POV-Ray : Newsgroups : povray.binaries.images : Weird problem with transparent box Server Time
27 Sep 2022 14:13:43 EDT (-0400)
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From: William F Pokorny
Subject: Re: Weird problem with transparent box
Date: 24 Jun 2022 03:20:02
Message: <62b565a2$1@news.povray.org>
On 6/23/22 22:33, Chris R wrote:
>   Would you prefer it in bug reports, sources, or here in the
> images newsgroup?

Either OK for me. For future reference a post to bug reports with some 
sort of pointer or mention of this thread in binary images is likely 
better.

---
Given you do put everything into a scene union, it'd be worth trying a 
render where you include the transparent box at outside the union. You'd 
do this by commenting your box ID reference or raw box code inside the 
union and then include the box code as you posted it at the bottom of 
your scene file. (Supposing no transforms on the union itself)

Trying something other than a quartic for the spout water drop would 
tell us something too. I've run across some quartic specific code 
somewhere - csg code perhaps...

Alain's idea about coincident surfaces as a cause is one scenario in my 
head for an extra surface(a) due order reduction causing trouble, but 
the image doesn't look quite right for it to me. However, if your wall 
texture itself mirrors across the ground plain who knows...

(a) - In it, the additional order reduction surface - you might not know 
you have - becomes the one of the coincident surfaces.

Hmm, Have you tried a render where you remove the reflection block from 
finish block of the spout water drop?

Bill P.


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From: m@b
Subject: Re: Weird problem with transparent box
Date: 24 Jun 2022 09:49:38
Message: <62b5c0f2@news.povray.org>
On 23/06/2022 6:46 pm, Chris R wrote:
.......
> 
> Any ideas?  It's driving me crazy
> 
> -- Chris R.

Try:    finish{phong 0}

Solved a similar problem for me.

m@


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From: Chris R
Subject: Re: Weird problem with transparent box
Date: 27 Jun 2022 10:30:00
Message: <web.62b9bebb3b7b329089a9c4065cc1b6e@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:
> On 6/23/22 22:33, Chris R wrote:
> >   Would you prefer it in bug reports, sources, or here in the
> > images newsgroup?
>
> Either OK for me. For future reference a post to bug reports with some
> sort of pointer or mention of this thread in binary images is likely
> better.
>
> ---
> Given you do put everything into a scene union, it'd be worth trying a
> render where you include the transparent box at outside the union. You'd
> do this by commenting your box ID reference or raw box code inside the
> union and then include the box code as you posted it at the bottom of
> your scene file. (Supposing no transforms on the union itself)
>
> Trying something other than a quartic for the spout water drop would
> tell us something too. I've run across some quartic specific code
> somewhere - csg code perhaps...
>
> Alain's idea about coincident surfaces as a cause is one scenario in my
> head for an extra surface(a) due order reduction causing trouble, but
> the image doesn't look quite right for it to me. However, if your wall
> texture itself mirrors across the ground plain who knows...
>
> (a) - In it, the additional order reduction surface - you might not know
> you have - becomes the one of the coincident surfaces.
>
> Hmm, Have you tried a render where you remove the reflection block from
> finish block of the spout water drop?
>
> Bill P.

I was able to create a simple example with the same problem and posted it in the
bug reports news group:

http://news.povray.org/povray.bugreports/thread/%3Cweb.62b9bd71ec325a4a89a9c4065cc1b6e@news.povray.org%3E//povray.bugre
ports/thread/%3Cweb.62b9bd71ec325a4a89a9c4065cc1b6e@news.povray.org%3E/

In the example, I removed the outer union of all objects in the scene and the
bug remained.  I was also able to remove the normal and finish elements of the
water drip without changing the results.  Removing the interior { ior 1.33 },
however, caused both the drip and the box to disappear from the scene.

Also, the test scene has the box resting 0.1 units above the ground plane, so
there shouldn't be any coincident surfaces.

-- Chris R.


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From: Thomas de Groot
Subject: Re: Weird problem with transparent box
Date: 28 Jun 2022 07:54:46
Message: <62baec06$1@news.povray.org>
Op 24-6-2022 om 09:20 schreef William F Pokorny:
> [snip]
> Trying something other than a quartic for the spout water drop would 
> tell us something too. I've run across some quartic specific code 
> somewhere - csg code perhaps...
> 
> [snip]
> 

Replacing the quartic object by a sphere{} solves the problem, so it 
definitely seems to be a quartic problem to me.

-- 
Thomas


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From: William F Pokorny
Subject: Re: Weird problem with transparent box
Date: 28 Jun 2022 09:07:15
Message: <62bafd03$1@news.povray.org>
On 6/28/22 07:54, Thomas de Groot wrote:
> Op 24-6-2022 om 09:20 schreef William F Pokorny:
>> [snip]
>> Trying something other than a quartic for the spout water drop would 
>> tell us something too. I've run across some quartic specific code 
>> somewhere - csg code perhaps...
>>
>> [snip]
>>
> 
> Replacing the quartic object by a sphere{} solves the problem, so it 
> definitely seems to be a quartic problem to me.
> 

Chris & Thomas,

Thank you for the test scene and experimental feedback.

I'm busy for 2-3 days or so. It will be a while until I can dig into the 
issue.

Bill P.


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From: MichaelJF
Subject: Re: Weird problem with transparent box
Date: 29 Jun 2022 12:19:27
Message: <62bc7b8f$1@news.povray.org>
Am 28.06.2022 um 15:07 schrieb William F Pokorny:
> On 6/28/22 07:54, Thomas de Groot wrote:
>> Op 24-6-2022 om 09:20 schreef William F Pokorny:
>>> [snip]
>>> Trying something other than a quartic for the spout water drop would 
>>> tell us something too. I've run across some quartic specific code 
>>> somewhere - csg code perhaps...
>>>
>>> [snip]
>>>
>>
>> Replacing the quartic object by a sphere{} solves the problem, so it 
>> definitely seems to be a quartic problem to me.
>>
> 
> Chris & Thomas,
> 
> Thank you for the test scene and experimental feedback.
> 
> I'm busy for 2-3 days or so. It will be a while until I can dig into the 
> issue.
> 
> Bill P.
I took a short look into this issue only. Most likely the interaction 
between the quartic and the water material is a problem. If you exchange

material { water_material }

with

pigment { colour Red }

within the Grip-object in the demo scene, Chris gave in the bugs report 
section, the problem do not show up.

Best regards,
Michael


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From: Leroy
Subject: Re: Weird problem with transparent box
Date: 23 Jul 2022 15:55:00
Message: <web.62dc51ae3b7b3290e02efe7bf712fc00@news.povray.org>
Just from the looks of it, max_trace_level in global_settings might have
something to do with this.
Either in your code or as a bug in 3.8.


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