hou.Node class

Return this node’s name. See also hou.Node.path.

Set the name of this node. Raises hou.OperationFailed if the new name contains characters other than letters, numbers, periods, dashes, or underscores. Raises hou.OperationFailed if the node could not be renamed (for example, another node already exists with the name, the node is the root node or top-level manager (e.g. /obj), or the node is inside a locked asset). If the unique_name parameter is set to True, the supplied name may be changed to ensure that it doesn’t match the name of any existing node.

Return the value of the last set of digits inside the node’s name, or 0 if there are no digits.

For example, the result is 102 for a node named geo102, and 34 for a node named light12to34.

Return the full path (i.e. starting with /) of this node in the network.

Return a relative path to another node object from this node.

>>> box1 = hou.node("/obj/box_object1/box1")
>>> sphere1 = hou.node("/obj/sphere_object1/sphere1")
>>> box1.relativePathTo(sphere1)
'../../sphere_object1/sphere1'
>>> hou.node("/obj").relativePathTo(box1)
'box_object1/box1'
>>> box1.relativePathTo(box1)
'.'

Return the node at the given path, or None if no such node exists. If you pass in a relative path (i.e. the path does not start with /), searches are performed relative to this node.

For example, to get the parent node of a node in the the variable n, use n.node(".."). To get a child node named geo5, use n.node("geo5"). To get a sibling node named light3, use n.node("../light3").

Note that the return value may be an instance of a subclass of Node. For example, if the node being found is an object node, the return value will be a hou.ObjNode instance.

If the path is an absolute path (i.e. it starts with /), this method is a shortcut for hou.node(node_path). Otherwise, it is a shortcut for hou.node(self.path() + "/" + node_path). See also hou.node_.

Return the node that contains this node.

This method is a shortcut for self.node(".."). Note that this method returns None if the node is the root (i.e. /).

>>> hou.node("/obj/box_object1").parent()
<hou.Node at /obj>
>>> print hou.node("/").parent()
None

Return a list of nodes that are children of this node. Using the file system analogy, a node’s children are like the contents of a folder/directory.

To find the number of children nodes, use len(node.children()).

The order of the children in the result is the same as the user defined ordering in Houdini. To see this order, switch the network view pane into list mode, and ensure that the list order is set to user defined. To reorder nodes, drag and drop them in the list.

def pc(node):
    '''Print the names of the children of a particular node.  This function
       can be handy when working interactively in the Python shell.'''
    for child in node.children():
        print child.name()

def ls():
    '''Print the names of the nodes under the current node.'''
    pc(hou.pwd())

The following expression evaluates to a list of children of a particular node type:

[c for c in node.children() if c.type() == node_type]

Recursively return all sub children of this node. For example, hou.node("/").allSubChildren() will return all the nodes in the hip file.

Note that a tuple is returned, not a generator. This means that it is safe to delete or create nodes while looping through the return value.

The following function deletes all children of a particular type that appear anywhere inside a given node:

def removeSubChildrenOfType(node, node_type):
    '''Recursively delete all children of a particular type.'''
    for child in allSubChildren(node):
        if child.type() == node_type:
            child.destroy()

This code, for example, removes all the visibility SOPs anywhere under /obj:

>>> removeSubChildrenOfType(hou.node("/obj"), hou.sopNodeTypeCategory().nodeTypes()['visibility'])

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Return a tuple of children nodes name matches the pattern.

The pattern may contain multiple pieces, separated by spaces. An asterisk (*) in a pattern piece will match any character. By default, Houdini will add the nodes from each pattern piece to those already matched. However, if the pattern piece begins with a caret (^), Houdini will remove the matches for that piece from the result.

This method returns an empty tuple if you pass in an empty pattern.

