[fontforge-users] Trouble with kern pairs in generated .otf font

[Robyn Broyles]

I am a relatively new user exploring the art of type design. I am having
trouble with consistency with kerning pairs in the OpenType font I am
working on. I'm operating the 31 Dec 2014 version of FontForge in Windows 7.

I did a lot of kerning work, mainly with the letter glyphs, all done by
pairs in the metrics window. When I first generated the font to fine-tune
the kerning with a word processor (Open Office Writer), the resulting .otf
had no kerning whatsoever. I tried again, checking "Windows-compatible
'kern'" under Options on the Generate Fonts dialog, which sort of fixed
it—but it's inconsistent. For example, all kerning pairs involving the
glyph i with another lowercase glyph are kerned except for ai ia ij in,
which are not kerned. And av is kerned correctly, but va is *partially
*kerned—in
other words, the advance width is showing up less than it would with
unkerned sidebearings, but still greater than what I set it for (av and va
are supposed to be equally kerned because the glyphs are symmetrical—it's a
small-caps font).

Weirdest of all, when I added the undefined glyph German sharp S (my
kerning text had this character), all kerning info disappears again. I did
some testing, and this problem seems to hold true for other undefined *Latin
*glyphs (such as thorn), but *not *for undefined *non-Latin* glyphs, such
as Greek letters.

Any idea what the problem is or how to fix? Thank you!