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15 Jul 2024 19:23:29 EDT (-0400)
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From: Josh
Subject: Re: Mapping Textures on irregular shapes
Date: 24 Apr 2020 23:25:01
Message: <web.5ea3ac8472e01857dc1270cd0@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:
> Le 2020-04-23 à 02:13, Josh a écrit :
> > As a starting point, any advice to create a variety of textures something like
> > these?
> >
> > https://opengameart.org/content/24-bigger-asteroids
> > https://opengameart.org/content/432-isometrics-rocks-and-asteroids
> >
> > Josh
> >
>
> Looking at those and I can tell that most of the effect come from the
> geometry itself. The textures themselves looks pretty simple.
>
> You should experiment with plain pigments as well as with the textures
> from stones.inc, stones1.inc and stone2.inc as well as those from
> textures.inc
>
> When using those, imagine that you are carving your object from a
> massive block made from those textures 3D.

Yes, I figured out more with textures and I agree, the textures should be
straightforward. Does anyone have ideas about how to make more complex geometry?
It's not too hard to add noise3d to a basic shape, but any ideas about how to
(programmatically?) create more of those complex rough rocky geometries? Thanks
to everyone for the help.

Josh


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From: Bald Eagle
Subject: Re: Mapping Textures on irregular shapes
Date: 25 Apr 2020 08:45:00
Message: <web.5ea42fe772e01857fb0b41570@news.povray.org>
"Josh" <nomail@nomail> wrote:

> It's not too hard to add noise3d to a basic shape, but any ideas about how to
> (programmatically?) create more of those complex rough rocky geometries? Thanks
> to everyone for the help.

I would suggest that you take a look at the isowood macros
http://www.imagico.de/iso_wood_en.php

And definitely the raymarching and signed distance function work of Inigo Quilez
https://www.youtube.com/watch?v=s5NGeUV2EyU
see the 4:00 mark.

Some mathy stuff to ponder the power of:
http://iquilezles.org/www/articles/proceduralgfx/inspire2008.pdf

http://wiki.povray.org/content/User:Wfpokorny/DensityFile/TubulenceWarpsExamples


I think that for deep crevices such as that, what you may want to do is model a
rough asteroid as a parent object, and then subtract very jagged shapes from it.
Simple ellipsoids, cylinders, or perhaps some sort of web/network shape like the
gyroid I've played with here and there.
You can avoid CSG differencing by using "isosurface differencing" right in the
equation.

http://www.povray.org/documentation/view/3.6.1/73/
 (1.3.3.3.6 Combining isosurface functions)
"Of course also "difference" is possible, we just have to add a minus (-) before
the second function:

function { max(fn_A(x, y, z), -fn_B(x, y, z)) }"

http://www.econym.demon.co.uk/isotut/combine.htm

and see here, where he shows crackle as an isosurface function
http://www.econym.demon.co.uk/isotut/pigment.htm

you could superimpose all those little floating chunks inside the asteroid and
difference them away to get all the pock marks and crevices.

etc, and so on, ad infinitum.

-Bill


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From: green
Subject: Re: Mapping Textures on irregular shapes
Date: 25 Apr 2020 18:25:01
Message: <web.5ea4b7d672e018576d8fea700@news.povray.org>
"Josh" <nomail@nomail> wrote:
> Alain Martel <kua### [at] videotronca> wrote:
> > Le 2020-04-23 à 02:13, Josh a écrit :
> > > As a starting point, any advice to create a variety of textures something like
> > > these?
> > >
> > > https://opengameart.org/content/24-bigger-asteroids
> > > https://opengameart.org/content/432-isometrics-rocks-and-asteroids
> > >
> > > Josh
> > >
> >
> > Looking at those and I can tell that most of the effect come from the
> > geometry itself. The textures themselves looks pretty simple.
> >
> > You should experiment with plain pigments as well as with the textures
> > from stones.inc, stones1.inc and stone2.inc as well as those from
> > textures.inc
> >
> > When using those, imagine that you are carving your object from a
> > massive block made from those textures 3D.
>
> Yes, I figured out more with textures and I agree, the textures should be
> straightforward. Does anyone have ideas about how to make more complex geometry?
> It's not too hard to add noise3d to a basic shape, but any ideas about how to
> (programmatically?) create more of those complex rough rocky geometries? Thanks
> to everyone for the help.
>
> Josh

this thread may be relevant to you;
some asteroids (from Paul Bourke) [122kb JPG]
http://news.povray.org/povray.binaries.images/thread/%3C42d91288%40news.povray.org%3E/

the link to bourke's page is defunct but this may the same material;
http://paulbourke.net/miscellaneous/asteroid/


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From: Alain Martel
Subject: Re: Mapping Textures on irregular shapes
Date: 26 Apr 2020 10:57:13
Message: <5ea5a149$1@news.povray.org>
Le 2020-04-24 à 23:21, Josh a écrit :

> Yes, I figured out more with textures and I agree, the textures should be
> straightforward. Does anyone have ideas about how to make more complex geometry?
> It's not too hard to add noise3d to a basic shape, but any ideas about how to
> (programmatically?) create more of those complex rough rocky geometries? Thanks
> to everyone for the help.
> 
> Josh
> 
> 
> 
> 
An isosurface sphere with some noise added.
With
#include "function.inc"
Possible noise sources : f_noise3d, granite, agate,...

sample code :
#declare R=seed(1);
function{
   f_sphere(x,y,z,1)
   +f_noise3d(x*10+rand(R),y*10+rand(R),z*10+rand(R))
   -f_agate(x*5+rand(R),y*5+rand(R),z*5+rand(R))
}

If you define and place 20 isosurfaces using that function in your 
scene, they will all be different.


