public static Fxyf Create(double x, double y, int f)
{
Fxyf temp = new Fxyf();
temp.fx = x;
temp.fy = y;
temp.face = f;
return(temp);
}
private static Fxyf FromHploc(Hploc loc)
{
Fxyf temp = new Fxyf();
double z = loc.z, phi = loc.phi;
double za = Math.Abs(z);
double tt = HealpixUtils.fmodulo((phi * Fxyf.inv_halfpi), 4.0); // in [0,4)
if (za <= Fxyf.twothird) // Equatorial region
{
double temp1 = 0.5 + tt;
double temp2 = z * 0.75;
double jp = temp1 - temp2; // index of ascending edge line
double jm = temp1 + temp2; // index of descending edge line
long ifp = (long)jp; // in {0,4}
long ifm = (long)jm;
long face_num = (ifp == ifm) ? (ifp | 4) : ((ifp < ifm) ? ifp : (ifm + 8));
temp.fx = HealpixUtils.fmodulo(jm, 1d);
temp.fy = 1d - HealpixUtils.fmodulo(jp, 1d);
temp.face = (int)face_num;
}
else // polar region, za > 2/3
{
int ntt = Math.Min(3, (int)tt);
double tp = tt - ntt;
double tmp;
if ((za < 0.99) || (!loc.have_sth))
{
tmp = Math.Sqrt(3 * (1 - za));
}
else
{
tmp = loc.sth / Math.Sqrt((1d + za) / 3d);
}
double jp = tp * tmp; // increasing edge line index
double jm = (1.0 - tp) * tmp; // decreasing edge line index
if (jp >= 1d)
{
jp = 1d; // for points too close to the boundary
}
if (jm >= 1d)
{
jm = 1d;
}
if (z >= 0)
{
temp.fx = 1d - jm; temp.fy = 1d - jp; temp.face = ntt;
}
else
{
temp.fx = jp; temp.fy = jm; temp.face = ntt + 8;
}
}
return(temp);
}
private void SetCorners()
{
Xyf xyf = Xyf.Create(tileX, tileY, face);
double dc = 0.5 / nside;
double xc = (xyf.ix + 0.5) / nside;
double yc = (xyf.iy + 0.5) / nside;
TopLeft = Fxyf.Create(xc + dc, yc + dc, xyf.face).toVec3();
BottomLeft = Fxyf.Create(xc - dc, yc + dc, xyf.face).toVec3();
BottomRight = Fxyf.Create(xc - dc, yc - dc, xyf.face).toVec3();
TopRight = Fxyf.Create(xc + dc, yc - dc, xyf.face).toVec3();
}
private Vector3d[] Boundaries(int x, int y, int step)
{
int nside = step * Math.Pow(2, Level);
Vector3d[] points = new Vector3d[4];
Xyf xyf = Xyf.Create(x + faceX * step, y + faceY * step, face);
double dc = 0.5 / nside;
double xc = (xyf.ix + 0.5) / nside;
double yc = (xyf.iy + 0.5) / nside;
points[0] = Fxyf.Create(xc + dc, yc + dc, xyf.face).toVec3();
points[1] = Fxyf.Create(xc - dc, yc + dc, xyf.face).toVec3();
points[2] = Fxyf.Create(xc - dc, yc - dc, xyf.face).toVec3();
points[3] = Fxyf.Create(xc + dc, yc - dc, xyf.face).toVec3();
return(points);
}
public static Fxyf FromVector(Vector3d v)
{
return(Fxyf.FromHploc(Hploc.Create(v)));
}