Join 2 curves not possible because "join" button is disabled

[gludion]

Hello I've created 2 arcs using pie tool, then I converted them to curves.

Now I want to join them. Spent 1h to find the process on internet (click "Join" in Node mode?), but the "join" button is not enabled when I select those curves (see attached image and file)

bug.afdesign

[RM f/g]

They seem lines but they are not.

Have a look at the attachment.

bug2.afdesign

[gludion]

oh I think I got it. The end-points of the arcs are not single points, they are probably double-points because because I created the arc with pie tool using thickness = 0. Hence the software thought the arcs were closed loops.

If I create arc normally and remove unused parts, the created arcs are "normal" and can be joined.

EDIT: thx @RM f/g I figured out the pb while you were answering I guess

[R C-R]

8 hours ago, RM f/g said:

They seem lines but they are not.

When I open the bug.afdesign file the two curves are not expanded or arcs as in your bug2 file -- they are just simple open curves with one node at each end.

In fact, if I start from scratch & like the OP create two pie shapes, convert them to curves & delete all but a pair of different-sized arcs like in the original bug file, Join curves is not greyed out & works as expected.

I have included bug3.afdesign in which I created two new pie shapes, converted them to curves, removed the unneeded curve segments, & joined them. The history is included so you can see how I did that.

So I do not know why Join Curves does not work on the OP's curves. What am I missing?

[RM f/g]

On 12/8/2023 at 8:47 PM, R C-R said:

So I do not know why Join Curves does not work on the OP's curves. What am I missing?

In OP's curves the nodes are not end nodes. The curves are not lines with a beginning and an end.

Think of them as symmetric shapes – like circles – of which one half is flipped and lies on top of the other half.

[firstdefence]

@R C-R See image for a visual of @RM f/g insight.

 

bug fm insight.afdesign

[Pšenda]

On 12/8/2023 at 12:06 PM, gludion said:

I've created 2 arcs using pie tool

If you are trying to create a spiral, you can try the new Spiral Tool.
https://affinity.help/designer2/English.lproj/pages/Tools/tools_spiral.html

[Pšenda]

4 hours ago, firstdefence said:

See image for a visual of @RM f/g insight.

It would probably be useful to distinguish between open and closed curves in the description of the layer type. Description/tooltip Curve does not say anything about the curve type.

[firstdefence]

1 hour ago, Pšenda said:

It would probably be useful to distinguish between open and closed curves in the description of the layer type. Description/tooltip Curve does not say anything about the curve type.

That's an interesting idea, but correct me if I'm wrong, the problem is a bug that needs correcting.

[gludion]

thx to everyone for investigating the issue

As I said above, I found the origin of the problem.

@Pšenda indeed I wanted to create a  spiral (how did u guess?^^) and I was aware of the spiral tool, which makes all the computation for the user. I only wanted to ensure that I could connect arcs in a logo context, were the logo should be constructed from guidlines/grid/etc, without any "mystery" computations...

[Pšenda]

25 minutes ago, gludion said:

indeed I wanted to create a  spiral (how did u guess?^^)

There is another segment in your document that looks strikingly similar to the process of creating a spiral 🙂

 

36 minutes ago, firstdefence said:

the problem is a bug that needs correcting

Yes, there is an bug in the document that needs to be corrected. But since many operations depend on whether or not the curve is closed, this explicit indication of the curve type would help easier identification of the bug/incorrect curve type. In the given case, it is clear that Affinity "knows" that the curve is closed - and therefore does not offer a Join, but the user "does not know" - because it is not obvious from the shape of the curve.

[R C-R]

56 minutes ago, firstdefence said:

That's an interesting idea, but correct me if I'm wrong, the problem is a bug that needs correcting.

Do you mean a bug in the programming of the app or something else like a procedural error? Just asking because when I use the OP's 'recipe' for creating the two curves, I do not get any extra coincident nodes.

[Pšenda]

13 minutes ago, R C-R said:

I do not get any extra coincident nodes.

The problem is not the extra coincident nodes, but the fact that they are two closed curves.

 

 

[gludion]

@R C-R To create the arcs I used the pie tool, but instead of removing the unused part (inner radius, etc) I dragged the radius handle to get radius = 0 (it was foolish, I confess😝) it was much earlier in a prototyping phase, but later I totally forgot this, converted them to curves, and assumed they were'nt closed

Now I realize I could have easily detected the mistake by dragging any point or curve, but I was not very confident in the point selection mode and stubborningly selected points using rectangle-select, which selected the 2 coincidental points 😬

[R C-R]

50 minutes ago, Pšenda said:

The problem is not the extra coincident nodes, but the fact that they are two closed curves.

I see that but from what the OP said, there is no bug in the app causing that, just a procedural error. Do I still have this wrong?

[firstdefence]

13 minutes ago, R C-R said:

I see that but from what the OP said, there is no bug in the app causing that, just a procedural error. Do I still have this wrong?

I tried to replicate this issue but I cannot, without clear instruction to replicate I don't think we can consider this to be a bug.

[lepr]

in Serif's words: "by design"

[Pšenda]

35 minutes ago, firstdefence said:

I tried to replicate this issue but I cannot, without clear instruction to replicate I don't think we can consider this to be a bug.

I think the process of creating an incorrectly closed curve instead of an open curve is that a zero-width Pie tool was used, when Convert to curve does not create an open curve, but a closed (zero-width shape) because the zero-width arc is not converted to the open curve command, but only a command to create a closed curve/shape with zero width.

P.S. Personally, I think it makes sense - the user didn't tell the application anywhere to convert the shape (albeit with zero width) to just an open curve.

Edited December 11, 2023 by Pšenda

[R C-R]

23 minutes ago, Pšenda said:

I think the process of creating an incorrectly closed curve instead of an open curve is that a zero-width Pie tool was used, when Convert to curve does not create an open curve, but a closed (zero-width shape) because the zero-width arc is not converted to the open curve command , but only a command to create a closed curve/shape with zero width.

I do not think there is any good reason for the Convert to Curves command to convert a pie shape to an open curve, even if the hole radius is set to 100%. It may be something some wants to use as a starting point for other shapes, a bit like in this admittedly contrived Silly shapes made from pies.afdesign example.

IOW, it seems to be just a case of the app doing exactly what it was intended to do, even if it is not obvious.

Edited December 11, 2023 by R C-R
corrected missing "not" in my reply

[firstdefence]

The way I understand it is that creating the arc in that manner is consistent with what I would expect to happen, making the pie hole 100% merely overlaps the inner radius over the outer radius resulting in a stack, the arc is still a pie shape until it is converted to a curve but the convert to curve action does not remove one of the stacked radii, it simply keeps it covered and the closed shape merely becomes a closed curve.

Everything is logical and there is no bug as far as I can see.

If I were to make an arc from a pie shape I would convert to a curve and break the nodes at the two end points of the arc'd radius and delete the remaining straight curves.

[firstdefence]

We do now have the spiral tool (v2.3.0) which can make all manner of arc and er! spirals.

[Pšenda]

12 hours ago, R C-R said:

it seems to be just a case of the app doing exactly what it was intended to do

Yes, it's the same as a Rectangle with zero width/height, where it's still a Rectangle (and thus its width/height can be expanded again), not a straight Line (without width and height parameter).