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24 Dec 2024 13:26:58 EST (-0500)
  problems using clipped_by (Message 1 to 3 of 3)  
From: spl
Subject: problems using clipped_by
Date: 2 Jan 2003 14:15:04
Message: <web.3e148eba32b2214528b61af20@news.povray.org>
I'm getting some unexpected (at least by me) results using the "clipped_by"
operator in POVray.

Specifically, when I clip triangle mesh objects, I get empty spaces where
I believe I should be getting objects.  It is as if the ray is terminated
by the clipped off part of the object and background color is rendered.

For instance, I rendered a simple open-ended cylinder using an OpenGL-based
application (screen grab at
ftp://ncmir.ucsd.edu/outgoing/spl/sv_cylinder.gif)
and with POVray (ftp://ncmir.ucsd.edu/outgoing/spl/pov_cylinder.gif).

Then I moved in the front clipping plane and rendered again,

 ftp://ncmir.ucsd.edu/outgoing/spl/sv_clipped_cylinder.gif

and

 ftp://ncmir.ucsd.edu/outgoing/spl/pov_clipped_cylinder.gif

show the OpenGL and POVray results, respectively.

The POVray scripts and the mesh file may be found at

 ftp://ncmir.ucsd.edu/outgoing/spl/pov_cylinder

 ftp://ncmir.ucsd.edu/outgoing/spl/pov_clipped_cylinder

and

 ftp://ncmir.ucsd.edu/outgoing/spl/cyl_synu.pov

The files are a bit ugly since they're machine generated but should be
fairly self explanatory.  The "clipped_by" operators are invoked at about
line 536 in both files.  The __far_clip is outside the bounding box of the
object.

Does "clipped_by" only work with non-mesh type objects?

Any clues or RTFMs welcome.

       spl


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From: Ken
Subject: Re: problems using clipped_by
Date: 2 Jan 2003 20:52:26
Message: <3E14EC79.55865C2D@pacbell.net>
spl wrote:
> 
> I'm getting some unexpected (at least by me) results using the "clipped_by"
> operator in POVray.
snip
> Does "clipped_by" only work with non-mesh type objects?
> 
> Any clues or RTFMs welcome.

Look for section 6.5.2.3.1  Solid Mesh and inside_vector in the docs :)

-- 
Ken Tyler


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From: spl
Subject: Re: problems using clipped_by
Date: 4 Jan 2003 11:15:04
Message: <web.3e1707bcc82fabb989b1b69d0@news.povray.org>
Ken wrote:
>> Any clues or RTFMs welcome.
>
>Look for section 6.5.2.3.1  Solid Mesh and inside_vector in the docs :)

Exactly the RTFM I was looking for!

I can hardly wait till the PDF version of the manual comes out and I
can print it for desk reference.

Thanx!

       spl


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