[XeTeX] problem rendering unicode Devanagari dependent vowel signs and ligatures

[Richard Cobbe]

On Wed, Feb 02, 2011 at 08:07:24PM +0100, Dominik Wujastyk wrote:
> I've done some tests on Leo's first problem (see below), and I also cannot
> find a way to separate, e.g., the visarga sign (similar to a Latin colon)
> from the dotted-circle that is used in Unicode font charts to signify that
> the visarga always follows a vowel.

I'm no expert, but it looks to me as though results will vary with the font
used.  My first clue to this, oddly enough, was the fact that both the
visarga and the anusvara in your email, Dominik, displayed without the
dotted circle.

I tried the following on a Mac OS 10.6 system:

    \documentclass{article}

    \usepackage{fontspec}
    \usepackage{xltxtra}
    \usepackage{xunicode}

    \newfontfamily{\SktAFont}[Mapping=velthuis-sanskrit]{Devanagari MT}
    \newfontfamily{\SktFont}[Mapping=velthuis-sanskrit,Script=Devanagari]{Sanskrit 2003}

    \begin{document}

    Devanagari MT: {\SktAFont .h .m atrya}

    Sanskrit 2003: {\SktFont .h .m atrya}

    \end{document}

Devanagari MT displays both the anusvara and the visarga without dotted
circles; Sanskrit 2003 displays them with.  (I'm guessing from this that
Apple's Terminal.app, in which I run my mail client, uses Devanagari MT for
the relevant range of Unicode code points, but I have no idea how OS X
chooses fonts for non-Ascii characters.)

> On 25 January 2011 11:16, Leo Brouwer <singhadaya at googlemail.com> wrote:
>
> > Secondly, it seems Xetex doesn't render the common ligature त्र्य correctly
> > for most freely available Devanagari fonts.

I wonder how much of this is XeTeX and how much of this is an issue of font
encoding and design, although I know very little about the internals of
either.

I can say, Leo, that I was certainly able to reproduce your results:
Sanskrit 2003 doesn't display the trya conjunct correctly, but Devanagari
MT does.  I suspect that font isn't available on non-Mac platforms, though,
so that's of limited utility to you.

Richard