Hello everyone. Apologies, I’m new. I’m trying to interpolate a glyph across different weights. There are many such examples in the typeface I’m working on but I’ve chosen the asterisk as a simple example. Each ‘arm’ of the asterisk has two bezier control points along the curve, between the two end nodes. But in one of the instances, there is only one control point, so the curve is simpler. The difference between these seems to be the only reason that the glyph doesn’t interpolate across all the weights. So, I can delete the ‘extra’ point in the other weights and painstakingly recreate the curve - but surely I can just add a control point to the one place that lacks one? I can’t seem to find any way to do this….? So, add an extra control point to the curve. Or - I guess simplify the other curves in an automated way…?
Why are you drawing with quadratic curves?
Are you sure this is your font?
Use Path > Convert to Cubic in order to have outlines that are manageable and interpolate easily.
Just using this as an example to try to learn how to interpolate. Is there no way to just give the simpler curve another control point then? Rather than have to simplify all the other curves to all have one less? Sorry if this is a silly question. Seems from your tone that it might be.
If you don’t have a good reason to work with TrueType, Convert to cubic as Sebastian suggested. Editing TrueType directly is very uncommon.
Thanks for the reply. I am learning by doing, before I try this with a new project - so am playing with existing TT fonts. I’ve combined them into one Glyphs file as masters and now I’m trying to interpolate them for variability. When I convert to cubic, I get a warning that I’m throwing away features, which feels destructive, so is there no way to just make the simpler curves more complex? So, add an extra control point to a curve that only has one in one instance, where it has two in the other instances? Seems safer in that one focuses place than removing complexity in a lot of others. Sorry if this makes no sense, I have searched online but not found an answer.
Where do you get this warning? Converting to cubic should work without such issues.
On selecting convert to cubic: “This glyph has low level instructions. The font was imported from a TrueType font that already had instructions. Converting outlines, the instructions will become invalid.”
That is OK. If you edit the outlines in any way the low level instruction will be invalid.
Thank you for the help everyone, apologies for the dumb questions!
You can certainly add extra points on the simpler curves. You just want to try and place them in a way that as the axis changes the point moves in a predictable way as you intend.
So if, say, a shallow v in a light weight with a notch in a heavier one you would put the extra points very close (perhaps even in-line with the curves) so that they move up and away as the weight increased.