exact formula is inside /lib/skybright.cal if this can help you to find the name.
{ RCSid: $Id$ } { Sky brightness function for sunny and cloudy skies.
Additional arguments required for calculation of skybright:
A1 - 1 for CIE clear, 2 for CIE overcast, 3 for uniform, 4 for CIE intermediate A2 - zenith brightness A3 - ground plane brightness A4 - normalization factor based on sun direction A5,A6,A7 - sun direction }
cosgamma = Dx*A5 + Dy*A6 + Dz*A7;
gamma = Acos(cosgamma); { angle from sun to this point in sky }
zt = Acos(A7); { angle from zenith to sun }
eta = Acos(Dz); { angle from zenith to this point in sky }
wmean(a, x, b, y) : (a*x + b*y) / (a + b);
skybr = wmean((Dz+1.01)^10, select(A1, sunnysky, cloudysky, unifsky, intersky), (Dz+1.01)^-10, A3);
sunnysky = A2 * (.91 + 10*exp(-3*gamma) + .45*cosgamma*cosgamma) * if( Dz - .01, 1.0 - exp(-.32/Dz), 1.0) / A4;
cloudysky = A2 * (1 + 2*Dz)/3;
unifsky = A2;
intersky = A2 * ( (1.35*sin(5.631-3.59*eta)+3.12)*sin(4.396-2.6*zt) + 6.37 - eta ) / 2.326 * exp(gamma*-.563*((2.629-eta)*(1.562-zt)+.812)) / A4;
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f the mesh was self-intersecting everywhere. So instead I used Millipede (isosurface) to get the same undulations, but ignore the complex 'folds', you can see the difference in cross section thickness. I then tessellated it with the inverse pattern of the outer surface.
To make it a single 3d printable mesh, i just deleted a single face on inner and outer skin, then lofted the naked edges. (creating a tiny hole through the model). Therefore creating a single mesh that folds in on itself, not sure if there is a better way of defining the space between two meshes as the solid area...
Full GH (Kangaroo - Meshmachine - Weaverbird - Millipede)
Special thanks to Laurent Delrieu for his interesting offset mesh method that i based my approach on.
http://www.grasshopper3d.com/forum/topics/offset-mesh-problems-with-3d-mesh-with-weaverbird…
Added by Nick Tyrer at 5:25am on December 10, 2015
ven if the number of panels inside each cell varies. The current solution works when the number of panels inside each cell is always two or other same numbers, but it wouldn't work if the number of panels inside frames are different in each cell. It would be perfect, if numbering of panels are automatically added correctly next to the cell number based on the number of panel division instead of feeding the fixed number.
To take an example, let's assume that the cell #80 has three panels and the #81 has two ones. In this case, three panels within the cell #80 would be numbered like 80-1, 80-2, 80-3, while two panels within the #81 would be numbered such as 81-1 and 81-2 automatically. …