path effect bend with convex, concave path

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chaffra
Posts: 6
Joined: Sat Nov 18, 2017 8:13 am

path effect bend with convex, concave path

Postby chaffra » Sat Nov 18, 2017 8:19 am

Hello,

When using path effect bend on 2 rectangle on top of each other, the resulting path is always bending downward irrespective of the fact the my arc path points upward or downward. I was expecting the bending to follow the path exactly.

I added the source code for a MWE as an attachment. Any help is appreciated.

ptest_path_effect_convex_concave.svg
(6.39 KiB) Downloaded 233 times

Moini
Posts: 3381
Joined: Mon Oct 05, 2015 10:44 am

Re: path effect bend with convex, concave path

Postby Moini » Sat Nov 18, 2017 8:26 am

Works for me - did you click on 'edit on canvas' in the path effect dialog (the node tool icon) and then manipulate the bend path?
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Moini
Posts: 3381
Joined: Mon Oct 05, 2015 10:44 am

Re: path effect bend with convex, concave path

Postby Moini » Sat Nov 18, 2017 9:45 am

Oh, I see. It's due to the bend path actually bein an 'arc' with a transform. Please convert to path first. Make sure to set Store transformations to 'Optimized', too, in the settings at Edit > Preferences > Behavior > Transforms.
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)

chaffra
Posts: 6
Joined: Sat Nov 18, 2017 8:13 am

Re: path effect bend with convex, concave path

Postby chaffra » Sat Nov 18, 2017 11:08 am

Thank you it works. Converting the arc to a path first does the trick.
Thanks for the prompt reply.

chaffra
Posts: 6
Joined: Sat Nov 18, 2017 8:13 am

Re: path effect bend with convex, concave path

Postby chaffra » Sat Nov 18, 2017 12:39 pm

Hum, never mind. It still does not work for the picture I actually want, even though I converted everything to paths. The path object is bending the wrong way and sometimes inkscape starts crashing when I paste the arc path in the "path effect bend" dialog. I am running Inkscape 0.92 on the latest ubuntu.

fpa_bending.svg
(136.37 KiB) Downloaded 247 times

Polygon
Posts: 393
Joined: Thu Dec 19, 2013 3:27 am

Re: path effect bend with convex, concave path

Postby Polygon » Sat Nov 18, 2017 5:11 pm

The only thing that works for me was to select all identical objects by color&fill and merge them with "cmd+" before grouping.
Now bend-LPE works with the copied curvature line:
BentGroup.png
BentGroup.png (22.75 KiB) Viewed 2618 times


Cheers
P.
Attachments
fpa_bending4U.svg
(69.69 KiB) Downloaded 224 times

chaffra
Posts: 6
Joined: Sat Nov 18, 2017 8:13 am

Re: path effect bend with convex, concave path

Postby chaffra » Sat Nov 18, 2017 9:51 pm

Thanks for the reply P. Except that it should be bending the other way (downward). But it only bends upward regardless of which way the copied Arc is pointing.

Thanks,
C.

Polygon
Posts: 393
Joined: Thu Dec 19, 2013 3:27 am

Re: path effect bend with convex, concave path

Postby Polygon » Sat Nov 18, 2017 10:05 pm

It will bent to whatever you like:
Bent.png
Bent.png (46.41 KiB) Viewed 2564 times


Cheers
P.
Attachments
fpa_bending4U2.svg
(157.56 KiB) Downloaded 213 times

Moini
Posts: 3381
Joined: Mon Oct 05, 2015 10:44 am

Re: path effect bend with convex, concave path

Postby Moini » Sat Nov 18, 2017 10:13 pm

Please adjust your transformation settings as advised above, chaffra. After this, move your bend path once before you copy-paste it into the path effect, to trigger a path rewrite.
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)

Polygon
Posts: 393
Joined: Thu Dec 19, 2013 3:27 am

Re: path effect bend with convex, concave path

Postby Polygon » Sat Nov 18, 2017 10:20 pm

@Moini. Have you tried it with the 250 parts group? It freezes Inkscape here when I try to use the copied curve.

Cheers
P.

chaffra
Posts: 6
Joined: Sat Nov 18, 2017 8:13 am

Re: path effect bend with convex, concave path

Postby chaffra » Sun Nov 19, 2017 12:00 am

I don't know what I am doing wrong. How do you select all identical shapes by color&fill? I do not see the merge function. Also I made sure the preference setting is correct as suggested. I also moved the paths to force a rewrite. But it's still bending the wrong way. I tried your example on my computer and it works but I can't reproduce how you did it.

The circle bend is an interesting case that might help solve it. How does Inkscape know which way to bend the pattern in that case?

Polygon
Posts: 393
Joined: Thu Dec 19, 2013 3:27 am

Re: path effect bend with convex, concave path

Postby Polygon » Sun Nov 19, 2017 12:48 am

It has to do with the direction of the path. You can flip/mirror it horizontally or vertically and see how the LPE changes the output accordingly. The actual version lets you adjust the direction and scale interactively:
BendLPE12.gif
BendLPE12.gif (194.58 KiB) Viewed 2512 times

Image

Cheers

Moini
Posts: 3381
Joined: Mon Oct 05, 2015 10:44 am

Re: path effect bend with convex, concave path

Postby Moini » Sun Nov 19, 2017 1:35 am

@Polygon: yes, the group also gets my computer fan whirling, with no apparent result after a couple of minutes (when I closed Inkscape forcefully).
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)

chaffra
Posts: 6
Joined: Sat Nov 18, 2017 8:13 am

Re: path effect bend with convex, concave path

Postby chaffra » Sun Nov 19, 2017 6:21 am

Ha, nice trick. It's working as I expect now. There's still the issue when I try to bend a big group of objects.
Thanks.

Polygon
Posts: 393
Joined: Thu Dec 19, 2013 3:27 am

Re: path effect bend with convex, concave path

Postby Polygon » Sun Nov 19, 2017 10:26 am

chaffra wrote:Ha, nice trick. It's working as I expect now. There's still the issue when I try to bend a big group of objects.
Thanks.

That´s the reason why I simplify the huge group to an oversee-able count of parts by merging objects which Inkscape can handle easily.
To do so make a right-click on an object and tell "select->by fill&contour then go Path->merge (cmd+"+")

Cheers
P.


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