So one of my objects and only this one, has this issue pictured where I can see through some of the mesh to the other side unless I zoom out a bit I can't see the behind edges, xray mode isn't on, but it's also glitching the knife tool out. It's like the position data for the edges are off somehow, it's saying the knife tool is connected but it's way off. I don't know how else to explain this it's all very weird. You can see in the last picture the knife tool is also ignoring the edges it's supposed to be cutting through on the right side.

I'm using 3.6, no editing plugins enabled.

I have xray mode off / face orientation is all good / it's non-manifold

can see edges from other side through selected face What it should look like what it's doing knife tool freaking out

  • $\begingroup$ It's difficult to tell from those images, but it sounds as if you have overlapping faces and/ or inverted normals. I think we'll need to see your Blend file. You can share it via blend-exchange.com following the instructions there to copy the link to it and then edit your question and paste the link into it. $\endgroup$
    – John Eason
    Aug 21, 2023 at 8:17
  • $\begingroup$ @JohnEason Thanks, I've added a file with a part of the mesh, which is having issues, I've checked normals, overlapping faces, and even recreated the topology there from scratch, and the new geo has the same issue too. $\endgroup$ Aug 22, 2023 at 11:30
  • $\begingroup$ Which part are you trying to use the Knife tool on? - It's still difficult to tell looking at your images and the various cuts I've tried have all worked ok. - I'm not sure what you used to model that mesh? Why is most of it triangulated? $\endgroup$
    – John Eason
    Aug 22, 2023 at 14:56
  • $\begingroup$ Try scaling the object down to more typical size and opening the .blend file using default UI (file->new.., then file->open, click the gear it top-right, unselect "load UI"). The issue might be caused by the viewport clip start and end, though their range has the same orders of magnitude as the default range… $\endgroup$ Aug 22, 2023 at 17:48
  • $\begingroup$ sorry, the straight part in the middle that's raised, it's trianulgated as it's going into a game engine, it's just very roughed out currently. @MarkusvonBroady I tried scaling it down to 100m and 10m, applied scale and knife tool went even crazier. Oddly, if I zoom out the viewport and do a cut it seems to work okay, but it's really hard to see being zoomed out so far, if I try to zoom in that's when I can start to see "through" the mesh to other bits and the knife tool freaks out, no matter the scale or clipping distance. Blank / fresh UI didn't do anything differently. $\endgroup$ Aug 23, 2023 at 7:03


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