Italic letterforms (sans serif)...

Mithil Mogare

Greetings, I was generating an italic sans serif with a 15-degree deviation from the regular axis. 

To what extent do italic letter forms differ from standard axis letter forms? (Please recommend videos, blogs, or literature)
Could you kindly provide a step-by-step explanation of the process? 
How should the caret offset be computed? Is a formula applicable to that? 

Can spacing and kerning of plain axial characters be replicated via copy-paste?

Thank you.

Craig Eliason

https://gaultney.org/jvgtype/italics/designing-italics/

Thomas Phinney

Victor Gaultney’s thesis is great!

Regarding slant and offset.... Basically, if you slant letters for a western italic angle, they end up sticking out to the right and getting away from the left bounds. If you are creating italics by starting with slanted upright letters, after slanting, you need to shift the letters back to the left.

The amount of shift would also be the amount of caret offset to apply.

More on those issues at the 43:32 mark in this video: https://youtu.be/tbc_O7bNROs?si=HN4Vq1Ubb13HzvjM&t=2612

jeremy tribby

italic offset can be computed as

x_shift = -round(tan(italic_angle * pi / 180) * (x_height * 0.5))

gunnlaugur briem's website is offline I believe but the fontlab site has backed up his method here, which is referenced by gaultney

Mark Simonson

https://web.archive.org/web/20180714143022/http://www.briem.net/

jeremy tribby

unfortunately I don’t think the wayback machine captured the images for that one (https://web.archive.org/web/20170811182312/http://briem.net/2/2.3.4a/2.3.4.34.curves.htm)

George Thomas

Curve Compensation from 2002:

https://web.archive.org/web/20020330150443/http://briem.ismennt.is/2/2.3.4a/2.3.4.34.curves.htm

John Hudson

With regard to spacing, the important thing is to establishing a common height between roman (upright) and italic at which to measure sidebearing distance. In a Latin typeface, this is best somewhere around the middle of the distance between the baseline and the x-height. Remember that the important thing is that a word set in italics between two words in roman type should appear optically centred between them.

Craig Eliason

Do other font editors nowadays use slanted sidebearings like Glyphs has always done, which I find to be an exceedingly convenient graphic representation of the 1/2-x-height convention just alluded to? With slanted boxes, I needn't compute any offsets, but rather just center glyphs in their (parallelogram) boxes, just like I'd do with the uprights.

John Hudson

Recent versions of FontLab enable slanted virtual sidebearings (I say virtual, because the sidebearings actually written to the font are not slanted). Setting the caret offset value in the font info may remain necessary in some situations, however, e.g. if one wants to maintain compatibility with older versions of a font with a specific caret offset.

Thomas Phinney

> Do other font editors nowadays use slanted sidebearings like Glyphs has always done

I thought that was pioneered by FontLab VI, and not in Glyphs until after version 2. Am I mistaken?

Craig Eliason

Thomas Phinney said:

> Do other font editors nowadays use slanted sidebearings like Glyphs has always done

I thought that was pioneered by FontLab VI, and not in Glyphs until after version 2. Am I mistaken?

Here's an archived page about Glyphs from 2011 that already notes the slanted bounding box. That's six years or so before FL VI was shipping. 

Thomas Phinney

Nice!