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| author |  Anton Lundin <glance@acc.umu.se> | 2015-06-13 11:54:33 +0200 |
|---|---|---|
| committer |  Dirk Hohndel <dirk@hohndel.org> | 2015-06-13 21:08:11 -0700 |
| commit | 7a594e3ec5e66f30a1604d492f3bb1af1259afd7 (patch) | |
| tree | b0fb86b70ad06b5386db0518d1d70df07c54bfe3 /divesite.c | |
| parent | 9ec155fad05d53aaac42c7a8b9460b7eb6a0c803 (diff) | |
| download | subsurface-7a594e3ec5e66f30a1604d492f3bb1af1259afd7.tar.gz | |
Simplify distance calculations
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>
Diffstat (limited to 'divesite.c')
| -rw-r--r-- | divesite.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/divesite.c b/divesite.c index 3caa7b3ba..e096c7172 100644 --- a/divesite.c +++ b/divesite.c @@ -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) |