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1 Jun 2024 05:31:42 EDT (-0400)
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From: Bald Eagle
Subject: Re: Stacking stones without overlapping
Date: 16 Jun 2017 13:15:01
Message: <web.5944111dd8d105e9c437ac910@news.povray.org>
Stephen <mca### [at] aolcom> wrote:
> .... Sam used an external program,
> he developed himself, to calculate the positions of the grains.

I'd say that he probably used Voroi++
http://math.lbl.gov/voro++/examples/

which from the download page, says that the output can be used in POV-Ray
http://math.lbl.gov/voro++/download/

What would be nice would be a way to shell out to Voroi++ to generate the data
for a scene and then render it.

I just don't know how to do that ([like many things] yet).


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From: Stephen
Subject: Re: Stacking stones without overlapping
Date: 16 Jun 2017 15:00:08
Message: <59442ab8$1@news.povray.org>
On 6/16/2017 6:10 PM, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>> .... Sam used an external program,
>> he developed himself, to calculate the positions of the grains.
>
> I'd say that he probably used Voroi++
> http://math.lbl.gov/voro++/examples/
>
> which from the download page, says that the output can be used in POV-Ray
> http://math.lbl.gov/voro++/download/
>
> What would be nice would be a way to shell out to Voroi++ to generate the data
> for a scene and then render it.
>
> I just don't know how to do that ([like many things] yet).
>
>
It is not really that difficult. At least it wasn't in Ver 3.5. When I 
last used the function. You write a text file in PovRay with the 
variables you need and get the 3rd party software to export the results 
of the calculations to a text file that PovRay can read.
Yes this would be an animation even if it is only two frames or a frame 
per layer.

I ask myself if something this complex is appropriate for a first year 
engineering course.  But then my first year at university detailed 
thermionic valves and ne'er a mention of semiconductors. :) So things 
might have changed.

-- 

Regards
     Stephen


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From: Bald Eagle
Subject: Re: Stacking stones without overlapping
Date: 16 Jun 2017 16:30:01
Message: <web.59443ebfd8d105e9c437ac910@news.povray.org>
Stephen <mca### [at] aolcom> wrote:

> It is not really that difficult. At least it wasn't in Ver 3.5. When I
> last used the function. You write a text file in PovRay with the
> variables you need and get the 3rd party software to export the results
> of the calculations to a text file that PovRay can read.
> Yes this would be an animation even if it is only two frames or a frame
> per layer.

I guess my question was whether or not Voro++ is set up to accept comman-line
parameters and return a file for immediate processing by POV-Ray.
If so, then it would be of great interest to those who have a continuing
interest in having direct access to the set of coordinates used for the crackle
pattern - by supplanting crackle with a Voro++ data file, that would be a great
workaround.

> I ask myself if something this complex is appropriate for a first year
> engineering course.  But then my first year at university detailed
> thermionic valves and ne'er a mention of semiconductors. :) So things
> might have changed.

It ought to be perfectly fine.
I remember the engineers on my floor constantly being immersed in Statics:

http://ruina.tam.cornell.edu/Book/RuinaPratap8-21-10.pdf


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From: dick balaska
Subject: Re: Stacking stones without overlapping
Date: 17 Jun 2017 02:12:46
Message: <5944c85e$1@news.povray.org>
Am 2017-06-16 03:35, also sprach Stephen:

> I read the thread and if I understood it*. Sam used an external program, 
> he developed himself, to calculate the positions of the grains.

I, too, use a Java program to position grains. I found SDL to be 
hideously slow when doing a 1600 x 1600 loop. ;)
http://www.buckosoft.com/tteoac/video/frames/ttfo0177.png

I love Sam's idea; pick a position and then alter the blob's shape and 
size to fit the position.


-- 
dik


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From: Ari
Subject: Re: Stacking stones without overlapping
Date: 17 Jun 2017 04:05:00
Message: <web.5944e215d8d105e99d2528170@news.povray.org>
Omg, Guys!
I just cannot believe how generous and warm this community is.
I am sorry that I just completely immersed myself in this software (I only got 2
months to learn this technique :( And it is making me anxious now) therefore I
cannot check this thread frequently. Thanks again for the big help! Even though
I cannot reply the messages one by one, I swear I would read all the useful
information I have received. Again, I just cannot how generous this community
could be at the first glance. A big shoutout to all of you :D.


