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Knife Tool produces bad geometry in certain cases (disconnected edges/vertices, overlapping faces)
Confirmed, NormalPublicBUG

Description

if i use tools knife i see this bug.

Event Timeline

Sebastian Parborg (zeddb) lowered the priority of this task from 90 to 30.Mar 7 2019, 11:17 AM

Can't reproduce this.

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In 2.79 there is no such thing, it normally cuts according to my form.
i download new version 2.80.47
blender-2.79.0-git.7ad367d0231d-windows64


The result should be a cut according to the shape that I drew on the cube as it was done in the screenshot at 2.79, at 2.80 it turns out that after clicking on Enter.

Sebastian Parborg (zeddb) raised the priority of this task from 30 to 90.Mar 11 2019, 12:04 PM

I still can't reproduce this. The knife tools cuts as I expect it to on the default cube.

I still can't reproduce this. The knife tools cuts as I expect it to on the default cube.

I asked many who use 2.8 for all, it works fine. It's very strange why it works for me. I will try a clean build without addons in the evening. Perhaps there is a bug. I also tried on the plane and got the same strange result.

Vyacheslav (Ghostil) added a comment.EditedMar 11 2019, 8:38 PM

I still can't reproduce this. The knife tools cuts as I expect it to on the default cube.

Hi. You no see this bug if you use default unit scale 1.0, change this as my 0.01 and you see this bug.

Sebastian Parborg (zeddb) lowered the priority of this task from 90 to 50.

Philipp Oeser (lichtwerk) renamed this task from knife bug in 2.8 to Knife Tool produces bad geometry in certain cases (disconnected edges/vertices, overlapping faces).Sep 3 2019, 11:37 AM

Like mentioned in T65090 / T68713, this seems to be dependent on (wide angle?) view points, also origin locations?

Hi. This looks the same issue I added here.
https://developer.blender.org/T70293

I hope it will help to solve the issue.
I have also found that if I change Blender's window size then the issue will be able to disappear. It looks like it depends on specific viewport view + window size.

Here is another one strange situation with the cut tool. It cuts really strange.
This model


i ran into a couple of issues aswell today with the knife tool (2.80 release).
mostly happens when puting points on edges manually. going from vert to vert with no manual points set on edges seems to go fine.

I ran into this problem at work today as well (2.81a). It seems to have to do with the Unit scale as mentioned above. If I work in unit scale 1 it usually works. Unless my geometry have very small or large dimensions. Going lower or higher gives me strange results. Another thing that helped was switching to Orthographic view instead. Then I could cut without any errors.

Richard Antalik (ISS) changed the task status from Confirmed to Needs Information from User.Jan 24 2020, 9:35 PM

I have re-triaged this report and can not reproduce it.
Can you please check if this is still an issue in latest build?
https://builder.blender.org/download/

@Richard Antalik (ISS)
I downloaded the latest version. And yes it still has the issue.

Richard Antalik (ISS) changed the task status from Needs Information from User to Confirmed.Jan 27 2020, 12:12 PM
Richard Antalik (ISS) changed the subtype of this task from "Report" to "Bug".

Saw some friends on discord speaking about the same problem, they even found a video on it...

https://www.youtube.com/watch?v=TjkaC6tdM9U