hou.Matrix4 class

A 4×4 matrix of floating point values.

4×4 matrices are typically used in Houdini to represent a 3D transformation (e.g. some combination of rotation, scaling, shearing, and translation). A single matrix compactly represents a transformation, and is much easier to deal with than multiple translate, rotate, scale, shear, transformation order, and rotation order values.

Note that Houdini’s matrices are stored in row-major format, and vectors that are multiplied with matrices are treated as row vectors. So, if `p` is a hou.Vector4 representing a point and `M` is a Matrix4, you write `p*M`, not `M*p`. Similarly, `p*M1*M2` will first transform `p` by `M1`, and then transform it by `M2`.

You can multiply Vector3s or Vector4s by Matrix4s. If you multiply a Vector3, it is the same as multiplying a Vector4 where the fourth component is 1 (see hou.Vector3.__mul__).

To transform a normal (as opposed to a point or vector), you need to multiply by the inverse transpose of the matrix. For example, suppose:

`p`

is a hou.Vector3 object representing a position (or a hou.Vector4 with `p[3]==1`)

`v`

is a hou.Vector4 object representing a vector (a direction with a length but no fixed location in space), with `v[3]==0`

`n`

is a hou.Vector4 object representing a normal, with `v[3]==0`

`m`

is a Matrix4 object representing a transform matrix

Then you would write:

```p * m # to transform the point
v * m # to transform the vector
n * m.inverted().transposed() # to transform the normal
# (note that m.inverted().transposed() is mathematically equivalent to m.transposed().inverted())
```

Here is a concrete example:

```>>> m = hou.hmath.buildTranslate((1, 1, 2))
>>> m
<hou.Matrix4 [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [1, 1, 2, 1]]>
>>> p = hou.Vector3(1, 2, 3)
>>> p * m
<hou.Vector3 [2, 3, 5]>
```

Both VEX and the UT_DMatrix4 class in the Houdini Development Kit (HDK) also store matrices in row-major format.

hou

Animation ¶

• Abstract base class for all keyframe class.

• Represents a Bookmark

• Class representing the default keyframe type, a numerical keyframe.

• Adds an Animation Layer to an existing Animation Layer Mixer.

• Module which contains functions for working with animation utilities.

• Enumeration of the bookmark events that can be handled by callback functions.

• Creates an Animation Clip Mixer from the parameters in the Channel List.

• Creates an Animation Layer Mixer from the parameters in the Channel List.

• Module containing functions related to inverse kinematics.

• Removes an Animation Layer from an existing Animation Layer Mixer.

• Enumeration of values for segment types used by channel primitives.

• Enumeration of values for default Slope Mode when inserting new keys into a channel.

apex ¶

• Represents an APEX node.

• Given an APEX node’s session ID, return an ApexNode object. Returns None if the ID does not correspond to a valid APEX node (e.g. if the node was deleted).

• Given an APEX wire’s session ID, return an ApexNodeConnection object. Returns None if the ID does not correspond to a valid APEX wire connection (e.g. if the wire was deleted).

• Given an APEX node’s session ID, return an ApexStickyNote object. Returns None if the ID does not correspond to a valid APEX sticky note (e.g. if the note was deleted).

Digital assets ¶

• Represents the definition of a houdini digital asset (HDA).

• User-defined Python module containing functions, classes, and constants that are stored with and accessed from a digital asset.

• Stores miscellaneous options about a houdini digital asset (HDA).

• Represents a section of data stored along with a digital asset.

• User-defined Python module containing the implementation and registration code of a python viewer handle stored in a digital asset.

• User-defined Python module containing the implementation and registration code of a python viewer state stored in a digital asset.

• Module containing functions related to Houdini Digital Assets.

• Given a node type category, operator name and digital asset library path, return an HDADefinition object. Return None if no such installed digital asset definition matches the arguments.

• Enumeration of types of events that can happen for digital asset libraries.

• Enumeration of digital asset license permission levels.

Channels ¶

• A copy of an Animation Editor Graph Selection.

• A copy of a list of channels from Channel List or Animation Editor.

• Class representing a CHOP node.

• Class representing an animation clip.

• 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.

• Evaluate an animation function for an animated parameter. The return value is always the left keyframe’s outgoing value.

• Smooth curve between the left keyframe’s outgoing slope and the right’s incoming slope.

• Repeats the motion between two times.

• Repeats the motion between two frames, lining up the first repeated value with the left keyframe’s value.

• Repeats the motion between two times, lining up the repeated values with the left keyframe’s value.

• Repeats the motion between two times.

• Interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.

• Interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.

• Interpolates between the values of two keyframes.

• Interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.

• Interpolates between the values of two keyframes.

• Interpolates between the values of two keyframes.

