I’ve been considering adding a contrast axis to my current type family which mapped to the well-supported Width parameter (width=0 is low-contrast, width=100 high-contrast). Currently, I’m using two masters (Hairline at weight 10, Bold at weight 150) with brace layers for some glyphs to restrict the excessive thinning needed in some Bold glyphs to the heavy weights only. I’m thinking of keeping the Hairline master fixed for all contrasts and just have an extra Bold master for high contrast.
How should I proceed, then? Duplicate the Hairline master, call it width=100, then duplicate all brace layers and call them, e.g., {48; 100}? Can I keep my existing {48} layers for the low-contrast, or would I have to rename them {48; 0}? Alternately, should I keep the single Hairline master {10; 0} and interpolate between that and the high-contrast Bold master {150; 100}? Would I then have to use something like {48; 0.3} for the high-contrast brace layers, since the instance are going to lie on the line {10, 0} and {150; 1}?
You need thee masters. One Hairline (10, 0), one Bold (150, 0) and one Bold-Contrast (150, 100). The brace layer can be kept like that.
That only ‘problem’ is how to calculate the instances between the Hairline and the Bold-Contrast. You need to make sure they all sit exactly on the diagonal.
Great, thanks. I guess I’ll set the contrast axis to run from 10 to 150 as well, then, so I can use the same value for weight and contrast in the diagonal brace layers.
Ok, but those, too, will be made easy with that trick.
Wait, does that mean I can’t have any half-contrast instances, then? I was counting on that… Couldn’t you first interpolate the {48, 0} and {48, 48} layers, e.g. to {48, 24}, and then use that to make a (60, 30) instance?
Otherwise, should I just export the high- and low-contrast series and use a third-party tool (gasp!) to interpolate the intermediates from the fonts at a given weight?
You only need to calculate the positions of the instances properly. The instance for 33% between Haurline and Contrast is at 55.2/33 at 50%: 80/50. So to change weight you need to change the contrast value, too.