Are Bézier with only one handle bad ?

ivan louette
ivan louette Posts: 327
in Technique and Theory
Often I hesitate to use Bézier with only one handle in my design. Is that bad or not, and which kind of issues could they generate ?

Comments

  • John Hudson
    John Hudson Posts: 3,186
    They can cause problems for conversion to TrueType quadratic curves.

    I recall this has been discussed here before, but can't think of appropriate search terms it seems.
  • Craig Eliason
    Craig Eliason Posts: 1,436
    There's a bit here on this Typophile thread.
  • ivan louette
    ivan louette Posts: 327
    Thanks a lot ! I saw in the Typophile thread that they can also cause rendering problems on some systems.

  • Hrant Հրանդ Փափազեան Papazian
    Hrant Հրանդ Փափազեան Papazian Posts: 2,044
    http://typedrawers.com/discussion/comment/35475/#Comment_35475
    It's a shame, since they can be so elegant.

    John Hudson said:
    can't think of appropriate search terms it seems.
    http://typedrawers.com/discussion/2563/search-fail
  • ivan louette
    ivan louette Posts: 327
    edited June 2018
    @Hrant H. Papazian You are absolutely right : that's a shame because they are visually and technically elegant at the same time.

  • Igor Freiberger
    Igor Freiberger Posts: 273
    The FontAudit tool in FontLab VI name them 'zero-length handles" and identify as an error, offering a quite precise auto fix. For me, who made not dozens or hundreds, but thousands of zero-length handles because I was not aware they are an issue, this was a real rubber ring.
     

  • Hrant Հրանդ Փափազեան Papazian
    Hrant Հրանդ Փափազեան Papazian Posts: 2,044
    edited June 2018
    The auto-fix in FL5 (clicking on the curve with Alt-Shift*) is not very robust, but I guess they improved it?

    * Which just happens to be the Windows keyboard switching hot-key, which means I have to immediately hit it again to undo it otherwise I'll be typing in Armenian...

    (BTW by "rubber ring" do you mean a flotation device? Is that from Portuguese? :-)
  • Igor Freiberger
    Igor Freiberger Posts: 273
    Yes, it was improved. And the resulting handles can be further adjusted with Tunni lines (another new tool in FontLab VI) or the Proportional test also added to FontAudit.

    And yes, it is a flotation device. Is uncommon to name it this way? Maybe it is more a British expression as I learnt it from a Smiths' song. :-)
  • Hrant Հրանդ Փափազեան Papazian
    Hrant Հրանդ Փափազեան Papazian Posts: 2,044
    Portuguese, British, it's all Greek to me.
    Over here we like our terms properly sterilized.
  • John Hudson
    John Hudson Posts: 3,186
    And yes, it is a flotation device. Is uncommon to name it this way? Maybe it is more a British expression as I learnt it from a Smiths' song. :-)
    I think the rubber ring referred to in the Smith's song is probably the sort of inflatable water toy, rather than the flotation device, which is known in England as a life preserver. 
  • Erwin Denissen
    Erwin Denissen Posts: 300
    John Hudson said:
    They can cause problems for conversion to TrueType quadratic curves.
    Trying to look into this some more I only see the specific typophile post which mentions an old bug in iOS. Has that bug been fixed?

    Are there other buggy renderers or was this the only problem concerning cubic bezier curves with a node and adjacent handle at the same coordinate?

  • Rainer Erich Scheichelbauer
    Rainer Erich Scheichelbauer Posts: 157
    edited June 2018
    There is no such thing as a curve segment ‘with only one handle’ in PostScript. The second handle is there, just retracted into the adjacent on-curve.

    Best to avoid it in shipping fonts. In short:
    • Display issues in all Apple renderers
    • Rendering bug in some printer drivers
    • Post-processing problems (drawing a parallel path or a thick contour can be difficult for host application, or things like autohinting may fail)
    • Conversion problems (as John mentioned)
    For Glyphs, I wrote the FixZeroHandles plug-in which effectively allows you to work with zero handles by fixing them automatically at export time.
  • Hrant Հրանդ Փափազեան Papazian
    Hrant Հրանդ Փափազեան Papazian Posts: 2,044
    Rainer Erich Scheichelbauer said:
    allows you to work with zero handles by fixing them automatically at export time.
    Nice! Is there also a way to see what it's doing during editing? In FL5 at least I usually have to tweak the result (although as per Igor, FL VI is better).
  • Nick Shinn
    Nick Shinn Posts: 2,207
    edited June 2018
    Morissey’s lyric may also be interpreted as a lament for the passing of the vinyl record, which he associates with the music of his youth—it was written around the time CD sales surpassed vinyl. A rubber ring is not only a flotation device for young swimmers, but an important part of a turntable, possibly three, in fact: the belt drive, the o-ring between the cartridge head and the rest of the arm, and the ring the platter sits on. In all these, the purpose of the rubber is to insulate the signal from untoward vibration.

Categories