Nodetree update optimization from Blender 3.1+ breaks my Addon #101378

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Thomas · 2022-09-26T12:30:22+02:00

Thomas commented

2022-09-26 12:30:22 +02:00

System Information
Operating system: -
Graphics card: -

Blender Version
Broken: 3.1+
Worked: 3.0.1

I'm the creator of Material Wizard Addon (https://wp.h0bb1t.de/index.php/about-material-wizard/) and have to admit, that I haven't touched it quite a long time. I now have planned to update it and stumbled across the fact, that it doesn't work as expected starting with Blender 3.1+. After some debugging, I figured out where the problem comes from and assume it is related to the Nodetree update optimization started in 3.1.

Material Wizard has its own Node Tree and reflects any changes to it in different Shader Node Trees. It does it by creating hidden NodeGroups and instanciate them in the respective material and links sockets according the settings in my own node space. Long story short, the problem arises when adding a node group to the shader node tree and try to loop over the inputs of this node group. It seems in Blender 3.1+, the inputs do not reflect the inputs of the node tree embedded to the group:

In the highlighted area in the lower left corner, len(node.inputs) is 0, while len(node.node_tree.inputs) is 8. In Blender pre 3.1, the first one was also 8, which is what I need. After my script has run, I get the correct node groups in my target material trees, but they don't have inputs or outputs. Subsequent calls to [Node.update()] in Blenders Python console fixes the problem.

I assume I need to force an update on the Shader Node Tree from my script, but havn't found any information how to do this. Calling update() on the node in my script (rectangular highlighted area in the code above) doesn't seem to help.

Please help me.
Thanks,
Thomas

**System Information** Operating system: - Graphics card: - **Blender Version** Broken: 3.1+ Worked: 3.0.1 I'm the creator of Material Wizard Addon (https://wp.h0bb1t.de/index.php/about-material-wizard/) and have to admit, that I haven't touched it quite a long time. I now have planned to update it and stumbled across the fact, that it doesn't work as expected starting with Blender 3.1+. After some debugging, I figured out where the problem comes from and assume it is related to the Nodetree update optimization started in 3.1. Material Wizard has its own Node Tree and reflects any changes to it in different Shader Node Trees. It does it by creating hidden NodeGroups and instanciate them in the respective material and links sockets according the settings in my own node space. Long story short, the problem arises when adding a node group to the shader node tree and try to loop over the inputs of this node group. It seems in Blender 3.1+, the inputs do not reflect the inputs of the node tree embedded to the group: ![node-tree-bug.png](https://archive.blender.org/developer/F13574654/node-tree-bug.png) In the highlighted area in the lower left corner, len(node.inputs) is 0, while len(node.node_tree.inputs) is 8. In Blender pre 3.1, the first one was also 8, which is what I need. After my script has run, I get the correct node groups in my target material trees, but they don't have inputs or outputs. Subsequent calls to [Node.update()] in Blenders Python console fixes the problem. ![node-tree-bug2.png](https://archive.blender.org/developer/F13574685/node-tree-bug2.png) I assume I need to force an update on the Shader Node Tree from my script, but havn't found any information how to do this. Calling update() on the node in my script (rectangular highlighted area in the code above) doesn't seem to help. Please help me. Thanks, Thomas

Thomas commented

2022-09-26 12:30:22 +02:00

Added subscriber: @h0bB1T

Jacques Lucke commented

2022-09-26 12:34:43 +02:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2022-09-26 12:34:43 +02:00

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

Jacques Lucke commented

2022-09-26 12:34:43 +02:00

Please try to reproduce the issue outside of your addon to make it easier to investigate for us.

Thomas commented

2022-09-26 14:12:59 +02:00

Ok, I've quickly hacked a script based on the custom nodes template that shows the problem. Tested with Blender 3.0 & 3.2, 3.2 is affected (but I assume 3.1+).

In the default scene:

Open script & run it.
Open custom node tree.
Add both available nodes.
Link any output to any input socket.
- This invokes update() on the custom node, which calls rebuild_tree() in the Tree class.
- This creates a simple node group (TestNode)
- .. and a new material and adds this node to the material tree.
Look at the node tree of TestMaterial. The node group has no sockets.

Adding the group to TestMasterial Shift-A/Group/TestNode fixes the problem.
Running create_node_group() + add_node_group() from script directly works as expected.

