HOM hou
Module containing all the sub-modules, classes, and functions to access Houdini.
Subtopics
Assets
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Represents the definition of a digital asset.
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User-defined module containing common functions, classes, and constants.
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Encapsulates various options that can be set on a digital asset.
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Represents a “section” of data stored along with a digital asset.
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Module containing functions related to Houdini digital assets.
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Returns the list of digital asset node types in the current scene.
Channels
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Class representing a CHOP node.
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Evaluate a Bezier interpolation spline for an animated parameter using the left keyframe’s outgoing value, tangent, and acceleration and the right keyframe’s incoming value, tangent, and acceleration.
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Evaluate an animation function for an animated parameter. The return value is always the left keyframe’s outgoing value.
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Smooth curve between the left keyframe’s outgoing slope and the right’s incoming slope.
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Repeats the motion between two frames, lining up the first repeated value with the left keyframe’s value.
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Repeats the motion between two times, lining up the repeated values with the left keyframe’s value.
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Interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.
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Interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.
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Interpolates between the values of two keyframes.
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Interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.
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Interpolates between the values of two keyframes.
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Interpolates between the values of two keyframes.
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Linearly interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.
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Creates a smooth curve between the left keyframe’s incoming slope and the right keyframe’s outgoing slope.
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Creates a straight line from the left keyframe’s incoming value, matching the left keyframe’s incoming slope.
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Creates a straight line from the right keyframe’s outgoing value, matching the right keyframe’s outgoing slope.
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Linearly interpolates between keyframes using quaternions.
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Evaluate an interpolation function for an animated parameter that gives a smooth curve between the left keyframe’s outgoing value and the right keyframe’s incoming value, using the left’s outgoing slope and acceleration and the right’s incoming slope and acceleration.
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Repeats the motion between two times.
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Repeats the motion between two times.
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Fits a spline through consecutive keyframe values.
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Matches the incoming and outgoing values and slopes.
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Matches the left keyframe’s incoming slope.
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Matches the right keyframe’s outgoing slope.
Cooking
Dynamics
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Class representing a DOP node.
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Enumeration of field types.
Exceptions
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Base class for all exceptions in the hou module.
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Exception class for when loading a hip file in Houdini generates warnings.
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Exception class for when an operation attempted to use a feature that is not available. This class is a subclass of .
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Exception class for when you use a stale variable to attempt to access something that was deleted in Houdini. This class is a subclass of .
General
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This class is the base class for an enumeration value. It cannot be instanced and is not meant to be used directly by the user.
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The variable() function returns a variable by name. The Variable class represents Houdini variables.
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Returns whether Houdini is in the process of exiting. This function is called internally by the interactive Houdini Python shell.
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Compares two numbers and returns True if they are almost equal in terms of how far apart they are when represented as floating point numbers.
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Appends the given source code to the hou.session module. The appended code is made available immediately. You do not have to re-import hou.session.
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Returns the application’s compilation date.
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Returns the application name.
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Returns the application’s version number as a tuple of integers – (major_version, minor_version, build_version).
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Returns the application’s version number as a string.
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Exits Houdini, returning the exit code to the operating system. If suppress_save_prompt is false, this function asks the user if he/she wants to save. If the user presses “Cancel”, the exit will be canceled and the next statement will execute.
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Houdini and 3D related math functions.
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Returns True if the application is an apprentice (non-commercial) version. Returns False otherwise.
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Release the currently held Houdini license.
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This module is used to define custom classes, functions and variables that can be called from within the current Houdini session. The contents of this module are saved into the .hip file.
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Returns the contents of the hou.session module.
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Sets the contents of the hou.session module. The new contents is made available immediately. You do not have to re-import hou.session.
Geometry
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Enumeration of attribute data types.
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Represents a surface node.
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Enumeration of attribute types.
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Enumeration of geometry component types.
IO
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Search the houdini path for the specified directory, returning a tuple of all the matches. The directory name specified should be relative to the houdini directory.
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Search the houdini path for a specified directory, returning the first match found. The directory name specified should be relative to the houdini directory.
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Search the houdini path for a specified file, returning the first match found. The filename specified should be relative to the houdini directory.
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Search the houdini path for the specified file, returning a tuple of all the matches. The filename specified should be relative to the houdini directory.
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Read a file, returning the contents in a string. Supports regular files, opdef: and oplib: paths, and http URLs.
Images
Keyframes
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Abstract base class for all keyframe class.
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Class representing the default keyframe type, a numerical keyframe.
Materials
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Represents a shader node.
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Enumeration of shader types.
Node Organization
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Represents a network box.
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Represents a node group.
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Enumeration of available node filters.
Node type categories
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Represents a category of node types, such as surface nodes (SOPs) or particle nodes (POPs).
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Return the NodeTypeCategory instance for Houdini channel container (chopnet) nodes.
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Return the NodeTypeCategory instance for Houdini channel (chop) nodes.
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Return the NodeTypeCategory instance for Houdini composite container (copnet) nodes.
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Return the NodeTypeCategory instance for Houdini composite (cop) nodes.
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Return the NodeTypeCategory instance for Houdini dynamic (dop) nodes.
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Return the NodeTypeCategory instance for Houdini manager nodes. The manager nodes are /obj, /out, /part, /ch, /shop, /img, and /vex.
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Returns a dictionary where the keys are the category names (e.g. “Object”, “Sop”) and the values are hou.NodeTypeCategory objects.
