POV-Ray : Newsgroups : povray.general : Image texture with alpha channel in POV? Server Time
4 Aug 2024 14:21:38 EDT (-0400)
  Image texture with alpha channel in POV? (Message 1 to 6 of 6)  
From: Andreas Kreisig
Subject: Image texture with alpha channel in POV?
Date: 18 May 2003 10:47:33
Message: <3ec79d05@news.povray.org>
Hi,

I use Blender for my scenes so the exported output is in mesh2 format. Now I 
need an (uv-mapped) image texture for a logo, but the finish under that 
should still be visible and it should not be influenced by the texture. Is 
this possible? A TGA-texture with alpha channel doesn't work properly 
because the finish is then invisible, too.

Regards,
Andreas

-- 
http://www.render-zone.com


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From: Gilles Tran
Subject: Re: Image texture with alpha channel in POV?
Date: 18 May 2003 10:58:16
Message: <3ec79f88$1@news.povray.org>

3ec79d05@news.povray.org...
> Hi,
>
> I use Blender for my scenes so the exported output is in mesh2 format. Now
I
> need an (uv-mapped) image texture for a logo, but the finish under that
> should still be visible and it should not be influenced by the texture. Is
> this possible? A TGA-texture with alpha channel doesn't work properly
> because the finish is then invisible, too.

Try an image_pattern, like in this page :
http://www.oyonale.com/ressources/english/xfrog2.htm
This is not exactly the same problem but I guess it should work.

G.


--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters


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From: Andreas Kreisig
Subject: Re: Image texture with alpha channel in POV?
Date: 18 May 2003 12:43:21
Message: <3ec7b829@news.povray.org>
Gilles Tran wrote:

> Try an image_pattern, like in this page :
> http://www.oyonale.com/ressources/english/xfrog2.htm
> This is not exactly the same problem but I guess it should work.

Hi Gilles!

Thanks for your response. I just have a question regarding your texture 
definition. You wrote on your website:

==========
texture{ 
    image_pattern{jpeg "autleaf_tr"} // used for the transparency 
    texture_map{ 
        [0 pigment{Clear}finish{ambient 0 diffuse 0}] // transparent part, 
no highlights or reflections 
        [1 pigment{image_map{jpeg "autleaf"}} finish{ambient 0 diffuse 1}] 
// leaf pigment 
   } 
} 
==========

What does "{Clear}" mean?

Regards,
Andreas

-- 
http://www.render-zone.com


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From: Andreas Kreisig
Subject: Re: Image texture with alpha channel in POV?
Date: 18 May 2003 13:31:38
Message: <3ec7c379@news.povray.org>
Andreas Kreisig wrote:

> ==========
> texture{
>     image_pattern{jpeg "autleaf_tr"} // used for the transparency
>     texture_map{
>         [0 pigment{Clear}finish{ambient 0 diffuse 0}] // transparent part,
> no highlights or reflections
>         [1 pigment{image_map{jpeg "autleaf"}} finish{ambient 0 diffuse 1}]
> // leaf pigment
>    }
> }
> ==========
> 
> What does "{Clear}" mean?

Okay, If "Clear" means something like "color rgbt <1,1,1,1>" I have the same 
problem as before. The whole mesh is invisible except the image wich is 
mapped on it.

Andreas


-- 
http://www.render-zone.com


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From: Gilles Tran
Subject: Re: Image texture with alpha channel in POV?
Date: 19 May 2003 12:40:56
Message: <3ec90918$1@news.povray.org>

3ec7c379@news.povray.org...
> Okay, If "Clear" means something like "color rgbt <1,1,1,1>" I have the
same
> problem as before. The whole mesh is invisible except the image wich is
> mapped on it.

In the example, the clear pigment is necessary to make the transparent part
really transparent. In your case, you need to use your regular texture
instead.

#declare T_mat=texture{
    image_pattern{ jpeg "mylogo_blackandwhite" interpolate 2}
//    pigment_pattern{image_map{jpeg "mylogo_blackandwhite" interpolate 2}}
// for more control
    texture_map{
        [0.5 T_MainTexture]
        [0.5 T_Logo]
    }
}

Of course, if there several logotypes, it may not be very easy... It's true
that there's no "decal" feature in POV-Ray to do this.

G.

--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters


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From: Andreas Kreisig
Subject: Re: Image texture with alpha channel in POV?
Date: 20 May 2003 10:37:05
Message: <3eca3d90@news.povray.org>
Gilles Tran wrote:

> In the example, the clear pigment is necessary to make the transparent
> part really transparent. In your case, you need to use your regular
> texture instead.
> 
> #declare T_mat=texture{
>     image_pattern{ jpeg "mylogo_blackandwhite" interpolate 2}
> //    pigment_pattern{image_map{jpeg "mylogo_blackandwhite" interpolate
> 2}} // for more control
>     texture_map{
>         [0.5 T_MainTexture]
>         [0.5 T_Logo]
>     }
> }
> 
> Of course, if there several logotypes, it may not be very easy... It's
> true that there's no "decal" feature in POV-Ray to do this.

Well, I think I'll try to copy the appropriate part of the mesh, move it 
(very) slightly and try to map the image on it - like your description on 
your website, so that the mesh itself is completely transparent. I hope 
that there are no edges visible when I prevent the object to cast shadows.

Thanks so far,
Andreas

-- 
http://www.render-zone.com


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