/// <summary>
/// Initializes the transform using the parameters from the specified coordinate system information
/// </summary>
/// <param name="projInfo">A ProjectionInfo class contains all the standard and custom parameters needed to initialize this transform</param>
protected override void OnInit(ProjectionInfo projInfo)
{
double pp;
/* get control point locations */
double phi1 = projInfo.GetPhi1();
double lam1 = projInfo.GetLam1();
double phi2 = projInfo.GetPhi2();
double lam2 = projInfo.GetLam2();
if (phi1 == phi2 && lam1 == lam2) throw new ProjectionException(-25);
Lam0 = Proj.Adjlon(0.5*(lam1 + lam2));
_dlam2 = Proj.Adjlon(lam2 - lam1);
_cp1 = Math.Cos(phi1);
_cp2 = Math.Cos(phi2);
_sp1 = Math.Sin(phi1);
_sp2 = Math.Sin(phi2);
_cs = _cp1*_sp2;
_sc = _sp1*_cp2;
_ccs = _cp1*_cp2*Math.Sin(_dlam2);
_z02 = Proj.Aacos(_sp1*_sp2 + _cp1*_cp2*Math.Cos(_dlam2));
_hz0 = .5*_z02;
double A12 = Math.Atan2(_cp2*Math.Sin(_dlam2),
_cp1*_sp2 - _sp1*_cp2*Math.Cos(_dlam2));
_ca = Math.Cos(pp = Proj.Aasin(_cp1*Math.Sin(A12)));
_sa = Math.Sin(pp);
_lp = Proj.Adjlon(Math.Atan2(_cp1*Math.Cos(A12), _sp1) - _hz0);
_dlam2 *= .5;
_lamc = HalfPi - Math.Atan2(Math.Sin(A12)*_sp1, Math.Cos(A12)) - _dlam2;
_thz0 = Math.Tan(_hz0);
_rhshz0 = .5/Math.Sin(_hz0);
_r2z0 = 0.5/_z02;
_z02 *= _z02;
}
/// <summary>
/// Initializes the transform using the parameters from the specified coordinate system information
/// </summary>
/// <param name="projInfo">A ProjectionInfo class contains all the standard and custom parameters needed to initialize this transform</param>
protected override void OnInit(ProjectionInfo projInfo)
{
double con;
double f;
double d;
double toRadians = projInfo.GeographicInfo.Unit.Radians;
_rot = projInfo.ParamI("no_rot") == 0;
bool azi = projInfo.ParamD("alpha") != 0.0;
if (azi)
{
_lamc = projInfo.ParamD("lonc")*toRadians;
_alpha = projInfo.ParamD("alpha") *toRadians;
if (Math.Abs(_alpha) < Tol ||
Math.Abs(Math.Abs(Phi0) - HalfPi) <= Tol ||
Math.Abs(Math.Abs(_alpha) - HalfPi) <= Tol)
throw new ProjectionException(32);
}
else
{
_lam1 = projInfo.GetLam1();
_phi1 = projInfo.GetPhi1();
_lam2 = projInfo.GetLam2();
_phi2 = projInfo.GetPhi2();
if(Math.Abs(_phi1 - _phi2) <= Tol ||
(con = Math.Abs(_phi1)) <= Tol ||
Math.Abs(con - HalfPi) <= Tol ||
Math.Abs(Math.Abs(Phi0) - HalfPi) <= Tol ||
Math.Abs(Math.Abs(_phi2) - HalfPi) <= Tol)
{
throw new ProjectionException(33);
}
}
_ellips = Es > 0;
double com = _ellips ? Math.Sqrt(OneEs) : 1;
if (Math.Abs(Phi0) > EPS10)
{
double sinph0 = Math.Sin(Phi0);
double cosph0 = Math.Cos(Phi0);
if (_ellips)
{
con = 1 - Es*sinph0*sinph0;
_bl = cosph0*cosph0;
_bl = Math.Sqrt(1 + Es*_bl*_bl/OneEs);
_al = _bl*K0*com/con;
d = _bl*com/(cosph0*Math.Sqrt(con));
}
else
{
_bl = 1;
_al = K0;
d = 1/cosph0;
}
if ((f = d*d - 1) <= 0)
{
f = 0;
}
else
{
f = Math.Sqrt(f);
if (Phi0 < 0) f = -f;
}
_el = f += d;
if (_ellips)
{
_el *= Math.Pow(Proj.Tsfn(Phi0, sinph0, E), _bl);
}
else
{
_el *= TSFN0(Phi0);
}
}
else
{
_bl = 1/com;
_al = K0;
_el = d = f = 1;
}
if(azi)
{
_gamma = Math.Asin(Math.Sin(_alpha)/d);
Lam0 = _lamc - Math.Asin((.5*(f - 1/f))*Math.Tan(_gamma))/_bl;
}
else
{
double h;
double l;
if(_ellips)
{
h = Math.Pow(Proj.Tsfn(_phi1, Math.Sin(_phi1), E), _bl);
l = Math.Pow(Proj.Tsfn(_phi2, Math.Sin(_phi2), E), _bl);
}
else
{
h = TSFN0(_phi1);
l = TSFN0(_phi2);
}
f = _el/h;
double p = (l - h)/(l + h);
double j = _el*_el;
j = (j - l*h)/(j + l*h);
if ((con = _lam1 - _lam2) < -Math.PI)
{
_lam2 -= Math.PI*2;
}
else if (con > Math.PI)
{
_lam2 += Math.PI*2;
}
Lam0 = Proj.Adjlon(.5*(_lam1 + _lam2) - Math.Atan(j*Math.Tan(.5*_bl*(_lam1 - _lam2))/p)/_bl);
_gamma = Math.Atan(2*Math.Sin(_bl*Proj.Adjlon(_lam1 - Lam0))/(f - 1/f));
_alpha = Math.Asin(d*Math.Sin(_gamma));
}
_singam = Math.Sin(_gamma);
_cosgam = Math.Cos(_gamma);
if(projInfo.ParamI("rot_conv") != 0)
{
f = _gamma;
}
else
{
f = _alpha;
}
_sinrot = Math.Sin(f);
_cosrot = Math.Cos(f);
if(projInfo.ParamI("no_uoff") != 0)
{
_u0 = 0;
}
else
{
_u0 = Math.Abs(_al*Math.Atan(Math.Sqrt(d*d - 1)/_cosrot)/_bl);
}
if (Phi0 < 0) _u0 = -_u0;
}