>>> obj = hou.node("/obj")
>>> obj.createNode("geo", "geo1")
<hou.ObjNode of type geo at /obj/geo1>
>>> obj.createNode("geo", "geo2")
<hou.ObjNode of type geo at /obj/geo2>
>>> obj.createNode("geo", "grid")
<hou.ObjNode of type geo at /obj/grid>
>>> obj.createNode("geo", "garbage")
<hou.ObjNode of type geo at /obj/garbage>
>>> obj.createNode("geo", "box")
<hou.ObjNode of type geo at /obj/box>

>>> def names(nodes):
... return [node.name() for node in nodes]

>>> names(obj.glob("g*"))
['geo1', 'geo2', 'grid', 'garbage']
>>> names(obj.glob("ge* ga*"))
['geo1', 'geo2', 'garbage']
>>> names(obj.glob("g* ^ga*"))
['geo1', 'geo2', 'grid']

See also hou.Node.recursiveGlob.

Like hou.Node.glob, return a tuple of children nodes whose name matches the pattern. However, any matching child will have all its chidren added, recursively. As well, the result may be filtered by node type.

Houdini first matches children nodes against the pattern, then recursively adds the subchildren of matching children, and then applies the filter.

The pattern and filter behaviour is very similar to that used by node bundles in Houdini. See hou.NodeBundle for more information.

Raises hou.OperationFailed if the pattern is invalid.

Create a new node of type node_type_name as a child of this node.

Raises hou.OperationFailed if this node cannot contain children. Raises hou.PermissionError if this node is inside a locked asset.

>>> obj = hou.node("/obj")

# Let Houdini choose a name based on the node type name.
>>> obj.createNode("geo")
<hou.ObjNode of type geo at /obj/geo1>

# Let Houdini choose a unique name.
>>> obj.createNode("geo")
<hou.ObjNode of type geo at /obj/geo2>

# Give the node a specific name.
>>> obj.createNode("geo", "foo")
<hou.ObjNode of type geo at /obj/foo>

# Let Houdini create a unique name from our suggested name.  Also, don't
# run the geometry object init scripts so the contents are empty.
>>> obj.createNode("geo", "geo1", run_init_scripts=False)
<hou.ObjNode of type geo at /obj/geo3>
>>> obj.node("geo1").children()
(<hou.SopNode of type file at /obj/geo1/file1>,)
>>> obj.node("geo3").children()
()

Delete this node.

If you call methods on a Node instance after it has been destroyed, Houdini will raise hou.ObjectWasDeleted.

Raises hou.OperationFailed if you try to delete a node inside a locked asset.

Return a boolean to indicate of the node is the last selected node in its network.

Each network (i.e. node containing children) stores its own list of selected nodes, and the last selected node has special meaning. For example, it is the node displayed in unpinned parameter panes.

See also hou.selectedNodes to get a tuple of all the selected nodes in all networks in Houdini. The last node in this list also has special meaning in Houdini, and corresponds to the global current node.

Set or unset this node as the last selected one.

Each network (i.e. node containing children) stores its own list of selected nodes, and the last selected node has special meaning. For example, it is the node displayed in unpinned parameter panes.

If on is True, this node will become the last selected node. If it is False and this node was the last selected one, it will be unselected and the second-last selected node will become the last selected node.

If clear_all_selected is true, Houdini will unselect every node in this network before performing the operation.

See also hou.Node.setSelected and hou.selectedNodes.

Return whether this node is selected.

See also hou.selectedNodes.

Select or deselect this node, optionally deselecting all other selected nodes in this network.

Return a tuple containing the children of this node that are selected. Note that the last selected node has special meaning, and can also be retrieved with hou.Node.isCurrent.

The following example will print the names of all selected objects in /obj:

for n in hou.node("/obj").selectedChildren():
    print n.name()

To find the total number of selected children nodes, use len(node.selectedChildren()).

Return the hou.NodeType object for this node.

For example, all camera node instances share the same node type.

Changes the node to a new type.

Keep_name, keep_parms, and keep_network_contents indicate that the node should keep the same name, parameter values, and contents, respectively, after its type has changed.

