I read the manual about interior texture. It says that it can be apply 
to triangle (and I assume mesh and mesh2) but I did not find (with a 
grep) the definition of backside and frontside for triangles, mesh and 
mesh2 ?

Moreover, the definition seems to differ from OpenGL's (order of 
vertices) and seems not to use normals either when they are given so I 
can not guess it !

Please help.

Thanks

Christophe Raffalli

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In article <403ccb81$1@news.povray.org> , Christophe Raffalli 
<raf### [at] univ-savoiefr>  wrote:

> I read the manual about interior texture. It says that it can be apply
> to triangle (and I assume mesh and mesh2) but I did not find (with a
> grep) the definition of backside and frontside for triangles, mesh and
> mesh2 ?
>
> Moreover, the definition seems to differ from OpenGL's (order of
> vertices) and seems not to use normals either when they are given so I
> can not guess it !
>
> Please help.

You cannot currently recreate the OpenGL backface cullling effect with
POV-Ray.  This effect only exists in OpenGL as a speed optimisation because
for OpenGL it is faster to not render backfacing triangles.  This is not the
case in POV-Ray.

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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Thorsten Froehlich wrote:
> In article <403ccb81$1@news.povray.org> , Christophe Raffalli 
> <raf### [at] univ-savoiefr>  wrote:
> 
> 
>>I read the manual about interior texture. It says that it can be apply
>>to triangle (and I assume mesh and mesh2) but I did not find (with a
>>grep) the definition of backside and frontside for triangles, mesh and
>>mesh2 ?
>>
>>Moreover, the definition seems to differ from OpenGL's (order of
>>vertices) and seems not to use normals either when they are given so I
>>can not guess it !
>>
>>Please help.
> 
> 
> You cannot currently recreate the OpenGL backface cullling effect with
> POV-Ray.

I am not sure I understand
>  This effect only exists in OpenGL as a speed optimisation because
> for OpenGL it is faster to not render backfacing triangles.  This is not the
> case in POV-Ray.
> 

What I want is to be able to choose which face if the backside and which 
face if the front face for a mesh2 in fact.

For the moment I get a nice patchwork (not completely random) because 
texture and interior texture are applied in a way I do not understand to 
each triangle in the mesh. (my mesh uses OpenGL convention for the order 
of vertices and has normals pointing to the outside).

Should I give a script sample ?

>     Thorsten
> 
> ____________________________________________________
> Thorsten Froehlich
> e-mail: mac### [at] povrayorg
> 
> I am a member of the POV-Ray Team.
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

Christophe Raffalli wrote:
> 
> I read the manual about interior texture. It says that it can be apply 
> to triangle (and I assume mesh and mesh2) but I did not find (with a 
> grep) the definition of backside and frontside for triangles, mesh and 
> mesh2 ?

AFAIK the use of interior_texture depends on the normal direction and 
the normal direction of a flat triangle in a mesh depends on the order 
of vertices.  In case of a smooth triangle this is of course more 
complicated, you probably can even create triangles with partly 
interior_texture and partly not.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 11 Jan. 2004 _____./\/^>_*_<^\/\.______

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In article <403### [at] univ-savoiefr> , Christophe Raffalli 
<raf### [at] univ-savoiefr>  wrote:

> What I want is to be able to choose which face if the backside and which
> face if the front face for a mesh2 in fact.

You cannot do this if you also desire to apply individual textures to each
face of the mesh.  You can of course split the mesh into as many faces as
you want to texture individually, but I am aware that doing so is not
feasible if you have many individual textures.

> For the moment I get a nice patchwork (not completely random) because
> texture and interior texture are applied in a way I do not understand to
> each triangle in the mesh.

interior_texture is only applied to those triangles which do not have their
own texture.  I understand that this may not always be desired, but
currently (POV-Ray 3.6 beta 1) you cannot get the effect you would like.

> Should I give a script sample ?

No, I completely understand what you are trying to do.  As said, you cannot
currently recreate the effect you desire as of POV-Ray 3.6 beta 1.

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

In article <g82### [at] tritonimagicode> , Christoph Hormann 
<chr### [at] gmxde>  wrote:

> AFAIK the use of interior_texture depends on the normal direction and
> the normal direction of a flat triangle in a mesh depends on the order
> of vertices.  In case of a smooth triangle this is of course more
> complicated, you probably can even create triangles with partly
> interior_texture and partly not.

Nope, the way interior_texture is currently implemented it won't work as
expected with meshes.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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Thorsten Froehlich wrote:
> 
> Nope, the way interior_texture is currently implemented it won't work as
> expected with meshes.

Well - i never tried it but at a first quick glance i can't find a 
reason why not.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 11 Jan. 2004 _____./\/^>_*_<^\/\.______

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In article <1q6### [at] tritonimagicode> , Christoph Hormann 
<chr### [at] gmxde>  wrote:

>> Nope, the way interior_texture is currently implemented it won't work as
>> expected with meshes.
>
> Well - i never tried it but at a first quick glance i can't find a
> reason why not.

Just believe me.  It is not obvious why it won't work, but I did have a very
close look at it very recently, and it will not work as expected.  In fact,
it cannot work as expected.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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Thorsten Froehlich wrote:
> In article <403### [at] univ-savoiefr> , Christophe Raffalli 
> <raf### [at] univ-savoiefr>  wrote:
> 
> 
>>What I want is to be able to choose which face if the backside and which
>>face if the front face for a mesh2 in fact.
> 
> 
> You cannot do this if you also desire to apply individual textures to each
> face of the mesh.  You can of course split the mesh into as many faces as
> you want to texture individually, but I am aware that doing so is not
> feasible if you have many individual textures.
> 

I only have two textures: one for all frontside and one for all back side.

>     Thorsten
> 
> ____________________________________________________
> Thorsten Froehlich
> e-mail: mac### [at] povrayorg
> 
> I am a member of the POV-Ray Team.
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

In article <403### [at] univ-savoiefr> , Christophe Raffalli 
<raf### [at] univ-savoiefr>  wrote:

> I only have two textures: one for all frontside and one for all back side.

So what is the problem?  As long as you don't specify per triangle textures
in a mesh, everything will work just fine.  All you need to do is specify
both texture and interior_texture.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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