Unable to set active material output node using Python #96292

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Greg Zaal · 2022-03-10T12:32:05+01:00

Greg Zaal commented

2022-03-10 12:32:05 +01:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 497.29

Blender Version
Broken: version: 3.1.0, branch: master, commit date: 2022-03-08 18:16, hash: c77597cd0e
Worked: 3.0

This changed in 7e712b2d6a

Short description of error
It seems to be (inconsistently) no longer possible to set the world/shader node tree's active output using python.

Running node.is_active_output = True in a fresh scene does anything. But if you (in the UI) click on one of the output nodes, setting it as the active output, then from that point onwards doing node.is_active_output = True will indeed work.

Exact steps for others to reproduce the error

Starting from factory defaults
In a python console editor, run: node = C.scene.world.node_tree.nodes.new('ShaderNodeOutputWorld') to create a new world output node. This node is named World Output.001. The original output node is named World Output.
Check the current state of the active output node:
C.scene.world.node_tree.nodes['World Output'].is_active_output - the result is True as this is the original node.
C.scene.world.node_tree.nodes['World Output.001'].is_active_output - the result is False as this is the new node.
Try set the new node as active output using C.scene.world.node_tree.nodes['World Output.001'].is_active_output = True. Nothing happens, the value remains False even after we set it.
In the UI, click on the newly created node, setting it as the active output (verify this with the code above if needed, is_active_output is now True for the new node)
Click on the original node to set that as the active output.
Run C.scene.world.node_tree.nodes['World Output.001'].is_active_output = True again, this time it successfully changes the tree's active output to that node.

As a side note, is there some other workaround way I can consistently set the node tree's active output? I need to fix an add-on and can't wait for this to be patched.

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 497.29 **Blender Version** Broken: version: 3.1.0, branch: master, commit date: 2022-03-08 18:16, hash: `c77597cd0e` Worked: 3.0 This changed in 7e712b2d6a **Short description of error** It seems to be (inconsistently) no longer possible to set the world/shader node tree's active output using python. Running `node.is_active_output = True` in a fresh scene does anything. But if you (in the UI) click on one of the output nodes, setting it as the active output, then from that point onwards doing `node.is_active_output = True` will indeed work. **Exact steps for others to reproduce the error** 1. Starting from factory defaults 2. In a python console editor, run: `node = C.scene.world.node_tree.nodes.new('ShaderNodeOutputWorld')` to create a new world output node. This node is named `World Output.001`. The original output node is named `World Output`. 3. Check the current state of the active output node: 4. `C.scene.world.node_tree.nodes['World Output'].is_active_output` - the result is `True` as this is the original node. 5. `C.scene.world.node_tree.nodes['World Output.001'].is_active_output` - the result is `False` as this is the new node. 6. Try set the new node as active output using `C.scene.world.node_tree.nodes['World Output.001'].is_active_output = True`. Nothing happens, the value remains `False` even after we set it. 7. In the UI, click on the newly created node, setting it as the active output (verify this with the code above if needed, `is_active_output` is now `True` for the new node) 8. Click on the original node to set that as the active output. 8. Run `C.scene.world.node_tree.nodes['World Output.001'].is_active_output = True` again, this time it successfully changes the tree's active output to that node. As a side note, is there some other workaround way I can consistently set the node tree's active output? I need to fix an add-on and can't wait for this to be patched.

Greg Zaal commented

2022-03-10 12:32:05 +01:00

Added subscriber: @GregZaal

Philipp Oeser commented

2022-03-10 13:06:31 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-03-10 13:06:31 +01:00

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

Philipp Oeser commented

2022-03-10 13:06:31 +01:00

Can confirm (to some extend).
In 3.0, it was possible to have 2 active outputs at the same time, setting World Output.001 active did not set World Output inactive (this was wrong, too).
There has probably been some fix that does not allow for that anymore (otoh, it did not take into account that this prevents setting it active from python in some situations), will check

Can confirm (to some extend). In 3.0, it was possible to have 2 active outputs at the same time, setting `World Output.001` active did not set `World Output` inactive (this was wrong, too). There has probably been some fix that does not allow for that anymore (otoh, it did not take into account that this prevents setting it active from python in some situations), will check

Pratik Borhade commented

2022-03-10 14:42:59 +01:00

Added subscriber: @PratikPB2123

Greg Zaal commented

2022-03-10 14:47:25 +01:00

I guess ideally we have some node_tree.set_active_output_node function in the API, and not have to rely on the python code having to make sure to set all outputs to False except one.