I hope this helps.

import bpy

from bpy.types import NodeTree, Node, NodeSocket

just_once = False


def create_node_group():
    ng = bpy.data.node_groups.new('TestNode', 'ShaderNodeTree')
    ng.inputs.new('NodeSocketFloat', 'TestSocket')
    
    
def add_node_group():
    m = bpy.data.materials.new('TestMaterial')
    m.use_nodes = True
    m.node_tree.nodes.clear()
    ng = m.node_tree.nodes.new(type='ShaderNodeGroup')
    ng.node_tree = bpy.data.node_groups['TestNode']
    print(len(ng.inputs))


class MyCustomTree(NodeTree):
    bl_idname = 'CustomTreeType'
    bl_label = "Custom Node Tree"
    bl_icon = 'NODETREE'
    
    
    def rebuild_tree(self):
        global just_once
        if not just_once:
            just_once = True
            create_node_group()
            add_node_group()    


class MyCustomTreeNode:
    @classmethod
    def poll(cls, ntree):
        return ntree.bl_idname == 'CustomTreeType'
    

class MyCustomNode(Node, MyCustomTreeNode):
    bl_idname = 'CustomNodeType'
    bl_label = "Custom Node"
    bl_icon = 'SOUND'

    def init(self, context):
        self.inputs.new('NodeSocketFloat', "Hello 123")
        self.inputs.new('NodeSocketFloat', "World")

    def copy(self, node): print("Copying from node ", node)
    def free(self): print("Removing node ", self, ", Goodbye!")

    def draw_buttons(self, context, layout): pass
    def draw_buttons_ext(self, context, layout): pass

    def update(self):
        self.id_data.rebuild_tree()
        

class MyCustomNode2(Node, MyCustomTreeNode):
    bl_idname = 'CustomNodeType2'
    bl_label = "Custom Node2"
    bl_icon = 'SOUND'

    def init(self, context):
        self.outputs.new('NodeSocketFloat', "Hello")
        self.outputs.new('NodeSocketFloat', "World")

    def copy(self, node): print("Copying from node ", node)
    def free(self): print("Removing node ", self, ", Goodbye!")

    def draw_buttons(self, context, layout): pass
    def draw_buttons_ext(self, context, layout): pass


import nodeitems_utils
from nodeitems_utils import NodeCategory, NodeItem

class MyNodeCategory(NodeCategory):
    @classmethod
    def poll(cls, context):
        return context.space_data.tree_type == 'CustomTreeType'


node_categories = [
    MyNodeCategory('SOMENODES', "Some Nodes", items=[
        NodeItem("CustomNodeType"),
        NodeItem("CustomNodeType2"),
    ])
]

classes = (
    MyCustomTree,
    MyCustomNode,
    MyCustomNode2,
)


def register():
    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)

    nodeitems_utils.register_node_categories('CUSTOM_NODES', node_categories)


def unregister():
    nodeitems_utils.unregister_node_categories('CUSTOM_NODES')

    from bpy.utils import unregister_class
    for cls in reversed(classes):
        unregister_class(cls)


if __name__ == "__main__":
    register()

