// Copyright (c) Microsoft Corporation. All rights reserved.
using System;
using Microsoft.SqlServer.Types;
namespace SQLSpatialTools
{
/**
* This class contains functions that are meant to be used internally in this library.
*/
class Util
{
// Convert a SqlGeography to an X,Y,Z vector.
public static Vector3 GeographicToCartesian(SqlGeography point)
{
return SphericalDegToCartesian(point.Lat.Value, point.Long.Value);
}
// Convert an X,Y,Z vector to a SqlGeography
public static SqlGeography CartesianToGeographic(Vector3 point, int srid)
{
return SqlGeography.Point(LatitudeDeg(point), LongitudeDeg(point), srid);
}
// Convert a Lat/Long in degrees to an X,Y,Z vector.
public static Vector3 SphericalDegToCartesian(double latitudeDeg, double longitudeDeg)
{
if (Math.Abs(latitudeDeg) > 90)
throw new ArgumentOutOfRangeException("|latitudeDeg| > 90");
double latitudeRad = ToRadians(latitudeDeg);
double longitudeRad = ToRadians(longitudeDeg);
double r = Math.Cos(latitudeRad);
return new Vector3(r * Math.Cos(longitudeRad), r * Math.Sin(longitudeRad), Math.Sin(latitudeRad));
}
// Convert a Lat/Long in radians to an X,Y,Z vector.
public static Vector3 SphericalRadToCartesian(double latitudeRad, double longitudeRad)
{
if (Math.Abs(latitudeRad) > Math.PI / 2)
throw new ArgumentOutOfRangeException("|latitudeRad| > PI / 2");
double r = Math.Cos(latitudeRad);
return new Vector3(r * Math.Cos(longitudeRad), r * Math.Sin(longitudeRad), Math.Sin(latitudeRad));
}
// Returns longitude in radians given the vector.
public static double Longitude(Vector3 p)
{
return Math.Atan2(p.y, p.x);
}
// Returns longitude in degrees given the vector.
public static double LongitudeDeg(Vector3 p)
{
return ToDegrees(Longitude(p));
}
// Returns latitude in radians given the vector.
public static double Latitude(Vector3 p)
{
return Math.Atan2(p.z, Math.Sqrt(p.x * p.x + p.y * p.y));
}
// Returns latitude in degrees given the vector.
public static double LatitudeDeg(Vector3 p)
{
return ToDegrees(Latitude(p));
}
// Converts degrees to radians.
public static double ToRadians(double a)
{
return a / 180 * Math.PI;
}
// Converts radians to degrees.
public static double ToDegrees(double a)
{
return a * 180 / Math.PI;
}
}
}
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