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root/radiance/ray/src/util/reinhartb.cal
Revision: 2.6
Committed: Fri Mar 27 18:58:06 2015 UTC (7 years, 6 months ago) by greg
Branch: MAIN
CVS Tags: rad5R0, rad5R2, rad5R1, rad5R3, HEAD
Changes since 2.5: +4 -2 lines
Log Message:
Hopeful fix to bugs in genBSDF due to lack of left-handed coordinates

File Contents

# Content
1 { RCSid $Id: reinhartb.cal,v 2.5 2014/08/26 18:56:19 greg Exp $ }
2 {
3 Compute Reinhart high-density sky patch bin (rbin)
4
5 MF - Subdivision value (usually a power of two)
6 Dx,Dy,Dz - Incident direction (normalized, towards surface face)
7 rNx,rNy,rNz - Surface normal (normalized, away from surface)
8 Ux,Uy,Uz - Up direction vector (does not need to be normalized)
9
10 Modified from reinhart.cal
11
12 July 2014 G. Ward
13 }
14 { Useful factors and functions }
15 DEGREE : PI/180;
16 Asin(x) : if(x-1, PI/2, if(-1-x, -PI/2, asin(x))) / DEGREE;
17 posangle(a) : if(-a, a + 2*PI, a) / DEGREE;
18 Atan2(y,x) : posangle(atan2(y,x));
19
20 { Default to Tregenza sky }
21 MF = 1;
22 { Set to -1 for left-handed coordinate system }
23 RHS = 1;
24 { Default axis orientation (+Y == north) }
25 rNx = 0; rNy = 0; rNz = -1;
26 Ux = 0; Uy = 1; Uz = 0;
27 { Compute oriented axis angles }
28 inc_dz = -Dx*rNx-Dy*rNy-Dz*rNz;
29 inc_rx = -RHS*(Dx*(Uy*rNz-Uz*rNy) + Dy*(Uz*rNx-Ux*rNz) + Dz*(Ux*rNy-Uy*rNx));
30 inc_ry = Dx*Ux+Dy*Uy+Dz*Uz + inc_dz*(rNx*Ux+rNy*Uy+rNz*Uz);
31
32 r_alt = Asin(inc_dz);
33 r_azi = Atan2(inc_rx,inc_ry);
34
35 alpha = 90/(MF*7 + .5); { Separation between rows in degrees }
36 { Number of patches per row }
37 tnaz(r) : select(r, 30, 30, 24, 24, 18, 12, 6);
38 rnaz(r) = if(r-(7*MF-.5), 1, MF*tnaz(floor((r+.5)/MF) + 1));
39
40 raccum(r) = if(r-.5, rnaz(r-1) + raccum(r-1), 0);
41
42 r_row = floor(r_alt/alpha);
43
44 r_inc = 360/rnaz(r_row);
45
46 r_azn = if(359.9999-.5*r_inc - r_azi, floor((r_azi +.5*r_inc)/r_inc), 0);
47
48 { Final bin value, -1 for "ground" }
49 rbin = if (r_alt, raccum(r_row) + r_azn, -1);
50
51 Nrbins = raccum(7*MF+1); { total number of bins }