Ok, I've quickly hacked a script based on the custom nodes template that shows the problem. Tested with Blender 3.0 & 3.2, 3.2 is affected (but I assume 3.1+). In the default scene: - Open script & run it. - Open custom node tree. - Add both available nodes. - Link any output to any input socket. - This invokes update() on the custom node, which calls rebuild_tree() in the Tree class. - This creates a simple node group (TestNode) - .. and a new material and adds this node to the material tree. - Look at the node tree of TestMaterial. The node group has no sockets. Adding the group to TestMasterial Shift-A/Group/TestNode fixes the problem. Running create_node_group() + add_node_group() from script directly works as expected. I hope this helps. ``` import bpy from bpy.types import NodeTree, Node, NodeSocket just_once = False def create_node_group(): ng = bpy.data.node_groups.new('TestNode', 'ShaderNodeTree') ng.inputs.new('NodeSocketFloat', 'TestSocket') def add_node_group(): m = bpy.data.materials.new('TestMaterial') m.use_nodes = True m.node_tree.nodes.clear() ng = m.node_tree.nodes.new(type='ShaderNodeGroup') ng.node_tree = bpy.data.node_groups['TestNode'] print(len(ng.inputs)) class MyCustomTree(NodeTree): bl_idname = 'CustomTreeType' bl_label = "Custom Node Tree" bl_icon = 'NODETREE' def rebuild_tree(self): global just_once if not just_once: just_once = True create_node_group() add_node_group() class MyCustomTreeNode: @classmethod def poll(cls, ntree): return ntree.bl_idname == 'CustomTreeType' class MyCustomNode(Node, MyCustomTreeNode): bl_idname = 'CustomNodeType' bl_label = "Custom Node" bl_icon = 'SOUND' def init(self, context): self.inputs.new('NodeSocketFloat', "Hello 123") self.inputs.new('NodeSocketFloat', "World") def copy(self, node): print("Copying from node ", node) def free(self): print("Removing node ", self, ", Goodbye!") def draw_buttons(self, context, layout): pass def draw_buttons_ext(self, context, layout): pass def update(self): self.id_data.rebuild_tree() class MyCustomNode2(Node, MyCustomTreeNode): bl_idname = 'CustomNodeType2' bl_label = "Custom Node2" bl_icon = 'SOUND' def init(self, context): self.outputs.new('NodeSocketFloat', "Hello") self.outputs.new('NodeSocketFloat', "World") def copy(self, node): print("Copying from node ", node) def free(self): print("Removing node ", self, ", Goodbye!") def draw_buttons(self, context, layout): pass def draw_buttons_ext(self, context, layout): pass import nodeitems_utils from nodeitems_utils import NodeCategory, NodeItem class MyNodeCategory(NodeCategory): @classmethod def poll(cls, context): return context.space_data.tree_type == 'CustomTreeType' node_categories = [ MyNodeCategory('SOMENODES', "Some Nodes", items=[ NodeItem("CustomNodeType"), NodeItem("CustomNodeType2"), ]) ] classes = ( MyCustomTree, MyCustomNode, MyCustomNode2, ) def register(): from bpy.utils import register_class for cls in classes: register_class(cls) nodeitems_utils.register_node_categories('CUSTOM_NODES', node_categories) def unregister(): nodeitems_utils.unregister_node_categories('CUSTOM_NODES') from bpy.utils import unregister_class for cls in reversed(classes): unregister_class(cls) if __name__ == "__main__": register() ```

Thomas commented

2022-09-26 18:27:22 +02:00

Hello Jacques,

in D16070 you mention there would be better ways to do this. I'm always open to better ways. As it is just a call to rebuild_tree, it's relatively fast to test different ways. What is the preferred way to let the Shader Node Tree stay in sync with my custom tree?
And, in case of your mentioned timer based solution, would it be ok (incrementally) sync tree layout on an e.g. 100ms timed cycle?

Hello Jacques, in [D16070](https://archive.blender.org/developer/D16070) you mention there would be better ways to do this. I'm always open to better ways. As it is just a call to rebuild_tree, it's relatively fast to test different ways. What is the preferred way to let the Shader Node Tree stay in sync with my custom tree? And, in case of your mentioned timer based solution, would it be ok (incrementally) sync tree layout on an e.g. 100ms timed cycle?

Jacques Lucke commented

2022-09-26 18:58:33 +02:00

It's not perfect but you could set some flag to true in the update function and then just check that flag in a timer so that it only syncs the tree when necessary. I'm not sure if there is a perfect solution for this scenario currently.

Thomas commented

2022-09-26 19:11:08 +02:00

Thanks, will try this :)

Thomas Dinges commented

2022-10-21 10:39:56 +02:00

Added subscriber: @ThomasDinges

Thomas Dinges commented

2022-10-21 10:39:56 +02:00

Any update here? Did you find a solution @h0bB1T ?

Thomas commented

2022-10-21 10:49:59 +02:00

Hi. Yes. I followed the idea of Jaques to use a dirty flag and a timer based update and it works nicely. At the end, it seems the better solution. So at least to my needs, it is not necessary to fix it (and the new solution works in older Blender versions too).

Thomas Dinges commented

2022-10-21 12:06:16 +02:00

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

Thomas Dinges closed this issue

2022-10-21 12:06:16 +02:00

Thomas Dinges commented

2022-10-21 12:06:16 +02:00

Great, thanks for your quick response. I am closing this then. :)

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Nodetree update optimization from Blender 3.1+ breaks my Addon #101378