SSS effect disappears when Mix Shader Node includes Shader To RGB Node #100904

New Issue

nagadomi · 2022-09-08T09:04:40+02:00

nagadomi commented

2022-09-08 09:04:40 +02:00

System Information
Operating system: Linux-5.15.0-47-generic-x86_64-with-glibc2.35 64 Bits
Graphics card: NVIDIA GeForce RTX 3070 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 515.65.01

Blender Version
Broken: version: 3.3.0, branch: master, commit date: 2022-09-06 15:39, hash: 0759f671ce
Worked: 2.93.9

Short description of error
SSS effect disappears when Mix Shader Node includes Shader To RGB Node.

Exact steps for others to reproduce the error

See the attached blend file and video.

sss_bug_report.blend
sss_bug_report.mp4

When the Factor of the Mix Shader Node is 0, the output of the Mix Shader Node is expected to be the same as the Principled BSDF Node.
According to the documentation this might be by design, but it worked fine in 2.93.

**System Information** Operating system: Linux-5.15.0-47-generic-x86_64-with-glibc2.35 64 Bits Graphics card: NVIDIA GeForce RTX 3070 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 515.65.01 **Blender Version** Broken: version: 3.3.0, branch: master, commit date: 2022-09-06 15:39, hash: `0759f671ce` Worked: 2.93.9 **Short description of error** SSS effect disappears when *Mix Shader Node* includes *Shader To RGB Node*. **Exact steps for others to reproduce the error** See the attached blend file and video. [sss_bug_report.blend](https://archive.blender.org/developer/F13467307/sss_bug_report.blend) [sss_bug_report.mp4](https://archive.blender.org/developer/F13467306/sss_bug_report.mp4) When the *Factor* of the *Mix Shader Node* is *0*, the output of the Mix Shader Node is expected to be the same as the *Principled BSDF Node*. According to the documentation this might be by design, but it worked fine in 2.93.

nagadomi commented

2022-09-08 09:04:40 +02:00

Added subscriber: @nagadomi-4

Germano Cavalcante commented

2022-09-09 00:46:16 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2022-09-09 00:46:16 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Germano Cavalcante commented

2022-09-09 00:46:16 +02:00

Looks like a variation of the same bug described in #100125

In the description of the commit 80859a6cb2 states that:

ShaderToRGB node will remove any SSR and SSS from a shader.

However, the manual states that:

(...) any upstream BSDF will be invisible (...)

So I'm still not sure if any downstream BSDF can work with ShaderToRGB + Screen Space Reflection.

Looks like a variation of the same bug described in #100125 In the description of the commit 80859a6cb2 states that: >- ShaderToRGB node will remove any SSR and SSS from a shader. However, the [manual ](https://docs.blender.org/manual/en/latest/render/shader_nodes/converter/shader_to_rgb.html) states that: > (...) any upstream BSDF will be invisible (...) So I'm still not sure if any downstream BSDF can work with ShaderToRGB + Screen Space Reflection.

nagadomi commented

2022-09-15 18:53:58 +02:00

Personally, I believe that in the special case of MixShader with Factor at 0 or 1, it should perform as SwitchNode.
This is because ShaderEditor does not have SwitchNode and Mix * Node has been used instead.
I am not sure if this is possible with the current implementation of Blender.

Also this is not a strong request, I just wanted to make sure this is the intended behavior.

Personally, I believe that in the special case of MixShader with Factor at 0 or 1, it should perform as SwitchNode. This is because ShaderEditor does not have SwitchNode and Mix * Node has been used instead. I am not sure if this is possible with the current implementation of Blender. Also this is not a strong request, I just wanted to make sure this is the intended behavior.

Romain Paindavoine commented

2022-09-28 16:02:00 +02:00

Added subscriber: @PaindavoineRomain

Romain Paindavoine commented

2022-09-28 16:02:00 +02:00

Is there a workaround ? For instance I need to switch from a NPR shader to a realistic shader with a mix node, should I stop the render, unplug the node, then render again ?
I think there should be a bypass when the mix shader is set to 0 or 1.
Also, there is no way to use the result of the SSR to use on a shader with Shader to RGB ?

Is there a workaround ? For instance I need to switch from a NPR shader to a realistic shader with a mix node, should I stop the render, unplug the node, then render again ? I think there should be a bypass when the mix shader is set to 0 or 1. Also, there is no way to use the result of the SSR to use on a shader with Shader to RGB ?

Miguel Pozo self-assigned this 2022-11-17 13:02:30 +01:00

blender-admin commented

2022-11-22 13:39:20 +01:00

This issue was referenced by 6d7a067a83

This issue was referenced by 6d7a067a83bbae7ebb965e364eb9a6b8d0f333f3

Miguel Pozo commented

2022-11-22 13:41:05 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Resolved'

Miguel Pozo closed this issue

2022-11-22 13:41:05 +01:00

Germano Cavalcante referenced this issue

2023-02-09 16:04:56 +01:00