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root/radiance/ray/src/cal/cal/blinds.cal
Revision: 1.1
Committed: Sat Feb 22 02:07:21 2003 UTC (21 years, 1 month ago) by greg
Branch: MAIN
CVS Tags: rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R5, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1
Log Message:
Changes and check-in for 3.5 release
Includes new source files and modifications not recorded for many years
See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release

File Contents

# Content
1 {
2 Compute Venetian Blinds angle to exclude direct sun.
3
4 3/19/93
5
6 Formula by Kostantinos Papamichael,
7 Translated by Greg Ward and Saba Rofchaei
8 }
9 {
10 Input variables are solar altitude and azimuth in degrees:
11
12 SALT - solar altitude (degrees)
13 SAZI - solar azimuth (degrees from South, West is positive)
14 }
15
16 L = .625; {slat's width}
17 D = .45833; {distance between slats}
18 ORIENT = 0.0; { Window orientation }
19 DEGREE : PI/180.0;
20
21 tan_lambda = tan(SALT*DEGREE) / cos((SAZI+ORIENT)*DEGREE);
22 lambda = atan(tan_lambda) / DEGREE;
23 a = tan_lambda*tan_lambda + 1.0;
24 b = -2.0*(D/L);
25 c = (D/L)*(D/L) - tan_lambda*tan_lambda;
26
27 det = sqrt(b*b - 4.0*a*c);
28
29 {calculating slats' angle corresponding to solar position}
30 POS1 = asin((-b+det)/(2.0*a)) / DEGREE;
31 POS2 = asin((-b-det)/(2.0*a)) / DEGREE;
32