Line spacing dissimilarity depending on font shape

mauro sacchetto
mauro sacchetto Posts: 353
edited December 2018 in Font Technology
Yet another problem with the font I'm working on (or at least I'm trying to work).
If the text is all in Roman, the line spacing is regular, that is homogeneous. If there is a italic word, the space between this line and the line above is larger. Which parameters can it depend on?
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Comments

  • Adam Jagosz
    Adam Jagosz Posts: 689
    edited December 2018
    The italic is a different font. So probably it has different vertical metrics. Since you are working with FF, you should be informed that FF calculates the metrics automatically based on lowest and highest point in all glyphs. You can adjust your metrics manually in Element > Font properties (Ctrl+Shift+F) > OS/2 > Metrics. Check the "Relative" checkboxes off and set the values the same in both fonts.
    If you are certain no glyphs in the italic cross the ascent line (not that they shouldn't), maybe you have a rogue point somewhere.
  • mauro sacchetto
    mauro sacchetto Posts: 353
    edited December 2018
    In creating the .otf I receive the message:
    Missing Points at Extrema
    for some glyphs... Can be this the problem'

    In any case, which of these values ​​must be equal? all or just some?
  • mauro sacchetto
    mauro sacchetto Posts: 353
    edited December 2018
    Oh solved changing the central boxes, thanx!
    Even if after the changes still receive
    Missing Points at <span>Extrema</span>
    but it would be a glyphs problem, not a metric one (if I'm not wrong)

  • James Puckett
    James Puckett Posts: 2,023
    Read the Glyphs Vertical Metrics tutorial. The Glyphs UI is different but the principles are the same: https://glyphsapp.com/tutorials/vertical-metrics
  • Kent Lew
    Kent Lew Posts: 1,010
    “Missing Points at Extrema” would be a warning, not necessarily an error.
  • AbrahamLee
    AbrahamLee Posts: 263
    edited December 2018
    It’s a warning that some glyphs do not have points at the extremes of the outline curves. This isn’t necessarily a problem, but it can mess with spacing in some applications.
  • Adam Jagosz
    Adam Jagosz Posts: 689
    FF will take where the extremum would be as the highest/lowest point, so there's no worry here.
  • Thomas Phinney
    Thomas Phinney Posts: 3,083
    Further to Adam's comment, "missing points at extrema" could possibly, in some font editors, cause errors in auto-calculating the metrics.

    Another reason (besides rasterization and hinting) to get your extrema points right.

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