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

"Josh" <nomail@nomail> wrote:
> Ya, the more I look at it, the more I think just going for procedural textures
> with surface-dependent modifiers is a good idea. Any ideas of where I can go to
> look for examples of good looking rock / asteroid / metal / alien type textures
> or procedures for asteroids?
>
> Josh
>
> "Bald Eagle" <cre### [at] netscapenet> wrote:
>
> > Depending on the effect you're going for, it may be best to try a procedural
> > texture with some surface-dependent texture modifiers like AOI, slope, slope or
> > normal maps (not like the one you used for the game engine), etc.
> >
> >
> > Now, maybe Jerome Grimbert might have a good idea about whether or not NURBS
> > allows you to model a shape from scratch AND get a uv-mapping function-of-sorts
> > as an incidental byproduct...
> >
> > Maybe post a sample asteroid shape and a sample or link(s) to the kind of thing
> > you're shooting for?  Folks may have some practical ideas.

Post a reply to this message

"Josh" <nomail@nomail> wrote:
> 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

Those look pretty simple.
Glossy, so use something like specular and/or phong highlighting in the finish
{} block of the texture.

My personal standard reference for rocks is of course:

http://hof.povray.org/pebbles.html
http://xlcus.com/povray/pebbles/pebbles.pov

Which if you look at the actual texturing, is just using pretty stock POV-Ray
patterns properly paired with normals based on the same pigment pattern in the
right scale and orientation.

Which is why I shamelessly (and lazily) ripped off all that code to do this:
http://news.povray.org/povray.binaries.images/thread/%3Cweb.5d3c5fe27be432e04eec112d0%40news.povray.org%3E/

:D

Once you get the idea, then you can look into setting up a basic marble pigment,
adding the turbulence, the modifiers that go with that, making an easily
adjustable color/pigment/texture/material map etc.

I'd say for rapid development, make a grid of asteroids like you've shown with a
nested loop and have each one be a little different, so you can look at a lot of
different variations with a single render.

http://f-lohmueller.de/pov_tut/loop/povlup1e.htm

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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.

Post a reply to this message

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

Post a reply to this message

"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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"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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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.

Post a reply to this message

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

Post a reply to this message

> 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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"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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