I have created a closed shape that has a straight line on one side. I duplicated the shape, flipped it, and aligned the two straight lines of the two shapes perfectly. I selected both shapes, clicked on Union, and nothing happens. The lines don't disappear and the two shapes aren't even stuck together. What am I doing wrong??

They probably weren't aligned perfectly so you ended up with two subpaths in one object. Turn on snapping to nodes and see if you can snap the straight line bit. Then do the Union.

Thanks, that worked. I was being so careful before and did it several times. I guess you really have to use snapping to nodes to get things aligned just right.

prkos wrote:They probably weren't aligned perfectly so you ended up with two subpaths in one object. Turn on snapping to nodes and see if you can snap the straight line bit. Then do the Union.

In situations like this I usually draw a rectangle or ellipse over the join between the subpaths, extending into each side, then union that with the original path. That gets me close enough that a little node editing is all that's required to tidy up the result (usually just deleting one or two errant nodes).

In fact for this type of task I tend to drag the straight edge of one or both of the objects to form a curve that's definitely overlapping before I perform the union. That should ensure that the union will produce a single-subpath object.

kearnine wrote:I was being so careful before and did it several times. I guess you really have to use snapping to nodes to get things aligned just right.

The 'Align and Distribute' dialog uses the visual bounding box to align selected objects i.e. aligning the outside edge of the stroke. You have to manually align by dragging with snapping nodes to nodes (and/or to paths) enabled if you need two coinciding path segments (i.e. aligned with the centerline of the stroke).

You can easily test it by using two basic shapes (e.g. squares) with a very wide stroke to see the difference.

Thank you, Xav and Suv. Very helpful information!

~suv wrote:

kearnine wrote:I was being so careful before and did it several times. I guess you really have to use snapping to nodes to get things aligned just right.

The 'Align and Distribute' dialog uses the visual bounding box to align selected objects i.e. aligning the outside edge of the stroke. You have to manually align by dragging with snapping nodes to nodes (and/or to paths) enabled if you need two coinciding path segments (i.e. aligned with the centerline of the stroke).

You can easily test it by using two basic shapes (e.g. squares) with a very wide stroke to see the difference.

There is a bug report on align and distribute not respecting the geometric bounding box selection https://bugs.launchpad.net/inkscape/+bug/473608

suv has posted in that bug report and provided the same suggestion as here (use snapping and move it with the selection tool).

It is currently not assigned so will not be resolved in any foreseen release.

-Rob A>