• Linearly interpolates between the left keyframe’s outgoing value and the right keyframe’s incoming value.

• Creates a smooth curve between the left keyframe’s incoming slope and the right keyframe’s outgoing slope.

• Creates a straight line from the left keyframe’s incoming value, matching the left keyframe’s incoming slope.

• Creates a straight line from the right keyframe’s outgoing value, matching the right keyframe’s outgoing slope.

• Linearly interpolates between keyframes using quaternions.

• 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.

• Repeats the motion between two times.

• Repeats the motion between two times.

• Fits a spline through consecutive keyframe values.

• Matches the incoming and outgoing values and slopes.

• Matches the left keyframe’s incoming slope.

• Matches the right keyframe’s outgoing slope.

Cooking ¶

• Return Houdini’s cook update mode (Auto Update/On Mouse Up/Manual) that is displayed in the status bar.

• Enumeration of interface update modes.

• Return Houdini’s cook update mode (Auto Update/On Mouse Up/Manual) that is displayed in the status bar.

Crowds ¶

• An agent primitive.

• An agent’s animation clip.

• The shared data for an agent primitive.

• An agent’s layer.

• Stores metadata in an agent definition.

• The rig of an agent primitive.

• An agent’s shape.

• A shape binding in an agent’s layer.

• A deformer for agent shapes.

• The shape library of an agent primitive.

• A group of transforms and channels in an agent’s rig.

• Enumeration of agent shape deformer types.

• Crowd-related functions.

Dynamics ¶

• A piece of data stored inside a DOP network’s simulation.

• Represents a dynamics node.

• A type of DOP data that contains an object in the simulation.

• A table of values stored inside a DopData.

• A type of DOP data that stores which DOP objects affect one another.

• A dynamics simulation contained inside a DOP network node.

• Returns the DOP Network node set as the current simulation in the UI.

• DOP related functions.

• Enumeration of field types.

Exceptions ¶

• Base class for all exceptions in the hou module.

• Raised if you try to modify SOP geometry from outside of a Python SOP.

• Raised if you try to use a custom handle that is not registered with the system.

• Exception raised when you try to access a reference to SOP Geometry that has since failed to cook.

• Raised if you try to set a node’s input to something invalid.

• Raised if you try to call a method on a Node that doesn’t support it.

• Raised if you try to set a node’s output to something invalid.

• Raised when you pass a sequence of the wrong length to a function.

• Exception class for when loading a hip file in Houdini generates warnings.

• Exception raised when a name conflict is detected during an operation.

• Raise this exception in a Python node to signal that the node is in error.

• Raise this exception in a Python node to signal that the node has a warning.

• Raised when you try to call an API function/method that is not available.

• Raised when you try to access a reference to an object that has since been deleted.

• Generic catch-all exception for various errors in Houdini that don’t have their own dedicated exception classes.

• Raised if you try to unregister a Python state that was never registered.

• Raised if a type conflict occurs during an operation. For instance, type conflicts may occur during the registration of a python state or python handle.

• Given a truthy condition, if the condition is False then raise an AssertionError. If the condition is True, then do nothing.

File I/O ¶

• 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.

• Search the Houdini path for a specified directory, returning the first match found. The directory name specified should be relative to the Houdini directory.

• Search the Houdini path for a specified file, returning the first match found. The filename specified should be relative to the Houdini directory.

• 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.

• Search the Houdini path for files with a particular extension, returning a tuple of all the matches. A subdirectory can also be optionally provided which is appended to each entry in the Houdini path before looking for files.

• Return the path to the Houdini directory in your \$HOME directory.

• Return the contents of the Houdini path as a tuple of strings.

• Given a binary string containing data in CPIO data format, decode the data and return a sequence of (name, value) pairs representing the data.

• Given a file containing data in index data format, decode the data and return a dictionary representing the data.

• Given a binary string containing data in index data format, decode the data and return a dictionary representing the data.

• Read a binary file, returning the contents in a bytes object. Supports regular files, opdef: and oplib: paths, and http URLs.

• Read a file, returning the contents in a string. Supports regular files, opdef: and oplib: paths, and http URLs.

• Given a sequence of (name, value) string tuples, encode that data into a string in CPIO format.

• Given a dictionary mapping strings to strings, encode that data in index data format and save it into a file.

• Given a dictionary mapping strings to strings, encode that data into a string in index data format.

General ¶

• 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.

• Use this class to turn any Python code block into an interruptable operation.

• Use this class to collect multiple redraws for any Python code block and only redraw once.

• Use this class to disable undos within a Python code block.

• Used to group all undos within a Python code block into a single action.

• Allow (or disallow) an environment variable to overwrite the value of a global variable saved in a hip file.

• 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.

• 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.

• Returns the application’s compilation date.

• Returns the application name.

