some Nuke Python snippets (and other general coolness)

If anyone has some cool snippets to share please feel free to leave them in a comment below.

*last updated: 23 December 2016

user knob value in an expression / particle expression

[value yourUserKnob]

random particle colour with particle expression node

*** a blendMat node must be applied before the emitter:

 operation: plus
 surface blend: modulate

the “color” parameter of a particleExpression node can be set using a 3dVector:
v( r, g, b )

and each channel can be referenced like this:
the red value for example :
x(color)

give the colour parameter a random value – (needs to be a 3dVector)
v(random*2, random, random/1.4 )

iterate over the animation curve of a Transform node copying the value of the Y position to a parameter of another Transform node.

dest = nuke.nodes.Transform()
destTransform = dest["translate"]
destTransform.setAnimated()
destAnim = dest["translate"].animation(1)
 
a = nuke.selectedNode()["translate"]
ypos = a.animation(1)
keys = ypos.keys()
 
for a in range(0,42):
    dest["translate"].animation(1).setKey(a, ypos.evaluate(a))

display the current duration since the first frame (useful when sequence doesn’t start at zero/one)
put this in a text node or in a node’s “label” tab

[python {int( nuke.frame() - nuke.root()['first_frame'].value() ) }]

take a RotoPaint and change each layer’s RGBA to a grey level based on it’s “depth” – useful for prep’ing for a stereo conversion i’d imagine

import random
a = nuke.selectedNode()
if a.Class() == "RotoPaint":
    knob = a['curves']
    i = 0.0
    for c in knob.rootLayer:
 
        pos = float ((len(knob.rootLayer) - i) / len(knob.rootLayer))
        i = i+1
 
        attrs = c.getAttributes()
        attrs.set(1, attrs.kRedOverlayAttribute, pos)
        attrs.set(1, attrs.kRedAttribute, pos)
        attrs.set(1, attrs.kGreenOverlayAttribute, pos)
        attrs.set(1, attrs.kGreenAttribute, pos)
        attrs.set(1, attrs.kBlueOverlayAttribute, pos)
        attrs.set(1, attrs.kBlueAttribute, pos)
        attrs.set(1, attrs.kAlphaOverlayAttribute, pos)
        attrs.set(1, attrs.kAlphaAttribute, pos)

for all selected Tracker nodes multiply their track values by a factor of 4

for a in nuke.selectedNodes():
    if a.Class()=="Tracker3":
 
	def scaleMe(track):
		if track.isAnimated():
			for j in range (0,2):
		        anim = track.animation(j)
		        keys = anim.keys()
		        scaleFactor = 4
		        while keys:
		            keys.pop().y *= scaleFactor
	#i am sure there is a much nicer way of iterating over all the knobs but this worked for what i quickly needed
	t1 = a['track1']
	t2 = a['track2']
	t3 = a['track3']
	t4 = a['track4']
	scaleMe(t1)
	scaleMe(t2)
	scaleMe(t3)
	scaleMe(t4)

set bbox to “B” for nodes inside all Group nodes

import nuke
 
def bboxGroup():
  for b in nuke.allNodes():
    if b.Class() == "Group":
      for a in nuke.toNode(b.name()).nodes():
        classTypes = ['Merge' , 'Keymix', 'Copy', ]
        print a.name()
        for n in classTypes:
          if n in a.Class():
            try:
              for p in a['bbox'].values():
                if 'B' in p:
                  a['bbox'].setValue(a['bbox'].values().index(p))
            except:
              pass

“Autowrite” node
Copy the following line into the python “beforeRender” field in a write node.
The write node’s “file” field will be filled based on the script’s name/path.
Obviously this all depends on your pipeline etc.

