Why does "nw_add_textures_for_principled" work w/ Existing Material but not w/ dynamically created ones?

Question

I have a default cube ‘Cube’ which has 1 default material (active_material_index = 0). I’m adding another material dynamically via script that adds a Principled BSDF texture setup (CTRL+SHIFT+T) for this second material at active_material_index = 1 using bpy.ops.node.nw_add_textures_for_principled() as in the code below. The weird thing is that if i use active_material_index = 0 or any index for a material that already exists and have its Principled BSDF node already selected, the script actually works and properly adds the texture setup. But it doesn't work if you dynamically create the material and dynamically select the Principled BSDF node (white outline). It looks like something asynchronous is happening where the creation of the material is not ready yet when nw_add_textures_for_principled executes. Any idea? If the problem was the context, then how was it possible to work for the existing material?

import bpy
mat = bpy.data.materials.new(name='dynamically_created')
mat.use_nodes = True
bpy.data.objects['Cube'].data.materials.append(mat)
bpy.context.object.active_material_index = 1
bpy.context.area.ui_type = 'ShaderNodeTree'
bpy.context.area.type = 'NODE_EDITOR'
m = bpy.context.object.active_material
m.node_tree.nodes['Material Output'].select = False
m.node_tree.nodes['Principled BSDF'].select = True
m.node_tree.nodes.active = m.node_tree.nodes.get("Principled BSDF")
r = bpy.ops.node.nw_add_textures_for_principled(filepath="E:\ZZZZ\Projects\blender\textures\metal\Metal021_1K-JPG\", directory="E:\ZZZZ\Projects\blender\textures\metal\Metal021_1K-JPG\", files=[ {"name":"Metal021_1K_Color.jpg", "name":"Metal021_1K_Color.jpg"}, {"name":"Metal021_1K_Displacement.jpg", "name":"Metal021_1K_Displacement.jpg"}, {"name":"Metal021_1K_Metalness.jpg", "name":"Metal021_1K_Metalness.jpg"}, {"name":"Metal021_1K_NormalDX.jpg", "name":"Metal021_1K_NormalDX.jpg"}, {"name":"Metal021_1K_NormalGL.jpg", "name":"Metal021_1K_NormalGL.jpg"}, {"name":"Metal021_1K_Roughness.jpg", "name":"Metal021_1K_Roughness.jpg"}, {"name":"Metal021_PREVIEW.jpg", "name":"Metal021_PREVIEW.jpg"}], relative_path=True)
print("result ==== ", r) #{'CANCELLED'}

UPDATE w/ Marty Fouts' Answer:

Thanks to Marty Fouts the context usage is properly implemented now but:

When I manually select the Principled BSDF node of material at index 0 (aka the already-existing material), the script does add the texture node setup but to material of index 0:

When NO Principled BSDF shader node is selected and i want the script to select this node from material index 1 (aka the dynamically generated material) it selects the node but unfortunately does NOT add the texture setup as I would have expected. The result is:

Hence the issue as described in the question title of this thread still persists

Here's the new complete script (make sure to use the default cube that already has 1 material on slot index 0):

import bpy
object = bpy.context.active_object
material = bpy.data.materials.new(name='dynamically_created')
object.data.materials.append(material)
object.active_material_index = len(object.material_slots) - 1
material.use_nodes = True
tree = material.node_tree
nodes = tree.nodes
material.node_tree.nodes['Material Output'].select = False
material.node_tree.nodes['Principled BSDF'].select = True
material.node_tree.nodes.active = material.node_tree.nodes.get("Principled BSDF")
filepath="E:\ZZZZ\Projects\blender\textures\metal\Metal021_1K-JPG\"
directory="E:\ZZZZ\Projects\blender\textures\metal\Metal021_1K-JPG\"
files=[
    {"name":"Metal021_1K-JPG.usda", "name":"Metal021_1K-JPG.usda"},
    {"name":"Metal021_1K-JPG.usdc", "name":"Metal021_1K-JPG.usdc"},
    {"name":"Metal021_1K_Color.jpg", "name":"Metal021_1K_Color.jpg"},
    {"name":"Metal021_1K_Displacement.jpg", "name":"Metal021_1K_Displacement.jpg"},
    {"name":"Metal021_1K_Metalness.jpg", "name":"Metal021_1K_Metalness.jpg"},
    {"name":"Metal021_1K_NormalDX.jpg", "name":"Metal021_1K_NormalDX.jpg"},
    {"name":"Metal021_1K_NormalGL.jpg", "name":"Metal021_1K_NormalGL.jpg"},
    {"name":"Metal021_1K_Roughness.jpg", "name":"Metal021_1K_Roughness.jpg"},
    {"name":"Metal021_PREVIEW.jpg", "name":"Metal021_PREVIEW.jpg"},
]
relative_path=True
#-----------------------------------------------------------------------------

