Drawing a line on Bing Maps through 180 deg long - windows-runtime

Question

Drawing a line through 180 degrees longitude on the Bing Maps control doesn't work as I expect. 180 degrees longitude runs from north to south through the Pacific Ocean, so if I wanted to draw a line from (10, 175) to (-10, -175) - expecting a small (10 degrees) line crossing the equator somewhat north of New Zealand - I get a line stretching all the way around the globe, crossing the equator at 0 degrees long (south of Greenwich). How can I draw a line that transverses 180 deg long?

Answer 1

It is possible to approximate this by drawing two lines, from point a almost on the 180 degree meridian then from just past the 180 degree meridian to point b. So in a method that returns an IEnumerable<MapPolyLine>, where a is the closest point with a negative longitude and b is the closest point with a positive longitude:
var aa = Math.Abs(b.Longitude - a.Longitude - 360);
var bb = Math.Abs(b.Latitude - a.Latitude);
var aaa = 180 + a.Longitude;
var bbb = (bb / aa) * aaa;
var line1 = new MapPolyline
{
Color = Color.FromArgb(255, 0, 255, 0),
Width = 5
};
line1.Locations.Add(a);
line1.Locations.Add(new Location(a.Latitude - bbb, -179.999));
yield return line1;
var line2 = new MapPolyline
{
Color = Color.FromArgb(255, 0, 0, 255),
Width = 5
};
line2.Locations.Add(new Location(b.Latitude + bb - bbb, 179.999));
line2.Locations.Add(b);
yield return line2;
This could be cleaned up further and is just a workaround. Also some artifacts can appear but this seems pretty reliable.