Adaptive displacement case leads to box-shaped culling
Open, LowPublic

Description

Not sure if bugs of experimental features such as adaptive displacement are "allowed" to be reported here but I don't see how to let you know otherwise.

Here is one case which renders very strangely by this feature, then a box-shaped culling is occurring:

I found out that it must have to do with the mode of shading being applied to the mesh. With flat shaded surfaces it fails, for smooth shading the culling disappears.

Here is the .blend file:

Tested with official release and buildbot build from yesterday, both for Windows.

Details

Type
Bug

This mesh is corrupt, so the bug is that you managed to make a corrupt mesh in the first place.

Can you re-create this mesh from scratch (or at least by some operations on a valid mesh)?

To check for invalid mesh data, run this Python snippet:

import bpy
bpy.context.object.data.validate(True)

Also, your mesh has a lot of doubles, after fixing these two things the issue disappeared.

Looks like only the vertex group data got corrupted, when removing the Mask vertex group validate() doesn't complain anymore but the issue persists. Not sure why the adaptive displacement feature wouldn't work with "doubles" in the first place, isn't this a very common thing in 3d modelling? Edge split something and you have doubles everywhere, not sure if this issue is actually resolved by now. But thank you for looking into it anyhow.

Aaron Carlisle (Blendify) triaged this task as Low priority.

I will leave open as low until someone like @Mai Lavelle (maiself) comments on the issue.