{ RCSid $Id: reinhartb.cal,v 2.4 2014/08/20 06:32:07 greg Exp $ } { Compute Reinhart high-density sky patch bin (rbin) MF - Subdivision value (usually a power of two) Dx,Dy,Dz - Incident direction (normalized, towards surface face) rNx,rNy,rNz - Surface normal (normalized, away from surface) Ux,Uy,Uz - Up direction vector (does not need to be normalized) Modified from reinhart.cal July 2014 G. Ward } { Useful factors and functions } DEGREE : PI/180; Asin(x) : if(x-1, PI/2, if(-1-x, -PI/2, asin(x))) / DEGREE; posangle(a) : if(-a, a + 2*PI, a) / DEGREE; Atan2(y,x) : posangle(atan2(y,x)); { Default to Tregenza sky } MF = 1; { Default axis orientation (+Y == north) } rNx = 0; rNy = 0; rNz = 1; Ux = 0; Uy = 1; Uz = 0; { Compute oriented axis angles } inc_dz = -Dx*rNx-Dy*rNy-Dz*rNz; inc_rx = -Dx*(Uy*rNz-Uz*rNy) - Dy*(Uz*rNx-Ux*rNz) - Dz*(Ux*rNy-Uy*rNx); inc_ry = -Dx*Ux-Dy*Uy-Dz*Uz - inc_dz*(rNx*Ux+rNy*Uy+rNz*Uz); r_alt = Asin(inc_dz); r_azi = Atan2(inc_rx,inc_ry); alpha = 90/(MF*7 + .5); { Separation between rows in degrees } { Number of patches per row } tnaz(r) : select(r, 30, 30, 24, 24, 18, 12, 6); rnaz(r) = if(r-(7*MF-.5), 1, MF*tnaz(floor((r+.5)/MF) + 1)); raccum(r) = if(r-.5, rnaz(r-1) + raccum(r-1), 0); r_row = floor(r_alt/alpha); r_inc = 360/rnaz(r_row); r_azn = if(359.9999-.5*r_inc - r_azi, floor((r_azi +.5*r_inc)/r_inc), 0); { Final bin value, -1 for "ground" } rbin = if (r_alt, raccum(r_row) + r_azn, -1); Nrbins = raccum(7*MF+1); { total number of bins }