POV-Ray : Newsgroups : povray.newusers : Transparent Objects Become Black : Re: Transparent Objects Become Black Server Time
28 Nov 2021 15:05:30 EST (-0500)
  Re: Transparent Objects Become Black  
From: bubble person
Date: 11 Nov 2021 12:25:00
Message: <web.618d508f28696f32a6f27af47c94cc22@news.povray.org>
"jr" <cre### [at] gmailcom> wrote:
> hi,
>
> "bubble_person" <nomail@nomail> wrote:
> > Hello Forum,
> >
> > I am relatively new to POV-RAY, but have a functional script .
> >
> > I am simulating air bubbles in a glass tube full of gel.  I am running into a
> > funny problem where, if I add too many bubbles to the script, they go from being
> > transparent and rendered correctly, to a completely opaque, black object through
> > which no light shines.
>
> not sure if it will help, or is even related to "the issue", but if I change the
> "bubble_r" to "(bubble_r - epsilon)" in the five spheres following comment "Add
> Bubble Voids here", they're visible.
>
> quick comment re "new to POV-Ray".  you have five identical (apart from
> location) spheres.  have a look at macros, they're ideal in such a situation.
> <https://wiki.povray.org/content/Reference:User_Defined_Macros#The_macro_Directive>
>
>
> regards, jr.

Hello Jr.,

Thank you for the response, and I appreciate your pointer to the Macros.  I'll
be taking a deeper look at this.

I tried what you suggested, and for my script, it causes the bubble surface to
be shiny (I can see reflection on the perimeter of the bubble), but it seems
like the center of the bubble remains black, unrendered, or something like that.
 Light is certainly not going through it.

In previous cases, light refracts through the center of the bubbles, so the fact
that the center is still dark tells me that I'm still encountering an issue.

One other idea that I had was using the "clipped_by{}" function when defining
the voids.  I reordered the merge{} definition for the gel and the used the
clipped_by{} function to subtract out the bubble voids.

I did this and the centers seem to have reappeared for all the bubbles.  The
light is refracting through the bubbles which is good, but I'm worried that I
might be missing a subtlety about how the "difference{}" and "clipped_by{}"
functions work.  I'm not sure why this has worked, and it's worrying me when my
goal is to simulate realistic refraction through this volume.


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