For my current situation each vfx shot has it’s own directory, which is then populated with “renders” & “scripts” subdirectories.
So for me I can do this:

nuke.thisNode()["file"].setValue(nuke.root().name().replace("scripts","renders").replace(".nk",".mov"))

delete all nodes that are not selected

s = nuke.selectedNodes()
b = nuke.allNodes()
 
for n in b:
    if n not in s:
        nuke.delete(n)

selects all dependencies (input nodes & their parents) from a selected node

a = nuke.selectedNode()
nodesToSelect = []
 
nodesToSelect.append(a)
def climb(node):
    # print node.name()
    for n in node.dependencies():
        nodesToSelect.append(a)
        climb(n)
 
climb(a)
 
for x in nodesToSelect:
	print x.name()
    # x.setSelected(1)

set all Read nodes to cache locally

for a in nuke.allNodes():
    if a.Class()=='Read':
        a['cached'].setValue(1)
        a['cacheLocal'].setValue(0)

print last frame of script

print nuke.root()['last_frame'].value()

create a backdrop based on selected Nodes

margin = 100
xpMax = nuke.selectedNode().xpos()
xpMin = nuke.selectedNode().xpos()
ypMax = nuke.selectedNode().ypos()
ypMin = nuke.selectedNode().ypos()
 
for a in nuke.selectedNodes():
    if a.xpos() &gt; xpMax:
        xpMax = a.xpos()
    if a.xpos() &lt; xpMin: xpMin = a.xpos() if a.ypos() &gt; ypMax:
        ypMax = a.ypos()
    if a.ypos() &lt; ypMin:
        ypMin = a.ypos()
 
bd = nuke.nodes.BackdropNode(bdwidth=(xpMax-xpMin)+margin, bdheight=(ypMax-ypMin)+margin) 
bd.setXpos(xpMin-margin/2)
bd.setYpos(ypMin-margin/2)

disable “postage stamps” on only “Read” nodes

for a in nuke.allNodes():
   if a.Class()=='Read':
       a['postage_stamp'].setValue(0)

disable “postage stamps” on all nodes

for a in nuke.allNodes():
    try:
        a['postage_stamp'].setValue(0)
    except:
        pass

“unhide” all nodes’ inputs – useful when receiving a sneaky comp/lighting script

for a in nuke.allNodes():
    try:
        a['hide_input'].setValue(0)
    except:
        pass

change the “first” frame of all selected nodes that are “Read” nodes:
(example changes the first frame to 1018)

for a in nuke.selectedNodes():
    if a.Class() == 'Read':
        a['first'].setValue(1018)

print a selected nodes’ methods

import struct
node = nuke.selectedNode()
for a in node['lookup'].animations():
    print dir(a)

print inputs (dependencies) of a selected node:

for a in nuke.selectedNode().dependencies():
    print a.name()

print outputs (dependents) of a selected node:

for a in nuke.selectedNode().dependent():
    print a.name()

find all the TimeOffset nodes in a Group called “Group2”, and change the value of each offset based on it’s position in the array of found time offsets

tos = []
for a in nuke.toNode('Group2').nodes():
	if a.Class()=='TimeOffset':
		tos.append(a)
for b in tos:
	b['time_offset'].setValue(tos.index(b))

set the ‘bbox’ for any selected Merge, Keymix & Copy nodes to “B”

for a in nuke.selectedNodes():
	classTypes = ['Merge' , 'Keymix', 'Copy', ]
	for n in classTypes:
		if n in a.Class():
			for p in a['bbox'].values():
				if 'B' in p:
					a['bbox'].setValue(a['bbox'].values().index(p))

remove all animation from a selected nodes

for a in nuke.selectedNode().knobs():
	nuke.selectedNode()[a].clearAnimated()

add keyframes – animate a mix

for a in nuke.selectedNodes():
	a['mix'].setAnimated()
	a['mix'].setValueAt(1,nuke.frame())
	a['mix'].setValueAt(0,(nuke.frame() - 1))

half the colour value of all the Constant nodes in a script

for a in nuke.allNodes():
	if a.Class() == "Constant":
		a['color'].setValue(a['color'].value()[0] / 2 , 0)
		a['color'].setValue(a['color'].value()[1] / 2 , 1)
		a['color'].setValue(a['color'].value()[2] / 2 , 2)

find all the transform nodes in a script, and if their input is a Crop, set the ‘scale’ value to be twice it’s current value (also checks if the scale is a list/array or a float)

