POV-Ray : Newsgroups : povray.binaries.images : Box division Server Time
7 Dec 2021 03:44:49 EST (-0500)
  Box division (Message 11 to 17 of 17)  
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From: Samuel B 
Subject: Re: Box division
Date: 25 Sep 2021 18:30:00
Message: <web.614fa1fe154a1cc3cb705ca46e741498@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:
> "Samuel B." <stb### [at] hotmailcom> wrote:
> >
> > I was looking through old files for something else and came across this scene.
>
> I like to use animation, along with a changing code value somewhere, just to see
> what happens with scenes. Here's a test, changing your 'gap' value...

That's... horrible, haha. Looks like my code isn't very robust. I'm guessing
what happened is that the widths of the divisions became negative values, which
in turn freaked out the wedge object used to clip the tori. I should have put
size limiters in there to prevent the divisions from going under a certain size.
Besides, doing so would have probably made the scene faster to render when using
higher iteration counts.

> .......I commented-out "shapes.inc" and instead pulled out the needed code
> snippets from the various include files, and stuck them directly into your
> scene...just to be slightly more efficient ;-)

Good call ;)

Sam


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From: Samuel B 
Subject: Re: Box division
Date: 25 Sep 2021 18:35:00
Message: <web.614fa388154a1cc3cb705ca46e741498@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 25/09/2021 om 03:42 schreef Samuel B.:
> The cheese did help! :-)

It always does :D (Except when it comes to losing weight. But they did tell to
do everything in our power to Fatten the Curve... I mean, that's what they said,
right? ;P)

> > Speaking of Jove, he probably does help us rest a bit more easily, with his
> > propensity of tugging away at cosmic threats and whatnot :)
> >
> Oh, certainly! After he almost helped us to kingdom come in the early
> days of the solar system (there was an very interesting series about the
> planets on the BBC, presented by Brian Cox, where that was explained).

What? You're saying Jupiter almost prevented our existence? Maybe I should look
into that series...

Sam


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From: Samuel B 
Subject: Re: Box division
Date: 25 Sep 2021 18:40:00
Message: <web.614fa4f4154a1cc3cb705ca46e741498@news.povray.org>
"jr" <cre### [at] gmailcom> wrote:
> hi,
>
> "Samuel B." <stb### [at] hotmailcom> wrote:
> > ...
> > Btw, did you ever hear the sounds the planets make? Not actual sounds, but radio
> > emissions. Great stuff. I like Jupiter the most. {...}
>
> interesting.  fwiw, Titan is nice, musical even, intriguing how similar Neptune
> + Earth sound.

Hi, jr.

Yeah, it's all really cool. In some of them, it's almost as if you can hear
wind, and at other times bell-like sounds... Or musical-sounding, like you said.
Based on the comments I've read in similar videos, people regard Saturn as being
somewhat disturbing though, lol.

Sam


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From: Bald Eagle
Subject: Re: Box division
Date: 25 Sep 2021 22:25:00
Message: <web.614fd977154a1cc31f9dae3025979125@news.povray.org>
"Samuel B." <stb### [at] hotmailcom> wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
> > Op 25/09/2021 om 03:42 schreef Samuel B.:
> > The cheese did help! :-)
>
> It always does :D (Except when it comes to losing weight. But they did tell to
> do everything in our power to Fatten the Curve... I mean, that's what they said,
> right? ;P)

Way to perpetuate that American stereotype, Sam.

;)

And speak for yourself.

:P


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From: Thomas de Groot
Subject: Re: Box division
Date: 26 Sep 2021 03:05:45
Message: <61501bc9@news.povray.org>
Op 26/09/2021 om 00:32 schreef Samuel B.:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Op 25/09/2021 om 03:42 schreef Samuel B.:
>> The cheese did help! :-)
> 
> It always does :D (Except when it comes to losing weight. But they did tell to
> do everything in our power to Fatten the Curve... I mean, that's what they said,
> right? ;P)
> 
>>> Speaking of Jove, he probably does help us rest a bit more easily, with his
>>> propensity of tugging away at cosmic threats and whatnot :)
>>>
>> Oh, certainly! After he almost helped us to kingdom come in the early
>> days of the solar system (there was an very interesting series about the
>> planets on the BBC, presented by Brian Cox, where that was explained).
> 
> What? You're saying Jupiter almost prevented our existence? Maybe I should look
> into that series...
> 

According to latest understandings of the evolution of the Solar System, 
Jupiter messed up the inner solar system by migrating inwards when it 
was out of enough 'food', only to be checked by Saturn. Earth and Mars 
(and asteroids) are what they are now because of this. Unchecked, 
Jupiter would probably have mopped up all the inner planets and become a 
'hot' Jupiter. This is the series: 
https://www.bbc.co.uk/iplayer/episodes/p07922lr/the-planets

-- 
Thomas


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From: William F Pokorny
Subject: Re: Box division
Date: 26 Sep 2021 07:09:57
Message: <61505505$1@news.povray.org>
On 9/25/21 6:18 PM, Samuel B. wrote:
> I did consider doing some 'manual' bounding for the tori (boxes sized to
> encompass only the clipped objects), but I'm not sure how much it would actually
> help since there would still be plenty of empty space where no ray could ever
> make an intersection.
> 
>> Someday need to play with something for arcs based upon 'carefully'
>> placed blobs -
> Are you talking about using blobs as the bounding objects, to take advantage of
> their bounding performance vs. the toruses' bounding performance?
> 
>> or maybe some kind of tori slice and dice into a union
>> for performance. My expectation is we can do better than that internal
>> Test_Thick_Cylinder() test bounding wise.
> Slicing and dicing tori for smaller bounding objects? Sound complex...
> 
> One thing I've noticed about slicing objects (using clipped_by, open geometry,
> etc.) and putting them into a union, is that weird artifacts can appear when
> rendering them. Especially if transparency in involved.

I did take a quick try manually bounding and rendering with -ur to 
prevent the manual bounding from being stripped (this a long while now 
the default). As you thought it didn't really help.

With the tori as blobs thinking of something like Bruno Cabasson's 
elliptic_torus.pov from back in 2005/6 - less the elliptic part. 
Something to create tori from blobs. Hmm, guess that could be tried to a 
first order by setting the major and minor elliptical axis to the major 
axis for each torus. There is in this approach a parse time vs render 
time trade off. There the minor axis is << the major one the parse times 
will start to become significant.

Yes, the slicing would need a merge over a union if there was any 
transparency and then when might not gain much in performance. I only 
ever tried the slicing approaches with isosurfaces and there too didn't 
often win. I don't know, an idea.

Aside: Never looked at it much, but in many places code wise the 
bounding and clipping mechanism is set up to support multiple shapes in 
a c++ vector... So guessing someone was thinking in the direction of 
more complex bounding at some point, but it's code not 'exploited' in 
that way as far as I know. Well, impossible currently to use it as the 
implementation is not complete. Not all shapes look to step through all 
the items in the vectors while looking to bound or clip intersections, 
for example. And yes, I think there is some performance overhead for 
having this mechanism partly there when all we seem to use is simpler 
single 'objects' while clipping or bounding (those can themselves be 
complex). Clipping also uses inside tests which for some of our shapes 
and for complex csg can be quite slow. Anyhow...

Bill P.


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From: Bill Pragnell
Subject: Re: Box division
Date: 29 Sep 2021 17:40:00
Message: <web.6154dc44154a1cc3b96893c06f35e431@news.povray.org>
Nice. Always interested in seeing things like this. A different slant on
greebling!

Bill


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