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knife buggy cut
Closed, ResolvedPublic

Description

System Information
Operating system and graphics card
windows and linux

Blender Version
Broken: Blender 2.71 "stable"
Worked: i don't remember a version of Blender in which the Bmesh knife was working without problems

Short description of error
Knife can duplicate vertices on cut edges, as reported here :
http://blenderartists.org/forum/showthread.php?317503-Problem-Knife-Tool-Strange-behavior&p=2691898&viewfull=1#post2691898

Exact steps for others to reproduce the error

  • Load the blend with Load UI so you get the same view and visual

  • press K and try to cut at these locations :

http://i.imgur.com/JmHHYPM.jpg

  • If you managed to did the cut roughly there, you'll notice the vertices there are doubled :

http://i.imgur.com/oZfSl5g.jpg

The oddity is that it does not happen everytime, but it happens.

Video of the bug from the original reporter on the Blenderartist board :
http://blenderartists.org/forum/showthread.php?317503-Problem-Knife-Tool-Strange-behavior&p=2692404&viewfull=1#post2692404

Event Timeline

Sanc Tuary (sanctuary) raised the priority of this task from to Needs Triage by Developer.
Sanc Tuary (sanctuary) updated the task description. (Show Details)
Sanc Tuary (sanctuary) set Type to Bug.

Thanks to Eppo pointing it, it looks like that problem can be avoided by scaling up the mesh, it looks like when edges are small (i mean something like 0.0x blender units, x being a number ) , the chances of the doubled vertices at a cut will increase a lot.

Sergey Sharybin (sergey) lowered the priority of this task from Needs Triage by Developer to Normal.Jul 28 2014, 12:49 PM

When I cut it in mid-point, double vertices does not seem to appear.

I'm not having any success in making this bug appear with the supplied buggyknife.blend. I'll read through the forum thread and see if I can find another condition that may trigger it for me.

Oh, I see, there are doubled vertices (which I can tell by box selecting in wire mode), not just separated the way they were in the screen shot. So I confirm the problem and can work on it.