for a in nuke.allNodes():
	if a.Class() == "Transform":
		if a.input(0).Class() == "Crop":
			x = a['scale'].value()
			if type(x).__name__ == 'list':
				a['scale'].setValue(x[0] * 2 , 0)
				a['scale'].setValue(x[1] * 2 , 1)
			if type(x).__name__ == 'float':
				a['scale'].setValue(x*2)

set all the gain values of all ColorCorrect nodes to be twice their current value

for a in nuke.allNodes():
	if a.Class() == "ColorCorrect":
		a['gain'].setValue(a['gain'].value() * 2)

print files with ‘mov’ in filename

for a in nuke.allNodes():
	if 'Read' in a['name'].value():
		if 'mov' in a['file'].value():
			print a['file'].value()

change font size of all “write” nodes in script

for a in nuke.selectedNodes():
	if "Write" in a['name'].value():
		a['note_font_size'].setValue(60)

create 20 constants with incrementing colour values

def makeConstants(amount):
	for i in range(amount):
		a= nuke.nodes.Constant()
		color= float( float(i) / float(amount) )
		a['color'].setValue(color)
makeConstants(20)

change the name of all Text nodes to contents the text “message”

for a in nuke.allNodes():
    if a.Class()=='Text':
        a.setName(a['message'].value())

##Expressions
(in an expression node) – alpha channel – if the y value of the pixel is even, make it 0, else make it 1 (for viewing fields?)
y%2==1?0:1

41 thoughts on “some Nuke Python snippets (and other general coolness)”

Adam says:

Thu 27, May 2010 at 8:09 am

some helpful code:

http://francoislord.com/blog/tag/python

Reply
Adam says:

Wed 16, June 2010 at 11:16 am

Changing the value of a specific node in a group through python?
http://www.gfxtalk.com/forum/showthread.php?p=91701

Reply
Chapman says:

Tue 7, September 2010 at 8:25 am

Hey Adam, nice one – I was doing some post Sucker experimenting with Nuke+python, found this then realised it was you.

Cheers,
AC.

Reply
Adam says:

Mon 13, September 2010 at 2:48 am

Thanks Chapman!

Found some cool nuke python trickery?
If you do feel free to put something up as a comment on this post!
Hope all is well back in Sydney!

Reply
Steve says:

Fri 24, September 2010 at 5:37 am

How do you disable Read node thumbnails only?

Thanks.

Reply
1. Adam says:
  
  Tue 28, September 2010 at 7:13 am
  Hey Steve sorry for the delay, am currently doing some travel in Mexico.
  
  Try this:
  for a in nuke.allNodes(): if a.Class()=='Read': a['postage_stamp'].setValue(0)
  for a in nuke.allNodes(): if a.Class()=='Read': a['postage_stamp'].setValue(0)
  Reply
Agoston says:

Sun 13, February 2011 at 1:57 am
#Set Read Nodes Missing Frames Nearest Frame
s = nuke.allNodes('Shuffle') for i in s: i['label'].setValue("[value in]")
s = nuke.allNodes('Shuffle') for i in s: i['label'].setValue("[value in]")
#Set Shuffle Nodes Write Their Incoming Channels Out
s = nuke.allNodes('Shuffle') for i in s: i['label'].setValue("[value in]")
s = nuke.allNodes('Shuffle') for i in s: i['label'].setValue("[value in]")
Reply
Adam says:

Sun 13, February 2011 at 1:59 am

Nice one Agoston!
Thanks for your code!

Reply
Anshul says:

Fri 6, January 2012 at 2:03 pm

Great work Adam,
being late for the party, found out your nuke forum now only.
I have a query:
How to get the paths in Read nodes and if anyone updated, how to reload that again in the scene, without reloading the whole scene

Reply
Anshul says:

Fri 6, January 2012 at 6:51 pm
getting paths of all read nodes
for n in nuke.allNodes(): if n.Class() == 'Read': print n['name'].value() + ' : ' + n['file'].value()
for n in nuke.allNodes(): if n.Class() == 'Read': print n['name'].value() + ' : ' + n['file'].value()
Reply
Adam says:

Tue 6, March 2012 at 3:30 am

Nice One Anshul! Thanks for sharing!

