Hi,

I've found that when I render text that is lit internally by an emission

color that when it is output as a PNG file that Microsoft Internet
Explorer V.5 does not show the color correctly.  However, Netscape
Navigator still does.  If I render the file as a bitmap and then use
CorelDRAW V. 8 to convert the file into a PNG file it will be displayed
correctly in both Internet Explorer and Netscape Navigator.  Is there
something I should know about the settings that will make the PNG file
rendered from Moray/Povray display correctly in MS Explorer?  Thanks.

Jennifer J. Hall
jjh### [at] acsubuffaloedu

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Jennifer J. Hall <jjh### [at] acsubuffaloedu> wrote:
> I've found that when I render text that is lit internally by an emission
>
> color that when it is output as a PNG file that Microsoft Internet
> Explorer V.5 does not show the color correctly.  However, Netscape
> Navigator still does.  If I render the file as a bitmap and then use
> CorelDRAW V. 8 to convert the file into a PNG file it will be displayed
> correctly in both Internet Explorer and Netscape Navigator.  Is there
> something I should know about the settings that will make the PNG file
> rendered from Moray/Povray display correctly in MS Explorer?  Thanks.

I would say the alpha channel in the PNG file is to blame.  A quick test
here shows that rendering media-filled objects with alpha channels to a PNG
files gives different results in MSIE as compared to Netscape.  Internet
Explorer actually supports the use of the alpha channel, so areas that
POV-Ray renders as transparent will be shown as transparent in the browser.
Netscape doesn't seem to support transparent PNG files, so you get the same
results as if you didn't use an alpha channel at all.

If you don't want an alpha channel (i.e. a semi-transparent PNG image in the
browser) you can render directly to PNG without alpha using +FN -UA on the
command line, or the following INI file options:

   Output_File_Type=N
   Output_Alpha=off

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However, if you give an emission color of yellow with a semitransparent brass
surface then why doesn't the emission color show from within MSIE even though
the surface is transparent?  When the file is rendered inside of POVRAY the text
is yellow as it is within Netscape also.  I'm thinking that maybe the
transparency setting is overriding the emission color.  Is this so?

Jennifer

Chris Colefax wrote:

> Jennifer J. Hall <jjh### [at] acsubuffaloedu> wrote:
> > I've found that when I render text that is lit internally by an emission
> >
> > color that when it is output as a PNG file that Microsoft Internet
> > Explorer V.5 does not show the color correctly.  However, Netscape
> > Navigator still does.  If I render the file as a bitmap and then use
> > CorelDRAW V. 8 to convert the file into a PNG file it will be displayed
> > correctly in both Internet Explorer and Netscape Navigator.  Is there
> > something I should know about the settings that will make the PNG file
> > rendered from Moray/Povray display correctly in MS Explorer?  Thanks.
>
> I would say the alpha channel in the PNG file is to blame.  A quick test
> here shows that rendering media-filled objects with alpha channels to a PNG
> files gives different results in MSIE as compared to Netscape.  Internet
> Explorer actually supports the use of the alpha channel, so areas that
> POV-Ray renders as transparent will be shown as transparent in the browser.
> Netscape doesn't seem to support transparent PNG files, so you get the same
> results as if you didn't use an alpha channel at all.
>
> If you don't want an alpha channel (i.e. a semi-transparent PNG image in the
> browser) you can render directly to PNG without alpha using +FN -UA on the
> command line, or the following INI file options:
>
>    Output_File_Type=N
>    Output_Alpha=off

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Jennifer J. Hall <jjh### [at] acsubuffaloedu> wrote:
> However, if you give an emission color of yellow with a semitransparent
brass
> surface then why doesn't the emission color show from within MSIE even
though
> the surface is transparent?  When the file is rendered inside of POVRAY
the text
> is yellow as it is within Netscape also.  I'm thinking that maybe the
> transparency setting is overriding the emission color.  Is this so?

I believe POV-Ray uses the transmittance value of the first surface it hits
as the transparency in the PNG's alpha channel.  A quick test reveals that
if you render a media container with pigment {rgbt 1} to a transparent PNG,
MSIE shows it as completely transparent.  A media container with pigment
{rgbf 1} is shown as opaque (so the media is visible).

In answer to your question, then, yes - the surface transparency
(transmittance) is hiding the media.  Changing your surface to use filtering
instead should make the media visible, while still allowing you to have a
transparent background.

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