QUESTION    Export as OpenType-SVG color font? How to make a Single Line font?

Hello all,

I you haven't seen it yet, the recent Relief SingleLine font prompted me to be curious about the OpenType-SVG format specifically:
https://github.com/isdat-type/Relief-SingleLine

This Relief SingleLine font effectively lets you use a single-line font inside Adobe Illustrator, so the characters are drawn with open paths which aren't closed/joined when Converting to Outlines within Illustrator.
This allows for much easier use with CNC machines, routers, etc. by being able to use these 'stick' fonts.

Per that linked GitHub page, it appears this was achieved in RoboFont with a Python script.

Relief SingleLine export as OpenType-SVG format was made possible thanks to [color=var(--color-accent-fg)]Frederik Berlaen[/color]’s otf-svgMaker Python script for [color=var(--color-accent-fg)]Robofont[/color]. This script permits to export any skeletal UFO-based font project towards a single-line OTF-SVG font. otf-svgMaker uses [color=var(--color-accent-fg)]roundingPen[/color] script by Frederik Berlaen. otf-svgMaker script will be soon available on Relief SingleLine Github repository.

I do not have RoboFont (or a Mac) or any sort of Python scripting experience.
So I'm wondering can this be achieved within FontLab? Would it have to be a script?
I haven't tried contacting Frederik Berlaen yet, because I wasn't sure if there are technical barriers that prevent even a script implementation.
(If it isn't possible, I guess this post may be more of a feature request than a question...)

Thank you for any and all replies!

Thanks @Alex_H for that helpful information! That doesn't exactly achieve what I'm hoping for, but it is still an improvement.

Opening the Glyphs source file, I see it does contain the characters drawn as a single line, but the Open_OTF-SVG font is the one recommended for use in Illustrator.
When I install that, type text into Illustrator, and convert it to outlines, it all remains single open paths (no duplicating and closing). I am hoping to achieve this same result.

When I open the Relief SingleLine-Regular_svg.otf in FontLab 7 I can see two layers. One appears to be for the SVG.
When I right-click I have the option to 'Make SVG Editable' but if I click that it appears to just flip vertically. (Bug?)
What I see:


In any case, is the SVG-ness of this font file what allows for the paths to remain open after conversion in Illustrator?

From using it in Illustrator, it seems like the 'bw' layer in FontLab is what is used for displaying the live text. (These are the normal 'filled' paths which are closed.)
So the 'Regular' layer seems to contain the single-line open paths that are preserved/revealed when Converting to Outlines in Illustrator.

What I see in Illustrator:

I use an Astute Graphics plugin (PathScribe) which is handy for showing if paths are closed. You can see if I check the vertical stroke of the exclamation point, it is simply a single segment with two points, and it is open.

I'm not familiar with how precisely/technically SVG fonts work, but that seems to be what is allowing the original font to perform with these desired single-line open path results.
Icon in Illustrator's font menu:


I'm not especially concerned with the appearance of my live text, I just want to have single-line open paths once I convert to outlines. So I can modify this font as I like, but I still don't know how (if at all) I can output it in a format that will behave the same way in Illustrator.

Hopefully this clarifies or helps things somehow. Thank you again for any and all replies.

The flipping of the glyphs, when making the SVGs editable (which doesn’t seem to work) must be due to the way FontLab interprets the transformation matrix data inside the SVG. I fear one of the developers would have to chime in here, in order to explain what’s happening.