
}
}
return res;
}
/*
* tries to find closest item, first it descend into the quadtree as much as possible, then if no point is found go up n levels and flood
*/
struct quadtree_item*
quadtree_find_nearest(struct quadtree_node* this_, struct quadtree_item* item) {
struct quadtree_item*res = NULL;
double distance_sq = MAX_DOUBLE;
if( ! this_ ) {
return NULL;
}
if( this_->is_leaf ) {
int i;
for(i=0;i<this_->node_num;++i) {
double curr_dist_sq = dist_sq(item->longitude,item->latitude,this_->items[i].longitude,this_->items[i].latitude);
if(curr_dist_sq<distance_sq) {
distance_sq = curr_dist_sq;
res = &this_->items[i];
}
}
//go up n levels
if(!res && this_->parent) {
struct quadtree_item*res2 = NULL;
struct quadtree_node* anchestor = this_->parent;
int cnt = 0;
while (anchestor->parent && cnt<4) {
anchestor = anchestor->parent;
++cnt;
}
res2 = quadtree_find_nearest_flood(anchestor,item,distance_sq,NULL);
if(res2) {
res = res2;
}
}
}
else {
if(
this_->aa &&
this_->aa->xmin<=item->longitude && item->longitude<this_->aa->xmax &&
this_->aa->ymin<=item->latitude && item->latitude<this_->aa->ymax
) {
res = quadtree_find_nearest(this_->aa,item);
}
else if(
this_->ab &&
this_->ab->xmin<=item->longitude && item->longitude<this_->ab->xmax &&
this_->ab->ymin<=item->latitude && item->latitude<this_->ab->ymax
) {
res = quadtree_find_nearest(this_->ab,item);
}
else if(
this_->ba &&
this_->ba->xmin<=item->longitude && item->longitude<this_->ba->xmax &&
this_->ba->ymin<=item->latitude && item->latitude<this_->ba->ymax
) {
res = quadtree_find_nearest(this_->ba,item);
}
else if(
this_->bb &&
this_->bb->xmin<=item->longitude && item->longitude<this_->bb->xmax &&
this_->bb->ymin<=item->latitude && item->latitude<this_->bb->ymax
) {
res = quadtree_find_nearest(this_->bb,item);
}
else {
if(this_->parent) {
//go up two levels
struct quadtree_node* anchestor = this_->parent;
int cnt = 0;
while (anchestor->parent && cnt<4) {
anchestor = anchestor->parent;
++cnt;
}
res = quadtree_find_nearest_flood(anchestor,item,distance_sq,NULL);
}
}
}
return res;
}
void
quadtree_add(struct quadtree_node* this_, struct quadtree_item* item) {
if( this_->is_leaf ) {
this_->items[this_->node_num++] = *item;
if(QUADTREE_NODE_CAPACITY == this_->node_num) {
quadtree_split(this_);
}
}
else {
if(
this_->xmin<=item->longitude && item->longitude<this_->xmin+(this_->xmax-this_->xmin)/2.0 &&
this_->ymin<=item->latitude && item->latitude<this_->ymin+(this_->ymax-this_->ymin)/2.0
) {
if(!this_->aa) {
this_->aa = quadtree_node_new( this_, this_->xmin, this_->xmin+(this_->xmax-this_->xmin)/2.0 , this_->ymin, this_->ymin+(this_->ymax-this_->ymin)/2.0 );
}
quadtree_add(this_->aa,item);
}
else if(
this_->xmin+(this_->xmax-this_->xmin)/2.0<=item->longitude && item->longitude<this_->xmax &&
this_->ymin<=item->latitude && item->latitude<this_->ymin+(this_->ymax-this_->ymin)/2.0
) {
if(!this_->ab) {
this_->ab = quadtree_node_new( this_, this_->xmin+(this_->xmax-this_->xmin)/2.0, this_->xmax , this_->ymin, this_->ymin+(this_->ymax-this_->ymin)/2.0 );
}
quadtree_add(this_->ab,item);
