Can't create Output sockets for a NodeGroupInput, bug?

Coding Python Support
1

I was updating from 2.66 to 2.68 an importer that loads models with cycles materials and creates node groups.

I could update everything find reading the release notes, wiki and this bug report, but what I can’t figure out is why you can’t create node sockets (outputs) for a nodegroupInput unless you create a link to something first.

Examples:

  1. Manually you can’t create an output unless you link it to something

http://i44.tinypic.com/kuq6c.png

  1. Once you created a link, you can create as many new outputs as you want in the N panel.
    http://i39.tinypic.com/of0zzo.png

So this looks to me to a limitation both in python and in the UI compared to the old way node groups worked.
This code should create a nodeGroupInput with all the sockets(outputs) I want but it doesn’t, and it doesn’t give any warnings either. It just creates a Group input without any socket/outputs:


import bpy

NodeGroup= bpy.data.node_groups.new("GroupTest", type='ShaderNodeTree')

Input_group = NodeGroup.nodes.new("NodeGroupInput")
Input_group.outputs.new('RGBA', "Tex Diffuse")
Input_group.outputs.new('RGBA', "Tex Specular")
Input_group.outputs.new('RGBA', "Tex Normal")

Can someone confirm this looks like a bug?
This is something important for scripts since you want to create only one group with their inputs but they might not be used always in all materials.

2

I wrote a group node writer a while ago and this was the way i handled inputs / outputs


import bpy


x = bpy.data.node_groups.new("rayTransparency","ShaderNodeTree")
ngo = x.nodes.new(type="NodeGroupOutput")
ngi = x.nodes.new(type="NodeGroupInput")




mth = x.nodes.new(type="ShaderNodeMath")




x.links.new(mth.inputs[0],ngi.outputs[0])


x.links.new(mth.outputs[0],ngo.inputs[0])
x.inputs[0].name = "Transparency"
x.inputs[0].default_value = 1
x.outputs.new

Pretty much you cant just hit create new for some strange reason in python… you have to link it to a socket then rename.

3

Yeah, that’s my point, in the previous way of creating nodes by python was much convenient. I couldn’t find any discussion about this though.

4

maybe submit it as a bug to the bug tracker?

5

Yeah, I think I will because in this case in 2.67 when the node groups were overhauled this counts like a broken features. But any other opinion before submitting will be good

6

is this a bug ?

i think there are other bug also for some other method to access I/O
but will avhe to see it it is corrected
right now only way i was able to do it was with index method
other 2 methods did nto work!

thanks

7

Well, I opened a bug and Lukas pointed me in the right direction thankfully.
Turns out you don’t have to reference the Input group node, but group.inputs, as in 2.67.

8

can you show update example

thanks

9

Ricky, Lucas posted this:


import bpy
TestGroup = bpy.data.node_groups.new("Test", type='ShaderNodeTree')
Input_node = TestGroup.nodes.new("NodeGroupInput")

# Use the nodetree.inputs/outputs collections for extending the node group interface
TestGroup.inputs.new('NodeSocketColor', "Tex Diffuse") 
TestGroup.inputs.new('NodeSocketColor', "Tex Specular")

cheers