private void UpdateRotationMatrix(ATime atime)
{
if (PaintEnabled)
{
Matrix mtxPrec = Matrix.PrecMatrix(Astro.JD2000, atime.JD);
Matrix mtxEqt2Ecl = Matrix.RotateX(ATime.GetEp(atime.JD));
MtxToEcl = mtxEqt2Ecl.Mul(mtxPrec);
EpochToEcl = atime.JD;
}
}
/// <summary>
/// Create Precession Matrix
/// </summary>
/// <param name="oldEpoch"></param>
/// <param name="newEpoch"></param>
/// <returns></returns>
public static Matrix PrecMatrix(double oldEpoch, double newEpoch)
{
double jd = 0.0;
bool swapEpoch = false;
bool outerNewcomb = false;
if (newEpoch == oldEpoch)
{
return(new Matrix(1.0, 0.0, 0.0,
0.0, 1.0, 0.0,
0.0, 0.0, 1.0));
}
double T = (oldEpoch - Astro.JD2000) / 36525.0;
if (T < -PrecLimit || PrecLimit < T)
{
swapEpoch = true;
double temp = newEpoch;
newEpoch = oldEpoch;
oldEpoch = temp;
T = (oldEpoch - Astro.JD2000) / 36525.0;
}
double T2 = T * T;
double tt, t;
tt = t = (newEpoch - oldEpoch) / 36525.0;
if (tt < -PrecLimit)
{
outerNewcomb = true;
t = -PrecLimit;
jd = -PrecLimit * 36525.0 + Astro.JD2000;
}
if (PrecLimit < tt)
{
outerNewcomb = true;
t = PrecLimit;
jd = PrecLimit * 36525.0 + Astro.JD2000;
}
double t2 = t * t;
double t3 = t2 * t;
double zeta0 = ((2306.2181 + 1.39656 * T - 0.000139 * T2) * t + (0.30188 - 0.000344 * T) * t2 + 0.017998 * t3) / 3600.0;
double zpc = ((2306.2181 + 1.39656 * T - 0.000139 * T2) * t + (1.09468 + 0.000066 * T) * t2 + 0.018203 * t3) / 3600.0;
double theta = ((2004.3109 - 0.85330 * T - 0.000217 * T2) * t - (0.42665 + 0.000217 * T) * t2 - 0.041833 * t3) / 3600.0;
Matrix mtx1, mtx2, mtx3;
mtx1 = RotateZ((90.0 - zeta0) * Math.PI / 180.0);
mtx2 = RotateX(theta * Math.PI / 180.0);
mtx3 = mtx2.Mul(mtx1);
mtx1 = RotateZ((-90 - zpc) * Math.PI / 180.0);
Matrix mtxPrec;
mtxPrec = mtx1.Mul(mtx3);
if (outerNewcomb)
{
double dJd;
if (tt < -PrecLimit)
{
dJd = (newEpoch - oldEpoch) + PrecLimit * 36525.0;
}
else
{
dJd = (newEpoch - oldEpoch) - PrecLimit * 36525.0;
}
double precPrm = -dJd / 365.24 * GeneralPrec * Math.PI / 180.0;
double eps = ATime.GetEp(jd);
mtx1 = RotateX(eps);
mtx2 = RotateZ(precPrm);
mtx3 = mtx2.Mul(mtx1);
mtx2 = RotateX(-eps);
mtx1 = mtx2.Mul(mtx3);
mtxPrec = mtx1.Mul(mtxPrec);
}
if (swapEpoch)
{
mtxPrec.Invert();
}
return(mtxPrec);
}