}
else if(
this_->xmin<=item->longitude && item->longitude<this_->xmin+(this_->xmax-this_->xmin)/2.0 &&
this_->ymin+(this_->ymax-this_->ymin)/2.0<=item->latitude && item->latitude<this_->ymax
) {
if(!this_->ba) {
this_->ba = quadtree_node_new( this_, this_->xmin, this_->xmin+(this_->xmax-this_->xmin)/2.0 , this_->ymin+(this_->ymax-this_->ymin)/2.0 , this_->ymax);
}
quadtree_add(this_->ba,item);
}
else if(
this_->xmin+(this_->xmax-this_->xmin)/2.0<=item->longitude && item->longitude<this_->xmax &&
this_->ymin+(this_->ymax-this_->ymin)/2.0<=item->latitude && item->latitude<this_->ymax
) {
if(!this_->bb) {
this_->bb = quadtree_node_new( this_, this_->xmin+(this_->xmax-this_->xmin)/2.0, this_->xmax , this_->ymin+(this_->ymax-this_->ymin)/2.0 , this_->ymax);
}
quadtree_add(this_->bb,item);
}
}
}
void
quadtree_split(struct quadtree_node* this_) {
int i;
this_->is_leaf = 0;
for(i=0;i<this_->node_num;++i) {
if(
this_->xmin<=this_->items[i].longitude && this_->items[i].longitude<this_->xmin+(this_->xmax-this_->xmin)/2.0 &&
this_->ymin<=this_->items[i].latitude && this_->items[i].latitude<this_->ymin+(this_->ymax-this_->ymin)/2.0
) {
if(!this_->aa) {
this_->aa = quadtree_node_new( this_, this_->xmin, this_->xmin+(this_->xmax-this_->xmin)/2.0 , this_->ymin, this_->ymin+(this_->ymax-this_->ymin)/2.0 );
}
quadtree_add(this_->aa,&this_->items[i]);
}
else if(
this_->xmin+(this_->xmax-this_->xmin)/2.0<=this_->items[i].longitude && this_->items[i].longitude<this_->xmax &&
this_->ymin<=this_->items[i].latitude && this_->items[i].latitude<this_->ymin+(this_->ymax-this_->ymin)/2.0
) {
if(!this_->ab) {
this_->ab = quadtree_node_new( this_, this_->xmin+(this_->xmax-this_->xmin)/2.0, this_->xmax , this_->ymin, this_->ymin+(this_->ymax-this_->ymin)/2.0 );
}
quadtree_add(this_->ab,&this_->items[i]);
}
else if(
this_->xmin<=this_->items[i].longitude && this_->items[i].longitude<this_->xmin+(this_->xmax-this_->xmin)/2.0 &&
this_->ymin+(this_->ymax-this_->ymin)/2.0<=this_->items[i].latitude && this_->items[i].latitude<this_->ymax
) {
if(!this_->ba) {
this_->ba = quadtree_node_new( this_, this_->xmin, this_->xmin+(this_->xmax-this_->xmin)/2.0 , this_->ymin+(this_->ymax-this_->ymin)/2.0 , this_->ymax);
}
quadtree_add(this_->ba,&this_->items[i]);
}
else if(
this_->xmin+(this_->xmax-this_->xmin)/2.0<=this_->items[i].longitude && this_->items[i].longitude<this_->xmax &&
this_->ymin+(this_->ymax-this_->ymin)/2.0<=this_->items[i].latitude && this_->items[i].latitude<this_->ymax
) {
if(!this_->bb) {
this_->bb = quadtree_node_new( this_, this_->xmin+(this_->xmax-this_->xmin)/2.0, this_->xmax , this_->ymin+(this_->ymax-this_->ymin)/2.0 , this_->ymax);
}
quadtree_add(this_->bb,&this_->items[i]);
}
}
this_->node_num = 0;
}
void
quadtree_destroy(struct quadtree_node* this_) {
if(this_->aa) {
quadtree_destroy(this_->aa);
}
if(this_->ab) {
quadtree_destroy(this_->ab);
}
if(this_->ba) {
quadtree_destroy(this_->ba);
}
if(this_->bb) {
quadtree_destroy(this_->bb);
}
free(this_);
}
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