Some LPE alterates some curves segments with parallel handles

I reproduced the wrong curve systematically in any new file.

It occurs also when handles go in the same direction on parallel axes.

The parallel handles axes must not be horizontal or vertical ; any angle gives the error. It seems this is linked only to parallelism.

Ivan the bug is related to more than one LPE, for example happens with the same path with the bend path LPE, so not is a copy rotate bug. Change the title.

SVG Test with bend Path

I just update your bug. Thanks for fill it!

El dom, 20-03-2016 a las 15:18 +0000, ivan louette escribió:
> I reproduced the wrong curve systematically in any new file.
>
> It occurs also when handles go in the same direction on parallel
> axes.
>
> The parallel handles axes must not be horizontal or vertical ; any
> angle
> gives the error. It seems this is linked only to parallelism.
>

Confirmed Debian Stretch in 0.91+devel r.14726

Based on tests with archived builds using bend-curve-error.svg (r12920 ok, r12921 not ok), this issue was introduced/exposed with the changes of the 2geom update in r12921:
https://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/12921

Thanks for test it su_v!

Excellent work ! And of course that was better to change the title !

attached is a proposed fix for this bug. I have tested it only with the file rotate-copies-curve-error.svg.
any further testing would be welcome.

Thanks Alvin for the patch, I hope this weekend I could do some test.

Thanks for the patch ! I don't have the technical skills to test it but I am confident :-)
ivan

    Le Samedi 2 avril 2016 1h30, Alvin Penner <email address hidden> a écrit :

 attached is a proposed fix for this bug. I have tested it only with the file rotate-copies-curve-error.svg.
any further testing would be welcome.

** Patch added: "sbasis-to-bezier_1559721.diff"
  https://bugs.launchpad.net/inkscape/+bug/1559721/+attachment/4620002/+files/sbasis-to-bezier_1559721.diff

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Title:
  Some LPE alterates some curves segments with parallel handles

Status in Inkscape:
  Confirmed

Bug description:
  Attached is a curve segment with handles going in opposite directions
  along parallel axes. LPE Rotate Copies draws it erroneously, as seen
  if one select the object with the Node Editor (F2).

  This happens for example in Bend LPE and in Rotate copies LPE

  When moving around any node, or the segment itself or the entire LPE
  object the curvature at the right node suddently inverts.

  The only way I found to remove the problem without changing my
  original curve is adding a node at any place on it.

  Otherwise, breaking the parallelism between the two handles result in
  a correctly redrawn curve too.

  Inkscape 0.91 devel ppa on Kubuntu 14.04

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fix committed to rev 14762.
I'll commit this as well to 2geom in a few days if there are no objections.

Thanks Alvin, sorry, I coulden't get time to make more tests this weekend.

same fix committed to github:
https://github.com/inkscape/lib2geom