Z-fighting in wireframe moded #84592

New Issue

Michał Pęczak · 2021-01-11T12:04:54+01:00

Michał Pęczak commented

2021-01-11 12:04:54 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 432.00

Blender Version
Broken: version: 2.90.1, branch: master, commit date: 2020-09-23 06:43, hash: 3e85bb34d0
Also tested with the latest 2.92 alpha build. Same results.

Short description of error
I experience Z-fighting in wireframe mode when there are overlapping faces.
Wireframe mode should only render edges. Z-fighting indicates that faces are rendered too, but it only happens when they partially overlap.

Exact steps for others to reproduce the error
Duplicate the default cube and move it slightly in one axis, so that faces of the two cubes partially overlap. Switch to wireframe mode and you will see faces flickering where they overlap. You won't see it if the two cubes fully overlap by staying roughly in the same spot.

wireframe glitch.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 432.00 **Blender Version** Broken: version: 2.90.1, branch: master, commit date: 2020-09-23 06:43, hash: `3e85bb34d0` Also tested with the latest 2.92 alpha build. Same results. **Short description of error** I experience Z-fighting in wireframe mode when there are overlapping faces. Wireframe mode should only render edges. Z-fighting indicates that faces are rendered too, but it only happens when they partially overlap. **Exact steps for others to reproduce the error** Duplicate the default cube and move it slightly in one axis, so that faces of the two cubes partially overlap. Switch to wireframe mode and you will see faces flickering where they overlap. You won't see it if the two cubes fully overlap by staying roughly in the same spot. [wireframe glitch.blend](https://archive.blender.org/developer/F9559706/wireframe_glitch.blend)

Michał Pęczak commented

2021-01-11 12:04:54 +01:00

Added subscriber: @michalpe

Falk David commented

2021-01-11 12:41:56 +01:00

Added subscribers: @fclem, @filedescriptor

Falk David commented

2021-01-11 12:41:56 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Falk David commented

2021-01-11 12:41:56 +01:00

I can reproduce this. I am not sure if this should be considered a bug or a limitation though. This is working as intended in some sense. @fclem any thoughts on this?

Michał Pęczak commented

2021-01-11 13:00:42 +01:00

I am actually not sure either. I first made a post on Right Click Select to change this but the community (way more advanced users than me; I'm just a Blender beginner) suggested posting it here.
It doesn't seem to block any native functionality of Blender. It just:

looks ugly when you work in 2D, with maps for instance, and you are bound to have overlapping faces,
might affect behaviour of CAD Transform add-on which has trouble snapping when there is overlapping geometry, so I started using wireframe mode but this glitch appeared.

I am actually not sure either. I first made a post on Right Click Select to change this but the community (way more advanced users than me; I'm just a Blender beginner) suggested posting it here. It doesn't seem to block any native functionality of Blender. It just: 1) looks ugly when you work in 2D, with maps for instance, and you are bound to have overlapping faces, 2) might affect behaviour of CAD Transform add-on which has trouble snapping when there is overlapping geometry, so I started using wireframe mode but this glitch appeared.

Loïc DAUTRY commented

2021-01-14 15:35:15 +01:00

Added subscriber: @L0Lock

Loïc DAUTRY commented

2021-01-14 15:35:15 +01:00

In what sense is it intended? To me, wireframe is supposed to show only wires, edge display. Here we see what would be part of a face display.

Since it seem to be a z-fighting thing, I guess there's a technical reason as to why it happens, but can't this be tackled?

This doesn't happen in the latest stable 2.79:

So is it introduced by 2.8's way of getting its wireframe mode from a full xray + wire?

In what sense is it intended? To me, wireframe is supposed to show only wires, edge display. Here we see what would be part of a face display. Since it seem to be a z-fighting thing, I guess there's a technical reason as to why it happens, but can't this be tackled? This doesn't happen in the latest stable 2.79: ![image.png](https://archive.blender.org/developer/F9578788/image.png) So is it introduced by 2.8's way of getting its wireframe mode from a full xray + wire?

AnityEx commented

2021-01-17 17:26:06 +01:00

Added subscriber: @AnityEx

AnityEx commented

2021-01-17 17:26:06 +01:00

my two cents: Z fighting dissapears when behind another object
left has a plane over / right normal view

some workaround i did was to parent a plane to camera and then lock camera to view
without plane

with plane

my two cents: Z fighting dissapears when behind another object left has a plane over / right normal view ![image.png](https://archive.blender.org/developer/F9583307/image.png) some workaround i did was to parent a plane to camera and then lock camera to view without plane ![image.png](https://archive.blender.org/developer/F9583312/image.png) with plane ![image.png](https://archive.blender.org/developer/F9583309/image.png)

Michał Pęczak commented

2021-01-21 19:30:49 +01:00

Ok, so we have a workaround.
Though I think we need a real solution.
I can tell one serious limitation involved with it: Blender cannot snap through obscured faces (like SketchUp can do, for example). You can switch your view to x-ray or wireframe but when you grab any geometry and try to snap it to any other geometry that is placed behind a wall (plane), Blender won't snap. It just doesn't see snapping targets behind geometry, even though you can see them in viewport. This is a pain for architecture modelling where there's a ton of obscuring and overlapping geo.
So my thoughts are: make wireframe render truly as wireframe, so that snapping can be performed "through" faces.

Ok, so we have a workaround. Though I think we need a real solution. I can tell one serious limitation involved with it: Blender cannot snap through obscured faces (like SketchUp can do, for example). You can switch your view to x-ray or wireframe but when you grab any geometry and try to snap it to any other geometry that is placed behind a wall (plane), Blender won't snap. It just doesn't see snapping targets behind geometry, even though you can see them in viewport. This is a pain for architecture modelling where there's a ton of obscuring and overlapping geo. So my thoughts are: make wireframe render truly as wireframe, so that snapping can be performed "through" faces.

Philipp Oeser removed the

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Z-fighting in wireframe moded #84592