I have created a pretty swanky texture which simulates how a desert or
river-bed dries and crackles up. However, it is a skin texture (which I
have applied to a plane): and where the cracks are, you can see through
it. What I am trying to achieve are extruded segments, so that the
surface has depth.
As far as I know, all POV textures are skin textures - so, whatever
transformations I do to them, I assume that they will always remain as
skin textures (i.e. although I have it on a plane, a 2D surface;
applying it to a huge cube, and transforming the texture so it has depth
in the appropriate axis won't do me much good). I tried doing the
upside-down ground fog trick (underneath a hollow plane), but that
didn't work at all.

Other than using a height map (which is just kinda inconvenient for the
scale I'm talking about), I can't think of anyway to do this... Does
anyone have any suggestions?
Thanks :^)

Chris Harrison
http://www.ChrisHarrison.co.uk/

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What is a 'skin texture'? Can't you just use a normal?

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"David Fontaine" <dav### [at] faricynet> wrote in message
news:3899FE33.E4BE4D41@faricy.net...
| What is a 'skin texture'? Can't you just use a normal?

Just means it's surface-only, as all textures usually are.  Can also stand for
uv-mapped texture I believe.  I'd think that a 'normal_map' or similar would be
all you could do in the official POV-Ray, unless layering planes, however
there's a good chance that what you want to do can be done using unofficial
MegaPov 0.4 [http://nathan.kopp.com/download.htm] 'isosurface' as plane with a
pigment function since it isn't as limiting as HF in it's structure but then you
can't use a slope-based texture.  So it's a decision to make there.
Examples can be found in the povray.text.scene-files group I think and in the
HTML or Help files, also check out Samuel Benges' isosurface tutorials:
http://members.aol.com/stbenge/ or How to Make a Moon:
http://www.xenoarch.com/tutorials/moon.html

Bob

<<
I have created a pretty swanky texture which simulates how a desert or
river-bed dries and crackles up. However, it is a skin texture (which I
have applied to a plane): and where the cracks are, you can see through
it. What I am trying to achieve are extruded segments, so that the
surface has depth.
As far as I know, all POV textures are skin textures - so, whatever
transformations I do to them, I assume that they will always remain as
skin textures (i.e. although I have it on a plane, a 2D surface;
applying it to a huge cube, and transforming the texture so it has depth
in the appropriate axis won't do me much good). I tried doing the
upside-down ground fog trick (underneath a hollow plane), but that
didn't work at all.

Other than using a height map (which is just kinda inconvenient for the
scale I'm talking about), I can't think of anyway to do this... Does
anyone have any suggestions?
Thanks :^)

Chris Harrison
http://www.ChrisHarrison.co.uk/
>>

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A normal modifier can do an excellent job.

  For example, the floor in the following image is just a plane:

http://www.cs.tut.fi/~warp/tnt/Detonaattori.jpg

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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In article <3899FC63.8E258F28@ChrisHarrison.co.uk> , Chris Harrison 
<Me### [at] ChrisHarrisoncouk>  wrote:

> As far as I know, all POV textures are skin textures - so, whatever
> transformations I do to them, I assume that they will always remain as
> skin textures (i.e. although I have it on a plane, a 2D surface;

POV-Ray textures are procedural textures, maybe best explained as
complicated functions in 3D space.  Textures in POV-Ray are not mapped on
the surface of the object, they 'fill'* the whole object in the sense that
when you for example cut out a part of the object with a CSG operation you
will see a different 'part' of the texture, not the previous surface texture
part remapped on that area.


     Thorsten


* 'Fill' does not imply the object is really filled with anything, just that
the texture (function) is defined inside as well as outside of the object.
For details refer to the POV-Ray documentation "interior" section.

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That's a much better explanation of the texture patterns.  In other words, where
there is a surface there is a intersecting texture.

Bob

"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:389ae604@news.povray.org...
| In article <3899FC63.8E258F28@ChrisHarrison.co.uk> , Chris Harrison
| <Me### [at] ChrisHarrisoncouk>  wrote:
|
| > As far as I know, all POV textures are skin textures - so, whatever
| > transformations I do to them, I assume that they will always remain as
| > skin textures (i.e. although I have it on a plane, a 2D surface;
|
| POV-Ray textures are procedural textures, maybe best explained as
| complicated functions in 3D space.  Textures in POV-Ray are not mapped on
| the surface of the object, they 'fill'* the whole object in the sense that
| when you for example cut out a part of the object with a CSG operation you
| will see a different 'part' of the texture, not the previous surface texture
| part remapped on that area.
|
|      Thorsten
|
| * 'Fill' does not imply the object is really filled with anything, just that
| the texture (function) is defined inside as well as outside of the object.
| For details refer to the POV-Ray documentation "interior" section.

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Chris Harrison wrote:

> I have created a pretty swanky texture which simulates how a desert or
> river-bed dries and crackles up. However, it is a skin texture (which I
> have applied to a plane): and where the cracks are, you can see through
> it. What I am trying to achieve are extruded segments, so that the
> surface has depth.

Several ideas come to mind.
1. You can very well create a texture that changes both in the x-z plane and
the y direction, by using pigment_map or texture_map
texture{
    gradient y
    texture_map{
      [0 BottomTexture] // this one for the deep cracks
      [1 TopTexture]     //  this one for the upper crust
   }
}
2. Using a height field is a less bad idea that it seems, even at large
scale, because, like meshes, height fields can be replicated a great number
of times without much memory overhead. I you make a tileable height_field,
you may very well use it on a large surface.

 3. Using an isosurface based on a crackle pigment, possibly the one used in
the TopTexture, is another option. It may give lengthy renders though.

G.

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Thanks for all the suggestions... I have finally, with a lot of fiddling,
created a tile-able heightmap along with an improved texture, which all
looks very nice :^)

Thanks again :^)

Chris Harrison
http://www.ChrisHarrison.co.uk/

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