Sketcher linked geometry

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emills2
Posts: 875
Joined: Tue Apr 28, 2015 11:23 pm

Sketcher linked geometry

Post by emills2 »

is there a strong reason externally linked geometry cannot have an option to be used as sketch geometry? it seems that as it is, it behaves more or less like construction geometry. i know the solver has to do more work with construction geometry, but that not what i'm talking about. what i mean is the geometry output of the sketch.

having to trace everything after linking it is a lot of work.

Tracing may not seem like a big deal at first glance, but in serious (large) models, the ratio of driving geometry to derived geometry is extremely small. picking an edge is easy, retracing is an order of magnitude more work.

so we're not talking about twice the work here, but potentially dozens, hundreds of times more work.

A major improvement would also be to allow selection of an entire face and linking it's projected wire to the sketch, but that is admittedly a bunch of work.

Allowing the linked geometry the option to be included in output geometry could be a low hanging fruit
chrisb
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Re: Sketcher linked geometry

Post by chrisb »

That's a longterm wish, and as far as I can remember, Abdullah was working on it. However, he hadn't much time to invest into FreeCAD
emills2 wrote: Thu Feb 27, 2020 6:47 am Allowing the linked geometry the option to be included in output geometry could be a low hanging fruit
Go for it!
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emills2
Posts: 875
Joined: Tue Apr 28, 2015 11:23 pm

Re: Sketcher linked geometry

Post by emills2 »

[/quote]Go for it!
[/quote]

if i could write C++ i'd offer a PR :)

just guessing, but it could even use the same "toggle construction" UI button. However i have no clue what is involved in outputting geometry.
chrisb
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Re: Sketcher linked geometry

Post by chrisb »

emills2 wrote: Thu Feb 27, 2020 7:30 am if i could write C++ i'd offer a PR :)
It's not a god given ability, every other programmer had to learn it too, so you may give it a try
just guessing, but it could even use the same "toggle construction" UI button.
I'm afraid it is more complicated than that: Appropriate constraints have to be added depending on the type of reference.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
emills2
Posts: 875
Joined: Tue Apr 28, 2015 11:23 pm

Re: Sketcher linked geometry

Post by emills2 »

chrisb wrote: Thu Feb 27, 2020 10:13 am I'm afraid it is more complicated than that: Appropriate constraints have to be added depending on the type of reference.
i'll take your word for it. i was simply looking at it from the perspective that right now, i can have a sketch with externally linked geometry, normal geometry and construction geometry. this is the current state. the output of the sketch to be used downstream is it's shape, which is a wire or a compound of wires. right now, only normal geometry is being sent to the output shape.

in principle, without adding any new information to the sketch, one could use the information of the external geometry and write an additional wire in the shape compound. in principle...and my C++ is way too weak.

>>> obj
<Sketcher::SketchObject>
>>> obj.Shape.Wires
[<Wire object at 000001325262D7F0>, <Wire object at 000001325262D570>, <Wire object at 000001325262D4F0>, <Wire object at 000001325262D970>]
>>>

i guess the tricky part would be to figure out the correct stage to add the geometry so it can still be inspected when the output wires are being looked at to form closed wires. i suppose maybe that might be dependent on the constraints as you said.
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