On 31-12-2011 5:30, Cousin Ricky wrote:
> Alain<aze### [at] qwertyorg>  wrote:
>> Effectively, if I remember correctly, the background now need a filter
>> or transmit value to allow alpha transparency.
>
> Thanks, that works.  I guess it hasn't made it into the documentation yet.
>

It seems not indeed, or not clear enough. In section 3.1.2.4.1 Output 
File Type, the relevant paragraph reads (text put between * * by me):

[quote]
The alpha channel stores a transparency value for each pixel, just like 
there is also stored a value for red green and blue light for each 
pixel. In POV-Ray, when the alpha channel is turned on, *all areas of 
the image where the background is partly or fully visible will be partly 
or fully transparent*. Refractions of the background will also be 
transparent, but not reflections. Also anti-aliasing is taken into account
[/quote]

In highlighted phrase filter and transmit should be mentioned explicitly.

Thomas

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Alain <aze### [at] qwertyorg> wrote:
> Effectively, if I remember correctly, the background now need a filter
> or transmit value to allow alpha transparency.

Except that anti-aliasing doesn't appear to work properly.

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On 12/31/2011 02:56 AM, Thomas de Groot wrote:
> On 31-12-2011 5:30, Cousin Ricky wrote:
>> Alain<aze### [at] qwertyorg> wrote:
>>> Effectively, if I remember correctly, the background now need a filter
>>> or transmit value to allow alpha transparency.
>>
>> Thanks, that works. I guess it hasn't made it into the documentation yet.
>>
>
> It seems not indeed, or not clear enough. In section 3.1.2.4.1 Output
> File Type, the relevant paragraph reads (text put between * * by me):
>
> [quote]
> The alpha channel stores a transparency value for each pixel, just like
> there is also stored a value for red green and blue light for each
> pixel. In POV-Ray, when the alpha channel is turned on, *all areas of
> the image where the background is partly or fully visible will be partly
> or fully transparent*. Refractions of the background will also be
> transparent, but not reflections. Also anti-aliasing is taken into account
> [/quote]
>
> In highlighted phrase filter and transmit should be mentioned explicitly.
>
> Thomas
>
>
After re-reading the section, I guess a little clarification wouldn't 
hurt. The highlighted section you mentioned has been changed ... also 
found the same "Note" here: 
http://wiki.povray.org/content/Documentation:Reference_Section_5#Using_the_Alpha_Channel

and changed it there too! Thanks everyone.

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Thomas de Groot <tenDOTlnDOTretniATtoorgedDOTt> wrote:
> In highlighted phrase filter and transmit should be mentioned explicitly.

Yes, that would be helpful.  Thanks.

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On 12/31/2011 08:23 AM, Cousin Ricky wrote:
> Alain<aze### [at] qwertyorg>  wrote:
>> Effectively, if I remember correctly, the background now need a filter
>> or transmit value to allow alpha transparency.
>
> Except that anti-aliasing doesn't appear to work properly.
>
>
look at the bottom of this section:
http://wiki.povray.org/content/Documentation:Reference_Section_1.3#Anti-Aliasing_Options

perhaps the problem you are seeing can be mitigated by specifying +AG1.0 
which effectively gives neutral behavior ... 2.5 is the default. Haven't 
tried this ... maybe for a shot ;-)

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On 12/31/2011 09:03 AM, Jim Holsenback wrote:
> On 12/31/2011 08:23 AM, Cousin Ricky wrote:
>> Alain<aze### [at] qwertyorg> wrote:
>>> Effectively, if I remember correctly, the background now need a filter
>>> or transmit value to allow alpha transparency.
>>
>> Except that anti-aliasing doesn't appear to work properly.
>>
>>
> look at the bottom of this section:
>
http://wiki.povray.org/content/Documentation:Reference_Section_1.3#Anti-Aliasing_Options
>
>
> perhaps the problem you are seeing can be mitigated by specifying +AG1.0
> which effectively gives neutral behavior ... 2.5 is the default. Haven't
> tried this ... maybe for a shot ;-)

LOL ... should be "maybe worth a shot" ... still sounds funny ;-)

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Am 31.12.2011 14:23, schrieb Cousin Ricky:
> Alain<aze### [at] qwertyorg>  wrote:
>> Effectively, if I remember correctly, the background now need a filter
>> or transmit value to allow alpha transparency.
>
> Except that anti-aliasing doesn't appear to work properly.

Can you be more specific?

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clipka <ano### [at] anonymousorg> wrote:
> Am 31.12.2011 14:23, schrieb Cousin Ricky:
> > Except that anti-aliasing doesn't appear to work properly.
>
> Can you be more specific?

See post in povray.binaries.images.

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Am 16.01.2012 02:20, schrieb Cousin Ricky:
> clipka<ano### [at] anonymousorg>  wrote:
>> Am 31.12.2011 14:23, schrieb Cousin Ricky:
>>> Except that anti-aliasing doesn't appear to work properly.
>>
>> Can you be more specific?
>
> See post in povray.binaries.images.

Ah, yes - this actually has nothing to do with anti-aliasing, but is a 
side effect of various changes to the alpha channel handling introduced 
with 3.7.beta.38, which apparently break down in case the resulting 
transparency is exactly 1.0 (as opposed to e.g. 0.9999), and generally 
don't play nice with colored yet transparent background colors.

I guess it's back to the drawing board for me.

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clipka <ano### [at] anonymousorg> wrote:
> Am 16.01.2012 02:20, schrieb Cousin Ricky:
> > clipka<ano### [at] anonymousorg>  wrote:
> >> Am 31.12.2011 14:23, schrieb Cousin Ricky:
> >>> Except that anti-aliasing doesn't appear to work properly.
> >>
> >> Can you be more specific?
> >
> > See post in povray.binaries.images.
>
> Ah, yes - this actually has nothing to do with anti-aliasing, but is a
> side effect of various changes to the alpha channel handling introduced
> with 3.7.beta.38, which apparently break down in case the resulting
> transparency is exactly 1.0 (as opposed to e.g. 0.9999), and generally
> don't play nice with colored yet transparent background colors.

Workaround:

sphere
{  0, HUGE_RADIUS
   pigment { rgb BACKGROUND_COLOR }
   finish { ambient 0 diffuse 0 emission 1 }
   no_image
}

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