This has probably been asked before, but not since I started looking. Can
POV or MegaPOV do transparency maps? (i.e. like a hightfield image is used
for displacement with light and dark areas, use an image to effect transp.)

thanks for listening

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Mitch Klein wrote:
> 
> This has probably been asked before, but not since I started looking. Can
> POV or MegaPOV do transparency maps? (i.e. like a hightfield image is used
> for displacement with light and dark areas, use an image to effect transp.)
> 
> thanks for listening

You might have a look at the material_map section in the pov docu,
furthermore you can also specify a transmit value for the different color
indices in an indexed image_map.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Thanks Christoph. I figured it was something like that. I'm just starting to
get into advanced texturing and there's definitely a lot to learn :-)

"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3A229D6A.FAD96C60@gmx.de...
>
>
> Mitch Klein wrote:
> >
> > This has probably been asked before, but not since I started looking.
Can
> > POV or MegaPOV do transparency maps? (i.e. like a hightfield image is
used
> > for displacement with light and dark areas, use an image to effect
transp.)
> >
> > thanks for listening
>
> You might have a look at the material_map section in the pov docu,
> furthermore you can also specify a transmit value for the different color
> indices in an indexed image_map.
>
> Christoph
>
> --
> Christoph Hormann <chr### [at] gmxde>
> Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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>This has probably been asked before, but not since I started looking. Can
>POV or MegaPOV do transparency maps? (i.e. like a hightfield image is used
>for displacement with light and dark areas, use an image to effect transp.)

>thanks for listening

I'm not sure exactly what you mean, but if an image being used as an
image map has an alpha channel (32-bit .tga and I think .png can do
this), povray will use the alpha channel to determine transparency.

Or did you mean something else?

Pete

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Thanks for the reply, Pete. That's IS what I meant. So, if the alpha map is
embedded in the image, using the image as a map automatically adds the
alpha? or do you have to specify? I'm a little fuzzy on that part. I've seen
a specific gray scale image applied as a separate map for alpha/transparency
in other software.

"Pete" <Pet### [at] nymaliasnet> wrote in message
news:496### [at] nymaliasnet...
> >This has probably been asked before, but not since I started looking. Can
> >POV or MegaPOV do transparency maps? (i.e. like a hightfield image is
used
> >for displacement with light and dark areas, use an image to effect
transp.)
>
> >thanks for listening
>
> I'm not sure exactly what you mean, but if an image being used as an
> image map has an alpha channel (32-bit .tga and I think .png can do
> this), povray will use the alpha channel to determine transparency.
>
> Or did you mean something else?
>
> Pete
>

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Mitch Klein wrote:
> 
> Thanks for the reply, Pete. That's IS what I meant. So, if the alpha map is
> embedded in the image, using the image as a map automatically adds the
> alpha?

Since I've been playing with this the last few days, I'll go ahead and
answer; please keep in mind that I'm a novice, too, so I may not give a
complete answer.

Yes, that's correct.  If you use a PNG with an alpha channel (to date,
the only program I've found that fully supports alpha channels for PNG
is 'The Gimp' (http://www.gimp.org)), POV will automatically use the
alpha channel for transparency mapping.

The nice thing about this is that PNG supports separate transparency
values for every color in an index, so you can get some interesting effects.

-- 
Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in Neurology!"
McK### [at] maccom   |					-- Justine Devlin, M.D.

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You're doing fine, Dawn, but your answer was a little incomplete.  Adobe Photoshop
saves the first alpha channel data into PNG format as well, and I beleive Paint Shop
Pro does, but I haven't used it.

Another thing to note is that the first that you try it you might find the background
shows up, but part you want to keep is hollow, and to fix it you need to reverse the
alpha channel of the image.