Return the hou.NodeTypeCategory corresponding to the children of this node. For example, if this node is a geometry object, the children are SOPs. If it is an object subnet, the children are objects.

Return the parameter at the given path, or None if the parameter doesn’t exist.

Evaluates the specified parameter and returns the result.

Return a list of the parameters on this node.

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Return the parm tuple at the given path, or None if it doesn’t exist.

This method is similar to parm(), except it returns a hou.ParmTuple instead of a hou.Parm.

Evaluates the specified parameter tuple and returns the result.

Return a list of all parameter tuples on this node.

This method is similar to parms(), except it returns a list of hou.ParmTuple instead of hou.Parm.

Return a list of parameters in a folder on this node. Returns all parameters in the folder and its subfolders (if any).

Raises hou.OperationFailed if the folder specified by folder_names does not exist.

See also hou.Parm.containingFolders and hou.Parm.containingFolderSetParmTuples

Return a list of the parameter tuples in a folder on this node. This method is similar to parmsInFolder(), except it returns a list of hou.ParmTuple instead of hou.Parm. See parmsInFolder() above for information about the arguments.

See also hou.Parm.containingFolders and hou.Parm.containingFolderSetParmTuples

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Return the node’s default expression language.

When you enter an expression in a parameter that does not already contain an expression, the node’s expression language is used to determine how that expression should be evaluated. You can change a node’s expression language in the parameter dialog in the GUI.

Changing the node’s expression language will not change the language in parameters already containing expressions (i.e. parameters with keyframes).

Note that if a parameter already contains an expression and you change that expression in the GUI, the expression language will not change, regardless of the value of the node’s expression language. To change the language of an existing expression in a parameter from Python, use hou.Parm.setExpression, as in parm.setExpression(parm.expression(), language).

Set the node’s default expression language. See expressionLanguage() for more information.

Return a dictionary of parameter aliases on the node’s parameters. The keys in the dictionary are the parameters that have aliases and the values are the alias names.

Removes all alias names from parameters on the node.

Return a list of the spare (user-defined) parameters on this node.

Add a spare parameter tuple to the end of the parameters on the node. If in_folder is not an empty sequence, this method adds the parameters to the end of the parameters in a particular folder.

See also the removeSpareParmTuple() and addSpareParmFolder() methods.

Removes the specified spare parameter tuple.

See also addSpareParmTuple().

Adds a folder to the spare parameters.

Note that all the folders in a set correspond to one parameter. If this is the first folder to go in the set, parm_name will be used as the parameter name. Otherwise, parm_name will be ignored and the parameter name of the first folder in the set is used.

If this is the first folder in the set and parm_name is None, it will default to 'sparefolder0'. If parm_name is already in use, a unique name will be automatically generated.

If create_missing_folders is True, this method will create the folders in in_folder that don’t exist. So, this method can be used to add spare folders and a spare parameter at the same time.

See also the removeSpareParmFolder() and addSpareParmTuple() methods.

Removes an empty folder from the spare parameters.

folder is a sequence of folder names. So, to remove the Output folder, use ("Output",) instead of "Output".

See also addSpareParmFolder().

Replace an existing spare parameter tuple with a new one. The old parameter tuple is removed and the new one is added in its place.

The new parameter tuple may or may not have the same name as the old one. By providing a parameter tuple with the same name, you can modify an existing spare parameter tuple.

Note that you cannot replace non-spare parameter tuples. However, you can change the visibility of non-spare parameters using hou.ParmTuple.hide.

To change a parameter for all instances of digital asset, use hou.HDADefinition.replaceParmTuple.

Return a tuple of the nodes connected to this node’s inputs.

This method is a shortcut for [connection.outputNode() for connection in self.inputConnections()].

Return a tuple of the nodes connected to this node’s outputs.

This method is a shortcut for [connection.inputNode() for connection in self.outputConnections()].

Return a tuple of NodeConnection objects for the connections coming into the top of this node. If nothing is wired into this node, return an empty tuple.

