Exporting Thai Fonts - OT features not working

Hi! I’m currently working on a Thai font. I’ve added anchors and generated the automated OpenType features in the app to get the vowel marks working. I’ve had two issues:

  1. When I first generated the OpenType code, I got this error message:

Please understand that I have very limited knowledge of how these codes are supposed to work. I tried to make it work by unchecking the “generate feature automatically” and changing the last line as shown:

Somehow this did remove the error. But I wasn’t sure if I broke anything by doing this so just wanted to put it out there that this is what I did first.

  1. After I generated the code, thankfully all of my vowel marks started behaving correctly, even the tricky stacked small/narrow ones. When I previewed them inside the app, it works pretty well (I think):

I proceeded to export the font and tested it out in idiotproofed.com, where most other Thai fonts seem to render text correctly (Some doesn’t work in InDesign for some reason). But as you can see, mine didn’t work properly and the vowel marks are overlapping:

Any idea on how to solve this issue? Am I doing something wrong during the exporting process or the way I handled generating the OpenType features? Any help would be greatly appreciated.

The problem with the mark placement is probably bad anchor placement in the marks. Select them, press Cmd-U and move the red anchors to appropriate positions.

You can preview in Glyphs with the Mark Preview plug-in available in Window > Plugin Manager.

Solved it! Cmd-U gave me predefined anchors, which I replaced with the anchors I had made before. Thank you!

Was there something wrong with the default anchors?

I meant to say, I replaced my old ones with the default ones! The positions are the same, but maybe naming them top and bottom did the trick? (they were named mark0 and mark1 before)

1 Like

New question. I was studying other Thai fonts and it seems like all the marks had 0 width and negative sidebearings, so that’s how I formatted the marks for my font. Is there a benefit/reason to this?

Yes, top and bottom are required for creating mark-to-base and mark-to-mark features, which is exactly what you see in working when it works. :slight_smile:

You do not need to zero the width yourself, Glyphs does that automatically when you export the font. That way, editing is much easier of course.

1 Like