nodes w/one handle that won't rotate - bug?

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brynn
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nodes w/one handle that won't rotate - bug?

Postby brynn » Fri Oct 10, 2008 10:04 am

Hi Friends,
I've recently noticed that on nodes with only one handle showing (one retracted), the handle won't rotate. Is that by design? I don't see any bugs about it at Launchpad. And I seem to remember being able to rotate single handles in the past, although that may have been in v 0.44. I'm using 0.46 now. And this is happening only on non-end nodes. The single handle on an end node rotates as expected. And as soon as I pull out the retracted handle of non-end nodes, they both rotate normally.

Has anyone else noticed this? Is it supposed to happen? Because it's kind of annoying. So I'd like to either report as a bug, or request a new feature, that allows it to rotate. Can you give me any guidance or advice?

Thanks for your help :D

PS - More info - If a node has 2 handles, and I retract one, the remaining one rotates normally. It's only one-handled nodes that have been created with the paint bucket tool :tool_paintbucket: that don't rotate. I don't have an example at the moment, because I just pulled out the 2nd handle of one of these, but I should come across another one shortly. Then I'll make up a sample SVG and upload it. B

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microUgly
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Re: nodes w/one handle that won't rotate - bug?

Postby microUgly » Fri Oct 10, 2008 11:26 am

I think this may be by design. You'll find it only happens when the node-type is "smooth" (as opposed to "cusp"). In a way it makes sense that you can't rotate the handle of a smooth node with one handle. Take the following example:
Image
The handle on node 1 cannot be rotated because it's a smooth type. If it could be rotated it wouldn't produce a smooth path. To rotate it you have to make it a cusp node.

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brynn
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Re: nodes w/one handle that won't rotate - bug?

Postby brynn » Fri Oct 10, 2008 1:15 pm

Thanks micro.
It happens with cusp nodes as well as smooth. I've just made up a sample and uploaded it, but it's a smooth node. So I'll wait until I find a one-handled cusp node that won't rotate, before I post it.

How did you make your example where the one-handled smooth node won't rotate? Because I haven't been able to do it, except with the paint bucket tool by accident.

It does raise another question, though. What is the difference between a one-handled smooth node and a one-handled cusp node? Don't they behave exactly alike?

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Re: nodes w/one handle that won't rotate - bug?

Postby microUgly » Fri Oct 10, 2008 2:04 pm

brynn wrote:It happens with cusp nodes as well as smooth.

If it does then Inkscape must have a bug where it's giving the node the wrong shaped node icon. I can't think of a situation where the angle of a one-handled cusp node can be restricted by it's adjacent nodes.

How did you make your example where the one-handled smooth node won't rotate?

Select a segment (i.e. two adjacent nodes) and click the "Make selected segments lines" button (the one that has a straight line between two nodes) or press ShiftL

It does raise another question, though. What is the difference between a one-handled smooth node and a one-handled cusp node? Don't they behave exactly alike?

No. I just illustrated that in my previous post :) Node 1 is a one-handled smooth node and node 2 is a one-handled cusp node. Notice how the handle on node 1 is at the exact same angle as the path between node 1 and 2? It can't possibly be at any other angle if it is to maintain a straight line between those nodes. If you move either node 1 or node 2 the handle will move to ensure the segment remains straight.

But you'll notice that the handle on Node 2 is at a very different angle to that segment and that's because it's a "Cusp" node. You can move it's handle at any angle to create a cusp in the path whilst still allow the segment to be straight.

Note that a one-handled smooth node can be rotated with the adjacent node has two handles. When the other node has two handles the segment is no longer a straight line and it can actually create a cusp despite being smooth--this is also correct behaviour.

If something needs changing, it should be the trace function to stop producing one-handled nodes--when it comes to editing automatically generated path it can be frustrating work with such nodes and the same shape can be produced without using them.

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brynn
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Re: nodes w/one handle that won't rotate - bug?

Postby brynn » Sun Oct 12, 2008 10:21 pm

Oh dear :oops: When I asked
What is the difference between a one-handled smooth node and a one-handled cusp node? Don't they behave exactly alike?

and
How did you make your example where the one-handled smooth node won't rotate?

I was thinking about curved lines (gently curved or otherwise). I'm sorry I wasn't more specific, but I think of nodes on straight lines as not needing handles. Anyway, on non-straight lines, don't they normally behave alike? Can you make a one-handled node on a non-straight line that won't rotate?
Note that a one-handled smooth node can be rotated with the adjacent node has two handles. When the other node has two handles the segment is no longer a straight line and it can actually create a cusp despite being smooth--this is also correct behaviour.

Ooooooh!! Ok, every time I've found a non-rotating one-handled node, it's right next to a corner node (cusp or smooth) with both handles retracted. :idea: And that makes that segment a straight line :!: Ok, ok, I think I'm understanding it now. Yes, it makes sense now!
If something needs changing, it should be the trace function to stop producing one-handled nodes--when it comes to editing automatically generated path it can be frustrating work with such nodes and the same shape can be produced without using them.

Agreed!
Especially when it puts one one-handled node, right on top of another, with their handles on opposite sides. Ya gotta wonder why the code doesn't just putting a single node with 2 handles :lol: (no offense intended)

Well anyway, thanks microUgly, I think I understand this now :D

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Re: nodes w/one handle that won't rotate - bug?

Postby microUgly » Sun Oct 12, 2008 10:38 pm

brynn wrote:Can you make a one-handled node on a non-straight line that won't rotate?

No. It's difficult to explain why. This of it this way, if you could, what angle would it be fixed at?

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Re: nodes w/one handle that won't rotate - bug?

Postby brynn » Mon Oct 13, 2008 2:23 pm

No, I understand now, micro, why it can't be done.
I would have said, well then why does the paint bucket tool make them. But your earlier comments made me realize the the node next door has no handles, forming a straight segment there. So I understand now :D

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Re: nodes w/one handle that won't rotate - bug?

Postby EarlyBlake » Sun Dec 07, 2008 6:37 pm

I getting something like that on paths that have fill, but no stoke. I can't move the handle until I get the second node handle to pop out out. (I think it's happening on both node types but not 100% sure.) I usually can grab the second handle if I turn on stroke. Occasionally I have to turn on stroke and change the magnification. I turned down the grab radius in preferences because of anther problem, that could have something to do with it. I've forgotten what the problem I was having that made me turn it down. :lol:


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