To get a list of the connected nodes themselves, use hou.Node.inputs.

Note that this method is a shortcut for [connectors[0] for connectors in self.inputConnectors() if len(connectors) != 0].

>>> cookie = hou.node("/obj").createNode("geo").createNode("cookie")
>>> cookie.setInput(1, cookie.parent().createNode("box"))
>>> cookie.inputConnections()
(<hou.NodeConnection from grid1 output 0 to cookie input 1>,)
>>> cookie.inputConnectors()
((), (<hou.NodeConnection from grid1 output 0 to cookie input 1>,))

See also hou.Node.inputConnectors.

Return a tuple of NodeConnection objects for the connections going out of the bottom of this node. If nothing is wired into the output of this node, return an empty tuple.

To get a list of the connected nodes themselves, use hou.Node.outputs.

Note that this method is a shortcut for: reduce(lambda a, b: a+b, self.outputConnectors(), ()). Since most nodes have only one output connector, though, this method is usually equivalent to self.outputConnectors()[0].

>>> box = hou.node("/obj").createNode("geo").createNode("box")
>>> box.parent().createNode("xform").setFirstInput(box)
>>> box.parent().createNode("subdivide").setFirstInput(box)
>>> box.outputConnections()
(<hou.NodeConnection from box1 output 0 to xform1 output 0>, <hou.NodeConnection from box1 output 0 to subdivide1 input 0>)

See also hou.node.outputConnectors.

Return a tuple of tuples of hou.NodeConnection objects. The length of the result tuple is equal to the number of input connectors on this node. Each subtuple contains exactly one node connection if something is wired into the connector; otherwise it is the empty tuple.

See also hou.NodeConnector and hou.Node.inputConnections.

Return a a tuple of tuples of hou.NodeConnection objects. The length of the result tuple is equal to the number of output connectors on this node. Each subtuple contains all the connections going out of that connector, and is empty if nothing is wired to that connector.

>>> split = hou.node("/obj").createNode("dopnet").createNode("split")
>>> split.parent().createNode("rbdsolver").setFirstInput(split)
>>> split.parent().createNode("gravity").setFirstInput(split, 1)
>>> split.parent().createNode("merge").setFirstInput(split, 1)
>>> split.outputConnectors()
((<hou.NodeConnection from split1 output 0 to rbdsolver1 input 0>,), (<hou.NodeConnection from split1 output 1 to gravity2 input 0>, <hou.NodeConnection from split1 output 1 to merge1 input 0>), (), ())

See also hou.NodeConnection and hou.Node.outputConnections.

Return the hou.SubnetIndirectInput objects of a subnet.

Raises hou.InvalidNodeType if this node is not a subnetwork.

Return a tuple of all input ancestors of this node. If include_ref_inputs is False, then reference inputs are not traversed. If follow_subnets is True, then instead of treating subnetwork nodes as a single node, we also traverse its children starting with its display node.

See also the inputs() method.

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Return this node’s extra output nodes.

When a parameter in node A has a channel reference to a parameter in node B, node A becomes an extra output of node B. Note, though, that node B is not an extra input of node A.

>>> a = hou.node("/obj").createNode("geo")
>>> b = hou.node("/obj").createNode("geo")
>>> a.parm("tx").set(b.parm("tx"))
>>> b.extraOutputs()
(<hou.ObjNode of type geo at /obj/geo2>,)

If node_to_become_input is not None, connect the output connector of another node to an input connector of this node. Otherwise, disconnect anything connected to the input connector.

Raises hou.InvalidInput if output_index is invalid. Raises hou.OperationFailed if node_to_become_input is not in the same network as this node. Raises hou.PermissionError if the node is inside a locked asset.

A shortcut for self.setInput(node_to_become_input, 0). See hou.Node.setInput for more information.

Connect the output connector from another node into the first unconnected input connector of this node.

