Shader Node Graph is stuck in a strange incorrect state. Making a change that forces a refresh and then undoing the change returns it to a different state! #92433

New Issue

Dave F · 2021-10-23T11:42:22+02:00

Dave F commented

2021-10-23 11:42:22 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA TITAN X (Pascal)/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.68
Also tested on 2015 Macbook Pro running MacOs/Blender 2.93.5, same bug occurs

Blender Version
Broken: version: 2.93.5, branch: master, commit date: 2021-10-05 12:04, hash: a791bdabd0

Short description of error
This shader node graph is not evaluating correctly in EEVEE, although it displays correctly in Cycles. After making changes to the shader node graph and then undoing those changes, it displays correctly in both EEVEE and Cycles. Seems like it must be a bug?

Exact steps for others to reproduce the error

Open the attached file bug_shaderProblem_020.blend and switch the viewport to render view.
Using EEVEE, The texture on the plane in the viewport will (wrongly) display a single white rectangle, while with Cycles it correctly displays two overlaid grey rectangles.
Make a change to the node network that triggers a refresh - for example, as in the video, delete a node that is not even connected to the output. I'm not totally sure what triggers refreshing but you can see the viewport texture go blank for a moment as the shader rebuilds.
Undo that change.
The texture on the plane in the viewport now correctly displays two overlaid grey rectangles in both Cycles and EEVEE!

See attached video for demonstration.
blender_shader_bug_2021-10-22 18-20-24.mp4

I have no idea what caused it to get into this weird state - the only thing I did recently that may be related is use a python script to add and configure a load of Attribute nodes and object properties, and it appears that some of those are evaluating incorrectly. Hard to see what's going on without debugging but I thinkthe values for TestPlane['lip_halfSize_scale_x'] and TestPlane['lip_outer_halfSize_scale_x'] may be coming through wrongly? Might be totally unrelated, but thought it was worth mentioning!

bug_shaderProblem_020.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: NVIDIA TITAN X (Pascal)/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.68 Also tested on 2015 Macbook Pro running MacOs/Blender 2.93.5, same bug occurs **Blender Version** Broken: version: 2.93.5, branch: master, commit date: 2021-10-05 12:04, hash: `a791bdabd0` **Short description of error** This shader node graph is not evaluating correctly in EEVEE, although it displays correctly in Cycles. After making changes to the shader node graph and then undoing those changes, it displays correctly in both EEVEE and Cycles. Seems like it must be a bug? **Exact steps for others to reproduce the error** 1. Open the attached file `bug_shaderProblem_020.blend` and switch the viewport to render view. 2. Using EEVEE, The texture on the plane in the viewport will (wrongly) display a single white rectangle, while with Cycles it correctly displays two overlaid grey rectangles. 3. Make a change to the node network that triggers a refresh - for example, as in the video, delete a node that is not even connected to the output. I'm not totally sure what triggers refreshing but you can see the viewport texture go blank for a moment as the shader rebuilds. 4. Undo that change. 5. The texture on the plane in the viewport now correctly displays two overlaid grey rectangles in both Cycles and EEVEE! See attached video for demonstration. [blender_shader_bug_2021-10-22 18-20-24.mp4](https://archive.blender.org/developer/F11419673/blender_shader_bug_2021-10-22_18-20-24.mp4) I have no idea what caused it to get into this weird state - the only thing I did recently that may be related is use a python script to add and configure a load of Attribute nodes and object properties, and it appears that some of those are evaluating incorrectly. Hard to see what's going on without debugging but I *think*the values for `TestPlane['lip_halfSize_scale_x']` and `TestPlane['lip_outer_halfSize_scale_x']` may be coming through wrongly? Might be totally unrelated, but thought it was worth mentioning! ![image.png](https://archive.blender.org/developer/F11419873/image.png) [bug_shaderProblem_020.blend](https://archive.blender.org/developer/F11419566/bug_shaderProblem_020.blend)

Dave F commented

2021-10-23 11:42:22 +02:00

Added subscriber: @df-1

Dave F commented

2021-10-24 13:20:55 +02:00

After exploring this further, I suspect this issue is caused by the limitation described here: https://developer.blender.org/T92448

Philipp Oeser commented

2021-10-26 14:28:33 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-10-26 14:28:33 +02:00

Can confirm, but since the problem really goes away if 8 (or less) attribute nodes are used will assume the underlying problem is indeed a duplicate of blender/documentation#92448 (Attribute Node in Object Mode seems to have undocumented limit of 8 attributes in EEVEE, and exhibits unpredictable behaviour when more are used), will merge these reports.

Philipp Oeser commented

2021-10-26 14:28:40 +02:00

Closed as duplicate of blender/documentation#92448

Philipp Oeser closed this issue

2021-10-26 14:28:40 +02:00

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Shader Node Graph is stuck in a strange incorrect state. Making a change that forces a refresh and then undoing the change returns it to a different state! #92433