Houdini 20.5 Nodes Channel nodes

Stash channel node

Caches the input motion in the node on command, and then uses it as the node’s output.

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Since 17.0

Overview

When you click Stash input, the node will cook the input and cache the motion in a data parameter. The node does not otherwise cook its input and will simply output the cached motion. (You can even disconnect the input and the node will continue to output its stored geometry.) You can click Stash input again to re-cache if the input changes.

This node is conceptually very similar to locking a Null CHOP, however it has several additional features:

  • The interaction is slightly more convenient.

  • You can modify or overwrite the cached motion with hou.Motion objects through scripting.

  • You can link the motion parameter to a parameter on a parent asset. This allows assets to inject motion into a network without making the contents editable.

  • The node never passes the input directly to the output, so Houdini doesn’t see downstream nodes as depending on upstream nodes. This is useful if a live connection would create a dependency cycle.

Notes

  • The stashed motion is saved as part of the node instance when you save the scene, so stashing large motion can bloat the size of the .hip file.

  • You can discard the cached motion by disconnecting the node’s input and clicking Stash input.

Parameters

Motion Stash

The data parameter (internal name stash) where the node stores the motion.

Stash Input

Click to cook the input and cache its motion in the data parameter above. Once motion is cached, the node will output the cached motion.

Channel nodes

  • Acoustic

    Design audio filters and sound materials for the spatial audio system.

  • Agent

    Imports an animation clip from an agent primitive.

  • Area

    Calculates the area under a channel’s graph, which is the same as calculating the integral of a channel, or integrating the channel.

  • Attribute

    Adds, removes or updates attributes of the input chop.

  • Audio In

    Receives audio input from the analog audio ports or the digital port.

  • Band EQ

    A 14-band equalizer which filters audio input channels in the same way that a conventional band equalizer uses a bank of sliders to filter fixed-frequency bands of sound.

  • Beat

    Manually tap the beat of a piece of music, and automatically generate a repeating ramp or pulse that continues to keep time with the music after the taps stop.

  • Blend

    Combines two or more chops in input 2, 3 and so on, by using a set of blending channels in input 1.

  • BlendPose

    Performs multi-dimensional, example-based interpolation of channels.

  • Channel

    Creates channels from the value of its parameters.

  • Channel VOP

    Contains a VOP network that can manipulate channel data.

  • Channel Wrangle

    Runs a VEX snippet to modify channel data.

  • Composite

    Layers (blends) the channels of one CHOP on the channels of another CHOP.

  • Constant

    Create up to forty new channels.

  • Constraint Blend

    Combines two or more CHOP inputs using a list of weights specified as parameters.

  • Constraint Get Local Space

    Returns an Object Local Transform.

  • Constraint Get Parent Space

    Returns an Object Parent Transform.

  • Constraint Get World Space

    Returns an Object World Transform.

  • Constraint Lookat

    Constrains rotation so it always points toward a target position.

  • Constraint Object

    Compares two objects and returns information on their relative positions and orientations.

  • Constraint Object Offset

    Compares two objects and returns information on their relative positions and orientations.

  • Constraint Object Pretransform

    Returns an Object Pretransform.

  • Constraint Offset

    Applies an transformation offset after evaluating a constraint.

  • Constraint Parent

    Reparent an object.

  • Constraint Path

    Position an object on a path and orient it to the path’s direction.

  • Constraint Points

    Position and Orient an object using point positions from a geometry.

  • Constraint Sequence

    Combines multiple chops by blending the inputs in sequence.

  • Constraint Simple Blend

    Combines two chops by using a single weight specified as a parameter.

  • Constraint Surface

    Position and Orient an object using the surface of a geometry.

  • Constraint Transform

    Takes translate, rotate, and/or scale channels and transforms them.

  • Copy

    Produces multiple copies of the second input along the timeline of the first input.

  • Count

    Counts the number of times a channel crosses a trigger or release threshold.

  • Cycle

    Creates cycles.

  • Delay

    Delays the input, and can be run in normal or time-sliced mode.

  • Delete

    Removes channels coming from its input.

  • Device Transform

    Turns data from device inputs into transform data

  • Dynamic Warp

    Time-warps the node’s first input (source clip) using its second input (reference clip) as a reference.

  • Dynamics

    Extracts any information from a DOP simulation that is accessible through the dopfield expression function.

  • Envelope

    Outputs the maximum amplitude in the vicinity of each sample of the input.

  • Euler Rotation Filter

    Fixes discontinuity of rotation data after cracking matrices

  • Export

    A convenient tool for exporting channels.

  • Export Constraints

    Export Constraints Network on any object

  • Export Transforms

    Export Transforms to Constraints Network of many objects

  • Expression

    Modify input channels by using expressions.

  • Extend

    Only sets the extend conditions of a chop, which determines what values you get when sampling the CHOP before or after its interval.

  • Extract Bone Transforms

    (Deprecated) Extracts the current world or local space bone transforms from a geometry object.

  • Extract Locomotion

    Extracts locomotion from an animation clip.

  • Extract Pose-Drivers

    (Deprecated) Creates channels from the specified derived transforms, node parameters and CHOP channels for pose-space deformation.

  • FBX

    Reads in channel data from an FBX file.

  • Fan

    Used for controlling other CHOPs.

  • Feedback

    Get the state of a chop as it was one frame or time slice ago.

  • Fetch Channels

    Imports channels from other CHOPs.

  • Fetch Parameters

    Imports channels from other OPs.

  • File

    Reads in channel and audio files for use by chops.

  • Filter

    Smooths or sharpens the input channels.

  • Foot Plant

    Computes when position channels are stationary.

