Author Topic: Delete part of a polyline  (Read 894 times)

Offline klypso

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Delete part of a polyline
« on: January 16, 2020, 03:52:43 am »
Hi,

I'd like to delete a part of a polyline to modify the form, any idea ? (as you can see it's too tight i want to enlarge it but moving the dots is not precise enough to be done)

Online dh42

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Re: Delete part of a polyline
« Reply #1 on: January 16, 2020, 04:16:13 am »
Hello

Draw 2 small lines that cross your polyline where you want to cut it then select the polyline and the 2 lines ; hit CTRL B (break at intersection) and you get a separate polyline for the section you want.

You can also draw the replacement polyline, with the ends that cross the older one, then CTRL B with the 2 polylines selected and then you can remove the "rest" of lines that you do not want (then "join" the results)

another way is to use Eddy's polyline add/remove points to remove/add some points in the area of interest without cutting the polyline, then move the points of the polyline with the mouse to get the new shape you want.

http://www.atelier-des-fougeres.fr/Cambam/Aide/Plugins/polyaddpoints_FR.html

in the case off your drawing, you can first remove most of the points in the area to modify to obtain something more easy to "form" a "draft" shape, then add new points where you want more "flex" to fine tune the shape.

edit: still no reply from Andy about your topic that is broken.

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David
« Last Edit: January 16, 2020, 05:33:37 am by dh42 »

Offline klypso

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Re: Delete part of a polyline
« Reply #2 on: January 18, 2020, 02:00:14 am »
Thanks for your answer dh42,

So i tried the cut at intersect methode, it just breaks my polyligne in many parts, even with the lines that cross it

I tried the edd's polyline plug in, but i can't add point on the polyline, i zoomed too much to properly touch the line, my dot it either upper of down the line.

 ???
« Last Edit: January 18, 2020, 02:06:23 am by klypso »

Online dh42

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Re: Delete part of a polyline
« Reply #3 on: January 18, 2020, 02:14:14 am »
Hello

To add/remove points the polyline to treat must be selected.

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David
« Last Edit: January 18, 2020, 05:52:53 am by dh42 »

Online dh42

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Re: Delete part of a polyline
« Reply #4 on: January 18, 2020, 05:53:54 am »
Quote
I tried the edd's polyline plug in, but i can't add point on the polyline, i zoomed too much to properly touch the line, my dot it either upper of down the line.

bee sure the "snap to grid" is disabled. (accrochage à la grille désactivé) ; if not, the "point" jump from a grid point to another and you can't place it on the line.

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David

Offline klypso

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Re: Delete part of a polyline
« Reply #5 on: January 18, 2020, 05:55:13 am »
Thanks a lot David ! It works ! :)

Online dh42

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Re: Delete part of a polyline
« Reply #6 on: January 18, 2020, 06:32:44 am »
Nice !

This plugin is very very useful !

Another one is useful in some cases, smoothpolylines
http://www.atelier-des-fougeres.fr/Cambam/Aide/Plugins/PolylineSmooth_FR.html
http://www.atelier-des-fougeres.fr/Cambam/Aide/Plugins/PolylineSmooth.html

One of the workflow that I use sometimes to modify this kind of design that contain only straight lines it is the following.

- use smoothpolyline to get a regular placement of the points (on complex polyline, it may be a good idea to first split the polyline in multiple polylines that need different treatments)

- use the add/remove points plugin to redesign the area you want

- use an arc fit to try to replace straight lines by arcs ... It may need multiple test to get suitable values.

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David
« Last Edit: January 18, 2020, 07:19:40 am by dh42 »

Online dh42

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Re: Delete part of a polyline
« Reply #7 on: January 18, 2020, 07:12:39 am »
« Last Edit: January 18, 2020, 07:20:06 am by dh42 »

Offline klypso

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Re: Delete part of a polyline
« Reply #8 on: January 18, 2020, 15:24:20 pm »
Awesome ! Thanks for the diagram ! i'll look at it asap :)

Offline Bob La Londe

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Re: Delete part of a polyline
« Reply #9 on: January 19, 2020, 01:25:41 am »
One thing to know is that sometimes CamBam doesn't show a complex polyline exactly as it is. 
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

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http://www.CNCMOLDS.com

Offline onekk

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Re: Delete part of a polyline
« Reply #10 on: January 21, 2020, 17:03:44 pm »
hitting "CTRL +B" could lead to many segments as the algorithm seem to break also the angles, or when the polyline change direction, like when two arcs are not in the same convexity.

The problem could be avoided tracing the "limiting lines" and then using:

Edit - Intersection Points

selecting the created pointlist and then

Edit - Polyline - Break at Points

If the created pointlist has unwanted points, you could explode it (CTRL+E)  and select only needed points and rejoin with "CTRL+J"

This method make the things more clean using only the standard menu items, unfortunately the former commands  lacks of keyboard shortcuts.

Regards

Carlo D.
Carlo D. (onekk)

eShapeoko #343 750x1000 mm + GRBL + bCNC + CamBam