@mekkablue if I want to do this, should I change something in my metrics info? And might I have any kind of problems with this? Will it work as a normal 1000 UPM font?
I would even leave out step 2.
So, just set the UPM to 1200.
why?
Isnât a little bit strange to have 1200 of UPM and metrics for 1000 UPM?
Scaling the coordinates will lead to rounding errors and possibly near misses in alignment zones and stuff like this.
There are quite a few fonts out there with UPMs other than 1000 and 2048, and there are some problems if you go way off, like more than 3000, but 1200 should not be a problem.
FreeHand had live interpolation and extrapolation on the canvas, which I used to design a font family once. Not available in Illustrator. Glyphs does live extrapolation?
From experience: TrueType on 4096 works fine, as long as coordinates stay within 2 to the power of 14.
(not sure if that limit is still true for cff)
I remember a problem with Windows (I believe it was XP or Vista) on the Client machines like a decade ago. And the fonts would have all kinds of rendering troubles once we crossed UPM 3k. Do not remember the format, but I am pretty sure we tested both TTF and CFF. We tried to get a font with complex shapes to render in PowerPoint and Word. Since then, I stay below 3k.
Low UPM works pretty well OTOH. I once did a font with UPM 16.
What exactly did it do? In Glyphs you can in/extrapolate with the outlines in background, but you mean something else, do you?
the only problem I personally found was: if any glyph within the WinAnsi range has a node beyond a third of the actual limit (2 to the power of 14) in the X-direction, then the spacing would collapse, but only in PowerPoint, and only if ClearType was switched on. A bug: ClearType multiplies everything by 3 behind the scenes. Fixed long ago.
I was drawing Regular and Bold, while seeing live preview of extrapolated Light and Bold. Even spacing could be judged precisely.
I asked Yuri long ago for synthetic masters/glyphs that are defined by recipies.
E.g. this glyph or master is an interpolation of those other masters with X/Y interpolation.
And to make it more complicated: this superior glyph in the Light master is an x/y interpolation of another Glyph somewhere between Light and Black, with some extra sidebearings and shift.
I even proposed such synthetic glyphs/fonts to be part of variable fonts, because it could save a lot of data, but that idea was not picked up.
You can add extrapolating instances and show (one of) it in the preview. Is that the right direction?
And you can use the ShowInterpolation extension for displaying the shape inside the edit view. For spacing use the Preview area or one of the plug-ins (Waterfall and SILE, but the latter hasnât worked for me recently).