• Returns a string containing information about the system that compiled this version of Houdini.

• Returns the application’s version number as a tuple of integers – (major_version, minor_version, build_version).

• Returns the application’s version number as a string.

• Functions related to playing audio using Houdini’s playbar.

• Returns a CHOP node path pattern to take precedence when exporting to the same channel.

• Represents a connection to a clone process.

• Registers a callback method to be run any time a is modified.

• Registers a callback method to be run any time a receives a new image.

• Return a specific object.

• Return a tuple of all objects.

• Return a tuple of all registered connection change callbacks.

• Creates a new object.

• Deletes a .

• Deletes all disconnected .

• Return a tuple of all registered image change callbacks.

• Deregister all connection change callback methods.

• Deregister all image change callback methods.

• Deregisters a specific connection change callback method.

• Deregisters a specific image change callback method.

• Causes the current process to operate as a clone process.

• 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.

• Returns the HDK API version number.

• Functions for working with the current scene (.hip) file.

• Enumeration of the hip file event types that can be handled by callback functions.

• Houdini and 3D related math functions.

• Module containing hotkey related functions.

• Return whether the application is an apprentice (non-commercial) version.

• Return the category of license (Commercial, Apprentice, ApprenticeHD, etc.) in use.

• Enumeration of license category values.

• Module containing functions and classes for logging warnings and errors.

• Returns the name of the computer used with this Houdini session.

• Returns the number of threads used for processing.

• Enumeration of numeric value types.

• Release the currently held Houdini license.

• Enumeration of hip file save modes.

• Returns the scale factor from Meters-Kilograms-Seconds units into the Houdini session’s current units.

• Returns the scale factor from Meters-Kilograms-Seconds units into the Houdini session’s current units.

• 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.

• Returns the contents of the hou.session module.

• Sets a CHOP node path pattern to take precedence when exporting to the same channel.

• Sets the maximum number of threads to use for multi-processing.

• Sets the contents of the hou.session module. The new contents is made available immediately. You do not have to re-import hou.session.

• Starts a Houdini Engine debugging session in Houdini if no session is currently active

• Returns a dictionary describing the version of each third-party library used by Houdini.

• Deprecated: Use InterruptableOperation.

• Returns the user name for the current Houdini session.

• Returns a dictionary about the version of VDB built into Houdini.

• Returns the video encoders that are registered with a given driver and optionally, which encoders are available on the current platform and license type.

Geometry ¶

• This class stores information about a Geometry attribute.

• Used for detecting when contents of geometry have changed

• A ChannelPrim is a geometry primitive (Prim object) which stores channel data.

• Each Edge object resides inside a Geometry object and stores an edge. Edges are reprsented as pairs of points.

• A named group of edges inside a Geometry object.

• A Face is a kind of geometry primitive (Prim object) that contains a sequence of vertices (Vertex objects). How these vertices are used depends on the type of face; polygons, for example, use the vertices to define the edges of the polygon, while NURBS curves use them as control points.

• A Geometry object contains the points and primitives that define a 3D geometric shape. For example, each SOP node in Houdini generates a single Geometry object.

• Geometry delta provides access to the geometry differences (deltas) stored by some Geometry nodes such as the edit SOP.

• Geometry Ray Cache allows caching of ray-intersection structures.

• Describes properties of an index pair attribute.

• A packed fragment primitive.

• A packed geometry primitive.

• A packed primitive.

• Represents a point on a geometry primitive, such as a polygon or NURBS surface.

• A named group of points inside a Geometry object.

• A Polygon is a kind of Face whose vertices are connected via straight lines.

• Each Prim resides inside a Geometry object and stores some sort of 3D geometric primitive, like a polygon, a NURBS curve, or a volume. Each primitive usually contains a set of Vertex objects, each of which references a Point object.

• A named group of primitives inside a Geometry object.

• A Quadric is a kind of geometry primitive (Prim object) that represents a 3-dimensional surface defined by a quadratic polynomial equation (e.g. a sphere or tube).

• A class that represents a geometry component selection.

• Represents a surface node.

• Represents the code of a surface node.

• A Surface is a kind of geometry primitive (Prim object) that contains a two dimensional grid of vertices (Vertex objects). How these vertices are used depends on the type of surface: meshes, for example, use the vertices to define a quadrilateral mesh, while NURBS surfaces use them as control points.

• A VDB is a kind geometry primitive (Prim object) that stores data in a three dimensional grid of voxels.

• Existing inside a Geometry object, a Vertex object is contained in exactly one Prim, and references exactly one Point.

• A named group of vertices inside a Geometry object.

• A Volume is a kind geometry primitive (Prim object) storing a three dimensional array of voxels.

• Enumeration of attribute data types.

• Enumeration of geometry attribute types.

• Enumeration of component loop types.

