/// <summary>
/// Is loop clockwise oriented?
/// </summary>
/// <param name="loop"></param>
/// <param name="isTransmeridian"></param>
/// <returns></returns>
internal static bool IsClockwiseNormalized(this GeoFence loop, bool isTransmeridian)
{
decimal sum = 0m;
GeoCoord a;
GeoCoord b;
// INIT_ITERATION;
int loopIndex = -1;
while (true)
{
if (++loopIndex >= loop.NumVerts)
{
break;
}
a = loop.Verts[loopIndex];
b = loop.Verts[(loopIndex + 1) % loop.NumVerts];
// If we identify a transmeridian arc (> 180 degrees longitude),
// start over with the transmeridian flag set
if (!isTransmeridian && Math.Abs(a.Longitude - b.Longitude) > Constants.H3.M_PI)
{
return(loop.IsClockwiseNormalized(true));
}
sum += (b.Longitude.NormalizeLongitude(isTransmeridian) -
a.Longitude.NormalizeLongitude(isTransmeridian)) *
(b.Latitude + a.Latitude);
}
return(sum > 0);
}
/// <summary>
/// Is GeoFence clockwise?
/// </summary>
/// <param name="loop"></param>
/// <returns></returns>
public static bool IsClockwise(this GeoFence loop)
{
return(loop.IsClockwiseNormalized(false));
}