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root/radiance/ray/src/gen/glaze2.cal
Revision: 2.2
Committed: Mon Jun 30 18:12:24 2003 UTC (20 years, 9 months ago) by greg
Branch: MAIN
CVS Tags: rad5R4, rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1, rad5R3, HEAD
Changes since 2.1: +2 -2 lines
Log Message:
Updated Fresnel approximation

File Contents

# User Rev Content
1 greg 2.2 { RCSid: $Id: glaze2.cal,v 2.1 2003/02/22 02:07:23 greg Exp $ }
2 greg 2.1 {
3     glaze2.cal - double-pane fritted and low-E glazings
4    
5     Uses BRTDfunc type to get correct behavior.
6     Oct. 2002 Greg Ward
7    
8     We only provide support functions for the nasty expressions
9     spat out for dual-glazings by glaze.csh.
10     }
11     { Fresnel approximation }
12 greg 2.2 fresne = exp(-5.85*abs(Rdot)) - exp(-5.85);
13 greg 2.1 fr(r) = r + fresne*(1 - r);
14     ft(t) = t*(1 - fresne);
15     { glass reflectance and transmittance }
16     rclr = fr(0.076);
17     tclr = ft(0.883);
18     { combined double-pane reflectance }
19     cr(rf,t,rb) : rf + t*t*rb;