• Enumeration of geometry component types.

• Enumeration of the halves of a key, used when setting keyframe data in a Channel Primitive.

• Enumeration of primitive types.

• Enumeration of scale inheritance modes for transforms.

• Enumeration of voxel data types.

Images ¶

• Minimal class representing a compositing view pane.

• Represents a compositing node.

• Enumeration of image depths (data formats) for representing the pixels in an image plane.

• Return the resolution of an image in a file.

• Create an image file from color and alpha pixel data.

Nodes ¶

• Represents a connection (wire) between two APEX Nodes.

• Information common to all instances of a type of APEX node.

• An abstract base class for a network item that can be used as an input to nodes in the same network, but which is not a node itself.

• Represents a lighting node.

• Represents a lighting node.

• A small dot in a network that allows wires to be routed along specific paths without affecting the data passing through them.

• The base class for all visible elements within a network.

• The base class for all visible elements within a network, such as Nodes, Network Boxes, and Sticky Notes.

• The base class for all abstract nodes in Houdini (OP, APEX, etc.)

• Represents a connection (wire) between two Nodes.

• A tree structure designed to contain information about nodes and the data they generate.

• Information common to all instances of a type of node, such as the parameters.

• An abstract base class for an indirect input in an OP network.

• A small dot in an OP network that allows wires to be routed along specific paths without affecting the data passing through them.

• The base class for all nodes in Houdini (objects, SOPs, COPs, etc.) An instance of this class corresponds to exactly one instance of a node in Houdini.

• Represents a connection (wire) between two OP Nodes.

• Information common to all instances of a type of OP node.

• A node-like item that appears inside OP subnets and corresponds to the node wired into the subnet.

• This kind of NodeType contains extra attributes specific to SOP nodes.

• A node-like item that appears inside subnets and corresponds to the node wired into the subnet.

• Represents a task node.

• Enumeration of types of appearance change events that can happen to nodes.

• 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().

• Clears the selected state for all nodes, network boxes, and other subclasses of hou.NetworkMovableItem in the Houdini session.

• Copy all given nodes to a new place in node hierarchy.

• Copies a list of nodes to the clipboard.

• Return the default color for a particular network element.

• Given a path string, return a NetworkMovableItem object. Return None if the path does not refer to an item.

• Given an item’s session id and an item type, return a NetworkMovableItem object. Return None if the id does not correspond to a valid item.

• Takes a sequence of node path strings and returns a tuple of NetworkMovableItem objects.

• Move all given nodes to a new place in node hierarchy.

• Given a network box’s session id, return a NetworkBox object. Return None if the id does not correspond to a valid network box.

• Given a dot’s session id, return a NetworkDot object. Return None if the id does not correspond to a valid dot (e.g. if the dot was deleted).

• Given a path string, return a Node object. Return None if the path does not refer to a node.

• Given a node’s session id, return a Node object. Return None if the id does not correspond to a valid node (e.g. if the node was deleted).

• Given a node’s session id and an input index, return a NodeConnection object. Return None if the id does not correspond to a valid node (e.g. if the node was deleted), or the specified input index is not connected.

• Enumeration of types of events that can happen to nodes.

• Enumeration of the different node flags.

• Takes a category object and a name, or just a full name string, and returns the corresponding NodeType object.

• Enumeration of node type sources.

• Takes a sequence of node path strings and returns a tuple of Node objects.

• Enumeration of a generic tri-state value.

• Return the parent of the current node.

• Paste previously copied nodes to a given network.

• A shortcut for hou.pwd().hdaModule().

• Given a node type name that includes the category and optionally a parent node, return the corresponding NodeType object after evaluating aliases. Return None if there is no such type with that name.

• If called from an evaluating parm, return the node containing the parm. Otherwise, return Houdini’s global current node. You can change this current node with hou.cd

• Return the root node (i.e. /).

• Enumeration of types of events that can happen when a ROP node is rendering.

• Return a list of all selected node connections.

• Return a list of all selected nodes, network boxes, sticky notes, subnet indirect inputs, and network dots.

• Return a list of all selected nodes.

• Return the setDefault color for a particular network element.

• Make the given node Houdini’s current node. This function is equivalent to hou.cd(node.path()).

• Given a tuple of path strings, return a tuple of path strings sorted in input/outputs order. Invalid node paths won’t be part of the sorted list.

• Given a tuple of , return a tuple of sorted in input/outputs order.

• Given a sticky note’s session id, return a StickyNote object. Return None if the id does not correspond to a valid sticky note.

• Given a subnet input’s session id, return a SubnetIndirectInput object. Return None if the id does not correspond to a valid subnet input (e.g. if the subnet containing the input was deleted).

• Enumeration of TOP Node cook states.

• Enumeration of drivers that provide video functionality.

