POV-Ray : Newsgroups : povray.general : Smooth level for smooth_triangle. : Re: Smooth level for smooth_triangle. Server Time
1 Mar 2024 18:09:03 EST (-0500)
  Re: Smooth level for smooth_triangle.  
From: Alain Martel
Date: 26 Nov 2023 11:24:11
Message: <6563712b@news.povray.org>
Le 2023-11-25 à 13:43, GioSeregni a écrit :
> Alain Martel <kua### [at] videotronca> wrote:
>> Le 2023-11-25 à 12:40, GioSeregni a écrit :
>>> "GioSeregni" <gms### [at] hotmailcom> wrote:
>>>> "Kenneth" <kdw### [at] gmailcom> wrote:
>>>>> "GioSeregni" <gms### [at] hotmailcom> wrote:
>>>>>> "Bald Eagle" <cre### [at] netscapenet> wrote:
>>>>>>> And if you DO see red there, then try moving the camera around, and viewing it
>>>>>>> from different angles - because it may just disappear and pop up in different
>>>>>>> areas.
>>>>>> It seems that they always arise on the
>>>>>> perimeter of the volumes (in positions tangential to the cone of vision)...
>>>>> Yes, that is where those artifacts sometimes appear on a smooth-triangle object.
>>>>> I think it also depends on the lighting angle, and maybe even the size of the
>>>>> triangles.
>>>>> What you are seeing is a known effect of raytracing the smooth normals when they
>>>>> are viewed at that raking angle. (I thought that there was a short technical
>>>>> explanation of this in the documentation, but I cannot find it.) The camera is
>>>>> picking up the unlighted (black) interior of the object.
>>>>> If I make a low-rez height_field and add the 'smooth' keyword, the same thing
>>>>> happens. The interior_texture trick is one way to try and make these artifacts
>>>>> less noticable. Or try adding the 'double_illuminate' keyword to the object. If
>>>>> I recall, this was a recommended 'fix' for the problem. It seems to work most of
>>>>> the time, but not in every situation.
>>>> Ok, thank! I am working on .. it does not seems by light position, but by the
>>>> angle between WP and smooth_triangle (s) ...
>>>> Many thanks again!
>>>> G.
>>> Bug hacked?
>>> old sprites concept? I'm under no illusions, I'll do more tests, but in this way
>>> I don't see the bug anymore
>> Even better :
>> interior_texture{pigment{rgbt 1}}
>> or
>> interior_texture{pigment{rgbf 1}}
>> That way, no need to use any image file.
> Well , I will check... anyway the gif image is only a transparence...
> but I call the object twice, swapping inside/outside
> Do you mean the same thing? To understand I would have to see your code on
> pigments
> TX!
> G.

Just something like this :

First instance become
texture{pigment{rgbt 1}}
interior_texture{pigment{ Something }}

The other become
texture{pigment{ Something }}
interior_texture{pigment{rgbt 1}}

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