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greg |
1.1 |
{
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The following calculation uses the BRTDfunc type to reproduce the
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calculation used by LBL's Window 4 program for the transmittance
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and reflectance of coated glazings. This calculation is based
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on fits for the angular dependence for clear and bronze-coated
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glazing, and is not terribly accurate.
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5/20/93 Greg Ward
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Arguments used for this material should look like:
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mod BRTDfunc my_glazing
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10 rrho grho brho
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rtau gtau btau
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0 0 0
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glazing.cal
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0
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18 0 0 0
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0 0 0
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0 0 0
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FRRHO FGRHO FBRHO
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BRRHO BGRHO BBRHO
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RTAU GTAU BTAU
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where:
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FRRHO FGRHO FBRHO is front normal spectral reflectance
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BRRHO BGRHO BBRHO is back normal spectral reflectance
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RTAU GTAU BTAU is normal spectral transmittance
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}
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{ get normal reflectance }
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rbase = if(Rdot,10,13); { different front and back }
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Rred = arg(rbase)*CrP;
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Rgrn = arg(rbase+1)*CgP;
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Rblu = arg(rbase+2)*CbP;
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{ get normal transmittance }
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Tred = arg(16)*CrP;
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Tgrn = arg(17)*CgP;
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Tblu = arg(18)*CbP;
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{ reflectance coefficients }
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Rclear = .999 + RdotP*(-.563 + RdotP*(2.043 + RdotP*(-2.532 + RdotP*1.054)));
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Rbronze = .997 + RdotP*(-1.868 + RdotP*(6.513 + RdotP*(-7.862 + RdotP*3.225)));
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{ transmittance coefficients }
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Tclear = -.0015 + RdotP*(3.355 + RdotP*(-3.840 + RdotP*(1.460 + RdotP*.0288)));
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Tbronze = -.002 + RdotP*(2.813 + RdotP*(-2.341 + RdotP*(-.05725 + RdotP*.599)));
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Tcutoff : .645; { transmittance cutoff constant }
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{ returned spectral reflectance }
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rrho = Rred*if(Tred-Tcutoff, Rclear, Rbronze);
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grho = Rgrn*if(Tgrn-Tcutoff, Rclear, Rbronze);
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brho = Rblu*if(Tblu-Tcutoff, Rclear, Rbronze);
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{ returned spectral transmittance }
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rtau = Tred*if(Tred-Tcutoff, Tclear, Tbronze);
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gtau = Tgrn*if(Tgrn-Tcutoff, Tclear, Tbronze);
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btau = Tblu*if(Tblu-Tcutoff, Tclear, Tbronze);
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