[Radiance-general] trans+texfunc
Peter Apian-Bennewitz
[email protected]
Wed, 10 Apr 2002 23:54:44 +0200
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Greg Ward wrote:
> The trouble is, trans doesn't really know WHAT to do with a surface
> normal perturbation in the case of a transmitted ray. If an object were
> really infinitely thin, then a texture would perturb both incoming and
> outgoing normals identically, having no effect at all on the transmitted
> ray. I assume that the user wants an effect when they apply a texture,
> and this is a semantic difference between a true texture and a
> "smoothing operation." Unfortunately, Radiance treats the two cases the
> same, so this is the result. I don't have a fix for it. Smoothing
> doesn't work with the trans material, and that's the bottom line.
>
> -G
>
> > From: Peter Apian-Bennewitz <[email protected]>
> > Date: Wed Apr 10, 2002 05:14:27 AM US/Pacific
> > To: Greg Ward <[email protected]>
> > Subject: trans+texfunc
> >
> > Hi Greg,
> >
> > do I get this right ?
> >
> > using
> >
> > void trans t
> > 0
> > 0
> > 7 .90 .90 .95 .001 0 .95 1
> >
> > on a non-convex body, plus texfunc for Phong-interpolation doesn't
> > work, because with trans, the surface normals are auto-flipped towards
> > the incoming ray, which jeopardizes the Phong interpolation ?
one for the archive ...
--
pab-opto, Freiburg, Germany, www.pab-opto.de
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Greg Ward wrote:
<blockquote TYPE=CITE>The trouble is, trans doesn't really know WHAT to
do with a surface
<br>normal perturbation in the case of a transmitted ray. If an object
were
<br>really infinitely thin, then a texture would perturb both incoming
and
<br>outgoing normals identically, having no effect at all on the transmitted
<br>ray. I assume that the user wants an effect when they apply a
texture,
<br>and this is a semantic difference between a true texture and a
<br>"smoothing operation." Unfortunately, Radiance treats the two
cases the
<br>same, so this is the result. I don't have a fix for it.
Smoothing
<br>doesn't work with the trans material, and that's the bottom line.
<p>-G
<p>> From: Peter Apian-Bennewitz <[email protected]>
<br>> Date: Wed Apr 10, 2002 05:14:27 AM US/Pacific
<br>> To: Greg Ward <[email protected]>
<br>> Subject: trans+texfunc
<br>>
<br>> Hi Greg,
<br>>
<br>> do I get this right ?
<br>>
<br>> using
<br>>
<br>> void trans t
<br>> 0
<br>> 0
<br>> 7 .90 .90 .95 .001 0 .95 1
<br>>
<br>> on a non-convex body, plus texfunc for Phong-interpolation doesn't
<br>> work, because with trans, the surface normals are auto-flipped towards
<br>> the incoming ray, which jeopardizes the Phong interpolation ?</blockquote>
one for the archive ...
<pre>--
pab-opto, Freiburg, Germany, www.pab-opto.de</pre>
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