Regression: Cycles Bump node producing broken normals in 3.4 #103049

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Matouš Marek · 2022-12-09T00:57:36+01:00

Matouš Marek commented

2022-12-09 00:57:36 +01:00

System Information
Operating system: Windows 10 64-bit
Graphics card: Nvidia RTX 3060 Ti, also reproduced on Nvidia GTX 1660

Blender Version
Broken: 3.4.0
Worked: 3.3.0

Short description of error
The Bump node in Cycles produces wrong, inverted-like normals that cause light to leak through from the other side. This is especially apparent in the corners of interiors with a world lighting, or when placing a point light inside an object with a bump-node shader (see attached .blend file). The same scene works flawlessly in Eevee and in the 3.3 release of Cycles.

Exact steps for others to reproduce the error
Use a bump node in a Cycles shader, plug any texture into the bump node height input. Place a light on the other side of the mesh with said material. There will be light leaking as if the mesh was illuminated by the light.

Wrong behaviour in 3.4.0:

Correct behaviour in 3.3.0:

Bump Node Test.blend

**System Information** Operating system: Windows 10 64-bit Graphics card: Nvidia RTX 3060 Ti, also reproduced on Nvidia GTX 1660 **Blender Version** Broken: 3.4.0 Worked: 3.3.0 **Short description of error** The Bump node in Cycles produces wrong, inverted-like normals that cause light to leak through from the other side. This is especially apparent in the corners of interiors with a world lighting, or when placing a point light inside an object with a bump-node shader (see attached .blend file). The same scene works flawlessly in Eevee and in the 3.3 release of Cycles. **Exact steps for others to reproduce the error** Use a bump node in a Cycles shader, plug any texture into the bump node height input. Place a light on the other side of the mesh with said material. There will be light leaking as if the mesh was illuminated by the light. Wrong behaviour in 3.4.0: ![Wrong.png](https://archive.blender.org/developer/F14045683/Wrong.png) Correct behaviour in 3.3.0: ![Correct.png](https://archive.blender.org/developer/F14045681/Correct.png) [Bump Node Test.blend](https://archive.blender.org/developer/F14045701/Bump_Node_Test.blend)

Matouš Marek commented

2022-12-09 00:57:36 +01:00

Added subscriber: @Mylapqn

Omar Emara commented

2022-12-09 10:23:08 +01:00

Added subscriber: @OmarEmaraDev

Omar Emara commented

2022-12-09 10:23:08 +01:00

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

Omar Emara commented

2022-12-09 10:23:08 +01:00

This seems to be fixed in master, will look at the log and possibly bisect to see what might have fixed it.

Omar Emara changed title from ~~Cycles Bump node producing broken normals~~ to Regression: Cycles Bump node producing broken normals in 3.4

2022-12-09 10:23:23 +01:00

Matouš Marek commented

2022-12-09 20:08:26 +01:00

In #103049#1457413, @OmarEmaraDev wrote:
This seems to be fixed in master, will look at the log and possibly bisect to see what might have fixed it.

Would you recommend to just use 3.5 Alpha for now? This is quite a critical issue for my ongoing projects and due to the backwards-incompatible Mix node change in 3.4, it's difficult to revert to 3.3 now.

> In #103049#1457413, @OmarEmaraDev wrote: > This seems to be fixed in master, will look at the log and possibly bisect to see what might have fixed it. Would you recommend to just use 3.5 Alpha for now? This is quite a critical issue for my ongoing projects and due to the backwards-incompatible Mix node change in 3.4, it's difficult to revert to 3.3 now.

Omar Emara commented

2022-12-09 21:57:13 +01:00

It is not known when a corrective release for 3.4 will happen, so if this is a show stopper for you, going to 3.5 seems like your only option for now.

Matouš Marek commented

2022-12-09 22:03:10 +01:00

Thank you!

Konnie Recker commented

2022-12-09 23:37:50 +01:00

Added subscriber: @aerobraking

Konnie Recker commented

2022-12-09 23:37:50 +01:00

Just for the record, this bug also appears when using the "Normal Map" Node. I quickly saw it in one of my projects as the rendering looked different to 3.3.

Matouš Marek commented

2022-12-10 00:10:03 +01:00

Yes, besides Normal and Bump I also noticed the problem in the Displacement node. Must be something with the way normals are rendered in general.

I managed to sort of work around the problem by using the Solidify modifier on the affected meshes (any thickness works) in case this helps anyone. This is still not ideal, of course, but gets rid of the problem quickly in most cases.

Yes, besides Normal and Bump I also noticed the problem in the Displacement node. Must be something with the way normals are rendered in general. I managed to sort of work around the problem by using the Solidify modifier on the affected meshes (any thickness works) in case this helps anyone. This is still not ideal, of course, but gets rid of the problem quickly in most cases.

Cassidy Graces Incandela commented

2022-12-12 05:46:50 +01:00

Added subscriber: @cassidy

blender-admin commented

2022-12-15 21:29:56 +01:00

This issue was referenced by fd3943dbd5

This issue was referenced by fd3943dbd5d95ec5d5dda24acf7646796280997f

blender-admin commented

2022-12-15 21:29:56 +01:00

This issue was referenced by 3d29bbcc38

This issue was referenced by 3d29bbcc387feea063b48ce747668d1143f312f7

Brecht Van Lommel commented

2022-12-15 22:08:06 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Brecht Van Lommel closed this issue

2022-12-15 22:08:06 +01:00

Brecht Van Lommel self-assigned this 2022-12-15 22:08:06 +01:00

blender-admin commented

2022-12-15 22:09:23 +01:00

This issue was referenced by None@63157

thin soldier commented

2022-12-20 22:15:15 +01:00

Added subscriber: @thinsoldier

thin soldier commented

2022-12-20 22:15:15 +01:00

Removed previous comment. Looks like I was very late to the discussion. Seems all my problems are fixed, both inside and out, in today's build of 3.5 and 3.4.1

Thomas Dinges added this to the 3.4 milestone 2023-02-07 19:01:34 +01:00

Germano Cavalcante referenced this issue

2023-02-17 14:45:48 +01:00

3.4: Potential candidates for corrective releases #102967

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