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From: Josh
Subject: Re: Mapping Textures on irregular shapes
Date: 26 Apr 2020 16:40:08
Message: <web.5ea5f0df72e01857dc1270cd0@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:
> Le 2020-04-23 à 02:13, Josh a écrit :
> > As a starting point, any advice to create a variety of textures something like
> > these?
> >
> > https://opengameart.org/content/24-bigger-asteroids
> > https://opengameart.org/content/432-isometrics-rocks-and-asteroids
> >
> > Josh
> >
>
> Looking at those and I can tell that most of the effect come from the
> geometry itself. The textures themselves looks pretty simple.
>
> You should experiment with plain pigments as well as with the textures
> from stones.inc, stones1.inc and stone2.inc as well as those from
> textures.inc
>
> When using those, imagine that you are carving your object from a
> massive block made from those textures 3D.

I thought I already posted a reply, but can't find it so sorry if this double
posts. I agree, I figured out quite a bit with generated textures, I now need to
work more on generating the geometry itself. Any ideas for how to generate some
of the shapes like in those examples? TIA.

Josh


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From: Josh
Subject: Re: Mapping Textures on irregular shapes
Date: 26 Apr 2020 16:55:05
Message: <web.5ea5f47372e01857dc1270cd0@news.povray.org>
> I thought I already posted a reply, but can't find it so sorry if this double
> posts. I agree, I figured out quite a bit with generated textures, I now need to
> work more on generating the geometry itself. Any ideas for how to generate some
> of the shapes like in those examples? TIA.
>
> Josh

Sorry, I did double post! Thanks for all the replies, I'm looking at them now!

Josh


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From: Josh
Subject: Re: Mapping Textures on irregular shapes
Date: 26 Apr 2020 17:50:06
Message: <web.5ea600f372e01857dc1270cd0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:

> And definitely the raymarching and signed distance function work of Inigo Quilez
> https://www.youtube.com/watch?v=s5NGeUV2EyU
> see the 4:00 mark.
>
> http://wiki.povray.org/content/User:Wfpokorny/DensityFile/TubulenceWarpsExamples
>

Lots of good information and links from everyone. I've already learned a lot and
found some great examples. I would like to get followup on two suggestions
though.

1) I would love to use the example from Inigo Quilez about rounding. Say I have
a simple function for a box used in an isosurface. How would I implement his
idea in povray to make the corners round? I tried changing the threshold of the
isosurface, but that doesn't do it. A simple example would be super helpful.

2) I also like how you can create df3 files and use them as a function from the
warp example. Is there any 3d modelers that can export df3? Are there other
programs/ways to create simple df3 files of simple shapes?

Josh


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From: Bald Eagle
Subject: Re: Mapping Textures on irregular shapes
Date: 26 Apr 2020 21:25:01
Message: <web.5ea6343372e01857fb0b41570@news.povray.org>
"Josh" <nomail@nomail> wrote:

> 1) I would love to use the example from Inigo Quilez about rounding. Say I have
> a simple function for a box used in an isosurface. How would I implement his
> idea in povray to make the corners round? I tried changing the threshold of the
> isosurface, but that doesn't do it. A simple example would be super helpful.

http://www.iquilezles.org/www/articles/distfunctions2d/distfunctions2d.htm

float sdBox( in vec2 p, in vec2 b )
{
    vec2 d = abs(p)-b;
    return length(max(d,0.0)) + min(max(d.x,d.y),0.0);
}

It may take some fiddling to get the vectors that ShaderToy allows you to use in
its functions into a POV-Ray function.
#declare PX = VecP.x;
And then you can use PX in the function.

> 2) I also like how you can create df3 files and use them as a function from the
> warp example. Is there any 3d modelers that can export df3? Are there other
> programs/ways to create simple df3 files of simple shapes?

There should be a function to make a df3 from POV-Ray.
http://wiki.povray.org/content/Reference:Arrays.inc

Arrays.incReference
This file contains macros for manipulating arrays.

ARRAYS_WriteDF3(Array, FileName, BitDepth): Write an array to a df3 file.

Parameters:

Array = The array that contains the data.
FileName = The name of the file to be written.
BitDepth = The size of the binary word.
Note: See the #write directive for more information.



I would have gotten to this sooner, and maybe wrote out some more detailed help,
but I spent all day writing and developing Arduino code in cpp proper.
I still have one or two things to do that I don't quite understand.   ;)


But this should get you going if you play with it a bit.


https://www.desmos.com/calculator


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From: jr
Subject: Re: Mapping Textures on irregular shapes
Date: 27 Apr 2020 11:05:01
Message: <web.5ea6f46272e01857898043f30@news.povray.org>
hi,

"Josh" <nomail@nomail> wrote:
> ...
> 2) I also like how you can create df3 files and use them as a function from the
> warp example. Is there any 3d modelers that can export df3? Are there other
> programs/ways to create simple df3 files of simple shapes?

if you're using some Linux, there's the 'df3 tools':

<http://news.povray.org/web.5b43d8aa43fdfea9635cc5ad0%40news.povray.org>


regards, jr.


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From: Thomas de Groot
Subject: Re: Mapping Textures on irregular shapes
Date: 28 Apr 2020 03:11:03
Message: <5ea7d707@news.povray.org>
Op 26/04/2020 om 23:45 schreef Josh:
> 2) I also like how you can create df3 files and use them as a function from the
> warp example. Is there any 3d modelers that can export df3? Are there other
> programs/ways to create simple df3 files of simple shapes?
> 

You may be interesting in: 
https://www.oyonale.com/modeles.php?lang=en&page=36

-- 
Thomas


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