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Simplify distance calculations

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This simplifies the distance calculations and removes a dependency.

This version uses propper math instead of my to simple previous version.

Signed-off-by: Anton Lundin <glance@acc.umu.se>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
This commit is contained in:
Anton Lundin 2015-06-13 11:54:33 +02:00 • committed by Dirk Hohndel
parent 9ec155fad0
commit 7a594e3ec5
4 changed files with 26 additions and 14 deletions
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23
divesite.c
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@ -2,6 +2,8 @@
#include "divesite.h"
#include "dive.h"
#include <math.h>
struct dive_site_table dive_site_table;
/* there could be multiple sites of the same name - return the first one */
@ -34,8 +36,21 @@ uint32_t get_dive_site_uuid_by_gps(degrees_t latitude, degrees_t longitude, stru
return 0;
}
/* this is in globe.cpp, so including the .h file is a pain */
extern double getDistance(int lat1, int lon1, int lat2, int lon2);
// Calculate the distance in meters between two coordinates.
static unsigned int get_distance(degrees_t lat1, degrees_t lon1, degrees_t lat2, degrees_t lon2)
{
double lat1_r = udeg_to_radians(lat1.udeg);
double lat2_r = udeg_to_radians(lat2.udeg);
double lat_d_r = udeg_to_radians(lat2.udeg-lat1.udeg);
double lon_d_r = udeg_to_radians(lon2.udeg-lon1.udeg);
double a = sin(lat_d_r/2) * sin(lat_d_r/2) +
cos(lat2_r) * cos(lat2_r) * sin(lon_d_r/2) * sin(lon_d_r/2);
double c = 2 * atan2(sqrt(a), sqrt(1.0 - a));
// Earth radious in metres
return 6371000 * c;
}
/* find the closest one, no more than distance meters away - if more than one at same distance, pick the first */
uint32_t get_dive_site_uuid_by_gps_proximity(degrees_t latitude, degrees_t longitude, int distance, struct dive_site **dsp)
@ -43,10 +58,10 @@ uint32_t get_dive_site_uuid_by_gps_proximity(degrees_t latitude, degrees_t longi
int i;
int uuid = 0;
struct dive_site *ds;
double cur_distance, min_distance = distance + 0.001;
unsigned int cur_distance, min_distance = distance;
for_each_dive_site (i, ds) {
if (dive_site_has_gps_location(ds) &&
(cur_distance = getDistance(ds->latitude.udeg, ds->longitude.udeg, latitude.udeg, longitude.udeg)) < min_distance) {
(cur_distance = get_distance(ds->latitude, ds->longitude, latitude, longitude)) < min_distance) {
min_distance = cur_distance;
uuid = ds->uuid;
if (dsp)