Collision detection and Kern On

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albertomalossi
Posts: 4
Joined: 23 Apr 2021

Collision detection and Kern On

Post by albertomalossi »

Hi,

Per title I'm wondering about best practices for finding collisions while using Kern On. Can I use KernCrasher while Kern On is running? Should the colliding pairs become indipendent pairs?

Thanks in advance,
Alberto
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Tim Ahrens
Site Admin
Posts: 284
Joined: 11 Jul 2019

Re: Collision detection and Kern On

Post by Tim Ahrens »

Hello Alberto, yes, you can use KernCrasher while Kern On is running (or while it is sleeping) to help you find colliding pairs. Any script or plug-in that doesn’t modify the font (or a glyph) is safe to use while KO is running.

Don’t switch the pairs in question to independent, it’s much better (and more powerful) to work with models.

It should be enough to set up a handful of model pairs that would be colliding if unkerned, then Kern On will apply the principle to the autokerned pairs as well. So you may only need 2–3 models to avoid crashing, depending on the design and your taste, of course.

The general idea of Kern On is to check the (auto)kerning of the font and whenever a pair does not have the right kerning value you simply correct the value, which automatically switches it to model.
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Tim Ahrens
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Posts: 284
Joined: 11 Jul 2019

Re: Collision detection and Kern On

Post by Tim Ahrens »

I just noticed that KernCrasher doesn’t work properly while KO is running. One reason is that while KO is running, it only auto-kerns visible pairs. Then KernCrasher opens a tab with some colliding pairs and in that moment they get autokerned.

Another problem is that KernCrasher checks every thinkable glyph combination, even combinations that will not occur in real life, such as ÍĬ (/Iacute/Ibreve). Kern On does not kern them as it does not consider them relevant (as you will see, even the auto segment is no selected). You can explicitly set them to auto, which makes them “user-set auto pairs” and kerns them apart.

In other words, I don’t think it’s worth trying to “silence” KernCrasher. Kern On will reliably avoid collisions for all relevant pairs (usually, even if you don’t explicitly set models for these cases).
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