Reply
Marc Gutowski says:

Thu 15, March 2012 at 5:23 pm
# print all nodes with no connected output
(maybe helpful to find dead branches end in high complex comps)
for node in nuke.allNodes(): if not len(node.dependent()): if not node.maxOutputs() == 0: print node.name()
for node in nuke.allNodes(): if not len(node.dependent()): if not node.maxOutputs() == 0: print node.name()
Reply
Adam says:

Thu 15, March 2012 at 7:57 pm

Looks great Marc! Thanks for sharing your code!

Reply
NIK says:

Thu 19, April 2012 at 12:37 pm

Can you help me please?! I’m having trouble duplicating a node through python.

I have a group node with a few nodes inside. I also have 10 read nodes. What I would like to do it is select all my read nodes and have the script duplicate the group and place input to the read.

any help would be greatly appreciated!
Thanks

Reply

Hi Adam, Great stuff!
I see you have code to select all read nodes but how do you select all read nodes above a selected node?

Hey Douglas!

Thanks for the nice words!

I had a quick look, try this (i´ll add it above):

a = nuke.selectedNode()
nodesToSelect = []
 
nodesToSelect.append(a)
def climb(node):
  # print node.name()
  nodesToSelect.append(node)
  for n in node.dependencies():
    climb(n)
 
climb(a)
 
for x in nodesToSelect:
  print x.name()
  x.setSelected(1)

Adam says:

Fri 27, April 2012 at 4:57 am

another Nuke Python resource:
http://nullege.com/codes/search/nuke.ask

Reply
Marc Gutowski says:

Sat 5, May 2012 at 8:40 pm

Hey Adam,

i’ve put some of my Nuke Snippets online:
http://ewok1.com/resources/

best regeards,
Marc

Reply
1. Adam says:
  
  Sun 6, May 2012 at 2:27 am
  
  Hey Marc!
  
  Thanks for sharing your your snippets!
  Some great ones in there from what I can see.
  
  Keep up the great work!
  
  Cheers
  
  Adam
  
  Reply
Boris says:

Fri 25, May 2012 at 11:17 pm

Hi Adam,

I´ve read some of your really nice python scripts and i´m actually trying to make some scripting by my self too -i confess i´ve just started-. Well i´m trying to write some script (it has to be really easy) to set all my Roto´s output to “none”. I have something like this, but i don´t know how to keep on.. Could you give me a hand?
thnx in advance!

for a in nuke.allNodes():
if a.Class() == “Roto”:

Reply
1. Adam says:
  
  Sat 26, May 2012 at 12:12 am
  Hey Boris!
  
  Cool question. When you say you want to set all your Roto’s output to “none”, could this be it?:
  for a in nuke.allNodes(): if a.Class() == “Roto”: a['output'].setValue(“none”) if a.Class() == “RotoPaint”: a['output'].setValue(“none”)
  for a in nuke.allNodes(): if a.Class() == “Roto”: a['output'].setValue(“none”) if a.Class() == “RotoPaint”: a['output'].setValue(“none”)
  Reply
boris says:

Sat 26, May 2012 at 7:28 pm

Hey Adam thanks a lot!, this makes exactly what i wanted. I guess this would work with any node and attribute so it could be really time saving… i keep on reading you 🙂

Reply
1. Adam says:
  
  Sat 26, May 2012 at 9:13 pm
  
  Best of luck!
  Also great stuff in the foundry’s doc:
  http://docs.thefoundry.co.uk/nuke/63/pythondevguide/index.html
  
  Reply

hi Adam thx alot ,i had an issue . i need to random color for rotopaint node,.inside it i had root layer under had name of object,character so i need to set value for each shapes increase or decrease order.,

Adam says:

Wed 10, October 2012 at 7:28 pm

hey Balaji i am not sure if i get what you mean – you want the colour of each of a rotoshape’s layers to be random?

