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Sculpt Tool will not work on 2D plane in Orthographic Mode if View Clip End set to 656 m or higher
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Description

System Information
Windows 8.1 64 bit; EVGA GTX 970

Blender Version
Broken: (2.78c e92f235283)

Short description of error

Hi all, I just discovered a bug with the sculpt tool: it does not work on a 2D plane in orthographic mode if your view clip end is set to 656 m or higher. It works at 655m for some reason. Also, if you switch to perspective, it works. Weirdly, it will sometimes partially work in orthographic mode (or on areas already sculpted), but the brush strokes will miss intermittently.

Exact steps for others to reproduce the error

  1. In a new blank project, from front ortho view, add a plane aligned to view.
  1. In the Scene Tab, select Metric with a Unit Scale of 0.01.
  1. Begin Sculpting.
  1. Set View Clip End to 656m. Sculpting will cease to work. Set to 655m. Sculpting will work normally again.

Thanks so much for looking into this.

-Adam

Details

Type
Bug

Event Timeline

65535 is the limit of a 16bit data. Maybe the sculpt brush was only able to ray-trace up to 65535 centimeters(blender units). View clipping is a tricky subject, not to mention the non 1.0 scene unit scale.
What are you trying to do? In normal scenario the view clipping wouldn't have to be set to that far at all.

Sergey Sharybin (sergey) closed this task as Archived.
Sergey Sharybin (sergey) claimed this task.

Lots of tools will use depth test based on OpenGL depth buffer. With such a clip end distance you've got really big difference between start and end clipping, which ryuins accuracy of OpenGL dept buffer.

For some more details you can visit https://docs.blender.org/manual/ko/dev/troubleshooting/3d_view.html#depth-buffer-glitches

Thanks for the report, but it's not something we can fix from Blender side without re-implementing OpenGL.

No problem, thank you Brent and Sergey for your clarification. I ran into this issue initially creating large environment assets for use in UE4. The scene unit scale has to be set to 0.01 to convert to centimeters in UE4 (at least it used to, not sure if it's still required). I had my clipping distance set to 1 KM to accommodate a very large mesh, so I initially couldn't figure out why the sculpt tool wasn't working. :-) Thanks for the helpful troubleshooting link. Have a great day, guys.