cal/cal/blinds.cal

{
        Compute Venetian Blinds angle to exclude direct sun.

        3/19/93

        Formula by Kostantinos Papamichael,
        Translated by Greg Ward and Saba Rofchaei
}
{
        Input variables are solar altitude and azimuth in degrees:

                SALT    - solar altitude (degrees)
                SAZI    - solar azimuth (degrees from South, West is positive)
}

L = .625;    {slat's width}
D = .45833;     {distance between slats}  
ORIENT = 0.0;           { Window orientation }
DEGREE : PI/180.0;
  
tan_lambda = tan(SALT*DEGREE) / cos((SAZI+ORIENT)*DEGREE);
lambda = atan(tan_lambda) / DEGREE;
a = tan_lambda*tan_lambda + 1.0;
b = -2.0*(D/L);
c = (D/L)*(D/L) - tan_lambda*tan_lambda;

det = sqrt(b*b - 4.0*a*c);

    {calculating slats' angle corresponding to solar position}     
POS1 = asin((-b+det)/(2.0*a)) / DEGREE;
POS2 = asin((-b-det)/(2.0*a)) / DEGREE;

Revision:	1.1
Committed:	Sat Feb 22 02:07:21 2003 UTC (21 years, 2 months 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
#	User	Rev	Content
1	greg	1.1	{
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(SALTDEGREE) / 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_lambdatan_lambda;
26
27			det = sqrt(bb - 4.0a*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