Josh

Dawn McKnight wrote:

> Mitch Klein wrote:
> >
> > Thanks for the reply, Pete. That's IS what I meant. So, if the alpha map is
> > embedded in the image, using the image as a map automatically adds the
> > alpha?
>
> Since I've been playing with this the last few days, I'll go ahead and
> answer; please keep in mind that I'm a novice, too, so I may not give a
> complete answer.
>
> Yes, that's correct.  If you use a PNG with an alpha channel (to date,
> the only program I've found that fully supports alpha channels for PNG
> is 'The Gimp' (http://www.gimp.org)), POV will automatically use the
> alpha channel for transparency mapping.
>
> The nice thing about this is that PNG supports separate transparency
> values for every color in an index, so you can get some interesting effects.
>
> --
> Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in Neurology!"
> McK### [at] maccom   |                                    -- Justine Devlin, M.D.

--
Josh English -- Lexiphanic Lethomaniac
eng### [at] spiritonecom
The POV-Ray Cyclopedia http://www.spiritone.com/~english/cyclopedia/

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Thanks for the help guys! I think I get it now.

Mitch

"Josh English" <eng### [at] spiritonecom> wrote in message
news:3A26959E.326A719F@spiritone.com...
> You're doing fine, Dawn, but your answer was a little incomplete.  Adobe
Photoshop
> saves the first alpha channel data into PNG format as well, and I beleive
Paint Shop
> Pro does, but I haven't used it.
>
> Another thing to note is that the first that you try it you might find the
background
> shows up, but part you want to keep is hollow, and to fix it you need to
reverse the
> alpha channel of the image.
>
> Josh
>
> Dawn McKnight wrote:
>
> > Mitch Klein wrote:
> > >
> > > Thanks for the reply, Pete. That's IS what I meant. So, if the alpha
map is
> > > embedded in the image, using the image as a map automatically adds the
> > > alpha?
> >
> > Since I've been playing with this the last few days, I'll go ahead and
> > answer; please keep in mind that I'm a novice, too, so I may not give a
> > complete answer.
> >
> > Yes, that's correct.  If you use a PNG with an alpha channel (to date,
> > the only program I've found that fully supports alpha channels for PNG
> > is 'The Gimp' (http://www.gimp.org)), POV will automatically use the
> > alpha channel for transparency mapping.
> >
> > The nice thing about this is that PNG supports separate transparency
> > values for every color in an index, so you can get some interesting
effects.
> >
> > --
> > Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in
Neurology!"
> > McK### [at] maccom   |                                    -- Justine
Devlin, M.D.
>
> --
> Josh English -- Lexiphanic Lethomaniac
> eng### [at] spiritonecom
> The POV-Ray Cyclopedia http://www.spiritone.com/~english/cyclopedia/
>
>

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"Christoph Hormann" <chr### [at] gmxde> wrote...
>
> You might have a look at the material_map section in the pov docu,
> furthermore you can also specify a transmit value for the different color
> indices in an indexed image_map.

Alternatavely, with MegaPov you can use an image_pattern to create a pattern
and then use your texture and a clear texture for the two entries.  For
example, you could use something like this (syntax may be a bit off):
texture{
  image_pattern{ png "img.png" }
  texture_map{
    [0 pigment{rgbt 1}]
    [1 MyTexture]
  }
}

Black parts of img.png will turn out clear, white parts will show MyTexture,
and anything in between will have a blend of the two.

-Nathan

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Neat idea. I'll give it a try! Thanks

"Nathan Kopp" <Nat### [at] Koppcom> wrote in message
news:3a29dfc4$1@news.povray.org...
>
> "Christoph Hormann" <chr### [at] gmxde> wrote...
> >
> > You might have a look at the material_map section in the pov docu,
> > furthermore you can also specify a transmit value for the different
color
> > indices in an indexed image_map.
>
> Alternatavely, with MegaPov you can use an image_pattern to create a
pattern
> and then use your texture and a clear texture for the two entries.  For
> example, you could use something like this (syntax may be a bit off):
> texture{
>   image_pattern{ png "img.png" }
>   texture_map{
>     [0 pigment{rgbt 1}]
>     [1 MyTexture]
>   }
> }
>
> Black parts of img.png will turn out clear, white parts will show
MyTexture,
> and anything in between will have a blend of the two.
>
> -Nathan
>
>

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