{ RCSid $Id: rskysrc.cal,v 1.2 2009/07/14 16:16:20 greg Exp $ }
{
	Reinhart sky patch positions & solid angles

	Greg Ward	June 2009

	Based on tregsrc.cal
	MF controls patch density

	Input is Rbin from 1-(144*MF+1) and optional x1 x2 random variables
	Output is Dx Dy Dz theta (degree full angle of source)
}
DEGREE : PI/180;

x1 = .5; x2 = .5;		{ default rand. var. settings for midpoint }

MF : 2^2;			{ Multiplication factor }
alpha : 90/(MF*7 + .5);		{ Separation between rows in degrees }
				{ Number of patches per row }
tnaz(r) : select(r, 30, 30, 24, 24, 18, 12, 6);
rnaz(r) : if(r-(7*MF-.5), 1, MF*tnaz(floor((r+.5)/MF) + 1));

raccum(r) : if(r-.5, rnaz(r-1) + raccum(r-1), 0);

RowMax : 7*MF + 1;
Rmax : raccum(RowMax);

Rfindrow(r, rem) : if(rem-rnaz(r)-.5, Rfindrow(r+1, rem-rnaz(r)), r);
Rrow = if(Rbin-(Rmax-.5), RowMax, Rfindrow(0, Rbin));
Rcol = Rbin - raccum(Rrow) - 1;


Razi_width = 2*PI / rnaz(Rrow);

RAH : alpha*DEGREE;

Razi = (Rcol + x2 - .5)*Razi_width;
Ralt = (Rrow + x1)*RAH;

Romega = if(Rmax-.5-Rbin, 
	Razi_width*(sin(RAH*(Rrow+1)) - sin(RAH*Rrow)),
	2*PI*(1 - cos(RAH/2)) );

cos_ralt = cos(Ralt);

Dx = sin(Razi)*cos_ralt;
Dy = cos(Razi)*cos_ralt;
Dz = sin(Ralt);

theta = 2/DEGREE * acos(1 - Romega/(2*PI));