Hey,
I’m working on a custom filter plugin to dynamically generate masters during variable font export — essentially to create VF subsets from instances that don’t have dedicated masters. Let me explain the use case:
I have a font with Compressed and Normal width masters. However, I also need to export a Condensed VF, even though Condensed only exists as an instance, not a master.
To handle that, I want to:
- Generate Condensed masters on the fly at export time (based on the Condensed instances).
- Remove any masters not relevant for this export.
- Avoid using “Disable Masters” since it runs before the filter, and if all masters are disabled, the export fails due to having no masters left.
My current script does the following:
- Defines a filter with the instances I want to turn into temporary masters (including setting the VF origin if needed).
- Removes all other masters manually — without relying on the “Disable Masters” CP.
- Proceeds with the VF export using only the relevant, dynamically generated masters.
But I’m still facing issues at the end about problem with the designspace.
Fun fact, is if I generate the font, open it and export it without my custom filter, export work.
Here is the repo with the Filter Plugin :