This method is roughly equivalent to:

for input_index, conectors in enumerate(self.inputConnectors()):
    if len(connectors) == 0:
        self.setInput(input_index, node_to_become_input, output_index)
    raise hou.InvalidInput("All inputs are connected")

Raises hou.InvalidInput if all inputs are connected. See hou.Node.setInput for more information.

Insert an input wire. In other words, for each input connector after input_index, shift the contents of that input connector to the next one, and then call hou.Node.setInput. See hou.Node.setInput for the meanings of the parameters.

Given a sequence of children nodes of this node, collapse them into a subnetwork. In other words, create a subnet inside this node’s network and move the specified children of this network inside that subnet.

Raises hou.OperationFailed if a node inside child_nodes is not a child of this network, or if child_nodes is an empty sequence.

This example function takes a single node and replaces it with a subnet, moving the node into the subnet..

def collapseSingleNodeIntoSubnet(node, subnet_name=None):
    node.parent().collapseIntoSubnet((node,), subnet_name=None)

Move the children of this subnet node to become siblings of this node, and then delete this node. The method is the opposite of collapseIntoSubnet().

Raises hou.InvalidNodeType if this node is not a subnetwork.

Create a digital asset from this node. You would typically call this method on subnet nodes.

Unlocks a digital asset so its contents can be edited.

To use this function, you must have permission to modify the HDA.

If this node is an unlocked digital asset, change its contents to match what is stored in the definition and lock it. The parameter values are unchanged.

If this node is locked or is not a digital asset, this method has no effect.

See also hou.Node.matchesCurrentDefinition and hou.Node.isLocked.

Return whether the contents of the node match its type definition. A locked digital asset instance will always match its definition, but an unlocked one may not.

If this node is an instance of a digital asset, return whether or not it is locked. Otherwise, return False.

To differentiate between unlocked digital assets and nodes that are not instances of digital assets, check if the node’s type has a definition:

def isUnlockedAsset(node):
    return not node.isLocked() and node.type().definition() is not None

See hou.HDADefinition.updateFromNode for an example of how to save and lock all unlocked digital asset instances.

Return whether this node is inside a locked digital asset. If this node is not inside a locked HDA, the node may deviate from the OTL definition.

This method is a shortcut for `self.type().hdaModule() to reduce the length of expressions in Python parameters and button callbacks. See hou.NodeType.hdaModule for more information.

Return the node’s comment string.

Sets the comment associated with this node. See also appendComment().

Appends the given text to the comment associated with this node.

Return the color of this node’s tile in the network editor.

Sets the color of this node’s tile in the network editor to the given hou.Color.

Return the position of this node’s tile in the network editor graph as a Vector2. See also move() and setPosition().

Sets the position of this node’s tile in the network editor graph. Raises hou.InvalidInput if the node cannot have the given position.

Moves this node’s tile in the network editor graph by the increments in the given hou.Vector2.

To position a node absolutely, use setPosition().

To get the node’s current graph position, use position().

Raises hou.InvalidInput if the node cannot move to the position specified.

Moves a node to a well-spaced position near its inputs or outputs and returns the new position of the node.

Automatically position all or some children of this node in the network editor.

Return the size of this node’s tile in the network editor graph as a Vector2.

Return whether the node is hidden in the network editor. Note that Houdini also uses the term “exposed” to refer to nodes that are not hidden.

If a visible node is connected to a hidden node, the network editor will display dashed lines for the wire going from the visible node to the hidden node.

See also hou.Node.hide.

Hide or show a node in the network editor. See hou.Node.isHidden for more information about hidden nodes.

Asks or forces the node to re-cook.

Return the text of any errors from the last cook of this node, or the empty string ("") if there were no errors.

Return the text of any warnings from the last cook of this node, or the empty string ("") if there were no warnings.

Return the text of any messages from the last cook of this node, or the empty string ("") if there were no messages.

Return a list of the network boxes inside this node.

Return a network box with the given name inside this node, or None if no network box with the given name exists.

Return a list of network boxes inside this node whose names match a pattern.

