Polyline from selection without changing line angles

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jamesjconnell
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Posts: 8
Joined: Thu Feb 24, 2022 8:56 pm

Polyline from selection without changing line angles

Post by jamesjconnell » Thu Nov 10, 2022 1:44 am

I'm not sure if this is a "How do I" or a feature request but hopefully this is an OK place to put it.

I have a task that regularly requires offsetting some, but not all, lines in a shape (usually a rectangle). I then need to close those back up in order to make a fill hatch. I've been trying to tweak the polyline from selection settings as well as the arrow key move settings to make this as automated as possible.

Here are my settings:
Move Settings.PNG
Move Settings.PNG (9.14 KiB) Viewed 2362 times
Draw Poly Settings.PNG
Draw Poly Settings.PNG (4.56 KiB) Viewed 2362 times
Here is an example of a rectangle that I might need to make after three of the lines have been nudged by 0.1":
Lines Open.PNG
Lines Open.PNG (31.37 KiB) Viewed 2362 times
Here is the result after using the polyline from selection tool:
Lines Closed.PNG
Lines Closed.PNG (31.76 KiB) Viewed 2362 times
As you can see the bottom corners are fine as only one of the lines was nudged out of position. However on the top where both lines have been nudged I get a chamfer on one side and an angled line on the other. For my purposes the chamfer would actually be aceptable if not desired. However having the top line change it's angle wont work for the use case.

Is there an alternative way to accomplish this or could a setting be added for the polyline creation that essentially runs the command as it is with the added restriction that lines can't change their relative angle. Essentially this would be like using the trim both tool on anywhere where the gap is found.

I should also note that I'm aware of the trim both tool and that is curently what I use. What I'm looking for here is a means of automating as I do this process a lot. The reason I need to do this is because I'm setting up cut files for a router where there are rabbet joints and dado joints and if we make the joint line fall exactly in line with the outer part cut line there can be small fuzz of material left over. By offsetting the joint route out by 0.1" we make sure all the material is removed before coming back and doing the parts cut out pass. This is also why only some of the lines of the shape are adjusted as moving internal lines would make the joint larger than needed.

Thanks!

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Husky
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Re: Polyline from selection without changing line angles

Post by Husky » Thu Nov 10, 2022 2:42 am

Hi,

for clarification reasons ... :wink:

You have a rectangle e.g. 8" x 5",
you move the vertical lines each by 0.1" (one to the right, one to the left),
then you have to close this modified rectangle,
the result shout then be a 8.2" by 5" rectangle. Correct? Oh no, I see now you moved 3 lines. Doesn't matters ...

What I would do ... e_surprised
Make sure the source rectangle (8" by 5") is a polyline. Should be easy to accomplish ...
then select the rectangle, check the Property Editor for "Size", change the 8 by 5 to 8.2 by 5.1 and see what happens ...
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CVH
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Re: Polyline from selection without changing line angles

Post by CVH » Thu Nov 10, 2022 9:02 am

jamesjconnell wrote:
Thu Nov 10, 2022 1:44 am
As you can see the bottom corners are fine as only one of the lines was nudged out of position. However on the top where both lines have been nudged I get a chamfer on one side and an angled line on the other.
This is a known behavior for both OG, OC & OL.
Where nudging or bridging gaps occur can be explained knowing at what segment you indicate.
The tool starts looking backwards first and does a plain copy of the other ending its coordinate.
It then may alter the nearest point of the next segment or add a bridge.

The problem also exist with arc segments.
In such cases the bulge factor may not reflect the correct value concerning the start and endpoint and the arc segment isn't the same anymore.

There is nothing you can do about that.
There is no variant of OG, OC & OL that trims entities in the direction of the intersection.
Even now with new resources: https://www.qcad.org/rsforum/viewtopic. ... 158#p34978

The only advise that I can give is to trim all the contour segments pairwise before creating a Polyline.

Also see:
https://www.qcad.org/rsforum/viewtopic. ... 158#p33158
https://www.qcad.org/rsforum/viewtopic. ... 361#p36361
https://www.qcad.org/rsforum/viewtopic. ... 782#p34782

Regards,
CVH
Last edited by CVH on Sun Nov 13, 2022 8:46 am, edited 1 time in total.

jamesjconnell
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Posts: 8
Joined: Thu Feb 24, 2022 8:56 pm

Re: Polyline from selection without changing line angles

Post by jamesjconnell » Thu Nov 10, 2022 6:02 pm

Husky,
Thanks for the response. That unfortunately won't work because it always scales from the center. In one direction it works because I'm offsetting equally in both directions. In the other direction it splits the 0.1" into 0.05" on each side when I need a 0.1" all on one side.

CVH,
Thanks for all the references. At least I know now I'm searching for a solution that probably can't be found at least with the software as it stands. The selection pair wise does seem to work though and that at least improves the time it takes to process if not completely automate it.

Thanks,
J

CVH
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Posts: 3416
Joined: Wed Sep 27, 2017 4:17 pm

Re: Polyline from selection without changing line angles

Post by CVH » Thu Nov 10, 2022 8:42 pm

J,

Sure there are solutions, with scripting almost anything can be achieved. :wink:
And in this case like in most, 'Polyline from Selection' is merely a script, a PRO script, proprietary and not open source.

Polyline creation with auto trimming is one on my TODO list, but it is a long list. :lol:
I have no problem with just 4 sides of a rectangle but rather with thousands of arc segments. :wink:

Regards,
CVH
Last edited by CVH on Sun Nov 13, 2022 8:47 am, edited 1 time in total.

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Husky
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Re: Polyline from selection without changing line angles

Post by Husky » Thu Nov 10, 2022 9:57 pm

jamesjconnell wrote:
Thu Nov 10, 2022 6:02 pm
That unfortunately won't work because it always scales from the center. In one direction it works because I'm offsetting equally in both directions. In the other direction it splits the 0.1" into 0.05" on each side when I need a 0.1" all on one side.
Ok, good point. :wink:

However - even if I do it step by step as a user who is not used to that task I need 24 second to accomplish that task. Is that really so bad that it needs improvement ...?

Rectangle manipulation.gif
Rectangle manipulation.gif (458.72 KiB) Viewed 2251 times
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