Ron Parker wrote in message <35dc8acf.0@news.povray.org>...


>>   light_source { 0, color rgb 1 clipped_by{sphere{0,100}} translate
>>TheLight}
>Ah.  I see now that you and I have different views of what it means to clip
>a light source.  I was wanting to clip them so that they only illuminate,
>say, the pyramidal area projected by a square cutout.  Such light sources
>could be used to simulate specular reflection from plane surfaces.

Right - I had some difficulties with understanding the clipping/reflection
relationship, but I got it... while replying last time. The sphere centered
on the
light example was very simple; but if you want:

light_source
  { 0 color rgb <1,1,1>

pped_by{ 
     prism { .... conic_sweep.... matrix/*shearing*/} /* or any object you like */ }
  }

The light_source doesn't have to be in the clipping object, even if it was
in my example. The syntax is simple, already learned and seemed logical
to me (and, yes, I am a bit lazy).

By the way, the cylindrical light_source does seem to be a clipped
light_source (from an user perspective - I dont know about the inner
working) so light_clipping should be possible in POV.


>Yep.  I posted one a while back.  I think it may have been in 
>povray.programming.
I got it. That's already much better. Thank you very much.


Sincerely,

Philippe

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