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Return the NodeTypeCategory instance for Houdini object nodes. For example, if /obj/model is an object, hou.node(“/obj/model”).nodeTypeCategory() == hou.objectNodeTypeCategory() will return True.
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Return the NodeTypeCategory instance for Houdini particle container (popnet) nodes.
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Return the NodeTypeCategory instance for Houdini particle (pop) nodes.
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Return the NodeTypeCategory instance for Houdini root (/) node. There is only one instance of the root node, and it has its own node type category.
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Return the NodeTypeCategory instance for Houdini output (rop) nodes.
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Returns the NodeTypeCategory object corresponding to shader (SHOP) nodes.
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Return the NodeTypeCategory instance for Houdini geometry (sop) nodes.
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Return the NodeTypeCategory instance for Houdini vex builder container (vopnet) nodes.
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Return the NodeTypeCategory instance for Houdini vex builder (vop) nodes.
Nodes
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The node() function returns a node in the scene by its path. The Node class is the base class for all Houdini nodes.
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Represents a connection (wire) between two nodes.
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hou.NodeType is a class representing a type of a node. hou.nodeType() is a function which returns the NodeType object for a node type name.
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Represents a particle node.
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Change the current node. Houdini has one current node, analogous to a current directory in a file system. If a relative path is given, it is relative to the node returned by hou.pwd().
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Copy all given nodes to a new place in node hierarchy.
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Move all given nodes to a new place in node hierarchy.
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Returns a node by its path string. Returns None if the node does not exist.
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Returns a NodeType object given category and a name, such as Sop and “copy”. Returns None if the type does not exist.
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Enumeration of node type sources.
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Enumeration of permission flag combinations.
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Return the current node or the node containing the evaluating parm. Houdini has one current node, analogous to a current directory in a file system. You can change the current node with cd().
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Return the root node (i.e. /).
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Return a list of all selected nodes.
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Make the given node Houdini’s current node. This function is equivalent to hou.cd(node.path()).
Parameter templates
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Describes a button parameter.
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Describes a set of folders.
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Describes a label parameter.
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Describes a menu parameter.
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Parameter template for a ramp parameter.
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Template for a separator parameter. Separators are just lines between parameters.
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Enumeration of parameter data types.
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Enumeration of available looks for a parameter
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Enumeration of available naming schemes for a parameter.
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Enumeration of parameter template types.
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Enumeration of string parameter types.
Parameters
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The parm() function returns a parameter by its path. The Parm class represents a parameter on a node.
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The parmTuple() function returns a parameter tuple by its path. The ParmTuple class represents a parameter tuple on a node.
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The same as evalParm(). Provided for backward compatibility.
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Evaluate a parameter that references a node, and return the absolute path to the node.
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Evaluate a parameter, given either an absolute or a relative path to it. Relative path searches are done from the node returned by . This function is a shortcut for hou.parm(path).eval().
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Evaluate a parameter, given either an absolute or a relative path to it. Relative path searches are done from the node returned by . This function is a shortcut for hou.parmTuple(path).eval().
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Enumeration of available expression languages.
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Enumeration of file types.
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Return the value of a node’s local variable. Call this function from expressions inside node parameters.
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Returns a parameter by its path string. Returns None if the parameter does not exist.
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Returns a parameter tuple by its path string. Returns None if the parameter tuple does not exist.
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Enumeration of available script languages.
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Enumeration of interface update modes.
Rendering
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Represents a render output node.
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Enumeration of dependency rendering methods.
Scripting
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Used internally by Houdini to preload icons for speed.
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This function is used internally by the Houdini Python shell for argument auto-completion on functions of the hou module.
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Evaluates the given string expression and returns the result.
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Evaluates the given string expression at a certain frame and returns the result.
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Executes the given hscript command and returns a 2-tuple of strings where the first string contains the regular output of the executed command and the second string contains the error output. You can specify multiple commands by using ';' or the newline character as the separator.
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Return the text help of an hscript command. This function is used to help re-implement hscript commands in Python.
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Deprecated: Use expandString.
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Evaluate an Hscript expression.
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Evaluate an Hscript expression as a float.
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Evaluate an Hscript expression as a vector.
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Evaluate an Hscript expression as a float.
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Evaluate an Hscript expression as a vector.
Shelf
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Represents the shelf area at the top of the screen, within which shelf sets and shelf tabs exist.
Timeline
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Return the number of frames per second.
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Return the playbar’s current frame. Note that Houdini can be on a fractional frame.
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Convert from a given frame value to a time value.
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Set the number of frames per second.
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Set the playbar’s current frame. Note that the frame may be a fractional value.
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Set the playbar’s time.
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Return the playbar’s current time, in seconds of playback.
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Convert from a given time value to a frame value, rounding the result to a integer if it is close to an integer.
UI
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Class representing a Houdini desktop (a pane layout).
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Class representing a help browser pane tab. Provides methods for controlling the help browser.
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Represents a Houdini UI pane tab.
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Represents a Houdini UI pane tab.
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Return whether or not the hou.ui module is available.
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Enumeration of pane tab types.
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Enumeration of pane types.
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Enumeration of dialog message severities.
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Module containing user interface related functions.
Utility
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A 4×4 matrix of floating point values.
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Represents a ramp, such as would be returned from a ramp parameter.
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Enumeration of color types.
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Enumeration of ramp interpolation types.
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Enumeration of ramp types.
VEX
Viewer
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A class representing a context viewer pane tab.
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Enumeration of component types.
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Enumeration of connectivity types.
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Enumeration of scene viewer viewport types.
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Enumeration of spaces.
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Enumeration of viewer shading modes.