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googlefonts / fontmake

Compile fonts from sources (UFO, Glyphs) to binary (OpenType, TrueType).
Apache License 2.0
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Interpolation / kerning errors #373

Open jeremymickel opened 7 years ago

jeremymickel commented 7 years ago

I'm making a 2-axis variable font. I can generate through fontmake without error, but I'm seeing some strange things when I proof in Illustrator / Photoshop 2018.

screen shot 2017-11-09 at 2 42 39 pm

There are kerning pairs that have no basis in the masters. In this example .N is -50 and OT is -110. In the masters these values are both 0.

screen shot 2017-11-09 at 4 22 56 pm

There are lots of interpolation errors that show up at seemingly random places as you drag through the width and weight options. I don't see the same interpolation errors when I proof in FontView.

I'm attaching my designspace doc for reference (saved as .txt). I'm new to this so I'm sure there are some things wrong, but I wanted to report in case these are actual errors in fontmake.

Thanks in advance!

CHOP-Variable_ALL.txt

behdad commented 7 years ago

Sounds like Adobe bug discussed at https://github.com/fonttools/fonttools/issues/1084

Does it work with FontView?

anthrotype commented 7 years ago

or also try to drag and drop it in the Axis Praxis site with Chrome or Safari: http://www.axis-praxis.org

jeremymickel commented 7 years ago

I see the same kerning errors in FontView and Axis Praxis. There are some interpolation errors, but they're less extreme than in Illustrator.

However, a variable font generated by Glyphs doesn't have any interpolation errors in any of these apps. That's what makes me think fontmake has something to do with the errors.

Is it possible that something is happen in the quadratic conversion? Is it automatically changing start points or contour directions?

behdad commented 7 years ago

Humm. Then we need to see the font source I guess. Can you email me please?

anthrotype commented 7 years ago

I see the same kerning errors in FontView and Axis Praxis. There are some interpolation errors, but they're less extreme than in Illustrator.

I built the fonts you sent and tested in fonview and Axis Praxis on latest Chrome and can't reproduce the issues with kerning or "interpolation errors but less extreme Illustrator" you talk about. Can you provide screenshots maybe comparing the rendering of the Glyphs.app's generated font with the fontmake one? Also maybe could you send us the source glyphs file as well? Maybe the issue is that glyphsLib (the library used by fontmake that converts glyphs to UFO) hasn't exported some piece of data.

Is it possible that something is happen in the quadratic conversion?

no

jeremymickel commented 7 years ago

Thanks Cosimo. Will send you guys the .glyphs file.

Here's a comparison of a font built with fontmake vs. a font generated from Glyphs (not using fontmake)

screen shot 2017-11-13 at 11 58 11 am

Both the fontmake AND Glyphs fonts show errors in FontView, primarily in the '0' width position.

screen shot 2017-11-13 at 9 39 29 am

I don't see interpolation errors in either font in axis-praxis. But the kerning errors are only in the fontmake font.

screen shot 2017-11-13 at 12 01 04 pm screen shot 2017-11-13 at 12 01 16 pm
jeremymickel commented 6 years ago

Hi guys, just wanted to follow up on this.

The edits you made to FontTools corrected the kerning error. I'm still seeing the glyph outline interpolation errors in Illustrator.

I read here that it's a known Adobe issue that will be addressed in a future release.

FYI, I am able to export the variable font from a Glyphs source file (not using FontMake) and there are no interpolation errors in Illustrator.

Thanks again for your help with this.