[FIXED] Kerning Values Different for Identical Glyphs

Post your bug reports here. Include information that helps us to understand and reproduce the bug.
Post Reply
Bhikkhu Pesala
Top Typographer
Top Typographer
Posts: 9873
Joined: Tue Oct 29, 2002 5:28 am
Location: Seven Kings, London UK
Contact:

[FIXED] Kerning Values Different for Identical Glyphs

Post by Bhikkhu Pesala »

I have two glyph classes — r_lc and r_lc_top. Apart from the accents above the glyphs, they are identical in terms of bearings and advance width, so why are the kerning values returned by Autokern so different?
r_lc.png
r_lc.png (9.49 KiB) Viewed 5662 times
r_lc_top.png
r_lc_top.png (11.3 KiB) Viewed 5662 times
My FontsReviews: MainTypeFont CreatorHelpFC15 + MT12.0 @ Win 10 64-bit build 19045.2486
MikeW
Posts: 625
Joined: Mon May 20, 2013 2:51 pm

Re: Kerning Values Different for Identical Glyphs

Post by MikeW »

racute hyphen is exactly the same value for me (-53 x-advance) in your font project.

But unless there is a reason not to, I would combine both of these classes anyway.
Bhikkhu Pesala
Top Typographer
Top Typographer
Posts: 9873
Joined: Tue Oct 29, 2002 5:28 am
Location: Seven Kings, London UK
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Bhikkhu Pesala »

MikeW wrote:racute hyphen is exactly the same value for me (-53 x-advance) in your font project.
Thanks for looking. I adjusted the values manually after taking the screen shot, but the calculated XAdvance value for r_lc_top is -8, as shown in my screen shot.
MikeW wrote:But unless there is a reason not to, I would combine both of these classes anyway.
Yes, there is a reason for separating the “r”s into two classes. I use the naming convention “@class_name_top” for those glyphs that are likely to clash with the top of capital T, V, W, Y, etc.

I am still refining the kerning classes to have as few classes as necessary, while avoiding overlaps. The method of “@class_name_first” and “@class_name_second” works better in some cases. I have attached an updated project file to this post and removed the older version from the previous post.
Tr.png
Tr.png (24.78 KiB) Viewed 5650 times
Tr_top.png
Tr_top.png (27.45 KiB) Viewed 5650 times
Attachments
Talapanna Regular.fcp
(596.44 KiB) Downloaded 374 times
My FontsReviews: MainTypeFont CreatorHelpFC15 + MT12.0 @ Win 10 64-bit build 19045.2486
Erwin Denissen
Moderator
Moderator
Posts: 11108
Joined: Fri Oct 04, 2002 12:41 am
Location: Bilthoven, The Netherlands
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Erwin Denissen »

MikeW wrote:racute hyphen is exactly the same value for me (-53 x-advance) in your font project.
I've just run Autokern (right-click the lookup) with glyph spacing factor 27, and both get 61.
Erwin Denissen
High-Logic
Proven Font Technology
Bhikkhu Pesala
Top Typographer
Top Typographer
Posts: 9873
Joined: Tue Oct 29, 2002 5:28 am
Location: Seven Kings, London UK
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Bhikkhu Pesala »

Erwin Denissen wrote:
MikeW wrote:racute hyphen is exactly the same value for me (-53 x-advance) in your font project.
I've just run Autokern (right-click the lookup) with glyph spacing factor 27, and both get 61.
I tried with spacing value of 27 and got positive kerning values of 39 and 77.

With my spacing value of 23, I still get -53 and -8.

I noted that c_lc hyphen and c hyphen give the same results (-104), but z_lc hyphen (-88) and z_lc_top hyphen (-83) do not.
My FontsReviews: MainTypeFont CreatorHelpFC15 + MT12.0 @ Win 10 64-bit build 19045.2486
Erwin Denissen
Moderator
Moderator
Posts: 11108
Joined: Fri Oct 04, 2002 12:41 am
Location: Bilthoven, The Netherlands
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Erwin Denissen »

I'm puzzled.

I've reduced the pairs to:

lookup PairAdjustmentLatin {
subtable Subtable_0 {
pos @r_lc @hyphen <61> <0>;
pos @r_lc_top @hyphen <61> <0>;
}
}

And right-click the lookup to Autokern keeps them the same.
Erwin Denissen
High-Logic
Proven Font Technology
Bhikkhu Pesala
Top Typographer
Top Typographer
Posts: 9873
Joined: Tue Oct 29, 2002 5:28 am
Location: Seven Kings, London UK
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Bhikkhu Pesala »

Erwin Denissen wrote:I'm puzzled.
Me too. I tried with just those two pairs and still get the same results as before:

53, -8 @ 23 space factor
39, 77 @ 27 space factor

So, at least it's consistently wrong! :?

We're both using the same project file, and the same build 10.1.0.2257 so what else could be different? Is it the rendering dll again?
My FontsReviews: MainTypeFont CreatorHelpFC15 + MT12.0 @ Win 10 64-bit build 19045.2486
Erwin Denissen
Moderator
Moderator
Posts: 11108
Joined: Fri Oct 04, 2002 12:41 am
Location: Bilthoven, The Netherlands
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Erwin Denissen »

Bhikkhu Pesala wrote:
Erwin Denissen wrote:I'm puzzled.
Me too. I tried with just those two pairs and still get the same results as before:

53, -8 @ 23 space factor
39, 77 @ 27 space factor

So, at least it's consistently wrong! :?

We're both using the same project file, and the same build 10.1.0.2257 so what else could be different? Is it the rendering dll again?
I was testing with a more recent version; not released yet. Somehow that version works fine, so I might have accidentally fixed the problem.
Erwin Denissen
High-Logic
Proven Font Technology
Bhikkhu Pesala
Top Typographer
Top Typographer
Posts: 9873
Joined: Tue Oct 29, 2002 5:28 am
Location: Seven Kings, London UK
Contact:

Re: Kerning Values Different for Identical Glyphs

Post by Bhikkhu Pesala »

The latest update (FC 10.1 build 2272) has fixed this bug.
My FontsReviews: MainTypeFont CreatorHelpFC15 + MT12.0 @ Win 10 64-bit build 19045.2486
Post Reply