/usr/share/radiance/genSH.cal is in radiance-materials 4R0+20110410-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 | { RCSid $Id: genSH.cal,v 1.1 2005/02/16 15:51:45 greg Exp $ }
{
Synthesize light probe using Spherical Harmonic coefficients
2/16/2005 G. Ward
Constants:
map - light probe mapping (1=angular, 2=mirror)
rcoef(i) - red coefficient array
gcoef(i) - green coefficient array
bcoef(i) - blue coefficient array
Usage:
pcomb -x 640 -y 640 -e 'map:1' -f spharm.cal -f genSH.cal \
-f coef.cal > probe.pic
}
map : 1; { just angular for now }
h = 1/xres*x - .5;
v = 1/yres*y - .5;
beta_ang = 2*PI*sqrt(h*h + v*v);
gamma_ang = atan2(v, h);
sine_beta_ang = sin(beta_ang);
Dx_ang = cos(beta_ang);
Dy_ang = cos(gamma_ang)*sine_beta_ang;
Dz_ang = sin(gamma_ang)*sine_beta_ang;
theta_ang = acos(Dz_ang);
phi_ang = atan2(Dy_ang, Dx_ang);
cond = select(map, PI-1e-4-beta_ang);
theta = select(map, theta_ang);
phi = select(map, phi_ang);
ro = if(cond, SphericalHarmonicF(rcoef,theta_ang,phi_ang), 0);
go = if(cond, SphericalHarmonicF(gcoef,theta_ang,phi_ang), 0);
bo = if(cond, SphericalHarmonicF(bcoef,theta_ang,phi_ang), 0);
{ Uncomment for luminance only }
{
lo = if(cond, SphericalHarmonicF(lcoef,theta_ang,phi_ang), 0);
}
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