I am also new to type design and Glyphs, drawing my first hand drawn letters with the pencil tool on a tablet. Found this post while looking up the error message in the title, which I receive when trying to export a hand drawn variable font. I thought I had understood that masters don’t need to play by the compatibility rules if not interpolating. My quick pencil tool sketches don’t come close to same number of nodes, etc. But I had hoped to experiment rendering variable font weights in browsers.
Is it possible to export a variable font without interpolation instances? between hand drawn pencil sketches instances? Any tips for circumventing this error when not intending to interpolate between weights?
Two masters don’t have to be compatible if you don’t want to interpolate (or generate instances). If you want to experiment with different weights between your master using a variable font you are, in fact, interpolating. So either you want to interpolate, or you don’t
Stephen Nixon of Arrowtype has a repo on GitHub aiming at variable font preparation. varfont-prep
With some tweaking you can generate a variable font that only contains compatible glyphs and leaving out those that aren’t. (It’s UFO based though, but glyphs can also export UFO files).
Another workaround would be to set all incompatible glyphs to non-exporting if you want to stay in glyphs entirely.
Long story short:
Non compatible glyphs/masters = no interpolation = no variable font fun in the browser
Thanks for your swift responses @ddaanniiieeelll@GeorgSeifert! I also found Bas Jacobs’ simple exposition about variable fonts as interpolations from a single master instructive, correcting the mental model I’d imagined with multiple incompatible masters.
I have an idea now to use my sketchy pencil tool outlines for other weights as background guides to loosely explode out copies of a single weight, which I think should ensure compatibility. Thanks again!