Reply

maybe this:

1. select your rotoshape node (with some shapes in it).
2. run this from the script editor:

import random
 
a = nuke.selectedNode()
if a.Class() == "RotoPaint":
    knob = a['curves']
    for c in knob.rootLayer:
        rndR = random.random()
        rndG = random.random()
        rndB = random.random()
        attrs = c.getAttributes()
        attrs.set(1, attrs.kRedOverlayAttribute, rndR)
        attrs.set(1, attrs.kRedAttribute, rndR)
        attrs.set(1, attrs.kGreenOverlayAttribute, rndG)
        attrs.set(1, attrs.kGreenAttribute, rndG)
        attrs.set(1, attrs.kBlueOverlayAttribute, rndB)
        attrs.set(1, attrs.kBlueAttribute, rndB)

Jeff C says:

Sun 28, October 2012 at 3:43 am

How to apply DIFFERENT Feather Falloff amounts at EACH Control Point?
Hello Adam and Forum members,
sorry for the topic diversion but i hoped for any and all help or suggestions toward an answer very useful to a large number of Nuke users.

By using Ctrl + L.drag on a Roto Control Point a feathered edge is created with Greyscale falloff from the Roto control point to the Feather control point.
1) Using Nuke-Python script or coding, plugins, any method or different software: How to apply DIFFERENT Feather Falloff amounts at EACH Control Point instead of one falloff value for the entire shape?, ie: PER CONTROL POINT, Variable Transparency or Falloff.

Thanks again for any help,
Jeff

Reply
Alex says:

Tue 26, February 2013 at 6:23 pm

Hi Adam, I feel like I am kind of late to this page, but it has lots of interesting code snippets on it 🙂

I do have a question of my own though, how can I change the center of a transform node to 100 if a switch is at 1 and 200 if it is at 0?

Reply
1. Adam says:
  
  Wed 27, February 2013 at 2:05 am
  
  Hey Alex!
  
  Try this as an expression in your switch node:
  
  yourSwitchNode.which==1?100:200
  
  It means something like “if yourSwitchNodeName.parameter is equal to 1 set the value to 100, otherwise make it 200
  
  Apologies as I can’t remember the parameter name for the switch node – I think it is “which”
  
  Reply
  1. Adam says:
    
    Wed 27, February 2013 at 7:31 am
    
    Try this:
    
    Transform {
    center {{Switch1.which==1?100:200} {Switch1.which==1?100:200}}
    name Transform1
    xpos 57
    ypos -29
    }
    Switch {
    name Switch1
    xpos 55
    ypos 9
    }
    
    Reply
mackajay says:

Thu 21, March 2013 at 8:21 am

hey man – just noticed you have a minor bug in the select all dependencies, it just keeps adding the “a” or initial node to the list, modified (in the most minor of minor ways) code below

a = nuke.selectedNode()
nodesToSelect = []

nodesToSelect.append(a)
def climb(node):
# print node.name()
for n in node.dependencies():
nodesToSelect.append(n)
climb(n)

climb(a)

for x in nodesToSelect:
print x.name()

Reply
san says:

Mon 15, April 2013 at 1:20 am

can anyone tell me how should I duplicate a nuke node without using

[code]nukescripts.node_copypaste()[/code]

if I use the above technique it copies node information to clipboard which is what i dont want, I want to duplicate a reformat node and connect the duplicated one to copy node’s B input….

Reply
Boris says:

Tue 23, July 2013 at 12:58 am

Hi Adam, how are you 🙂

I bring another silly python question that you probably may kindly want to answer..well, pretty simple i think:

I have a NoOp node with a custom floating attribute which controls a switch node. Then i created a python script buttom in a Write node so that if my NoOp1.switcher(the name of the attribute) == 1, then my Write1.file_type = ‘jpeg’, else = ‘dpx’..

Here´s what i´ve came up with, in five minutes i confess:

n = nuke.toNode(‘NoOp1’);
w = nuke.toNode(‘Write1’);

if n[‘switcher’] == 1:
w[‘file_type’] = ‘jpeg’
else:
w[‘file_type’] = ‘dpx’

Well, it doesn´t work.

Thanks in advance and keep having such good times

Boris

Reply

Hi Adam, How r u . i used ur Roto Script thanks alot.
import random

a = nuke.selectedNode()
if a.Class() == “RotoPaint”:
knob = a[‘curves’]
for c in knob.rootLayer:
rndR = random.random()
rndG = random.random()
rndB = random.random()
attrs = c.getAttributes()
attrs.set(1, attrs.kRedOverlayAttribute, rndR)
attrs.set(1, attrs.kRedAttribute, rndR)
attrs.set(1, attrs.kGreenOverlayAttribute, rndG)
attrs.set(1, attrs.kGreenAttribute, rndG)
attrs.set(1, attrs.kBlueOverlayAttribute, rndB)
attrs.set(1, attrs.kBlueAttribute, rndB)

Actually what i need is in need to change roto whote color random Increase or decrease Look like u did like constant Script. i am digging with It. i need to use that for more than 200 Shapes under one root roto layer.

