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geodesic lines: improve the handling for lines that extend beyond the antimeridian. no odd straight line segments

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leaflet doesn't have particularly great handling for this, but this is a reasonable measure for now
This commit is contained in:
Jon Atkins
2013-11-21 05:30:21 +00:00
parent 08b7a5ec6f
commit e6c0c9a51a
1 changed files with 23 additions and 3 deletions
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26
external/L.Geodesic.js vendored
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@ -77,14 +77,28 @@ Modified by qnstie 2013-07-17 to maintain compatibility with Leaflet.draw
}
L.geodesicConvertLines = function (latlngs, fill) {
var i, j, len, geodesiclatlngs = [];
for (i = 0, len = latlngs.length; i < len; i++) {
if (latlngs.length == 0) {
return [];
}
for (var i = 0, len = latlngs.length; i < len; i++) {
if (L.Util.isArray(latlngs[i]) && typeof latlngs[i][0] !== 'number') {
return;
}
latlngs[i] = L.latLng(latlngs[i]);
}
// geodrsic calculations have issues when crossing the anti-meridian. so offset the points
// so this isn't an issue, then add back the offset afterwards
// a center longitude would be ideal - but the start point logitude will be 'good enougn'
var lngOffset = latlngs[0].lng;
// points are wrapped after being offset relative to the first point coordinate, so they're
// within +-180 degrees
latlngs = latlngs.map(function(a){ return L.latLng(a.lat, a.lng-lngOffset).wrap(); });
var geodesiclatlngs = [];
if(!fill) {
geodesiclatlngs.push(latlngs[0]);
}
@ -94,6 +108,12 @@ Modified by qnstie 2013-07-17 to maintain compatibility with Leaflet.draw
if(fill) {
geodesicConvertLine(latlngs[len], latlngs[0], geodesiclatlngs);
}
// now add back the offset subtracted above. no wrapping here - the drawing code handles
// things better when there's no sudden jumps in coordinates. yes, lines will extend
// beyond +-180 degrees - but they won't be 'broken'
geodesiclatlngs = geodesiclatlngs.map(function(a){ return L.latLng(a.lat, a.lng+lngOffset); });
return geodesiclatlngs;
}