Node types ¶

• Represents the node type category for APEX node types.

• Represents a category of node types, such as surface nodes (SOPs) or dynamics nodes (DOPs).

• Represents a category of OP node types, such as surface nodes (SOPs) or dynamics nodes (DOPs).

• Return the NodeTypeCategory instance for APEX nodes.

• Return the NodeTypeCategory instance for Houdini channel container (chopnet) nodes.

• Return the NodeTypeCategory instance for Houdini channel (chop) nodes.

• Return the NodeTypeCategory instance for Houdini composite container (cop2net) nodes.

• Return the NodeTypeCategory instance for Houdini composite (cop2) nodes.

• Return the NodeTypeCategory instance for Houdini data nodes. These nodes can never be instantiated, but exist to store namespaced data inside of HDAs that doesn’t belong to a specific operator.

• Return the NodeTypeCategory instance for Houdini dynamic (DOP) nodes.

• Return the NodeTypeCategory instance for Houdini lighting (lop) nodes.

• Return the NodeTypeCategory instance for Houdini manager nodes. The manager nodes are /obj, /out, /part, /ch, /shop, /img, and /vex.

• Return a dictionary where the keys are the category names (e.g. Object, Sop) and the values are hou.NodeTypeCategory objects.

• Return the NodeTypeCategory instance for Houdini object nodes. For example, if /obj/model is an object then hou.node(/obj/model).type().category() is hou.objectNodeTypeCategory().

• 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.

• Return the NodeTypeCategory instance for Houdini output (rop) nodes.

• Return the NodeTypeCategory object corresponding to shader (SHOP) nodes.

• Return the NodeTypeCategory instance for Houdini geometry (sop) nodes.

• Return the NodeTypeCategory instance for Houdini task (top) nodes.

• Return the NodeTypeCategory instance for Houdini vex builder container (vopnet) nodes.

• Return the NodeTypeCategory instance for Houdini vex builder (VOP) nodes.

Objects ¶

• An instance of an object node in the Houdini scene.

Organization ¶

• Represents a sticky note in an APEX network.

• Represents a network box.

• A named set of nodes whose contents can be from different networks. A bundle’s contents may be fixed or may be determined from a pattern, and the contents may be filtered by node type.

• Represents a node group.

• Represents a network box in an OP network.

• Represents a sticky note in an OP network.

• Represents a sticky note.

• Create a new node bundle with the specified name.

• Given a node bundle name, return the corresponding NodeBundle object, or None if there is not one with that name.

• Return a tuple containing all the node bundles in the current session.

• Enumeration of available node type filters.

• Return a tuple containing all the node bundles that are selected in the bundle list pane.

Parameters ¶

• A parameter in a node. Each parameter has a unique name within its node and exists inside a parameter tuple.

• A tuple of one or more node parameters. Each parameter tuple has a unique name within its node.

• Adds a callback to be executed when a default context option is changed.

• The same as evalParm(). Provided for backward compatibility.

• Evaluate a parameter that references a node, and return the absolute path to the node.

• Evaluate a parameter that references a node path list, and return a space separated list of absolute node paths.

• Returns the value of a cook context option.

• Returns all callbacks registered to be called when a default context option is changed.

• Returns the string that holds the UI configuration for the default value of a context option.

• Returns the names of all available cook context options.

• 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().

• 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().

• Return the parameter that is currently evaluating.

• Enumeration of available expression languages.

• Enumeration of file types.

• Returns True if the specified option exists in the current cook context.

• Indicate whether the given context option is an automatic option.

• Indicate whether the given context option is an automatic option that is currently overridden from its automatic value.

• Return the value of a node’s local variable. Call this function from expressions inside node parameters.

• Given a path string, return a Parm object. Return None if the path does not refer to a parameter.

• Enumeration of Bake Chop modes.

• Returns the contents of the parameter clipboard as a tuple of copied parameter dictionaries.

• Enumeration of available parameter conditional types.

• Enumeration of Extrapolation methods when evaluating value outside the keyframe range.

• Given a path string, return a ParmTuple object. Return None if the path does not refer to a parameter tuple.

• Stops all callbacks from being executed when a default context option is changed.

• Removes the default value for a cook context option.

• Stops a callback from being executed when a default context option is changed.

• Enumeration of available script languages.

• Sets the default value for a cook context option.

• Sets a string to hold the UI configuration for the default value of a context option.

Parameter templates ¶

• Describes a parameter tuple containing a button.

• Describes a parameter tuple containing data values.

• Describes a parameter tuple containing floating point values.

• Describes a folder in a parameter dialog.

• Describes a set of folders.

• Describes a parameter tuple containing integer values.

• Describes a label parameter. Unlike most other parameters, labels do not store parameter values.