Hi Adam, How r u . i used ur Roto Script thanks alot.
import random
a = nuke.selectedNode()
if a.Class() == “RotoPaint”:
knob = a[‘curves’]
for c in knob.rootLayer:
rndR = random.random()
rndG = random.random()
rndB = random.random()
attrs = c.getAttributes()
attrs.set(1, attrs.kRedOverlayAttribute, rndR)
attrs.set(1, attrs.kRedAttribute, rndR)
attrs.set(1, attrs.kGreenOverlayAttribute, rndG)
attrs.set(1, attrs.kGreenAttribute, rndG)
attrs.set(1, attrs.kBlueOverlayAttribute, rndB)
attrs.set(1, attrs.kBlueAttribute, rndB)
Actually what i need is in need to change roto rgb color into white color look like gradient feel random Increase or decrease Look like u did like in constant Script. i am digging with It. i need to use that for more than 200 Shapes under one root roto layer.to create look for depth information in every individual layer randomly. thanks in advance

Balaji i’m not sure if this is quite what you want but this takes a RotoPaint and changes each shape’s RGBA to a grey based on it’s position in the RotoShape.

import random
a = nuke.selectedNode()
if a.Class() == "RotoPaint":
    knob = a['curves']
    i = 0.0
    for c in knob.rootLayer:
 
        pos = float ((len(knob.rootLayer) - i) / len(knob.rootLayer))
        i = i+1
 
        attrs = c.getAttributes()
        attrs.set(1, attrs.kRedOverlayAttribute, pos)
        attrs.set(1, attrs.kRedAttribute, pos)
        attrs.set(1, attrs.kGreenOverlayAttribute, pos)
        attrs.set(1, attrs.kGreenAttribute, pos)
        attrs.set(1, attrs.kBlueOverlayAttribute, pos)
        attrs.set(1, attrs.kBlueAttribute, pos)
        attrs.set(1, attrs.kAlphaOverlayAttribute, pos)
        attrs.set(1, attrs.kAlphaAttribute, pos)

lalamax3d says:

Wed 15, April 2015 at 2:50 pm

Hi Adam, great post.
i wanted to ask, a question, how to detect, selected shape or curve from roto or rotopaint node from root layer. thanks for hint.
i m here…
n = nuke.selectedNode()
nodec = n[‘curves’]
nlayer = nodec.rootLayer
elements = []
getElements(nlayer)
for each in elements:
print each.isSelected() # this line not working, any idea.?

Reply
1. Adam says:
  
  Sat 18, April 2015 at 5:29 am
  
  hey mate, does the “getElements” function have anything to do with the issue?
  When you say that the last line isn’t working what is happening?
  I imagine that the last line is actually indented of course.
  Cheers!
  
  Reply
  1. haseeb ahmed (lala) says:
    
    Mon 27, April 2015 at 4:25 pm
    
    i am sure, last line >> ‘isSelected() was my guess based on maya or max… may be they have exposed that property. but it didn’t
    good thing is found this
    for selShape in selNode[‘curves’].getSelected():
    and it works.
    
    Reply
    1. Daniel says:
      
      Thu 15, December 2016 at 8:05 pm
      
      Make a set of frameholds over a range of frames.
      
      def range_of_frameholds(start, end, step=1):
      ”’Create one framehold per frame over specified range by step”’
      try:
      node=nuke.selectedNode()
      except:
      nuke.message(‘Please select a node’)
      return
      for f in range(start, end, step):
      n=nuke.createNode(‘FrameHold’, inpanel=False)
      n[‘first_frame’].setValue(f)
      n.setInput(0, node)
      
      Reply
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41 thoughts on “some Nuke Python snippets (and other general coolness)”

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