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28 May 2024 10:46:05 EDT (-0400)
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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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From: Bald Eagle
Subject: Re: Stacking stones without overlapping
Date: 19 Jun 2017 13:45:05
Message: <web.59480cabd8d105e9c437ac910@news.povray.org>
There's also the related isosurface method:

http://www.econym.demon.co.uk/isotut/printable.htm#CH_pigment

http://www.econym.demon.co.uk/isotut/pigment.jpg


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From: Ari
Subject: Re: Stacking stones without overlapping
Date: 20 Jun 2017 15:10:00
Message: <web.59497214d8d105e99d2528170@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> 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.

Hi, everyone.
I have been spending time searching on the internet and reading your guys'
information. However, I realized almost all of them required "some mathematical
background", especially Voronoi Diagram being shown the most frequently. I try
my best to understand them but I can't due to the lack of Maths background(I
only know some integration/sequence and differentiation from classes :( ). I
then try to work with an external program but I don't how to make use of it
well. (I installed the pyvoro in Python) So, I just went back to the basic now.
( Damn, I am stupid! Just want to cry in a corner) So far I just wrote this one:

#declare Grain = array[10000]   ;
#declare Nr = 0    ;
#declare Position = seed(100)  ;
#declare Size = seed(123)   ;
#while (Nr < 10000)
    sphere{<rand(Position), rand(Position), rand(Position)>, rand(Size)*.1
            pigment {color rgb<rand(Size), rand(Size), rand(Size)>} }
    #declare Grain[Nr] = sphere{<rand(Position), rand(Position),
rand(Position)>, rand(Size)*.1
            pigment {color rgb<rand(Size), rand(Size), rand(Size)>} }
    #declare Nr = Nr + 1;
#end

I think I will then try to develop it a little bit further according to the
'distance test formula' from the 'Pebbles' example. My idea now is to test every
Grain[Nr] vs Grain[Nr-1] Grain[Nr-2]......Grain[0] if their distance between two
centers is smaller than their sum of radii. It's 3 a.m. now here guys. I think I
might just sleep and work it out tomorrow. Thank you guys for helping me at
first but I think I have to say I am too stupid to understand them :'(.


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From: Ari
Subject: Re: Stacking stones without overlapping
Date: 20 Jun 2017 15:10:01
Message: <web.5949729fd8d105e99d2528170@news.povray.org>
Hi, everyone.
I have been spending time searching on the internet and reading your guys'
information. However, I realized almost all of them required "some mathematical
background", especially Voronoi Diagram being shown the most frequently. I try
my best to understand them but I can't due to the lack of Maths background(I
only know some integration/sequence and differentiation from classes :( ). I
then try to work with an external program but I don't how to make use of it
well. (I installed the pyvoro in Python) So, I just went back to the basic now.
( Damn, I am stupid! Just want to cry in a corner) So far I just wrote this one:

#declare Grain = array[10000]   ;
#declare Nr = 0    ;
#declare Position = seed(100)  ;
#declare Size = seed(123)   ;
#while (Nr < 10000)
    sphere{<rand(Position), rand(Position), rand(Position)>, rand(Size)*.1
            pigment {color rgb<rand(Size), rand(Size), rand(Size)>} }
    #declare Grain[Nr] = sphere{<rand(Position), rand(Position),
rand(Position)>, rand(Size)*.1
            pigment {color rgb<rand(Size), rand(Size), rand(Size)>} }
    #declare Nr = Nr + 1;
#end

I think I will then try to develop it a little bit further according to the
'distance test formula' from the 'Pebbles' example. My idea now is to test every
Grain[Nr] vs Grain[Nr-1] Grain[Nr-2]......Grain[0] if their distance between two
centers is smaller than their sum of radii. It's 3 a.m. now here guys. I think I
might just sleep and work it out tomorrow. Thank you guys for helping me at
first but I think I have to say I am too stupid to understand them :'(.


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From: Stephen
Subject: Re: Stacking stones without overlapping
Date: 20 Jun 2017 15:57:43
Message: <59497e37@news.povray.org>
On 6/20/2017 8:08 PM, Ari wrote:
>   I try
> my best to understand them but I can't due to the lack of Maths background(I
> only know some integration/sequence and differentiation from classes:(  ).

You and me both. :)

-- 

Regards
     Stephen


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From: Bald Eagle
Subject: Re: Stacking stones without overlapping
Date: 20 Jun 2017 16:55:00
Message: <web.59498b72d8d105e9c437ac910@news.povray.org>
"Ari" <win### [at] yahoocomhk> wrote:
> Hi, everyone.
> I have been spending time searching on the internet and reading your guys'
> information. However, I realized almost all of them required "some mathematical
> background", especially Voronoi Diagram being shown the most frequently. I try
> my best to understand them but I can't due to the lack of Maths background(I
> only know some integration/sequence and differentiation from classes :( ). I
> then try to work with an external program but I don't how to make use of it
> well. (I installed the pyvoro in Python) So, I just went back to the basic now.
> ( Damn, I am stupid! Just want to cry in a corner)

I think you'll be fine.
A lot of stuff was thrown at you all at once.
Voronoi / Delaunay is NOT an easy thing to do from scratch - which is why Sam
Benge used an external program to generate his data set.
Pov-ray's crackle pattern is essentially a Voronoi diagram, and you can use it
to make a pattern, or pass it to an isosurface as a function, to get "real 3d"
shapes.
I'd start with the spheres like you're doing, and then you can get a working
scene, and practice with POV-Ray's SDL syntax, and programming logic.


No worries - it'll be ok   ;)


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From: Stephen
Subject: Re: Stacking stones without overlapping
Date: 20 Jun 2017 17:04:39
Message: <59498de7$1@news.povray.org>
On 6/20/2017 8:57 PM, Stephen wrote:
> On 6/20/2017 8:08 PM, Ari wrote:
>>   I try
>> my best to understand them but I can't due to the lack of Maths
>> background(I
>> only know some integration/sequence and differentiation from
>> classes:(  ).
>
> You and me both. :)
>

So what I would do, knowing that most of the guys here have been using 
PovRay for years and they are wizards at maths and programming. Is to 
start simple then refine it as you go along.
The image you linked to was by someone who stuns everyone with his work. 
So it is not a fair goal to try and do in a couple of months.

If you look at the trace function it will tell you how far away an 
object is from a reference point. If you move that reference point in a 
regular scan. You can build up a pattern of spheres. When you are happy 
with that you can then add some randomness to what you are building. 
Irregular scaling of the spheres to be laid down to give the impression 
of stones. offset the trace reference point so the spheres don't stack 
up in columns etc.
Then you will get ideas of your own to enhance it.

Remember us enjuneers have to make thinks work. And if it doesn't fit 
use a bigger hammer. ;-)

-- 

Regards
     Stephen


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