nodes downstream of a mix node are still processed if the socket they are downstream is inactive based on the factor. #100091

New Issue

michael campbell · 2022-07-31T07:48:00+02:00

michael campbell commented

2022-07-31 07:48:00 +02:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.96

Blender Version
Broken: version: 3.3.0 Alpha, branch: master, commit date: 2022-06-27 22:46, hash: 7a44f62bdb
Worked: (newest version of Blender that worked as expected)

Short description of error
nodes downstream of a mix node are still processed if the socket they are downstream of is inactive based on the fac value of that mix node.

I'm not sure if this is a bug or a wet dream, but I know in the shader editor any nodes that are only downstream of a mix node are not calculated if the input socket they lead to on the mix node is inactive based on the fac value.

I reported a similar issue recently in the compositor where if there are multiple composite nodes, branches that are downstream of inactive composite node's are still calculated. I'm not sure if this is related?

Steps to Reproduce

Open .blend file
Each time you change the use alpha value (or any value on the viewer node), the denoise node recalculates, even though the bottom input of the mix node is turned off via the fac value

downstream of inactive mix node socket still calculates.blend

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.96 **Blender Version** Broken: version: 3.3.0 Alpha, branch: master, commit date: 2022-06-27 22:46, hash: `7a44f62bdb` Worked: (newest version of Blender that worked as expected) **Short description of error** nodes downstream of a mix node are still processed if the socket they are downstream of is inactive based on the fac value of that mix node. I'm not sure if this is a bug or a wet dream, but I know in the shader editor any nodes that are only downstream of a mix node are not calculated if the input socket they lead to on the mix node is inactive based on the fac value. I reported a similar issue recently in the compositor where if there are multiple composite nodes, branches that are downstream of inactive composite node's are still calculated. I'm not sure if this is related? **Steps to Reproduce** - Open .blend file - Each time you change the use alpha value (or any value on the viewer node), the denoise node recalculates, even though the bottom input of the mix node is turned off via the fac value [downstream of inactive mix node socket still calculates.blend](https://archive.blender.org/developer/F13328314/downstream_of_inactive_mix_node_socket_still_calculates.blend)

michael campbell commented

2022-07-31 07:48:00 +02:00

Added subscriber: @3di

Pratik Borhade commented

2022-08-01 03:32:40 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2022-08-01 03:32:40 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Pratik Borhade commented

2022-08-01 03:32:40 +02:00

@3di hi, thanks for the report. I did not understand the issue completely. Do you have a test .blend file which I can use as a reference?

michael campbell commented

2022-08-01 04:15:21 +02:00

@PratikPB2123 sure thing. Open the compositor and click the use alpha on the viewer node. Each time you change the use alpha value (or any value on the viewer node), the denoise node recalculates, even though the bottom input of the mix node is turned off via the fac value. I'm not sure if what I'm suggesting is possible, probably the denoise node is a bad example because it has to work on the full frame, but for branches that only contain nodes that can work on a per pixel basis, I think they also still recalculate if the current pixel being calculated by the mix node has a fac of 0.

downstream of inactive mix node socket still calculates.blend

@PratikPB2123 sure thing. Open the compositor and click the use alpha on the viewer node. Each time you change the use alpha value (or any value on the viewer node), the denoise node recalculates, even though the bottom input of the mix node is turned off via the fac value. I'm not sure if what I'm suggesting is possible, probably the denoise node is a bad example because it has to work on the full frame, but for branches that only contain nodes that can work on a per pixel basis, I think they also still recalculate if the current pixel being calculated by the mix node has a fac of 0. [downstream of inactive mix node socket still calculates.blend](https://archive.blender.org/developer/F13328314/downstream_of_inactive_mix_node_socket_still_calculates.blend)

Pratik Borhade commented

2022-08-02 02:49:55 +02:00

Changed status from 'Needs User Info' to: 'Confirmed'

Sergey Sharybin commented

2022-11-15 17:16:09 +01:00

Added subscriber: @Sergey

Sergey Sharybin commented

2022-11-15 17:16:09 +01:00

Thanks for the report, but this is limitation of the current design of the compositor.
Something what would would be nice to work on in the future, but the size of the project is beyond of what could be handled as a bug fix.

Thanks for the report, but this is limitation of the current design of the compositor. Something what would would be nice to work on in the future, but the size of the project is beyond of what could be handled as a bug fix.

Philipp Oeser removed the

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nodes downstream of a mix node are still processed if the socket they are downstream is inactive based on the factor. #100091