Knife Tool not working properly in Camera View
Closed, InvalidPublic

Description

System Information
Win10 64-bit , Nvidea Quadro K2000

Blender Version
Broken: Blender 2.78c (official release), Blender 2.79 testbuild (248bba81e7a)

Short description of error
the knife tool cut inaccurately from the camera view, while cutting shows 2 dots and cuts on the one thats not on the pointer. only happens in Camera view.

Exact steps for others to reproduce the error

  1. Open the attatched .blend file
  2. Hit K and try to cut a Window,
  3. hit Num0 to get out of camera view
  4. Try to cut out a Window Again.

I tried to confirm this on the default blender startup file, it doesn't happen there.

Details

Type
Bug
Sergey Sharybin (sergey) triaged this task as "Confirmed" priority.Jul 28 2017, 11:05 AM

There is indeed something weird going on with projection or so.

@Campbell Barton (campbellbarton), afraid you're the most experienced in this area, might having a look? Thanks!

This is caused by a very small near-clip plane, in general if you have too small & large clip planes set it will cause issues with screen-space operations.

While its worth looking into a fix for this, would rather not make risky changes for 2.79 release, just set near clip to a more reasonable value.

Currently its 0.0005. Try set it to 0.01 or more.

Closing since the near clip here is such an extreme value, the file doesn't even show properly in 2.8x.

Documented in https://docs.blender.org/manual/en/dev/modeling/meshes/editing/subdividing/knife_subdivide.html#known-limitations