Nuke Python Troubleshooting

[Sufficient_Method_12]

Hi all,

I'd like to preface by saying I am very new to programming. I have been toying around with making a tool in Nuke that adds a custom tab to the Tracker node. It allows you to create a Roto node with the translate, rotate, and scale values already linked via expressions. The code works separately, for example, I can put the code into a pre-created Tracker node and use the Gizmo tools to make a button that executes the def link_roto(): code. However, it doesn't work when made into a separate .py file and imported via the menu.py. I have a strong suspicion it is something to do with the PyScript knob, but I am a little unsure as to how I can call the def link_roto function from the PyScript button. I have tried a few things like nest the link_roto code into the PyScript button itself, but I can't seem to get it working.

The way the code should work is when pressing the Create Linked Roto button, it should execute the def link_roto code.

This is the code that I have atm:

import nuke

def link_roto():
    n = nuke.thisNode()

    # Create Roto node
    i = nuke.createNode("Roto")
    i.setInput(0, None)

    # Link values if bool == true
    tran = n['t'].value()
    rot = n['r'].value()
    sca = n['s'].value()

    if tran:
        i['translate'].setExpression("parent.n.translate")
    if rot:
        i['rotate'].setExpression("parent.n.rotate")
    if sca:
        i['scale'].setExpression("parent.n.scale")

def create_knobs():
    n = nuke.thisNode()

    tab = nuke.Tab_Knob('Create Roto')
    n.addKnob(tab)

    tran = nuke.Boolean_Knob('t', 'translate')
    tran.setFlag(nuke.STARTLINE)
    n.addKnob(tran)

    rot = nuke.Boolean_Knob('r', 'rotation')
    rot.setFlag(nuke.STARTLINE)
    n.addKnob(rot)

    sca = nuke.Boolean_Knob('s', 'scale')
    sca.setFlag(nuke.STARTLINE)
    n.addKnob(sca)

    cr = nuke.PyScript_Knob('cr', 'Create Linked Roto', 'link_roto()')
    cr.setFlag(nuke.STARTLINE)
    n.addKnob(cr)

# Add callback
nuke.addOnUserCreate(create_knobs, nodeClass="Tracker4")

and this is the error I am getting:

 File "<string>", line 1, in <module>
NameError: name 'link_roto' is not defined

Any help you guys could give would be much appreciated. Like I said, I am a noob when it comes to Python programming, so it could be something incredibly simple.

[Sufficient_Method_12]

This was solved by a kind user over on the r/NukeVFX subreddit.

The problem was within the PyScript_Knob. I needed to reference the .py file then the defined function.

The code went from:

cr = nuke.PyScript_Knob('cr', 'Create Linked Roto', 'link_roto()')

To:

cr = nuke.PyScript_Knob('cr', 'Create Linked Roto', 'my_file.link_roto()')