Cycles Lower Poly Meshes Having Obvious Black Edges When Shade Smoothed #91064

New Issue

Zijun Zhou · 2021-08-31T05:37:17+02:00

Zijun Zhou commented

2021-08-31 05:37:17 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA GeForce MX130/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.68

Blender Version
Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-08-30 22:27, hash: bd67bf4d10
Worked: 3.0.0 Alpha, branch: master, commit date: 2021-08-22 16:45, hash: b477333473
Caused by cd118c5581

Short description of error
Lower-poly shade-smoothed meshes would look like this in the latest 3.0 Alpha:

For comparison this is a screenshot from 3.0.0 Alpha, branch: master, commit date: 2021-08-22 16:45, hash: b477333473:

Exact steps for others to reproduce the error

Select default cube, and right click shade smooth, see the issue immediately
add subsurf modifier, see how the black edge gets thinner as the poly goes higher

or reproduce from file

Open .blend file
Switch to rendered mode

Test File:
#91064.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: NVIDIA GeForce MX130/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.68 **Blender Version** Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-08-30 22:27, hash: `bd67bf4d10` Worked: 3.0.0 Alpha, branch: master, commit date: 2021-08-22 16:45, hash: `b477333473` Caused by cd118c5581 **Short description of error** Lower-poly shade-smoothed meshes would look like this in the latest 3.0 Alpha: ![image.png](https://archive.blender.org/developer/F10355270/image.png) For comparison this is a screenshot from 3.0.0 Alpha, branch: master, commit date: 2021-08-22 16:45, hash: `b477333473`: ![image.png](https://archive.blender.org/developer/F10355268/image.png) **Exact steps for others to reproduce the error** 1. Select default cube, and right click shade smooth, see the issue immediately 2. add subsurf modifier, see how the black edge gets thinner as the poly goes higher --- or reproduce from file - Open .blend file - Switch to rendered mode Test File: [#91064.blend](https://archive.blender.org/developer/F10357381/T91064.blend)

Zijun Zhou commented

2021-08-31 05:37:17 +02:00

Added subscriber: @Eary

blender-admin commented

2021-08-31 05:37:17 +02:00

#91800 was marked as duplicate of this issue

blender-admin commented

2021-08-31 05:37:17 +02:00

#91737 was marked as duplicate of this issue

blender-admin commented

2021-08-31 05:37:17 +02:00

#91736 was marked as duplicate of this issue

blender-admin commented

2021-08-31 05:37:17 +02:00

#91593 was marked as duplicate of this issue

blender-admin commented

2021-08-31 05:37:17 +02:00

#91141 was marked as duplicate of this issue

Pratik Borhade commented

2021-08-31 07:51:09 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-08-31 07:55:35 +02:00

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

Pratik Borhade commented

2021-08-31 08:03:23 +02:00

Can confirm. Introduced between: b477333473 - eec1ea0ccf

Can confirm. Introduced between: b477333473 - eec1ea0ccf

Mikhail Matrosov commented

2021-08-31 11:17:06 +02:00

Added subscriber: @ktdfly

Pratik Borhade commented

2021-08-31 14:06:03 +02:00

Possibly caused by {cd118c5581}?
(not bisected btw)

Will set this to high priority since this is introduced recently.

Possibly caused by {cd118c5581}? (not bisected btw) Will set this to high priority since this is introduced recently.

Mikhail Matrosov commented

2021-08-31 16:43:38 +02:00

Added subscriber: @brecht

Mikhail Matrosov commented

2021-08-31 16:43:38 +02:00

Yep, looks like cd118c5581. I'll try to resolve the issue (again).

@Eary As a temporary solution, connect a Normal Map node as a Normal input:

@brecht Can we use ensure_valid_reflection() for all smooth shaded surfaces?

Yep, looks like cd118c5581. I'll try to resolve the issue (again). @Eary As a temporary solution, connect a Normal Map node as a Normal input: ![Screenshot from 2021-08-31 17-39-50.png](https://archive.blender.org/developer/F10357875/Screenshot_from_2021-08-31_17-39-50.png) @brecht Can we use `ensure_valid_reflection()` for all smooth shaded surfaces?

Brecht Van Lommel commented

2021-08-31 16:53:59 +02:00

@ktdfly, that seems reasonable. We just need to measure the performance impact and check it with the regression tests and benchmark scenes.

Lord Odin commented

2021-09-01 01:16:14 +02:00

Added subscriber: @derekbarker

Lord Odin commented

2021-09-01 01:16:14 +02:00

Does enabling ensure_valid_reflection() force tangent space to be calculated? Because that is a pretty slow part of Cycles (For denser meshes or large scenes) I have had production scenes take 40+ minutes to synchronize in the past because of tangent space, Lukas Stockner did a lot to optimize it but its still a weak point in larger renders if you are using normal maps.

MZw0y2wS9m.mp4

Does enabling `ensure_valid_reflection()` force tangent space to be calculated? Because that is a pretty slow part of Cycles (For denser meshes or large scenes) I have had production scenes take 40+ minutes to synchronize in the past because of tangent space, Lukas Stockner did a lot to optimize it but its still a weak point in larger renders if you are using normal maps. [MZw0y2wS9m.mp4](https://archive.blender.org/developer/F10359149/MZw0y2wS9m.mp4)

Brecht Van Lommel commented

2021-09-06 20:30:24 +02:00

No, ensure_valid_reflection does not require any tangents.

No, `ensure_valid_reflection` does not require any tangents.

HEYPictures commented

2021-09-06 22:18:21 +02:00

Added subscriber: @Florian-10