In T96394#1326520, @Pratik Borhade (PratikPB2123) wrote:

Create custom node tree by python

Hi, thanks for the report. You mean using default python template?

I don't think I understand steps for reproducing the problem. Are you using custom script? Can you attach that?
Also, please test again on latest 3.2 build: https://builder.blender.org/download/daily/
Similar reports I have seen where responsible commit was rB7e712b2d6a0d257d272ed35622b41d06274af8df

Thanks!

I codding add-on for batch rendering using node trees.
Steps:

1. Download archive batch_render_nodes.zip
   batch_render_nodes.zip129 KBDownload
2. Install zip-archive add-on in Blender 3.0 and Blender 3.1

3.Download test file Batch_Render_Nodes_UPDATE_TREE_TEST.blend

4. Open test file Batch_Render_Nodes_UPDATE_TREE_TEST.blend in Blender 3.0
5. Try change sockets values
6. Sockets output values updated

7. Open test file Batch_Render_Nodes_UPDATE_TREE_TEST.blend in Blender 3.1
8. Try change sockets values
9. Sockets output values not updated

I try Blender 3.2. Sockets output information also not updated

For update sockets and all node tree i used function https://docs.blender.org/api/current/bpy.types.NodeTree.html#bpy.types.NodeTree.interface_update

Also i upload screen videocapture

I'm not 100%, but right now this does not feel like a bug in Blender to me.

It seems like you expect Blender to call the update method on every node when you call interface_update. However, there is no reason why it should do that. interface_update is a method that was supposed to be called to force an update when the inputs or outputs of a node group changed. However, Blender never calls this function itself anymore, so maybe it should even be removed.

From what I can tell, the current update-logic in the addon is very brittle. This is also shown by the fact that you always call interface_update three times, so that data can propagate for three nodes. This might give the illusion that it works, but is still unreliable when there are longer chains of nodes.

A short term fix would be to just call node.update() for all the nodes manually.

@persistent
def updateNodeTreeTimerThread():

        for tree in bpy.data.node_groups:
            if tree.bl_idname == 'BatchNodesTree':
                for _ in range(3):
                    for node in tree.nodes:
                        node.update()

In addition you might have to loop over the different area/regions in the Blender UI and call tag_redraw on them.
For a more complete example see P2851.

I highly recommend you to implement a system that gives you control over when and in what order nodes are executed.

In T96394#1329178, @Jacques Lucke (JacquesLucke) wrote:

I'm not 100%, but right now this does not feel like a bug in Blender to me.

It seems like you expect Blender to call the update method on every node when you call interface_update. However, there is no reason why it should do that. interface_update is a method that was supposed to be called to force an update when the inputs or outputs of a node group changed. However, Blender never calls this function itself anymore, so maybe it should even be removed.

From what I can tell, the current update-logic in the addon is very brittle. This is also shown by the fact that you always call interface_update three times, so that data can propagate for three nodes. This might give the illusion that it works, but is still unreliable when there are longer chains of nodes.

A short term fix would be to just call node.update() for all the nodes manually.

@persistent
def updateNodeTreeTimerThread():

        for tree in bpy.data.node_groups:
            if tree.bl_idname == 'BatchNodesTree':
                for _ in range(3):
                    for node in tree.nodes:
                        node.update()

In addition you might have to loop over the different area/regions in the Blender UI and call tag_redraw on them.
For a more complete example see P2851.

I highly recommend you to implement a system that gives you control over when and in what order nodes are executed.

Thanks !I have updated the code, thanks to your advice. Update nodes works