A script or method to detect crossed BCPs?

Hi there,

Can you recommend a script or software to quickly detect these crossed BCPs that are often created in an extrapolated weight?  FL's FontAudit does not do it.

Thanks in advance.


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  • MS FontValidator could be of help... If the BCPs are crossing, in the glyf table should be a warning regarding the missing nodes at extremes.
  • Thanks! I am sort of solving it with Glyph Nany (Robofont extension)
  • hmm... I believe that FontAudit covers that, at least is should give you "Unnecessary  Extremum" error in (at least) two places

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  • He said extrapolation. A dangerous animal indeed.

    But yes, FL flags it just fine.
  • But even a strong extrapolation should not produce this. Can you show the masters for that part?
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  • Personally I use extrapolation quite a lot and, if controlled properly, with predictable proportional relations between node handles it actually works quite well.
  • Ramiro EspinozaRamiro Espinoza Posts: 797
    edited June 2016
    @James Montalbano @Georg Seifert @Vassil Kateliev,

    In my image I moved a bit the handlers so the problem is more visible. Otherwise it looks like a segment when in reality the handlers are crossed.

    It happens when you extrapolate (maybe also interpolate) a segment and a segment looking curve. Yes, sometimes I do use extrapolations when I want to go lighter or darker of the masters, but of course then I have to correct well the extrapolations because any small inconsistency is going to be increased. 

    I found out Glyph Nany extension for Robofont is a great contour audit tool. much more powerful than FL 5's audit. It's helping me to spot these problems.
  • Ramiro EspinozaRamiro Espinoza Posts: 797
    edited June 2016
    @Vassil Kateliev 
    FontAudit covers that, at least is should give you "Unnecessary  Extremum" error in (at least) two places
    Nope. FontAudit will detect the problem if the handlers have been moved like in my image, the real problem is when everything is resting on the same line. It's no visible and FontAudit does not detect it.

  • Vassil KatelievVassil Kateliev Posts: 56
    edited June 2016
    @Vassil Kateliev 
    FontAudit covers that, at least is should give you "Unnecessary  Extremum" error in (at least) two places
    Nope. FontAudit will detect the problem if the handlers have been moved like in my image, the real problem is when everything is resting on the same line. It's no visible and FontAudit does not detect it.

    Now, that is a bit different story - all resting on same line. Yes I have encountered the problem, but rarely and by chance - otherwise it is not easily spotted.

    Now I can confirm your results, that FontAudit will not detect the problem, but only under certain circumstances (or at least in all my tests). Audit will not report the problem if the BCP handles of the node are no longer than 14 units (strange), otherwise it will return "Unnecessary  Extremum". 

    Glad to know that "Glyph Nanny" does such a good job. I took a brief look at its code and I liked, what I saw - made me think about porting it to FontLab.
  • I'm still interested to see your masters to that node. 
  • @Georg Seifert No problem, I will try to send you something during the week.
  • @Georg Seifert Can you give me your email?
  • Thomas PhinneyThomas Phinney Posts: 2,031
    I would also be curious to know if the FL VI FontAudit does a better job on this case. It is significantly improved.
  • I would also like to see how FontCreator validates your outlines. Can you send me the font for testing purposes?
  • Ramiro EspinozaRamiro Espinoza Posts: 797
    edited June 2016
    Files sent.
  • Thomas PhinneyThomas Phinney Posts: 2,031
    Thanks!
  • It's good to see the latest Fontlab can spot such problems as well (please, have it ready in 2016!)


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