Eevee renders seam in generated noise, Cycles does not. #87478

New Issue

Robert Townsend · 2021-04-14T04:42:47+02:00

Robert Townsend commented

2021-04-14 04:42:47 +02:00

System Information
Operating system: Linux-4.15.0-141-generic-x86_64-with-glibc2.27 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.39

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-04-13 07:49, hash: 30ee57be60
Worked: (newest version of Blender that worked as expected)

Short description of error
In this simple test model, Eevee renders a seam in the generated texture, Cycles does not.

Exact steps for others to reproduce the error
Open attached file.
Render.
Note seam in generated noise on left object (it has an extra loop cut).
Switch to Cycles.
Bump up sunlight to 400.
Render. No seam in texture.

Bug Report Eevee 003.blend

**System Information** Operating system: Linux-4.15.0-141-generic-x86_64-with-glibc2.27 64 Bits Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.39 **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-04-13 07:49, hash: `30ee57be60` Worked: (newest version of Blender that worked as expected) **Short description of error** In this simple test model, Eevee renders a seam in the generated texture, Cycles does not. **Exact steps for others to reproduce the error** Open attached file. Render. Note seam in generated noise on left object (it has an extra loop cut). Switch to Cycles. Bump up sunlight to 400. Render. No seam in texture. [Bug Report Eevee 003.blend](https://archive.blender.org/developer/F9932862/Bug_Report_Eevee_003.blend)

Robert Townsend commented

2021-04-14 04:42:47 +02:00

Added subscriber: @rtownsend

Germano Cavalcante commented

2021-04-16 21:51:47 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-04-16 21:51:47 +02:00

I'm not sure what's going on but it seems to be related to the "Show Blackface" option.

Robert Townsend commented

2021-04-17 17:03:55 +02:00

Turning on 'Backface Culling' does change the behavior, and removes the seam. Looks like a good clue.

Pratik Borhade commented

2021-06-24 11:50:26 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-06-24 11:50:26 +02:00

@rtownsend , it seems Germano's message helped you in some way. If you think this is not a bug then can we close the task? :)

Germano Cavalcante commented

2021-06-24 19:06:46 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Robert Townsend commented

2021-06-26 05:02:33 +02:00

When I filed this report, I was not completely sure it was a bug. I'm still not. It does not seem to work correctly, but I'm not versed enough in Eevee vs Cycles to know. It's seems weird to me that checking 'Backface Culling' in the material settings in this particular example fixes the problem, but isn't usually required for other objects. It also seems weird that there's a case where Eevee would render a seam, and Cycles would not.

I've followed Blender for a long time, but I wouldn't call myself a power user. Maybe run it by Clement Foucault? Ton? Let me know if I can help in any way.

When I filed this report, I was not completely sure it was a bug. I'm still not. It does not seem to work correctly, but I'm not versed enough in Eevee vs Cycles to know. It's seems weird to me that checking 'Backface Culling' in the material settings in this particular example fixes the problem, but isn't usually required for other objects. It also seems weird that there's a case where Eevee would render a seam, and Cycles would not. I've followed Blender for a long time, but I wouldn't call myself a power user. Maybe run it by Clement Foucault? Ton? Let me know if I can help in any way.

Richard Antalik commented

2021-07-06 08:15:59 +02:00

Added subscriber: @iss

Richard Antalik commented

2021-07-06 08:15:59 +02:00

Changed status from 'Needs User Info' to: 'Archived'

Richard Antalik closed this issue

2021-07-06 08:15:59 +02:00

Richard Antalik commented

2021-07-06 08:15:59 +02:00

Seems this is cause by Show Backside option

This seems to be known issue - see https://docs.blender.org/manual/en/latest/render/eevee/materials/settings.html#sorting-problem

If enabled, all transparent fragments will be rendered. If disabled, only the front-most surface fragments will be rendered. Disable this option to ensure correct appearance of transparency from any point of view. Then using Alpha Blending this option should be disabled because with Alpha Blending, the order in which triangles are sorted is important.

Closing since this issue happens as documentation predicts.

Seems this is cause by Show Backside option This seems to be known issue - see https://docs.blender.org/manual/en/latest/render/eevee/materials/settings.html#sorting-problem >If enabled, all transparent fragments will be rendered. If disabled, only the front-most surface fragments will be rendered. Disable this option to ensure correct appearance of transparency from any point of view. Then using Alpha Blending this option should be disabled because with Alpha Blending, the order in which triangles are sorted is important. Closing since this issue happens as documentation predicts.

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Eevee renders seam in generated noise, Cycles does not. #87478