• Describes a menu parameter containing evaluating to integer values. Note that StringParmTemplates may also have menus.

• Describes a parameter tuple (its name, type, etc.). This is base class for all parameter templates.

• A group of parameter templates used to represent the parameter layout of a node or the parameters in a digital asset definition.

• Parameter template for a ramp parameter.

• Template for a separator parameter. Separators are just lines between parameters and do not store any parameter values.

• Describes a parameter tuple containing string values. These values can be arbitrary strings or references to files or nodes

• Describes a parameter tuple containing a checkbox.

• Enumeration of data parameter types.

• Enumeration of folder types for FolderParmTemplates.

• Enumeration of label parameter types.

• Enumeration of parameter menu types.

• Enumeration of parameter data types.

• Enumeration of available looks for a parameter

• Enumeration of available naming schemes for a parameter.

• Enumeration of parameter template types.

• Enumeration of string parameter types.

Performance ¶

• Represents an event that is recorded by the performance monitor and used to generate time and memory growth statistics for profiles.

• Represents a performance monitor profile.

• Represents the set of options used by the Performance Monitor and specifies the type of statistics to be recorded in a profile.

• Module containing performance monitor related functions.

Playbar ¶

• Return the number of frames per second.

• Return the playbar’s current frame. Note that Houdini can be on a fractional frame if fractional frames are enabled.

• Convert from a given frame value to a time value.

• Return the playbar’s current frame, rounded to the nearest integer.

• Enumeration of play modes for the main playbar in Houdini.

• The animation playbar module.

• Enumeration of the playbar events that can be handled by callback functions.

• Set the number of frames per second.

• Set the playbar’s current frame. Note that the frame may be a fractional value.

• Set the playbar’s time.

• Return the playbar’s current time, in seconds of playback.

• Convert from a given time value to a frame value, rounding the result to a integer if it is close to an integer.

Preferences ¶

• Add a user preference.

• Return a preference value.

• Return all the preference names.

• Refresh all user preferences.

• Remove a user preference.

• Sets a preference given a name and returns true on success.

• Enumeration of locations for radial menu items in Houdini.

• Enumeration of types for radial menu items in Houdini.

Rendering ¶

• Represents a render output node.

• Enumeration of dependency rendering methods.

Scripting ¶

• Use this to temporarily change the scripting evaluation context within a Python code block.

• A proxy object that replaces Python’s stdin, stdout, and stderr streams within Houdini.

• Decodes a variable or geometry attribute name that was previously encoded.

• Encodes any string into a valid variable or geometry attribute name.

• Expands global variables and expressions in a string at the current frame.

• Expands global variables and expressions in a string at a given frame.

• Return the globals dictionary used by the parameter expression evaluation namespace.

• Return the value of the specified Houdini environment variable.

• Return the base URL for all Houdini help pages.

• Executes an HScript command

• Return the text help of an hscript command. This function is used to help re-implement hscript commands in Python.

• Deprecated: Use expandString.

• Evaluate an Hscript expression.

• Evaluate an Hscript expression as a float.

• Evaluate an Hscript expression as a matrix.

• Evaluate an Hscript expression as a string.

• Evaluate an Hscript expression as a vector.

• Increments the number in a string, or appends a number to the string.

• Set the value of the specified Houdini environment variable.

• Tells Houdini’s web server to use the specified prefix as a handler to serve opdef requests.

• Unset the specified Houdini environment variable.

• A collection of gallery entries that can be applied to operator nodes to set their parameters to predefined values.

• A gallery entry that can be applied to operator nodes to set their parameters to predefined values.

• The base class for all SHOP nodes in Houdini. An instance of this class corresponds to exactly one instance of a node in Houdini.

• A class that represents a Houdini style sheet. It can be used to evaluate, test, and debug style sheet output.

• A module for managing galleries and their entries.

• A module for accessing standard render properties.

• Enumeration of SHOP shader types.

• A module for managing style sheets that are stored with the hip file.

Shelf ¶

• Represents a tab of shelf tools.

• Represents the shelf area at the top of the screen, within which shelf sets and shelf tabs exist.

• Superclass of shelf tools, shelf tabs, and shelf sets.

• Represents a collection of shelf tabs.

• Represents a tool on the shelf, encapsulating a script as well as a label, help, and other information.

• Contains functions for working with shelf tabs and shelf tools.

Solaris ¶

• Stores a string that expresses a pattern to select instances from a point instancer primitive by id.

• Guarantees the lifetime of a USD stage created by a LOP node.

• Provides the ability to author post-layer data on a LOP Network.

• Stores a set of rules that define how to make a selection of scene graph primitives.

• Stores a description of which payloads on the USD stage should be loaded into the viewport.

• Used to edit the current session overlay layer that is applied to the current LOP node’s scene graph.

