Feature request: equality constraint between lines and arcs in the Sketcher

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chrili_rakete
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Joined: Thu May 15, 2014 11:51 am

Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrili_rakete »

Hello!

It would be extremely helpful for me to constrain the length of also a line and an arc in the sketcher. So I could generate (rather trivial) sheet metal unroll jobs in the sketcher.

Thank you!
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chrisb
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Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrisb »

I have needed this from time to time too.
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hokieengr
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Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by hokieengr »

As in set the line length and the length between the two end points of the arc to the same value?
chrisb
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Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrisb »

hokieengr wrote:As in set the line length and the length between the two end points of the arc to the same value?
Yes, although that is a constraint which I can set but it does nothing.
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chrili_rakete
Posts: 54
Joined: Thu May 15, 2014 11:51 am

Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrili_rakete »

No, I would rather suggest that the line length should be equal to the length of the arc. Thank you!
chrili_rakete
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Joined: Thu May 15, 2014 11:51 am

Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrili_rakete »

I posted this as a feature request into the bugtracker: http://freecadweb.org/tracker/view.php?id=2939
triplus
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Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by triplus »

chrili_rakete wrote:I posted this as a feature request into the bugtracker: http://freecadweb.org/tracker/view.php?id=2939
I asked Abdullah on his opinion about this:

https://forum.freecadweb.org/viewtopic. ... 90#p161448

And in the past there was a discussion on how such constraint could be useful in for example creating belt length:

https://forum.freecadweb.org/viewtopic.php?f=24&t=17372

Bottom line it doesn't look like such constrain will be made anytime soon. But i guess you never know what the future holds.
chrili_rakete
Posts: 54
Joined: Thu May 15, 2014 11:51 am

Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrili_rakete »

Thank you triplus – I did not know about this interesting discussion. I am not absolutely sure, but I think that my request is similar, but much more trivial, as I was asking for the length of a simple arc (given e.g. center, starting and end-point geometry, radius) to constrain. Compared to splines or other complex curved geometry as it is discussed in your post, the algorithm of constraining the length of an arc to another length might be considerably simpler. And for me: very useful ;)
triplus
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Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by triplus »

chrili_rakete wrote:Thank you triplus – I did not know about this interesting discussion. I am not absolutely sure, but I think that my request is similar, but much more trivial, as I was asking for the length of a simple arc (given e.g. center, starting and end-point geometry, radius) to constrain. Compared to splines or other complex curved geometry as it is discussed in your post, the algorithm of constraining the length of an arc to another length might be considerably simpler. And for me: very useful ;)
Unfortunately i explicitly asked about Arc length constraint. And the answer was it wouldn't be trivial to implement such constraint.

P.S. I am wondering if expressions could be used in combination with existing constraints. I guess it depends on the use case.
chrili_rakete
Posts: 54
Joined: Thu May 15, 2014 11:51 am

Re: Feature request: equality constraint between lines and arcs in the Sketcher

Post by chrili_rakete »

triplus wrote: Unfortunately i explicitly asked about Arc length constraint. And the answer was it wouldn't be trivial to implement such constraint.
Oh yes, I did notice that – but I think that microelly2 and abdullah continued to talk about "curves" in their answers. (Sorry if I might be wrong!)
triplus wrote: P.S. I am wondering if expressions could be used in combination with existing constraints. I guess it depends on the use case.
Yes, this is possible, at least in 0.17 – for example you can constrain the length of a line in a sketch to the length of an arc (Draft) via the expression "=Arc.Shape.Length"
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