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From: Stephen
Subject: Re: Stacking stones without overlapping
Date: 17 Jun 2017 04:13:21
Message: <5944e4a1@news.povray.org>
On 6/17/2017 9:02 AM, Ari wrote:
> Omg, Guys!
> I just cannot believe how generous and warm this community is.

Oh! you have not received the invoice, yet. :)

-- 

Regards
     Stephen


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From: Thomas de Groot
Subject: Re: Stacking stones without overlapping
Date: 17 Jun 2017 07:16:13
Message: <59450f7d@news.povray.org>
On 17-6-2017 10:13, Stephen wrote:
> On 6/17/2017 9:02 AM, Ari wrote:
>> Omg, Guys!
>> I just cannot believe how generous and warm this community is.
>
> Oh! you have not received the invoice, yet. :)
>

I believe I sent it yesterday night... but as I forgot to drink my dried 
toadstool tea, I may have been remiss. :-0

-- 
Thomas


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From: Stephen
Subject: Re: Stacking stones without overlapping
Date: 17 Jun 2017 10:00:11
Message: <594535eb$1@news.povray.org>
On 6/16/2017 9:25 PM, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>
>> It is not really that difficult. At least it wasn't in Ver 3.5. When I
>> last used the function. You write a text file in PovRay with the
>> variables you need and get the 3rd party software to export the results
>> of the calculations to a text file that PovRay can read.
>> Yes this would be an animation even if it is only two frames or a frame
>> per layer.
>
> I guess my question was whether or not Voro++ is set up to accept comman-line
> parameters and return a file for immediate processing by POV-Ray.
> If so, then it would be of great interest to those who have a continuing
> interest in having direct access to the set of coordinates used for the crackle
> pattern - by supplanting crackle with a Voro++ data file, that would be a great
> workaround.
>

I misunderstood.

>> I ask myself if something this complex is appropriate for a first year
>> engineering course.  But then my first year at university detailed
>> thermionic valves and ne'er a mention of semiconductors. :) So things
>> might have changed.
>
> It ought to be perfectly fine.
> I remember the engineers on my floor constantly being immersed in Statics:
>
> http://ruina.tam.cornell.edu/Book/RuinaPratap8-21-10.pdf
>
>

It goes on forever -- and -- oh my God! -- it’s full of squiggles!

;)


-- 

Regards
     Stephen


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From: Stephen
Subject: Re: Stacking stones without overlapping
Date: 17 Jun 2017 10:02:49
Message: <59453689$1@news.povray.org>
On 6/17/2017 7:12 AM, dick balaska wrote:
> Am 2017-06-16 03:35, also sprach Stephen:
>
>> I read the thread and if I understood it*. Sam used an external
>> program, he developed himself, to calculate the positions of the grains.
>
> I, too, use a Java program to position grains. I found SDL to be
> hideously slow when doing a 1600 x 1600 loop. ;)
> http://www.buckosoft.com/tteoac/video/frames/ttfo0177.png
>

I liked that part. :)

> I love Sam's idea; pick a position and then alter the blob's shape and
> size to fit the position.
>
>

I suspect that could be classified as cheating. ;)

-- 

Regards
     Stephen


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From: Bald Eagle
Subject: Re: Stacking stones without overlapping
Date: 19 Jun 2017 10:10:01
Message: <web.5947db01d8d105e9c437ac910@news.povray.org>
dick balaska <dic### [at] buckosoftcom> wrote:


> I, too, use a Java program to position grains. I found SDL to be
> hideously slow when doing a 1600 x 1600 loop. ;)
> http://www.buckosoft.com/tteoac/video/frames/ttfo0177.png

It's always helpful when expediency is the goal -  to recognize the practical
solutions and take the path of least resistance.

> I love Sam's idea; pick a position and then alter the blob's shape and
> size to fit the position.

Yes, that's an interesting idea - well worth looking into to see how difficult
that would be to do well.

I was thinking something along the lines of this:

https://www.researchgate.net/figure/273284325_fig7_Figure-7-An-example-of-a-Voronoi-diagram-in-Laguerre-geometry-for-a-
set-of-multi-sized

Where the spaces and centers are well defined, and then the sphere radii could
be easily computed.  That would get one far along the path.  Although I think
that the appropriate crackle metric and offset settings would get it all done
lickety-split.


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