• Module containing functions related to Houdini LOP nodes.

• Specifies which primitives should be included and excluded during the traversal of a USD scene graph.

• Specifies a choice between the various pxr.Sdf.Layer objects available in a object.

UI ¶

• Provides an interface to any data source that can be used in association with an asset or snapshot gallery UI.

• Represents a Data Tree panetab.

• Class representing a Houdini desktop (a pane layout).

• Class representing a Houdini dialog.

• A floating window that contains one or more panes.

• Class representing a help browser pane tab. Provides methods for controlling the help browser.

• An interactive preview render (IPR) window.

• A value to adjust the appearance of a network editor without changing the underlying node data.

• Represents a Network Editor panetab.

• Describes the conditions under which a footprint ring should be displayed for a node in a network editor pane.

• Describes a background image that can be displayed in a network editor pane.

• The base class for extra shapes that can be drawn into a network editor.

• Describes a rectangular area that can be drawn into a network editor.

• Describes a wire that can be drawn into a network editor.

• Describes a line that can be drawn into a network editor.

• Describes a node shape that can be drawn into a network editor.

• A rectangular area of the desktop that contains one or more pane tabs.

• One of the tabs inside a desktop pane.

• Represents a Parameter Editor panetab.

• Represents a Performance Monitor panetab.

• Class representing a pane tab that can display an embedded PySide or PyQt interface.

• Represents the definition of a Python panel interface.

• Enumeration of confirmation dialog suppression options.

• Enumerator for the drawable display mode.

• Enumeration used with to specify the style of points to draw.

• Enumerator for the drawable primitive types.

• Enumeration used with to specify the reference point of the text within its bounding box.

• Enumeration of possible read/write modes for the file chooser.

• Return whether or not the hou.ui module is available.

• Enumeration of the specialized node footprints supported by the network editor.

• Enumeration of possible pane link values.

• Enumeration of pane tab types.

• Enumeration of Parameter filter criteria.

• Enumeration of Parameter filter modes.

• Enumeration of the different structures that are used to view objects in the Performance Monitor panetab.

• Enumeration of the different formats used when viewing times in the Performance Monitor panetab.

• Enumeration of the different units used when viewing times in the Performance Monitor panetab.

• Module containing functions related to Python panels.

• Module containing Qt related functions.

• Enumeration of the resource events that can be handled by callback functions.

• Enumeration of scrolling position modes.

• Enumeration of the secure selection options used by viewer state selectors.

• Enumeration of dialog message severities.

• Enumeration of possible node generation modes by states.

• Enumeration of state viewer types.

• Enumerator representing the type of action a state selector can perform if triggered with .

• Module containing user interface related functions.

• Values representing reasons Houdini generated a particular UI event.

• Enumerator for UI event value types.

• Enumeration of the different data types that may be manipulated by a value ladder.

• Enumeration of the different value ladder types.

Utility ¶

• An axis-aligned 3D rectangular region.

• An axis-aligned 2D rectangular region.

• Represents a color value.

• A 2×2 matrix of floating point values.

• A 3×3 matrix of floating point values.

• A 4×4 matrix of floating point values.

• An oriented 3D rectangular region.

• An oriented 2D rectangular region.

• A representation of a 3D rotation (or orientation). You can smoothly interpolate between two rotation values by interpolating between two quaternions.

• A Ramp represents a function that yields either floating point values or colors. You can evaluate this function between 0.0 and 1.0, and the function’s shape is determined by a sequence of values at key positions between 0.0 and 1.0.

• This kind of NodeType contains extra attributes specific to SHOP nodes.

• A sequence of 2 floating point values, with associated mathematical operations.

• A sequence of 3 floating point values, with associated mathematical operations.

• A sequence of 4 floating point values, with associated mathematical operations.

• This kind of NodeType contains extra attributes specific to VOP nodes.

• Enumeration of color spaces.

• Enumeration of compression types.

• Returns the hip extension based on the license category.

• Enumeration of ramp interpolation types.

• Enumeration of ramp types.

• Module containing Houdini-specific string manipulation methods.

VEX ¶

• Represents a VEX/VOP context. Different contexts allow the use of different functions/VOPs.

• Represents a VOP (VEX Operator) node.

• Invokes the main function in a compiled VEX file, returning the exported values.

• Takes a NodeTypeCategory object and returns a VexContext object representing the context of VOP networks the node would contain.

• Enumeration of the different node configurations that can be created for the inputs of a VOP node.

Views ¶

• The base class for advanced drawables.

• The grid (a.k.a. construction plane) in the scene viewer pane tab.

• A class representing a context viewer pane tab.

• The base class for drawables.

• A collection of options for the viewport flipbook dialog.

• The base class for a viewer resource gadget context.

• Represents a geometry drawable with picking and locating capabilities.