Starting in 3.2 context overrides are deprecated in favor of temp_override
https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override

They are scheduled to be removed in 3.3

def use_temp_override():
    ''' Determine whether Blender is 3.2 or newer and requires
        the temp_override function, or is older and requires
        the context override dictionary
    '''
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    if major < 3 or (major == 3 and minor < 2):
        return False
    else:
        return True
win = bpy.context.window
scr = win.screen
areas  = [area for area in scr.areas if area.type == 'NODE_EDITOR']
regions = [region for region in areas[0].regions if region.type == 'WINDOW']
if use_temp_override():
    with bpy.context.temp_override(window=win, area=areas[0], region=regions[0],
        screen=scr):
            bpy.ops.node.nw_add_textures_for_principled(
                filepath=filepath,
                directory=directory,
                files=files,
                relative_path=relative_path
            )
else:
    override = {
        'window': win,
        'screen': scr,
        'area': areas[0],
        'region': regions[0],
    }
    bpy.ops.node.nw_add_textures_for_principled(
        override,
        filepath=filepath,
        directory=directory,
        files=files,
        relative_path=relative_path
    )

If you check the console, you will see that it complains about no folder being selected Info: No Folder Selected. Do you want to set the folder programmatically or let the user pick (display the file browser)? — Robert Gützkow, Jun 24 '22 at 07:11
hi. not in my case. no errors. i tried running it now by removing all materials and it runs without errors where console is saying Matched Textures etc and result {"FINISHED"} but no textures were added. I want to set it automatically. I have a list of folders through which i will iterate each folder to one material. — Harry McKenzie, Jun 24 '22 at 07:17
it actually is inconsistent. sometimes its FINISHED sometimes CANCELLED. but it never adds the textures unless i run bpy.ops.node.nw_add_textures_for_principled() on an already created material. — Harry McKenzie, Jun 24 '22 at 07:23
If you want to do it programmatically, you will have to provide the parameter for the directory https://developer.blender.org/diffusion/BA/browse/master/node_wrangler.py$3143 — Robert Gützkow, Jun 24 '22 at 07:32
i did provide the parameters but i did not write the whole block in the snippet i provided. i just used ellipsis (for etc) as parameter with a comment saying that if ever someone was interested to test it they can generate this statement with their textures. I will update the post with the statement i used. — Harry McKenzie, Jun 24 '22 at 07:44
@HarryMcKenzie There are two problems with your script. 1) You need to set the object's active_material_index to the slot of the new material. 2) You've misspelled regions as region in the then branch of the if statement. I'll update my answer to cover that. — Marty Fouts, Jun 30 '22 at 17:35
hi @MartyFouts thanks for looking into it again. Unfortunately i still get CANCELLED with the "putting it all together" code and using my textures in "CHANGE ME" part and if you create a new file and leave everythig as is with default cube selected and the nodes in shader nodes selected, it will add the textures on the material with index 0. i need it to be added to the dynamically created material. can you show me a video of it working on your side including scrolling through the code? btw i updated my question with your complete code. — Harry McKenzie, Jul 01 '22 at 03:19
@MartyFouts i copied your code again for a third time and edited the code in my question just to check the diff, and there is no diff. so it is certainly your code i ran and i still get the same result: Info: Select Principled BSDF result: {'CANCELLED'} — Harry McKenzie, Jul 01 '22 at 04:03
Add your blend file to your question, please. I'll rename directories and textures; but you can see that the code works by having the Material Properties tab open and executing the first four lines. The active slot highlight changes. Are you at least seeing that? — Marty Fouts, Jul 01 '22 at 04:08
Ah, I have found a problem. If I paste my script into the Python console it works but if I run it it doesn't. I think the scene needs to be updated after the active material slot is changed — Marty Fouts, Jul 01 '22 at 04:13
@HarryMcKenzie I've confirmed that's the problem. If I run it interactively in the Python window then the node editor that is visible switches to the dynamic material and node wrangler operates on that material. But if you run it in the script, the switch isn't made until after the node wrangler routine runs. I'm out of time for today but maybe you can figure out how to make the window switch to the new material. — Marty Fouts, Jul 01 '22 at 04:26
@MartyFouts yes that's exactly the weird issue I had as well when running it in console works perfectly but not in the Text Editor that's why I had to resort to this site to find the answer to this "asynchronous" problem, I wonder if it is even possible XD — Harry McKenzie, Jul 01 '22 at 04:32

