Maniphest T68228

subsurface radius input bug
Closed, Archived
Actions

Assigned To
Richard Antalik (ISS)
Authored By
michael campbell (3di)
Aug 4 2019, 5:58 PM
Tags
  • BF Blender
  • EEVEE & Viewport
Subscribers
Clément Foucault (fclem)
Evan Wilson (EAW)
michael campbell (3di)
Richard Antalik (ISS)
Rodger Davis (RodDavis)
William Reynish (billreynish)

Description

System Information
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.70

Blender Version
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Worked: (optional)

Short description of error
the subsurface radius input is not overwritten by a vector input.

Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
video of the problem:

file here:

sss radius bug.blend906 KBDownload

same problem happens with the sss shader's radius input also.

Event Timeline

michael campbell (3di) created this task.Aug 4 2019, 5:58 PM
michael campbell (3di) added a comment.Aug 4 2019, 9:03 PM

this only happens with EEVEE by the way, in cycles the vector node works as expected.

Rodger Davis (RodDavis) added a subscriber: Rodger Davis (RodDavis).Aug 5 2019, 12:57 AM
Evan Wilson (EAW) added a subscriber: Evan Wilson (EAW).Aug 5 2019, 4:52 AM

This isn't a bug so much as it is a known limitation. From the manual Rendering » Eevee » Materials » Supported Nodes

Subsurface Scattering
Random Walk sampling is not supported. Per color channel Radius is specified by the default socket value. Any link plugged into this socket gets ignored. If Separate Albedo is off Texture Blur will be treated as always 1.0. Texture Blur is not accurate for any value other than 0.0 and 1.0.

I can confirm your results that a vector node plugged into the Subsurface Radius socket does not affect the amount of subsurface scattering.

Principled BSDF
Cumulate limitations from Diffuse BSDF, Glossy BSDF, Refraction BSDF and Subsurface Scattering. Anisotropy is not supported. Transmission Roughness is not supported. The Sheen layer is a crude approximation.

I think that the description here in the manual is somewhat incomplete. You have shown (and I can confirm) that a vector node plugged into the Subsurface Radius socket does affect the amount of subsurface scattering, just not in a predictable way. Perhaps this would be a better description for this report.

Here is more information on EEVEE's current limitations that you may wish to read.

William Reynish (billreynish) added subscribers: Clément Foucault (fclem), William Reynish (billreynish).Aug 5 2019, 9:09 PM

Right, I believe this is indeed an Eevee limitation and not a bug per se.

@Clément Foucault (fclem) should be able to confirm.

Philipp Oeser (lichtwerk) lowered the priority of this task from 90 to 80.Sep 23 2019, 11:24 AM
Philipp Oeser (lichtwerk) added a project: Eevee.
Richard Antalik (ISS) closed this task as Archived.Jan 20 2020, 10:34 PM
Richard Antalik (ISS) claimed this task.
Richard Antalik (ISS) added a subscriber: Richard Antalik (ISS).

This is explicitly stated as a limitation, so I will close this

michael campbell (3di) added a comment.Jan 20 2020, 10:46 PM
In T68228#854287, @Richard Antalik (ISS) wrote:

This is explicitly stated as a limitation, so I will close this

I think the manual states you can’t connect anything to the radius input. The thing is you can, and it works, it it’s acting as relative to what’s entered in the radius prior to connecting, rather than ignoring what’s already there. It is still using whatever’s connected though, just not on its own.

Clément Foucault (fclem) edited projects, added EEVEE & Viewport; removed Eevee.Jun 19 2020, 11:05 PM