• Advanced drawable for drawing guide geometries.

• A container of hou.GeometryDrawable objects.

• Represents a component selection performed by the user in a viewport.

• Represents a geometry spreadsheet pane tab.

• A viewport within a Scene Viewer pane, for viewing the scene at the Object or SOP level.

• A Display Set represents a group of 3D viewport display options that apply to a particular context of geometry.

• A collection of settings controlling a viewport’s view of the scene (such as the view angle and whether different guides are displayed). Many of this object’s methods correspond to settings in the Display Options dialog.

• Gives access to an handle bound to a viewer state.

• Defines the hotkey commands, contexts, and default bindings used by plugins like python states and handles.

• The reference grid (a.k.a. reference plane) in the scene viewer pane tab.

• Pane tab type dedicated to displaying the current scene. This is usually the biggest pane in the center of the pane layout.

• Describes how Houdini should prompt the user to choose geometry in the viewport when creating a new SOP node instance.

• Represents extra geometry to draw in the viewer alongside user content (for example, as guide geometry).

• A drawable object to render text in the viewport.

• Represents a user interface event, such as a mouse press. You can access this object in an event handler to respond to user input.

• Object containing methods for testing input-device-specific information on a UI event, such as which mouse button was pressed.

• A mechanism to support interactive dragging operations.

• Represents a user interface event specific to viewers.

• Represents the execution context of a Python viewer handle.

• Represents a dragger usable with Python viewer handles.

• Class for registering a python viewer handle in Houdini.

• Describes an interactive state for a viewer pane.

• Represents the execution context of a Python viewer state.

• Represents a dragger usable with Python viewer states.

• Builds a context menu for a viewer state.

• Contains attributes describing a custom viewer state (tool).

• Represents a viewport visualizer.

• Represents a viewport visualizer type.

• Enum for viewport boundary overlay.

• Enumeration of connectivity types.

• Enum of viewport geometry contexts.

• Enumeration used with to specify the style of faces to draw.

• Enumeration used with to specify the style of lines to draw.

• Enumeration of Geometry Drawable types.

• Enumeration used with to specify the highlight mode of a drawable matte.

• Enumeration used with to specify how to wrap the texture generated when using a ramp color (similar to OpenGL texture settings).

• Enum values for flipbook antialiasing settings.

• Enum values used to specify the motion blur subframe range.

• Enum values for setting the flipbook’s visible object types.

• Enumeration of image fit modes.

• Enumeration of the geometry viewport events that can be handled by callback functions.

• Enumeration of viewport layouts.

• Enumeration of scene viewer viewport types.

• Enum for viewport shading modes

• Enumeration of group list types.

• Enumeration of handle axes that can be aligned to a geometry normal.

• Enumeration of states for controling the panel.

• Enumeration to identify the HUD panel types.

• Enum of visibility options for marker visualizers.

• Enumeration of global orientation mode.

• Enum values for selecting a specific parameter source tab in the parameter interface dialog.

• Enumeration for describing the facing direction of pickable components.

• Enumeration of methods for modifying selections with new components.

• Enumeration of pick styles.

• Enumeration of spaces.

• Enumeration of resources such as viewer states and viewer handles.

• Enumeration of the UI events a scene viewer can listen to via a callback.

• Enumeration of selection modes.

• Enumeration of snapping modes.

• Enumeration of snapping priority.

• Enum for deforming agent quality

• Enum for agent wireframe mode display

• Background image view target for the viewport display options

• Viewport highlight of primitives with selected components

• Viewport Color Schemes

• Viewport Depth of Field Bokeh Shape

• The default material shader for the 3D viewer

• Viewport fog layer modes

• Viewport volume fog quality

• Geometry information display state

• Enum for grid numbering on viewport grids.

• Viewport guides

• Viewport font sizes for visualizer text

• Handle highlight size

• Automatic viewport clip plane adjustment during homing

• Lighting modes for the viewport

• Enum for the update frequency of viewport material assignments

• Enum for the culled packed geometry display mode.

• Viewport display option for particle display visualization.

• The quality of shadows produced in the viewport

• Replacement geometry for instances culled in the viewport.

• Stereoscopic viewport display modes

• Enum for the viewport texture bit depth limit

• Transparency rendering quality for the viewport

• Enumeration of the different categories of viewport visualizers.

• Enumeration of the different scopes of viewport visualizers.

• Module containing viewport visualizer functionality.

• Display options for viewport volume sampling quality

• Display options for viewport volume rendering quality

viewer ¶

• Viewport Prompt Message Type

• Scene Graph Selection Mask

• Filter for primitive snapping in the LOPs viewer

webServer ¶

• Functions and classes for running a web server inside a graphical or non-graphical Houdini session.

• Enumeration of Web Server verbosity level.