Creates a network box inside this network. Raises hou.OperationFailed if this node is not a network.

If you don’t specify a name, Houdini gives the box a default name.

Copies a network box and returns the copy.

If new_name is given, the network box will be copied to a new network box named new_name (a different name will be generated if there is already a network box with that name).

If channel_reference_original is True, all operators created by the copy will have their animatable parameters set to reference the original operators.

Raises hou.OperationFailed if this node is not a network or if the node child type does not match the network box’s node type.

Return a list of the sticky notes inside this node.

Return a sticky note with the given name inside this node, or None if no sticky note with the given name exists.

Return a list of sticky notes inside this node whose names match a pattern.

Creates a sticky note inside this network. Raises hou.OperationFailed if this node is not a network.

If you don’t specify a name, Houdini gives the note a default name.

Copies a sticky note and returns the copy.

If new_name is given, the sticky note will be copied to a new sticky note named new_name (a different name will be generated if there is already a sticky note with that name).

Raises hou.OperationFailed if this node is not a network or if the node child type does not match the sticky note’s node type.

Add a node group to the node and return the new group.

If a group of the given name already exists then this function simply returns the existing group without adding a new one. If the name of the group is None or an empty string, then a unique default name is automatically chosen.

This function can only be called on nodes that are networks. If it is called on a node that is not a network, then it raises hou.OperationFailed.

To remove a node group, use hou.NodeGroup.destroy.

Return a node group contained by the node with the given name, or None if the group does not exist.

Return the list of node groups in this node.

Runs the initialization script associated with this node’s type.

Return the script that will run when this node is deleted.

Sets the script that will run when this node is deleted.

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Saves compiled VEX code to a disk file (on nodes that support this).

Saves VEX/RSL source code to a disk file (on nodes that support this).

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Return whether this node was built explicitly (defaults to True). Most nodes are built explicitly, but some are implicitly created by Houdini. For example, if you select geometry from multiple SOPs and then perform an operation, Houdini will put down an implicit merge SOP before performing that operation. When reselecting geometry in SOPs, Houdini will automatically delete any SOPs that were created implicitly.

Set whether this node was built explicitly (default value is True). If set to False, this node will not show up in various menus and in the Network View pane’s list mode. This flag is typically used for intermediate utility nodes that one is unlikely to want to change its parameters.

Return whether the node is time dependent. A time dependent node is re-evaluated every time the frame changes.

Return a node path representing the location for storing clips. This location may or may not exist. To find or create such a network, use hou.Node.findOrCreateMotionEffectsNetwork.

Return a CHOP network node suitable for storing Motion Effects. By default, if the node doesn’t exist, it will be created.

See also hou.Parm.storeAsClip and hou.Node.motionEffectsNetworkPath.

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Given sequences of children nodes and network boxes, save a file containing those items. You can load this file using hou.Node.loadChildrenFromFile.

Raises hou.OperationFailed if any of the nodes or network boxes are node children of this node, or if the file could not be written to. Raises hou.PermissionError if you do not have permission to read the contents of this node.

Load the contents of a file saved with hou.Node.saveChildrenToFile into the contents of this node.

Raises hou.OperationFailed if the file does not exist or it is not the correct type of file. Raises hou.PermissionError if this node is a locked instance of a digital asset.

Prints the Python code necessary to recreate a node.

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This method is used internally by Houdini to perform autocompletion in the interactive Python shell.

Implements == between Node objects.

For example, hou.root() == hou.node(“/”) will return True.

There can be multiple Python Node objects for the same Houdini node. Two identical calls to hou.node() will return different Python Node objects, with each representing the same Houdini node. Comparing these nodes using == (which calls __eq__) will return True, while comparing them using is (the object identity test) will return false.

You can compare a node to None. This behavior is useful because hou.node() returns None if the node doesn’t exist. Comparing an node to anything other than another node or None raises TypeError.

Implements != between Node objects. See __eq__().