When designing italics should a curve's side handles be 90º or slanted to the italic angle?

Josh Nychuk
Josh Nychuk Posts: 30
in Technique and Theory
When creating a font's italics I have relied on a mixture of slanting, rotating and fixing curves until they look nice on my eyes. In this process I have always left the side handles for curves (e.g. in the 'o') at the italic's slant angle, but when inspecting other type designs I admire I've noticed they appear at 90º. I've attached screengrab to illustrate what I'm describing and noting I may be using incorrect terminology as a self-taught type designer.

I'm wondering if the 90º side handles are considered best practice in professional type design, and if so, are you aware of any documentation that would describe the how-to for the process?

PS: The 90º side handles seem to make italic curves look best, IMO.
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Answers

  • Georg Seifert
    Georg Seifert Posts: 679
    As fare as I know, it is technically OK to have slanted handles. Except if you like to do a very crisp TrueType hinting (you shouldn’t). 
    But if the shapes look better (not the curves, the look of the curves doesn’t matter), then follow your eyes.
  • Paul Hanslow
    Paul Hanslow Posts: 178
    Typically the handles should be 90 degs but there are occurrences/reasons where this isn't always possible due to the design of a typeface. An example I often use for 'odd' node handle placement is Inkwell by Hoefler&Co., which has chaotic node handles due to the curve shape taking precedent over 'correct' node placement.

    It's important to note that having odd node handles can present problems when exporting/outputting a font source to quadratic curves, but this is a technical discussion and I lack the ability to explain it succinctly. 
  • Josh Nychuk
    Josh Nychuk Posts: 30
    Thanks all! and thanks @Paul Hanslow for noting the technical reasons, and that it's not simply an aesthetic choice.
  • Christian Thalmann
    Christian Thalmann Posts: 2,001
    I'm very surprised to hear vertical handles are the norm. I always do slanted handles because the Glyphs tutorials seem to suggest that...? Something to do with sidebearings not being well-defined otherwise. But they are quite a pain to use, especially when I run Harmonize on them.
  • Thomas Phinney
    Thomas Phinney Posts: 2,959
    For me being old-school in this regard, on-curve points at the extrema are the norm, and I would only deviate from that with a “very good reason.”

    If I am slanting as a starting point for an italic, fixing the no-longer-vertical (and no longer quite at extrema) handles is a standard operation for me. It will generally help get better-looking curves anyway — looking more like a designed italic rather than just mechanically slanted (and therefore distorted).

    Of course, there are some typefaces even from major foundries that do just have a mechanically slanted oblique (mostly sans serifs and typewriter-style fonts). But I still believe that improving the curves is highly desirable, if time permits.
  • Linus Romer
    Linus Romer Posts: 192
    But they are quite a pain to use, especially when I run Harmonize on them.
    The slanted handles cause problems when you run Harmonize on them? Isn't continuity of curvature invariant under linear transformations (such as slanting)?
  • Christian Thalmann
    Christian Thalmann Posts: 2,001
    edited April 3
    @Thomas Phinney, I agree that artificially slanted curves need manual correction; that is quite independent of the location of the on-curve points.
    @Linus Romer, I run Harmonize on my curves precisely after the manual correction after slanting, or after drawing the Italic shape from scratch. The harmonization tool likes to change the orientation of the handles as part of its corrections (though that might be because I often choose «supersmooth diagonals»).
    In anycase, I'll happily stop the practice of slanted handles in future projects.
  • Igor Petrovic
    Igor Petrovic Posts: 315
    If handles are 90° that is safe for interpolation. On-curve points with slanted handles in masters can introduce kinks in intermediate positions on the axis.

    If it's still necessary to have such points, ensure that the difference in angle of slanted handles is less than 3° between masters, or to ensure that two on-curve points in two masters have the same proportion of handles (Point1Handle1 : Point1Handle2 = Point2Handle1 : Point2Handle2). Actually not necessarily the same, but inside a 5% difference.

    There is a plugin for Glyphs called "Dekink" that automatically sets these values to prevent a kink. Not sure if FL introduced some auto option for this in the FL8.
  • Nick Shinn
    Nick Shinn Posts: 2,256
    BTW Josh, you have used the ordinal /o in your post heading rather than the degree symbol, and not a proper “curly” apostrophe. These things are important too. 

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