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Kiryha edited this page Oct 16, 2018 · 39 revisions

Introduction

Here you can find small code chunks to perform miscellaneous tasks in Houdini.

You can explore the node parameters with Python Shel:

  • Create any node and tweak its parameters
  • Run Python Shell.
  • Type node = , drag node to Shell (you will get hou.node('path/to/node')), press enter.
  • Type print node.asCode()

Snippets

Get node from the scene
import hou
node = hou.node('/<nodePath>/<nodeName>') # By name
node = hou.selectedNodes()[0] # By selection
# Get node content
node.children()
Create node in the scene

To create any node wiyh Python you have to set parent node for that. You need to create Geometry node in OBJ context.

# Get scene root node
OBJ = hou.node('/obj/')
# Create Geometry node in scene root
geometry = OBJ.createNode('geo')
import hou
# Create transform node inside geo1
geometry = hou.node('/obj/geo1')
xform = geometry.createNode('xform') 
xform.moveToGoodPosition() # Align new node

# Create new transform node linked to existing transform
xformNew= xform.createOutputNode('xform')
Get and set parameters
import hou
node = hou.selectedNodes()[0]

# get translate X
node.parm('tx').eval() 
hou.parm('/obj/geo1/tx').eval()
hou.ch('/obj/geo1/tx')

# set translate XYZ
node.parmTuple('t').set([0,1,0])
hou.parm('/obj/geo1/tx').set(2)
Get Translate X keyframes of selected node
import hou
node = hou.selectedNodes()[0]

node.parm('tx').keyframes()
Run hscript command form Python
# Run Redshift IPR
hou.hscript('Redshift_openIPR')
Get all node parameters names
def getAllNodeParameters(node):
    # Return list of all parameters names for input node object 
    allParameters = [param.name()for param in node.parms()]
    return allParameters
Connect nodes
import hou
# Create transform nodes
xform_A = hou.node('/obj/geo1/transform1') 
xform_B = hou.node('/obj/geo1/transform2')
 # Connect transform_A to transform_B
xform_B.setInput(0, xform_A)

# Create merge
merge = node.createNode('merge')
# Connect xforms to a merge
merge.setNextInput(xform_A)
merge.setNextInput(xform_B)

# Get node inputs
merge.inputs()
# Get node outputs
merge.outputs()
Get groups
import hou

node = hou.selectedNodes()[0]
groups = [g.name() for g in node.geometry().primGroups()]
print groups
Builder workflow (shop context)

Create "Material Surface Builder" in SHOP context, dive inside.

import hou
shader = hou.node('/shop/vopmaterial1/lambert1')
out = hou.node('/shop/vopmaterial1/surface_output')
out.setNamedInput('Cf', shader, 'clr') # Set connection by name
out.setNamedInput(0, shader, 0) # Set connection by parameter index

# List all inputs for node 'surface_output'
print out.inputNames()
Filter node.children() output
import hou
selectedNode = hou.selectedNodes()

def extractVop(listOfChildrens):
    for node in listOfChildrens:
        if node.type().name() == 'vopsurface':
            return node

# return vopsurface nodes
vops = extractVop(selectedNode.children())

Same task with list comprehensions:

import hou
selectedNode = hou.selectedNodes()

# return vopsurface nodes
vops = [node for node in selectedNode.children() if node.type().name() == 'vopsurface']
Run PySide UI

Create and save a UI file with QT Designer. It could be just a blank widget (but not Main Window). In Houdini run this code in Python Source Editor window:

# Run *ui file in Houdini

import hou
from PySide2 import QtCore, QtUiTools, QtWidgets

class MyWidget(QtWidgets.QWidget):
    def __init__(self):
        super(MyWidget,self).__init__()
        ui_file = 'C:/path/to/file.ui'
        self.ui = QtUiTools.QUiLoader().load(ui_file, parentWidget=self)
        self.setParent(hou.ui.mainQtWindow(), QtCore.Qt.Window)

win = MyWidget()
win.show()

You should have your window opened.

Tools

Expand Alembic

# Expand Alembic
# Recreate alembic hierarchy by object groups and names
# Select Alembic node, set 

# Naming convention
# Hirarchy in alembic: OBJECT (group)/PART_01, ..., PART_## (meshes)
# OBJECTS: <objectName>_<objectVariation> : bootle_A
# PARTS: <objectName>_<objectVariation>_<objectPart> : bootle_A_label

import hou
    
# Get Alembic SOP
ABC = hou.selectedNodes()[0]

def checkConditions():
    '''
    Check if environment conditions allows to run script without errors
    '''
    if not ABC:  # If user select anything
        print '>> Nothing selected! Select Alembic SOP!'
        return 0


def buildObjectsMap(listGroups):
    # Create object map dictionary: each object = key, list of parts = values
    
    objectsMap = {} # { OBJ: [PARTs] }
    
    for partNameFull in listGroups:
        items = partNameFull.split('_')
        object = '{0}_{1}'.format(items[0], items[1])
        part = items[2]
        
        if not object in objectsMap.keys():
            objectsMap[object] = [part]
        else:
            objectsMap[object].append(part)
    
    return objectsMap
        
def buildGroupsList(object, listParts):
    # Create string for BLAST SOP with list of groups for each object    

    groupsList = ''
    for part in listParts:
        name = '{}_{}'.format(object, part)
        groupsList += ' ' + name

    return groupsList
    
    

def expandABC(OBJ, objectsMap):
    # Recreate alembic hierarchy
    
    for object in sorted(objectsMap.keys()):             
        groupsList = buildGroupsList(object, objectsMap[object])
        blast = OBJ.createNode('blast')
        blast.setNextInput(ABC)
        blast.setName(object)
        blast.parm('group').set(groupsList)
        blast.parm('negate').set(1)
        blast.moveToGoodPosition()

def run():
    if checkConditions() != 0:    
        # Setup Alembic properties
        ABC.parm('loadmode').set(1) 
        ABC.parm('groupnames').set(4) 
        # Get Alembic container
        OBJ = ABC.parent()
        
