I have been experimenting with a font that creates arbitary nut fractions on the fly - Nutso.otf (available under the CC0 licence).
When I save and attempt to export the font in Glyphs App I get the following MakeOTF error:
Error: “Target glyph class in sub-rule doesn’t have the same number of elements as the replacement class; the target has 10, the replacement, 20” in Feature afrc in line: 33
This is when working on unaltered versions of the features code and it seems not an error but more fundamental to the way the font works. Obviously I have an OTF version of the font working in Indesign (comes with the project) so is it down to the way Glyphs App handles the .fea code?
I also wanted to ask if anyone knew a way of getting the @NUMR (numerators) to centre align on the top line of the fraction rather than left align. I believe it is to do with the Mark to Mark Positioning features but I am a rookie and need this for a specific fix.
That means that two classes that are substituted for each other don’t match in size. There is something wrong in the code you tried to compile. The code on the link you posted seems fine though. So I tend to think something happened during transfering the data to Glyphs. How did you get by the .glyphs file you are exporting from?
I wanted to import the features.fea file into the Temp folder for the Glyphs file version of Nutso.otf that I opened and saved as a Glyphs file. I wanted to see the mark anchors but I wasn’t getting that in the Glyphs features panel so decided to try work on the .fea directly.
First stage of this was to download Nutso.otf, open it in Glyphs App, save it as a Glyphs App file, and then attempt to Export it. Without editing anything I get the MakeOTF error on unbalanced substitution. I agree that the code is correct.
Might also be easier to use it as a template and start with a fresh Glyphs file. Would using the features function to input the text/instructions (not copy and paste but rewrite) of the .fea be possible?