Warp <war### [at] tagpovrayorg> wrote:
>   For closed meshes in theory there's little significance on which direction
> you choose.

  I forgot to mention the other situation, ie. open meshes: In this case
the chosen direction is *very* crucial, as it determines which direction
the endless "interior" of the open mesh will face. For example, if you have
a "heightfield" built up as a mesh, placed on the xz plane, you want its
interior to be below it, ie. pointing to the negative y direction. In that
case you would use "inside_vector y" (which means that interior testing
rays are shot right up).

  (Solid open meshes can often be useful in conjunction with csg, and
perhaps sometimes even on their own, even though in this case you have
to take into account that the "interior" of the mesh will extend to
infinity at the opposite direction of the inside_vector.)

-- 
                                                          - Warp

Post a reply to this message