        # Get all groups (PARTS) from alembic
        listGroups = [g.name() for g in ABC.geometry().primGroups()]
        
        # Build Objects Map
        objectsMap = buildObjectsMap(listGroups)
        # Expand Alembic
        expandABC(OBJ, objectsMap)
        
        print '>> EXPANDING DONE!'     
        
run()

Import FBX into Houdini

import hou
import os 

dirFBX = 'P:/PROJECTS/NSI/PROD/3D/lib/ANIMATION/CHARACTERS/ROMA/FBX/' 
filesNamesFBX = [fileName for fileName in os.listdir(dirFBX) if os.path.isfile(os.path.join(dirFBX, fileName))]

for fileName in filesNamesFBX:
    fileFBX =  '{0}{1}'.format(dirFBX,fileName)
    if not hou.node('/obj/{}_fbx'.format(fileName.replace('.fbx',''))):
        hou.hipFile.importFBX(fileFBX) 
    else:
        print 'FBX {} EXISTS!'.format(fileName)

Convert imported FBX to geometry

# 256 Pipeline tools
# Convert FBX subnetwork to Geometry node
# Import FBX into Houdini, select FBX subnetwork, run script in Python Source Editor

import hou
# Get selected FBX container and scene root
FBX = hou.selectedNodes()
OBJ = hou.node('/obj/')

def checkConditions():
    '''
    Check if environment conditions allows to run script without errors
    '''
    if not FBX:  # If user select anything
        print '>> Nothing selected! Select FBX subnetwork!'
        return 0

def convert_FBX():
    '''
    Create Geometry node and import all FBX part inside
    '''
    # Create Geometry node to store FBX parts
    geometry = OBJ.createNode('geo', run_init_scripts = False)
    geometry.setName('GEO_{}'.format(FBX.name()))
    geometry.moveToGoodPosition()
    # Get all paerts inside FBX container
    geometry_FBX = [node for node in FBX.children() if node.type().name() == 'geo']
    
    # Create merge node for parts
    merge = geometry.createNode('merge')
    merge.setName('merge_parts')
    
    # Replicate FBX structure in Geometry node
    for geo in geometry_FBX: 
        # Create Object Merge node
        objectMerge = geometry.createNode('object_merge')
        objectMerge.setName(geo.name())
        # Set path to FBX part object
        objectMerge.parm('objpath1').set(geo.path())
        objectMerge.parm('xformtype').set(1)
        # Create Material node
        material = geometry.createNode('material')
        material.setName('MAT_{}'.format(geo.name()))
        # Link Material to Object Merge
        material.setNextInput(objectMerge)
        # Link part to Merge
        merge.setNextInput(material)
    
    # Set Merge Node flags to Render
    merge.setDisplayFlag(1)
    merge.setRenderFlag(1)
    # Layout geometry content in Nwtwork View 
    geometry.layoutChildren()

# Check if everything is fine and run script
if checkConditions() != 0:
    # Get FBX network
    FBX = FBX[0]
    # run conversion
    convert_FBX()
    print '>> CONVERSION DONE!'

Create Material Stylesheet UI

# Create Material Stylesheet parameter interface
# Select Geometry node, run script

import hou

# Get selected geometry node to create Stylesheet parameter
OBJ = hou.selectedNodes()[0]

# Define tags
dataTags = {'script_action_icon':'DATATYPES_stylesheet',
            'script_action_help':'Open in Material Style Sheet editor.',
            'spare_category':'Shaders',
            'script_action':"import toolutils\np = toolutils.dataTree('Material Style Sheets')\np.setCurrentPath(kwargs['node'].path() + '/Style Sheet Parameter')",
            'editor':'1'}

# Create parameter interface
group = OBJ.parmTemplateGroup()
folder = hou.FolderParmTemplate('folder', 'Shaders')
folder.addParmTemplate(hou.StringParmTemplate('shop_materialstylesheet', 'Material Style Sheet', 1, tags = dataTags))
group.append(folder)
OBJ.setParmTemplateGroup(group)

Flatten curve

# Flatten curve: set Y coord = 0
coordList_SRC = '39.1665,0.362686,22.4173 55.3542,0.365759,10.9339'
coords = coordList_SRC.split(' ')

coordList_RES = ''
for xyz in coords:
    listXYZ_SRC = xyz.split(',')
    listXYZ_SRC = '{0},0.0,{1} '.format(listXYZ_SRC[0], listXYZ_SRC[2])
    coordList_RES += listXYZ_SRC
 
print coordList_RES

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