"m_a_r_c" <jac### [at] wanadoofr> wrote:

> web.48bc338bcd5c21438abea67c0@news.povray.org...
> >>   See the trace() function at
> >> http://povray.org/documentation/view/3.6.1/229/#s02_02_01_04_05
> >
> > Thanks for this tip, but what, if the surface is not hit by a ray at the
> > location, I want to plant a tree?
> >
> If the surface is not hit by a ray with a -z direction, there is no terrain
> at this location.
>
> It is a good idea to test the length of the returned normal vector : it is
> null if the trace vector does not intersect the surface.
>
> Marc

Heya!

I've understood! Thanks a lot. I will try this tomorrow and tell you my results.

Phil

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