> it took me quite a while to notice that it's a side effect of two features
> that are turned on
>
> you can play with
>
> \definefontfeature
> [devanagari-one]
> [devanagari-one]
> [rphf=no]
>
> and
>
> \definefontfeature
> [devanagari-one]
> [devanagari-one]
> [half=no]
>
> maybe Kai can have a look at it: as these are dealt with in a different we
> probably don't need to enable them in the feature processor (even block them)
>
> btw, you can play with
>
> \showotfcomposition{file:chandas.ttf*devanagari-one}{l2r}{\char"0915
> \char"094D \char"0930}
>
> to see what happens
>
> (i also noticed a few possible further optimizations but that's for later)
>
> Hans
Thanks, Hans.
Those are indeed the relevant features. Unfortunately, turning them off
completely breaks other things. I have attached another demonstration below.
The good news is that we can now produce proper devanagari by switching the
features on and off as needed in the middle of words. I am understanding
OpenType better now and I will try again to look at the relevant source code
tonight.
-Peter
--------------------------
\definefontfeature[devyes][devanagari-one][rphf=yes,half=yes]
\definefontfeature[devno][devanagari-one][rphf=no,half=no]
\definefont [DevaWith] [file:chandas.ttf*devyes at 14pt]
\definefont [DevaWithout] [file:chandas.ttf*devno at 14pt]
\starttext
{\bf When rphf=yes (current default)}
r-first conjucts ([r]+[half]+\{consonant\}) work:
{\DevaWith [U+0930 \char"0930][U+094D \char"094D][U+0915 \char"0915]:
\char"0930 \char"094D \char"0915 ~(correct)}
but r-second conjucts (\{consonant\} +[half]+[r]) don't:
{\DevaWith [U+0915 \char"0915][U+094D \char"094D][U+0930 \char"0930]:
\char"0915 \char"094D \char"0930 ~(incorrect)}
\blank[big]
{\bf When rphf=no}
r-first conjucts ([r]+[half]+\{consonant\}) stop working:
{\DevaWithout [U+0930 \char"0930][U+094D \char"094D][U+0915 \char"0915]:
\char"0930 \char"094D \char"0915 ~(incorrect)}
but r-second conjucts (\{consonant\} +[half]+[r]) now work properly:
{\DevaWithout [U+0915 \char"0915][U+094D \char"094D][U+0930 \char"0930]:
\char"0915 \char"094D \char"0930 ~(correct)}
\blank[3*big]
{\bf When half=yes (current default)}
consonant clusters (\{consonant\}+[half]+\{consonant\}) work:
{\DevaWith [U+0915 \char"0915][U+094D \char"094D][U+0915 \char"0915]:
\char"0915 \char"094D \char"0915 ~(correct)}
but word-final viramas (\{consonant\} +[half]) don't:
{\DevaWith [U+0915 \char"0915][U+094D \char"094D] : \char"0915 \char"094D
~(incorrect)}
\blank[big]
{\bf When half=no}
consonant clusters (\{consonant\}+[half]+\{consonant\}) stop working:
{\DevaWithout [U+0915 \char"0915][U+094D \char"094D][U+0915 \char"0915]:
\char"0915 \char"094D \char"0915 ~(incorrect)}
but word-final viramas (\{consonant\} +[half]) work properly:
{\DevaWithout [U+0915 \char"0915][U+094D \char"094D] : \char"0915 \char"094D
~(correct)}
\blank[2*big]
With careful bracketing, it's possible to produce correct devanagari.
On: {\DevaWith
\char"092E\char"0915\char"094D\char"0915\char"092E\char"0915\char"094D} (no
good)
Off: {\DevaWithout
\char"092E\char"0915\char"094D\char"0915\char"092E\char"0915\char"094D} (no
good)
Mixed: {\DevaWith
\char"092E\char"0915\char"094D\char"0915\char"092E{\DevaWithout
\char"0915\char"094D}} (perfect)
That's not sustainable for long texts, perhaps, but it's a great move in that
direction.
\blank[big]
Note: I've used the consonant [U+0915: {\DevaWith \char"0915}] here throughout,
but you can substitute any consonant \{U+0915--U+0939, U+0958--U+095F\} and see
the same patterns.
\stoptext
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