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root/radiance/ray/src/gen/illum.cal
Revision: 2.6
Committed: Thu Dec 9 16:57:36 1993 UTC (30 years, 3 months ago) by greg
Branch: MAIN
Changes since 2.5: +2 -2 lines
Log Message:
changed from atan2() to Atan2() to be safe

File Contents

# User Rev Content
1 greg 1.1 { SCCSid "$SunId$ LBL" }
2    
3     {
4     Coordinate computations for mkillum output.
5    
6 greg 2.5 There are no arguments for the spherical case:
7 greg 1.1
8     il_alt - Altitude (1 to -1) for spherical coordinates
9     il_azi - Azimuth (0 to 2*PI) for sphere
10    
11 greg 2.5 For the hemispherical case, A1-A9 are the unit vectors for the
12 greg 1.1 hemisphere's coordinate system:
13    
14     il_alth - Altitude (1 to 0) for hemispherical coordinates
15     il_azih - Azimuth (0 to 2*PI) for hemisphere
16     }
17    
18     il_alt = Dz;
19 greg 2.6 il_azi = norm_rad(Atan2(Dy, Dx));
20 greg 1.1
21 greg 2.5 il_alth = sq(-Dx*A7-Dy*A8-Dz*A9);
22 greg 2.6 il_azih = norm_rad(Atan2(-Dx*A4-Dy*A5-Dz*A6, -Dx*A1-Dy*A2-Dz*A3));
23 greg 1.1
24 greg 2.5 norm_rad(r) = if( r, r, r+2*PI );