[AD] How to join separate open curves

[rubs]

Please enlighten me... I'm doing pretty advanced stuff in AD already, but right now I'm feeling stupid. I can easily Divide an open curve made of two segments (imported from elsewhere) into two separate curves, but I cannot find a way to join them together again as a compound curve. I tried Add, Combine, Join (here) and Close but they stay separate no matter what. I've attached an SVG with such a curve.

 

Thanks in advance.

curve-2.svg

[R C-R]

This had me going in circles for a while but I finally figured out that when I click "Divide" on your (Curves) object to make them separate curves, it closes each of them! You can see this if you use the Node tool to drag somewhere on their paths besides their two nodes.

 

This is probably a bug, but knowing what happens makes it possible to fix this -- you will have to break each node & discard one of each of the pairs of (once again) open paths before Join will work.

 

Still working on the Add & Combine issue ....

 

EDIT: Add only works to create a compound "Curves" object if the curves are closed and their paths enclose some non-zero area -- if you leave them as closed paths with two straight segments connecting their nodes (one not obvious because it is on top of the other) that path encloses zero area & the Add (union) operation does nothing.

 

So ... are we having fun yet?  :wacko:

Edited December 17, 2016 by R C-R

[rubs]

Thanks for your insights! The only workaround I found to convert the curves back to a compound "Curves" object is to drag the curves so they have some enclosed area, Combine or Add them, then break them and delete the extra nodes. This is incredibly complicated: a single Add or Combine should do it.

 

It seems that AD's implementation is flawed in several aspects:

 

1. Divide transforms open curves in closed ones, it shouldn't do that.

2. Geometric (Boolean) operations don't work with zero-area curves.

3. Add and Combine do nothing to open curves.

[rubs]

I just tried Add / Combine with the Alt modifier and the result was indeed a compound object... but it's invisible and non-selectable on screen. So that's flaw number four, I believe.

[gdenby]

Here's something weird I just noticed. If I divide the layer, I get 2 curves. After much frustration, I happened to select one, change to node tool, and I dragged the center of the line. I ended up w. a closed arc. Same for other. Somehow, the 2 lines are a closed object. I was able to duplicate the problem by using the pen tool, drop a node, extend the line, and then go back and click on the 1st node. An oddity produced by using the pen drawing method in an unexpected way.

[Alfred]

Here's something weird I just noticed. If I divide the layer, I get 2 curves. After much frustration, I happened to select one, change to node tool, and I dragged the center of the line. I ended up w. a closed arc. Same for other. Somehow, the 2 lines are a closed object.

 

That's what R C-R was describing earlier. The current (buggy?) behaviour of the Divide command is that any unclosed curves in the selected Curves object are automatically closed.

[Alfred]

The current (buggy?) behaviour of the Divide command is that any unclosed curves in the selected Curves object are automatically closed.

 

The other Geometry commands work the same way.

[gdenby]

That's what R C-R was describing earlier. The current (buggy?) behaviour of the Divide command is that any unclosed curves in the selected Curves object are automatically closed.

 

That's what happens when I try figuring something while working on the 1st cup of morning coffee. I'd run into that behavior w. curved objects, never ran into it , or noticed at least, w. single lines.

 

Something I don't understand is how the 2 line segments were in the same layer w/o being shown as separate curves. A side effect of converting file to SVG?

[Alfred]

Something I don't understand is how the 2 line segments were in the same layer w/o being shown as separate curves. A side effect of converting file to SVG?

 

It's standard behaviour, Greg. If you 'add' two Curve objects, you get a single Curves object (i.e. a polycurve). The oddity in Affinity is that the original objects become closed automatically, instead of either being left unclosed or refusing to join until you close them manually.

[R C-R]

Elsewhere I mentioned that it would be really helpful if on the Layers panel and/or in the document window there was some visual indication of open paths. In the Layers panel it could be as simple as changing the "(Curve)" layer type designator to "[Curve]" or "|Curve|" or something more obvious like "(Open Curve)."

 

In the document window maybe the red node indicator could be eliminated when a curve is closed -- as I understand it, that just indicates the end node of a curve, but I don't understand why that is needed when the curve is closed.

[Alfred]

Elsewhere I mentioned that it would be really helpful if on the Layers panel and/or in the document window there was some visual indication of open paths. In the Layers panel it could be as simple as changing the "(Curve)" layer type designator to "[Curve]" or "|Curve|" or something more obvious like "(Open Curve)."

 

In Serif DrawPlus, a closed curve is identified as "(Closed Curve)" and an open curve is identified simply as "(Curve)". I don't know why they haven't done something similar in the Affinity apps.

 

In the document window maybe the red node indicator could be eliminated when a curve is closed -- as I understand it, that just indicates the end node of a curve, but I don't understand why that is needed when the curve is closed.

 

I also don't understand why it's needed when the curve is closed.

[R C-R]

In Serif DrawPlus, a closed curve is identified as "(Closed Curve)" and an open curve is identified simply as "(Curve)". I don't know why they haven't done something similar in the Affinity apps.

Maybe because they are trying to leave more room for layer names? That is why I suggested the less noticeable change in bracket style. Anything is better than nothing.

I also don't understand why it's needed when the curve is closed.

 

So it is true that great minds work alike ... & so do ours.  :lol:

[Alfred]

LOL. (Thanks for quoting, and therefore highlighting, my "Closed/Cosed" typo. Now corrected!)

[R C-R]

Better now?  ;)