Interpolate disregards rotation/skew state of an ellipse

[Peter]

Running the interpolate extension on a rotated or skewed ellipse produces a result with the ellipses as originally drawn (ie. without the skew or rotation).

Inkscape version is 0.47pre4.

[su_v (suv-lp)]

possibly related:
Bug #491188 “Interpolate Extension fails if Preferences are set to Preserved”
https://bugs.launchpad.net/inkscape/+bug/491188

[Peter (walle)]

The preferences for Transforms do not affect this bug. Both preserved and optimized give the same result.

[su_v (suv-lp)]

reproduced with Inkscape 0.47 r 22583 and 0.47+devel r9066 on OS X 10.5.8

I think it is the same underlying issue (interpolate fails to take an explicit 'transform' attribute into account): shapes like ellipses, stars, polygons and spirals do keep a (preserved) 'transform' attribute - no matter whether the 'Transform' preference is set to 'optimized' or 'preserved' (see bug #233935 “Moves of circle stored in transform Attribute”).

[Kirk Cooper (enoted)]

I am finding the same issue where the interpolate does its own thing. Here is a visual example. It will describe the problem better than words

[Kirk Cooper (enoted)]

sorry I foregot to mention the results of the interpolate issue came from version 0.48 dev r10300

[su_v (suv-lp)]

@d$k - please attach the SVG file as well (the screenshot itself is not sufficient: this bug (bug #518768) is triggered by a transform attribute in the SVG source code, which is most easily verified if you make the SVG file used for the screenshot available here in the bug tracker).

[su_v (suv-lp)]

Disregard my earlier comment:

Steps to reproduce:
1) draw a circle
2) draw an ellipse
3) center the ellipse on the vertical axis relative to the circle (e.g. 'Relative to: First selected')
4) 'Extensions > Generate from Path > Interpolate…'

-> the 'translate()' transformation of the aligned ellipse is ignored by the extension and the interpolation is done between the position of the two shapes before they have been aligned.

Linking as duplicate to bug #518768. Please add a comment here and revert the duplicate status if you don't agree and think these are different issues.

[Alvin Penner (apenner)]

- attached is a modified version of interp.py.
- this will take into account the transform element that may be associated with each selected item.

[Kirk Cooper (enoted)]

ok here is the SVG of the file that shows the Interpolate function not working correctly.

The top and bottom circles are the two reference points. the version used was 0.48+dev r10300
thanks

[Alvin Penner (apenner)]

thanks for the svg file. could you try running this with the new interp.py file posted above?
You'll need to copy the interp.py file into the directory \Inkscape\share\extensions\ to replace the file that is currently there.

[Kirk Cooper (enoted)]

It works great so far ! Thanks

[Alvin Penner (apenner)]

good to hear, committed to bzr rev 10378

[jazzynico (jazzynico)]

Backported to the branch, revision 9813.

[Kirk Cooper (enoted)]

The fix works very well in 0.48.2 portable :D