The code is pretty simple. So long as the "up vector" is not parallel to the surface normal, it is used to orient the 0-degree azimuth position by projecting it into the plane of the surface normal at the ray intersection point. Make sense?
-Greg > From: David Geisler-Moroder <[email protected]> > Date: May 15, 2012 12:20:15 AM PDT > > Hi list, hi Greg, > > I have a question concerning the BSDF "up-vector". > For e.g. a facade-mounted fenestration system the definition of the vector is > clear. > But what, if I have a BSDF defining the material properties and use this BSDF > to > simulate the BSDF of a daylighting system (i.e. curved specular lamellae)? > > The comment in m_bsdf.c says that the "up-vector" together with the surface > normal > defines the local coordinate system. How exactly is that done?? Unfortunately > I did > not have time yet to dig deeper into the BSDF-code to find that out... > > Cheers, > David _______________________________________________ Radiance-dev mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/radiance-dev
