I’m making a font for my conscript, where vowels can be represented either by symbols or diacritics I’ve made some ligatures for syllables.
Symbol and diacritic on the left is for vowel a, while on the right is for vowel e.
I want to make a substitution rule, where the vowel symbols would turn into diacritics only when they’re preceded by a syllable (e.g. pa (syllable) + a (symbol) = paa (syllable + diacritic). I tried doing this with single and multiple substitutions, but it affects even isolated and initial states of these symbols, I don’t want that.
Such symbols should turn into diacritics only once and only if they’re preceded by a syllable.
Currently, it looks like this (screenshot above).
You will need a contextual lookup. See the Swashes for an example: