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geodesic lines - improved handling of lines that cross the antimeridian

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works fine as long as the longitude difference is under 180 degrees
This commit is contained in:
Jon Atkins 2013-10-27 16:06:35 +00:00
parent d268b0a79f
commit 51bb866dc6
1 changed files with 6 additions and 5 deletions
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9
external/L.Geodesic.js vendored
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@ -44,7 +44,7 @@ Modified by qnstie 2013-07-17 to maintain compatibility with Leaflet.draw
lat1, lat2, lng1, lng2, dLng, d, segments,
f, A, B, x, y, z, fLat, fLng;
dLng = Math.abs(endLatlng.lng - startLatlng.lng) * d2r;
dLng = (endLatlng.lng - startLatlng.lng) * d2r;
lat1 = startLatlng.lat * d2r;
lat2 = endLatlng.lat * d2r;
lng1 = startLatlng.lng * d2r;
@ -60,14 +60,15 @@ Modified by qnstie 2013-07-17 to maintain compatibility with Leaflet.draw
// rounding errors? maths bug? not sure - but it solves the issue! and is a slight optimisation)
for (i = 1; i < segments; i++) {
// http://williams.best.vwh.net/avform.htm#Intermediate
// modified to handle longitude above +-180 degrees
f = i / segments;
A = Math.sin((1-f)*d) / Math.sin(d);
B = Math.sin(f*d) / Math.sin(d);
x = A * Math.cos(lat1) * Math.cos(lng1) + B * Math.cos(lat2) * Math.cos(lng2);
y = A * Math.cos(lat1) * Math.sin(lng1) + B * Math.cos(lat2) * Math.sin(lng2);
x = A * Math.cos(lat1) * Math.cos(0) + B * Math.cos(lat2) * Math.cos(dLng);
y = A * Math.cos(lat1) * Math.sin(0) + B * Math.cos(lat2) * Math.sin(dLng);
z = A * Math.sin(lat1) + B * Math.sin(lat2);
fLat = r2d * Math.atan2(z, Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2)));
fLng = r2d * Math.atan2(y, x);
fLng = r2d * (Math.atan2(y, x)+lng1);
convertedPoints.push(L.latLng([fLat, fLng]));
}