score 3 · Accepted Answer · edited Jul 08 '22 at 05:27

Your problem starts with the fact that bpy.context.area is meant to be read-only. The randomness of behavior stems from that.

You need to establish a context override to use the node wrangler function. But that means you need to deal with context override dictionaries being deprecated in 3.2 and scheduled to be removed in 3.3. Here's a way to deal with that:

#-----------------------------------------------------------------------------
#
# Starting in 3.2 context overrides are deprecated in favor of temp_override
# https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override
#
# They are scheduled to be removed in 3.3
#
def use_temp_override():
    ''' Determine whether Blender is 3.2 or newer and requires
        the temp_override function, or is older and requires
        the context override dictionary
    '''
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    if major < 3 or (major == 3 and minor < 2):
        return False
    else:
        return True
win = bpy.context.window
scr = win.screen
areas3d = [area for area in scr.areas if area.type == 'VIEW_3D']
regions = [region for region in areas3d[0].regions if region.type == 'WINDOW']
if use_temp_override():
    with bpy.context.temp_override(window=win, area=areas3d[0], region=regions[0],
        screen=scr):
        print("place your bpy.ops call here, IE bpy.ops.view3d.camera_to_view()")
else:
    override = {
        'window': win,
        'screen': scr,
        'area': areas3d[0],
        'region': regions[0],
    }
    print("use an override here, IE bpy.ops.view3d.camera_to_view(override)")

but you're not overriding a 3d view, but rather the shader editor, so you'll need to adjust area and region.

EDIT: Your second problem is that you have to set the object's active_material_index to the index of the newly added material. the Node Wrangler ops operate on the active material. After you've appended the new material you need to add

object.active_material_index = len(object.material_slots) - 1

after

object.data.materials.append(material)

This works because the new material is appended into the last material slot.

Second Edit: As per an exchange described in a comment in the answer, you also need to set the space.active.node_tree for the appropriate Node Editor.

Also, there is a typo in the if statement in the latest version of your script in your question. in the with statement region[0] should be regions[0]. I think that came from my original answer. I've fixed all the spellings in the answer.

Putting it all together, tested with an example from my own collection of textures, but with the names changed:

import bpy
object = bpy.context.active_object
material = bpy.data.materials.new(name='dynamically_created')
object.data.materials.append(material)
object.active_material_index = len(object.material_slots) - 1
material.use_nodes = True
tree = material.node_tree
nodes = tree.nodes
material.node_tree.nodes['Material Output'].select = False
material.node_tree.nodes['Principled BSDF'].select = True
material.node_tree.nodes.active = material.node_tree.nodes.get("Principled BSDF")
filepath= "CHANGE ME"
directory="CHANGE ME"
files=[
    {"name":"CHANGE ME", "name":"CHANGE ME"},
] 
relative_path=True
#-----------------------------------------------------------------------------

Starting in 3.2 context overrides are deprecated in favor of temp_override
https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override

