C＃/ WinRT中两个位置之间的距离和其他内容

Question

How can I get the distance between two Location in C#? It also would be very nice to get the direction between two Locations if I have the compass value of the device.

is there any api for this?

Answer 1

It depends. What do you mean by Location ?

Case 1: When location is geographic point (Latitude, Longitude)

You need to go through spherical geometry. In fact you should make some calculation on a sphere (or Ellipsoid or other Spheroids). But the best way to avoid doing such complicated calculation is to use Microsoft.SqlServer.Types.dll (v.10 or v.11). If you have SQL Server 2012 (or 2008) installed on your system, you can find it somewhere like this (otherwise you may download it from the web):

"C:\Program Files\Microsoft SQL Server\110\Shared\Microsoft.SqlServer.Types.dll"

Then using this dll you can declare two SqlGeography type and call the STDistance() method and everything will be done correctly. (Remember there are lost of issue here, I'm not going to complicate it more than this). Here is the code:

SqlGeography p1 =
SqlGeography.STPointFromText(new System.Data.SqlTypes.SqlChars("POINT( lat1, long1)"), 4326); // SRID of WGS84: 4326

SqlGeography p2 =
SqlGeography.STPointFromText(new System.Data.SqlTypes.SqlChars("POINT( lat2, long2)"), 4326); // SRID of WGS84: 4326

double distance = p1.STDistance(p2).Value;

Case 2: When location is a simple local 2D point (x, y) on a plane

In this case you can use the famous formula to calculate the distance:

double distance = Math.Sqrt(dx*dx + dy*dy); //dx and dy are the difference of the x and y of the two points