Hi,
I currently have a program that ouputs mesh2 objects and adds texture 
info to them.  Unfortunately, my textures are standard Windows BMP 
files.  Since BMP files don't support an alha channel, so parts of the 
bitmap that are supposed to be transparent are not.  If I could tell my 
program to output PNG files I would but I can't at this time.

So...what I would like to know is who do I make a feature request to?  
What I would like to see is an option to specify "transmit color <R,G, 
B> .5" or something like that to tell POV-Ray, when you see this color 
in the texture, pretend its 50% transparent.  Does that make sense?

Currently, POV-Ray only supports "transmit all x.x", but I don't want to 
filter ALL of the texture, just one specific color of the texture.  If 
there is another way of going about doing this and I am just not 
understanding the documentation correctly, someone please feel free to 
offer advice :-)

Respectfully,
Mitselplik

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3d8a2629$1@news.povray.org...
>Currently, POV-Ray only supports "transmit all x.x", but I don't want to
filter ALL of the texture, just one specific color >of the texture.  If
there is another way of going about doing this and I am just not
understanding the documentation >correctly, someone please feel free to
offer advice :-)

There are 2 ways to do this. Look up "material_map" and "image_pattern" in
the docs.  Using material_map is closer to what you have in mind, but could
be clumsy to set up. Using image_pattern is easier but will always require
an extra map for defining the transparency (it acts like an independent
alpha channel).

G.


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Hello,

Please check out our Outlook Express tutorial at 
<http://www.povray.org/resources/newsgroups/oetut.php#FINETUNE>
in order to disable HTML posting.

    Thorsten

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Thorsten Froehlich
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Jeremy Wilson <jwi### [at] batchcomputercom> wrote:
> So...what I would like to know is who do I make a feature request to?  What I would
like to see is an option to specify "transmit color <R,G, B> .5" or something like
that to tell POV-Ray, when you see this color in the texture, pretend its 50%
transparent.  Does that make sense?

  There's a problem with that. RGB images use integer values between 0 and 255
for each color channel. POV-Ray uses floating point values between 0 and 1.

  For example if you want to say that 105,53,79 should be transparent, you
could write <105/255, 53/255, 79/255>, but I wonder if floating point
accuracy will play an important role in this...

  IMO it doesn't make much sense to be able to make just certain individual
colors transparent (because you need to know the exact values of that color),
but it would be more useful to be able to specify some kind of transparency
map for the image (this is already possible, but it works only for the
b/w values of the image, not the color values). I'm not sure exactly how
this should be implemented, though.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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"Jeremy Wilson" <jwi### [at] batchcomputercom> wrote in
news:3d8a2629$1@news.povray.org: 

> Hi,
> I currently have a program that ouputs mesh2 objects and adds texture
> info to them.  Unfortunately, my textures are standard Windows BMP
> files.  Since BMP files don't support an alha channel, so parts of the
> bitmap that are supposed to be transparent are not.  If I could tell my
> program to output PNG files I would but I can't at this time. 

You can use ImageMagick (available for Windows, among other systems) to 
transform your BMP images into PNG (for example), adding transparency to the 
given color (option: -transparent <color>).

I just tried:
convert -transparent #FFFFFF FairyCastle.bmp FC.png
checked transparency with an HTML page, looks OK.

HTH.

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Philippe Lhoste (Paris -- France)
Professional programmer and amateur artist
http://jove.prohosting.com/~philho/

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