I saw there was also a node_tree.active_output property, but this was always -1 and didn't seem writable.

I guess ideally we have some `node_tree.set_active_output_node` function in the API, and not have to rely on the python code having to make sure to set all outputs to `False` except one. I saw there was also a `node_tree.active_output` property, but this was always `-1` and didn't seem writable.

Philipp Oeser commented

2022-03-10 16:18:39 +01:00

This changed in 7e712b2d6a btw.

This changed in 7e712b2d6a btw.

Philipp Oeser commented

2022-03-10 16:23:52 +01:00

Added subscriber: @JacquesLucke

Philipp Oeser commented

2022-03-10 16:23:52 +01:00

Even though this was not quite right in 3.0 either, will still set this to High prio (since now it seems this is not possible to set at all).

@JacquesLucke: opinions?

Even though this was not quite right in 3.0 either, will still set this to High prio (since now it seems this is not possible to set at all). @JacquesLucke: opinions?

Jacques Lucke self-assigned this 2022-03-10 17:42:12 +01:00

Jacques Lucke commented

2022-03-10 17:42:12 +01:00

I saw there was also a node_tree.active_output property, but this was always -1 and didn't seem writable.

Think that's the index of the active output socket in a node group.

The fix seems to be to make the other outputs of the same type inactive.

> I saw there was also a node_tree.active_output property, but this was always -1 and didn't seem writable. Think that's the index of the active output socket in a node group. --- The fix seems to be to make the other outputs of the same type inactive.

Jacques Lucke commented

2022-03-10 17:45:41 +01:00

FYI, bug reports that require the python console are sometimes a bit annoying, because I have to type/copy so much every time I want to reproduce it. Usually I end up preparing myself a file that just has a small script in it that I can just run to reproduce the bug. It doesn't matter too much, but if you happen to report similar bugs in the future, maybe consider writing a small(!) script instead of using the console.

E.g. this is the script I used for this bug:

import bpy

n1 = bpy.context.scene.world.node_tree.nodes['World Output']
n2 = bpy.context.scene.world.node_tree.nodes['World Output.001']

n1.is_active_output = True
n2.is_active_output = True

print(n1.is_active_output, n2.is_active_output)

FYI, bug reports that require the python console are sometimes a bit annoying, because I have to type/copy so much every time I want to reproduce it. Usually I end up preparing myself a file that just has a small script in it that I can just run to reproduce the bug. It doesn't matter too much, but if you happen to report similar bugs in the future, maybe consider writing a small(!) script instead of using the console. E.g. this is the script I used for this bug: ``` import bpy n1 = bpy.context.scene.world.node_tree.nodes['World Output'] n2 = bpy.context.scene.world.node_tree.nodes['World Output.001'] n1.is_active_output = True n2.is_active_output = True print(n1.is_active_output, n2.is_active_output) ```

blender-admin commented

2022-03-10 18:04:07 +01:00

This issue was referenced by 40cbbe809c

This issue was referenced by 40cbbe809c0afe83068cdca97992204d7b135b9e

blender-admin commented

2022-03-10 18:04:07 +01:00

This issue was referenced by 22a341d9d8

This issue was referenced by 22a341d9d8d3d337f79df228ab2e4e0726f81430

Jacques Lucke commented

2022-03-10 18:04:31 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Jacques Lucke closed this issue

2022-03-10 18:04:31 +01:00

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Unable to set active material output node using Python #96292