They are scheduled to be removed in 3.3

def use_temp_override():
    ''' Determine whether Blender is 3.2 or newer and requires
        the temp_override function, or is older and requires
        the context override dictionary
    '''
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    if major < 3 or (major == 3 and minor < 2):
        return False
    else:
        return True
win = bpy.context.window
scr = win.screen
areas  = [area for area in scr.areas if area.type == 'NODE_EDITOR']
regions = [region for region in areas[0].regions if region.type == 'WINDOW']
Omar Emara informed Harry McKenzie that in order to solve the problem of this script
working when pasted into the console but not working when run
"You just need to assign the node tree to the node tree space type because the
operator uses that."  Harry McKenize posted an answer showing the exact
method.  I've adapted it to this code's flow.
areas[0].spaces.active.node_tree = material.node_tree
if use_temp_override():
    with bpy.context.temp_override(window=win, area=areas[0], region=regions[0],
        screen=scr):
            bpy.ops.node.nw_add_textures_for_principled(
                filepath=filepath,
                directory=directory,
                files=files,
                relative_path=relative_path
            )
else:
    override = {
        'window': win,
        'screen': scr,
        'area': areas[0],
        'region': regions[0],
    }
    bpy.ops.node.nw_add_textures_for_principled(
        override,
        filepath=filepath,
        directory=directory,
        files=files,
        relative_path=relative_path
    )

You would, of course, have to change the "CHANGE ME" strings and have at least one entry per texture from the directory.

hey sorry for the late response. thank u very much for ur help and time :) — Harry McKenzie, Jun 28 '22 at 15:11
hi i just got the time to test it, and while the script works with the override functionality, it unfortunately still does not solve the problem described in the title. The function will not add the texture nodes if the material is dynamically created. It only works on the second run with the already created material. — Harry McKenzie, Jun 30 '22 at 01:48
maybe i have to subscribe to an event that gets triggered when the material is successfully created and ready to be manipulated? and within this onUpdateComplete i can execute the texture setup function. — Harry McKenzie, Jul 02 '22 at 10:24
Maybe, but usually when things work interactively but not in a script its because the interpreter implicitly is flushing state but the script isn't. In this case it seems like the NW operator is working with a stale value of active_material_index. I've read the NW code but I can't see a problem, so I suspect that there's a flush of some sort needed. — Marty Fouts, Jul 02 '22 at 17:16
I gave you the bounty because i appreciate the time and effort you have given! But unfortunately i can't mark it as answered because the issue still stands XD Should i raise another bounty with a NEW question? — Harry McKenzie, Jul 06 '22 at 05:44
@HarryMcKenzie I appreciate the gesture. Thank you. Looks like you've gotten a solution. Congratulations, even though I don't understand why setting spaces.active.node_tree works in a script but isn't needed in the console. — Marty Fouts, Jul 06 '22 at 15:14
it also didnt work in the console for me so I logged it as a bug here and the blender developer told me to add that line for it to work, because the operator uses it. — Harry McKenzie, Jul 06 '22 at 15:45

Harry McKenzie · Answer 2 · 2024-01-31T11:55:51.390

1

I have finally gotten the last piece of the puzzle thanks to Omar Emara from this Blender ticket comment

You just need to assign the node tree to the node tree space type because the operator uses that.

areas  = [area for area in scr.areas if area.type == 'NODE_EDITOR']
areas[0].spaces.active.node_tree = material.node_tree

edited Jan 31 '24 at 11:55

answered Jul 06 '22 at 11:37

Harry McKenzie

10,995
8
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51

thanks to this i was able to help someone fix their issue https://blender.stackexchange.com/questions/267089/how-to-bulk-import-and-set-up-hundreds-of-pbr-textures-with-python – Harry McKenzie Jul 06 '22 at 12:52
this same snippet fixed this issue https://blender.stackexchange.com/questions/300077/what-is-the-proper-context-for-working-with-material-nodes – Harry McKenzie Aug 30 '23 at 12:23

Why does "nw_add_textures_for_principled" work w/ Existing Material but not w/ dynamically created ones?

Starting in 3.2 context overrides are deprecated in favor of temp_override

https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override

They are scheduled to be removed in 3.3

2 Answers2

Starting in 3.2 context overrides are deprecated in favor of temp_override

https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override

They are scheduled to be removed in 3.3

Omar Emara informed Harry McKenzie that in order to solve the problem of this script

working when pasted into the console but not working when run

"You just need to assign the node tree to the node tree space type because the

operator uses that." Harry McKenize posted an answer showing the exact

method. I've adapted it to this code's flow.

Linked