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Added workaround for antipode routes

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Fixes #155
This commit is contained in:
Martin Tůma 2021-10-16 14:11:22 +02:00
parent db4ed75757
commit 5e36d564aa
1 changed files with 34 additions and 4 deletions
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38
src/common/greatcircle.cpp
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@ -1,11 +1,41 @@
#include "greatcircle.h"
#define DELTA 1e-5
static bool antipodes(const Coordinates &c1, const Coordinates &c2)
{
return ((qAbs(c1.lat() + c2.lat()) < DELTA)
&& (qAbs(180.0 - qAbs(c1.lon() - c2.lon())) < DELTA));
}
GreatCircle::GreatCircle(const Coordinates &c1, const Coordinates &c2)
{
double lat1 = deg2rad(c1.lat());
double lon1 = deg2rad(c1.lon());
double lat2 = deg2rad(c2.lat());
double lon2 = deg2rad(c2.lon());
double lat1, lon1, lat2, lon2;
if (antipodes(c1, c2)) {
/* In case of antipodes (which would lead to garbage output without
this hack), move the points DELTA degrees closer to each other in
a way that the route never crosses the antimeridian. */
if (c1.lon() < c2.lon()) {
lon1 = deg2rad(c1.lon() + DELTA);
lon2 = deg2rad(c2.lon() - DELTA);
} else {
lon1 = deg2rad(c1.lon() - DELTA);
lon2 = deg2rad(c2.lon() + DELTA);
}
if (c1.lat() < c2.lat()) {
lat1 = deg2rad(c1.lat() + DELTA);
lat2 = deg2rad(c2.lat() - DELTA);
} else {
lat1 = deg2rad(c1.lat() - DELTA);
lat2 = deg2rad(c2.lat() + DELTA);
}
} else {
lat1 = deg2rad(c1.lat());
lon1 = deg2rad(c1.lon());
lat2 = deg2rad(c2.lat());
lon2 = deg2rad(c2.lon());
}
double cosLat1 = cos(lat1);
double cosLat2 = cos(lat2);