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{ RCSid $Id: reinhart.cal,v 1.4 2009/12/09 21:34:23 greg Exp $ } |
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{ |
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Compute Reinhart high-density sky patch bin (rbin) |
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MF - Subdivision value (usually a power of two) |
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Dx,Dy,Dz - Incident direction (normalized, towards surface face) |
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Nx,Ny,Nz - Surface normal (normalized, away from surface) |
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Ux,Uy,Uz - Up direction vector (does not need to be normalized) |
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Modified from reinhart.cal |
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|
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July 2014 G. Ward |
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} |
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{ Useful factors and functions } |
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DEGREE : PI/180; |
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Asin(x) : if(x-1, PI/2, if(-1-x, -PI/2, asin(x))); |
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posangle(a) : if(-a, a + 2*PI, a); |
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Atan2(y,x) : posangle(atan2(y,x)); |
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{ Default to Tregenza sky } |
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MF = 1; |
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{ Default axis orientation (+Y == north) } |
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Nx = 0; Ny = 0; Nz = 1; |
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Ux = 0; Uy = 1; Uz = 0; |
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{ Compute oriented axis angles } |
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inc_dz = -Dx*Nx-Dy*Ny-Dz*Nz; |
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inc_rx = -Dx*(Uy*Nz-Uz*Ny) - Dy*(Uz*Nx-Ux*Nz) - Dz*(Ux*Ny-Uy*Nx); |
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inc_ry = -Dx*Ux-Dy*Uy-Dz*Uz - inc_dz*(Nx*Ux+Ny*Uy+Nz*Uz); |
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r_alt = Asin(inc_dz)/DEGREE; |
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r_azi = Atan2(inc_rx,inc_ry)/DEGREE; |
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alpha = 90/(MF*7 + .5); { Separation between rows in degrees } |
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{ Number of patches per row } |
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tnaz(r) : select(r, 30, 30, 24, 24, 18, 12, 6); |
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rnaz(r) = if(r-(7*MF-.5), 1, MF*tnaz(floor((r+.5)/MF) + 1)); |
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raccum(r) = if(r-.5, rnaz(r-1) + raccum(r-1), 0); |
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r_row = floor(r_alt/alpha); |
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r_inc = 360/rnaz(r_row); |
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r_azn = if(359.9999-.5*r_inc - r_azi, floor((r_azi +.5*r_inc)/r_inc), 0); |
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{ Final bin value, -1 for "ground" } |
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rbin = if (r_alt, raccum(r_row) + r_azn, -1); |
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Nrbins = raccum(7*MF+1); { total number of bins } |
