This pages hilights the key differences between Skateboard and Superpolator.
(so you need something that makes UFOs)
(so you need RoboFont)
|Preview designspace format 4 rules||❌||✅|
|Export, import .designspace||Import .sp3|
|Interpolate with MutatorMath||✅||✅ #1|
|Interpolate with FontTools varlib||❌||✅|
|Generate Variable Font TTF||❌||✅|
|Updates with RoboFont Mechanic2||❌||✅|
|Create designspace from scratch||✅||❌ #2|
|Anisotropic locations||✅||❌ #3|
#1. MutatorMath automatically assigns the neutral because at the time it was convenient. In variable fonts this is impractical: you really have to know where the neutral is going to be.
#2. You can use the free DesignspaceEditor extension
#3. Anisotropic instances aren’t possible in variable fonts. I haven’t decided if and how to support it in Skateboard. If you want to experiment with anisotropy there are alternative tools.
I wrote MutatorMath in 2004 inspired on the mathematical model in Apple’s GX fonts. This was great until the OpenType Variable Fonts specification supported the actual Variations model. This has better support for non-aligning masters. But on the other hand varlib doesn’t extrapolate beyond the boundaries of the axes. And that has proven to be very useful during the design process. That’s why Skateboard supports both models, you can switch between them. Retrofitting Varlib to Superpolator is possible but not a priority.
|Extrapolation beyond axes extrema||✅||❌|
|Non-aligned, off-axis masters||❌||✅|
|Automatically assign a default in any system||✅||❌|
|Any number of axes||✅||✅|
|Any kind of math object||✅||✅|
Superpolator uses the
sp3 format. Skateboard uses
designspace, but it can import
sp3 files. The sp3 format is Superpolator’s own document. Both formats are XML and relatively easy to read. Some designers even manually edit and write them. The
designspace format is a public, documented format. The structure is very similar (in fact, designspace started from sp3), but now they’ve grown apart. Let’s have a look at the main differences:
|Source UFO paths||✅||✅|
|Instance Names, location||✅||✅|
|Axes names, geometry||✅||✅|
|Glyph specific masters and locations||✅||❌ #2|
#1. The Superpolator rules are much older than the Variable Font rules. The systems are quite different. When importing a sp3 file into Skateboard only compatible rules are used.
#2. “Glyph specific masters” are no longer needed. The designspace format allows them, but Skateboard doesn’t support them.