Back cull faces not active during render #57643

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Pierre Schiller · 2018-11-05T22:49:47+01:00

Pierre Schiller commented

2018-11-05 22:49:47 +01:00

Windows 7 x64, Intel i7 4930k, 24 Mb Ram, Nvidia Titan X

Blender Version
Broken: Blender 2.8 alpha - b4dfe00f60
Worked: (optional)

Short description of error
Backface culling (to hide inverted normals) only works on viewport , not on EEVEE render.
I´m using the backface cull method to create realtime outlines and render.

Exact steps for others to reproduce the error
Create a sphere.
Make a simple 3 tone ramp using diffuse->shader to rgb->Color ramp->Material output
Duplicate this sphere. Assign a new diffuse black material. Go to modifiers, Solidify: Flip normals, Material index offset : 1, offset: -0.8747, thickness: 0.5mm.
On the 3d view go to OVERLAYS and check "Back face culling"
Open a uv/image editor. Render EEVEE on the image editor. Only the black ball render appears, this is because the flip normals/cull back faces is not working on render, only on viewport.

Link to the file: http://pasteall.org/blend/index.php?id=50660

3 Tone with Black line.blend

Windows 7 x64, Intel i7 4930k, 24 Mb Ram, Nvidia Titan X **Blender Version** Broken: Blender 2.8 alpha - b4dfe00f60 Worked: (optional) **Short description of error** Backface culling (to hide inverted normals) only works on viewport , not on EEVEE render. I´m using the backface cull method to create realtime outlines and render. **Exact steps for others to reproduce the error** Create a sphere. Make a simple 3 tone ramp using diffuse->shader to rgb->Color ramp->Material output Duplicate this sphere. Assign a new diffuse black material. Go to modifiers, Solidify: Flip normals, Material index offset : 1, offset: -0.8747, thickness: 0.5mm. On the 3d view go to OVERLAYS and check "Back face culling" Open a uv/image editor. Render EEVEE on the image editor. Only the black ball render appears, this is because the flip normals/cull back faces is not working on render, only on viewport. ![no lines.PNG](https://archive.blender.org/developer/F5395147/no_lines.PNG) Link to the file: http://pasteall.org/blend/index.php?id=50660 [3 Tone with Black line.blend](https://archive.blender.org/developer/F5407489/3_Tone_with_Black_line.blend)

Pierre Schiller commented

2018-11-05 22:49:47 +01:00

Added subscriber: @PierreSchiller

Philipp Oeser commented

2018-11-06 12:36:08 +01:00

Added subscribers: @fclem, @lichtwerk

Clément Foucault was assigned by Philipp Oeser

2018-11-06 12:36:08 +01:00

Philipp Oeser commented

2018-11-06 12:36:09 +01:00

Can confirm that Backface Culling is respected in rendered viewport but not actual render F12.
While I am not sure if this is supposed to be included in render (or this was intended to be an overlay thing only), it is surely weird to have this respected in rendered viewport, but not F12.
I would go either support it for both, or support it for None of [rendered viewport & F12 rendering].

Also not sure how to properly handle this setting if Overlays are disabled [show_overlays]? Default is OFF for backface culling, so if this is changed to ON, but overlays are actually disabled, should this mean no backface culling?

That being said, you can get around it by using the Geometry Nodes Backfacing output to mix in a Transparent BSDF like so (note: you have to change the materials blend mode to something that respects alpha):
3 Tone with Black line tweaked.blend

Anyways, I guess @fclem should have a look?

Can confirm that Backface Culling is respected in rendered viewport but not actual render F12. While I am not sure if this is supposed to be included in render (or this was intended to be an overlay thing only), it is surely weird to have this respected in rendered viewport, but not F12. I would go either support it for both, or support it for None of [rendered viewport & F12 rendering]. Also not sure how to properly handle this setting if Overlays are disabled [`show_overlays`]? Default is OFF for backface culling, so if this is changed to ON, but overlays are actually disabled, should this mean no backface culling? That being said, you can get around it by using the `Geometry` Nodes `Backfacing` output to mix in a Transparent BSDF like so (note: you have to change the materials blend mode to something that respects alpha): [3 Tone with Black line tweaked.blend](https://archive.blender.org/developer/F5407560/3_Tone_with_Black_line_tweaked.blend) Anyways, I guess @fclem should have a look?

Clément Foucault commented

2018-11-12 16:45:22 +01:00

Added subscribers: @WilliamReynish, @pablovazquez

Clément Foucault commented

2018-11-12 16:45:22 +01:00

This is a tricky case. Because the backface culling is a per viewport option and when doing F12 render there is no "view 3D" involved, but only the camera. So yes the best way would be to do what @lichtwerk suggested but that comes with a cost so I don't really like this. Maybe @pablovazquez / @WilliamReynish have an idea.

Brecht Van Lommel commented

2018-11-12 17:19:18 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2018-11-12 17:19:18 +01:00

This doesn't look like a bug to me, but a feature that would be good to add. There could be a per object or mesh option for backface culling that each renderer can handle. It's pretty common in other apps and game engines as far as I know.

The feature in the 3D viewport is for inspecting the mesh, not a rendering feature.

This doesn't look like a bug to me, but a feature that would be good to add. There could be a per object or mesh option for backface culling that each renderer can handle. It's pretty common in other apps and game engines as far as I know. The feature in the 3D viewport is for inspecting the mesh, not a rendering feature.

Faber Miles commented

2018-12-16 12:07:04 +01:00

Added subscriber: @MilaniSe7en

Faber Miles commented

2018-12-16 12:07:04 +01:00

In #57643#550372, @lichtwerk wrote:
That being said, you can get around it by using the Geometry Nodes Backfacing output to mix in a Transparent BSDF like so (note: you have to change the materials blend mode to something that respects alpha):

Changing the blend mode to alpha solved not only my black outline material, but all the problems I had with eevee and backface culling. You are the mannn.

But ye this should be a feature.

> In #57643#550372, @lichtwerk wrote: > That being said, you can get around it by using the `Geometry` Nodes `Backfacing` output to mix in a Transparent BSDF like so (note: you have to **change the materials blend mode to something that respects alpha**): Changing the blend mode to alpha solved not only my black outline material, but all the problems I had with eevee and backface culling. You are the mannn. But ye this should be a feature.

Brecht Van Lommel commented

2019-03-16 17:56:31 +01:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2019-03-16 17:56:31 +01:00

Brecht Van Lommel commented

2019-03-16 17:56:31 +01:00

Closing as not a bug, this is a feature request.

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Back cull faces not active during render #57643