I'm trying to model a sheet of paper, that roles a bit ...
I'm going to use bezier patches for that, and (of course) uv-mapping
...

My intention is, to only show the image on one side, and leave the
backside white...

It should look like a printed poster ...

The question is, how to realize that ..

AFAIK it is not possible, to give the bezieres different fore-/back
textures...
should I model 2 different patches, and translate them a bit, or is
there another way to do that ?

--
background{rgb 1}camera{location<1,5,-2>look_at 0}#macro
m(a,b,i)#local d=(b-a)
/8;#local
e=vcross(d,y);#if(i)m(a-e,a+e+2*d,i-1)m(a+e,a+2*d-e,i-1)m(a+3*d-e,a+e
+3*d,i-1)m(a+3*d-e,a+5*d-e,i-1)m(a+6*d-e,a+e+6*d,i-1)m(a+8*d-e,a+e+8*d
,i-1)#else
cylinder{a,b,vlength(d)/3 pigment{rgb 0}}#end#end m(-4*x,2*x,4) // Jan
Walzer

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Jan Walzer wrote:
> 
> AFAIK it is not possible, to give the bezieres different fore-/back
> textures...
> should I model 2 different patches, and translate them a bit, or is
> there another way to do that ?
> 

The translation method only works if the paper is mainly flat, meaning
there is no real 'rolling'.  In this case you can also use a slope texture
like:

texture {
  slope y
  texture_map {
    [0.5 T_Side_1 ]
    [0.5 T_Side_2 ]
  }
}

(just from memory, not tested)

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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In article <3ac6040a@news.povray.org>, "Jan Walzer" <jan### [at] lzernet> 
wrote:

> AFAIK it is not possible, to give the bezieres different fore-/back
> textures...
> should I model 2 different patches, and translate them a bit, or is
> there another way to do that ?

Well, if you are using MegaPOV (which I assume you are, you mentioned UV 
mapping), you could just use interior_texture to texture each side 
separately. (one side of the patch will be "inside")

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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As I said, I want to make some complete roles ...
With translation I didn't mean, to only translate, but to remodel
another sheet.
As I'm using Moray, to do that, it wouln't be such a big problem, but
instead a lot of finetuning  to make both as close as possible, but to
have no intersections ...

I haven't used slopemaps yet (I have a small clue what they do) but I
don't know if they would fit into my problem...

But Chris Huff mentioned the interior_texture-Flag, I will use now ...

But thanks anyway ..

--
background{rgb 1}camera{location<1,5,-2>look_at 0}#macro
m(a,b,i)#local d=(b-a)
/8;#local
e=vcross(d,y);#if(i)m(a-e,a+e+2*d,i-1)m(a+e,a+2*d-e,i-1)m(a+3*d-e,a+e
+3*d,i-1)m(a+3*d-e,a+5*d-e,i-1)m(a+6*d-e,a+e+6*d,i-1)m(a+8*d-e,a+e+8*d
,i-1)#else
cylinder{a,b,vlength(d)/3 pigment{rgb 0}}#end#end m(-4*x,2*x,4) // Jan
Walzer

Post a reply to this message

Hmmm ... didn't know this feature yet ...
I think I'll have to read again through the docs

Thanks a lot ...

--
background{rgb 1}camera{location<1,5,-2>look_at 0}#macro
m(a,b,i)#local d=(b-a)
/8;#local
e=vcross(d,y);#if(i)m(a-e,a+e+2*d,i-1)m(a+e,a+2*d-e,i-1)m(a+3*d-e,a+e
+3*d,i-1)m(a+3*d-e,a+5*d-e,i-1)m(a+6*d-e,a+e+6*d,i-1)m(a+8*d-e,a+e+8*d
,i-1)#else
cylinder{a,b,vlength(d)/3 pigment{rgb 0}}#end#end m(-4*x,2*x,4) // Jan
Walzer

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Chris Huff wrote:
> 
> Well, if you are using MegaPOV (which I assume you are, you mentioned UV
> mapping), you could just use interior_texture to texture each side
> separately. (one side of the patch will be "inside")
> 

Correct me if i'm wrong, but AFAIK patches don't have a well defined
inside/outside.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

Post a reply to this message

In article <3AC61B40.C32EF703@gmx.de>, Christoph Hormann 
<chr### [at] gmxde> wrote:

> Correct me if i'm wrong, but AFAIK patches don't have a well defined
> inside/outside.

They don't have a specific area that is "inside", but they do have two 
sides that can be handled separately. In triangles, the order of the 
vertices determines which side is considered "inside", with bezier 
patches the situation is similar.

There is a demo scene using both UV mapping and interior_texture, a 
rendered image is on the Smellenbergh's site here:
http://users.skynet.be/smellenbergh/demo.html
It's the one titled "4-corner uv_vectors, interior_texture".

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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