Is it possible to export Variable Font in OTF format in Glyphs?

Hi there,

I am trying to create a single axis variable font (VF) with two masters. Is it possible to export VF in *.otf format in Glyphs? Since Noto Series VFs are in *.otf format, I think maybe it is possible?

The reason I need *.otf format is that since the VF export format only has *.ttf, the cubic bezier curves in Glyphs I draw, will be translated into quadratic bézier curves (TrueType curve).

Even though the curve of both master’s instances are correct (Image 1), but when VF goes into Adobe Illustrator, the font will be re-rendered as cubic curve, making some interpolations’ (between two masters’s value) curve seem strange or discontinuous (Image 2).

I have already increased font UPM from 1000 to 2000. The result seems better, but still not good enough. Also, I have installed Show TrueType Curves plugin and kept the curves well in both masters, but the strange curve is often happened between interpolations that I need to install and test the VF in Illustrator, which spending too many time for me.

Thus, I think the best way to solved the strange curves is to export in *.otf directly, to avoid the font being translated and re-rendered between cubic and quadratic curve.

Or are there any useful suggestions or tips for this issue?

Image 1: In Glyphs, using Show TrueType Curves plugin to show the interpolations between masters, the curves are continuous.

Image2: In Adobe Illustrator, the interpolations rendered strange and discontinuous curves

Thank you.

Could you show how your curves are constructed in both masters?

You probably could tweak the node positions to avoid kinks (which are also seen in your blue overlay if you look closely), as described here: Multiple Masters, part 2: keeping your outlines compatible | Glyphs

We are working on cubic variable fonts. But that will take some more time.

1 Like

Here are the nodes and handles:

  • value = 0

  • value = 100

  • Interpolations I expected

Those transitions are actually easier to get right with TrueType curves. Manually converting to compatible TrueType curves is a bit tricky.

You got a few oncurve points that change their angle from one master to the other. Also, their offcurve points‘ relative lengths change along the masters. Those things are causing the kinks.
You need to either keep the angle or the relative lengths the same, or even both.

You can use the „Show Smooth Node Angle and Proportion“ plugin to get guidance for repositioning these on and off curve points.