  • Foreach

    Divides the input channels into groups, cooking the contained network for each group.

  • Function

    Provides more complicated math functions than found in the Math CHOP such as trigonometic functions, logarithmic functions, and exponential functions.

  • Gamepad

    Turns input values for the gamepad or joystick device into channel outputs.

  • Geometry

    Uses a geometry object to choose a sop from which the channels will be created.

  • Gesture

  • Handle

    The engine which drives Inverse Kinematic solutions using the Handle object.

  • Hold

    Sample and hold the value of the first input.

  • IKSolver

    Solves inverse kinematics rotations for bone chains.

  • Identity

    Returns an identity transform.

  • Image

    Converts rows and/or columns of pixels in an image to CHOP channels.

  • Interpolate

    Treats its multiple-inputs as keyframes and interpolates between them.

  • InverseKin

    Generates channels for bone objects based on a bone chain and an end affector.

  • Invert

    Returns an invert transform of the input.

  • Jiggle

    Creates a jiggling effect in the translate channels passed in.

  • Keyboard

    Turns key presses into channel output.

  • Lag

    Adds lag and overshoot to channels.

  • Layer

    Mix weighted layers of keyframed animation from multiple Channel CHOPs to a base Channel CHOP.

  • Limit

    Provides a variety of functions to limit and quantize the input channels.

  • Logic

    Converts channels of all its input chops into binary channels and combines them using a variety of logic operations.

  • Lookup

    Uses a channel in the first input to index into a lookup table in the second input, and output values from the lookup table.

  • MIDI In

    The MIDI In CHOP reads Note events, Controller events, Program Change events, and Timing events from both midi devices and files.

  • MIDI Out

    The MIDI Out CHOP sends MIDI events to any available MIDI devices.

  • Math

    Perform a variety of arithmetic operations on and between channels.

  • Merge

    Takes multiple inputs and merges them into the output.

  • Mouse

    Outputs X and Y screen values for the mouse device.

  • Mouse 3D

    Turns input values for the Connexion space mouse into channel outputs.

  • Multiply

    Post multiplies all the input transformations.

  • Network

    Similar to the Pipe In/Out CHOPs in Network mode.

  • Noise

    Makes an irregular wave that never repeats, with values approximately in the range -1 to +1.

  • Null

    Used as a place-holder and does not have a function of its own.

  • Object

    Compares two objects and returns information on their relative positions and orientations.

  • ObjectChain

    Creates channels representing the transforms for a chain of objects.

  • Oscillator

    Generates sounds in two ways.

  • Output

    Marks the output of a sub-network.

  • Parametric EQ

    Filters an audio clip, and then applies other audio effects.

  • Particle

    Produces translate and rotate channels to move Objects according to the positions of particles in a POP Network.

  • Pass Filter

    Filters audio input using one of four different filter types.

  • Phoneme

    Translates english text into a series of phonetic values.

  • Pipe In

    Pipes data from custom devices into a CHOP, without needing the Houdini Developers' Kit or knowledge of Houdini internals.

  • Pipe Out

    Transmit data out of Houdini to other processes.

  • Pitch

    Attempts to extract the fundamental pitch of a musical tone from the input audio.

  • Pose

    Store a transform pose for later use by evaluating the input.

  • Pose Difference

    Computes the difference between two poses.

  • Pretransform

    Takes translate, rotate, and/or scale channels and transforms them using the pretransform of the given object.

  • Pulse

    Generates pulses at regular intervals of one channel.

  • ROP Channel Output

  • Record

  • Rename

    Renames channels.

  • Reorder

    Reorders the first input CHOP’s channels by numeric or alphabetic patterns.

  • Resample

    Resamples an input’s channels to a new rate and/or start/end interval.

  • Sequence

    Takes all its inputs and appends one chop after another.

  • Shift

    This time-shifts a CHOP, changing the start and end of the CHOP’s interval.

  • Shuffle

    Reorganizes a list of channels.

  • Slope

    Calculates the slope (or derivative) of the input channels.

  • Spatial Audio

    The rendering engine for producing 3D audio.

  • Spectrum

    Calculates the frequency spectrum of the input channels, or a portion of the channels.

  • Spline

    Edit the channel data by using direct manipulation of cubic or Bezier handles in the graph of the CHOP.

  • Spring

    Creates vibrations influenced by the input channels, as if a mass was attached to a spring.

  • Stash

    Caches the input motion in the node on command, and then uses it as the node’s output.

  • Stash Pose

    (Deprecated) Stashes the bone transforms and pose-drivers for use by the Pose-Space Deform SOP and Pose-Space Edit SOP nodes.

  • Stretch

    Preserves the shape of channels and the sampling rate, but resamples the channels into a new interval.

  • Subnetwork

    Allows for the simplification of complex networks by collapsing several CHOPs into one.

  • Switch

    Control the flow of channels through a CHOPnet.

  • Time Range

    This converts an input node in Current Frame mode to a Time Range mode by re-cooking it multiple times.

  • Time Shift

    This time-shifts a CHOP, re-cooking the node using different time.

  • Transform

    Takes translate, rotate, and/or scale channels and transforms them.

  • Transform VOP CVEX

    Contains a VOP network that can manipulate transform data.

  • TransformChain

    Combines a chain of translate, rotate, and/or scale channels.

  • Trigger

    Adds an audio-style attack/decay/sustain/release (ADSR) envelope to all trigger points in the input channels.

  • Trim

    Shortens or lengthens the input’s channels.

  • VEX Waveform

    This function is a sub-set of the waveform CHOP.

  • Vector

    Performs vector operations on a set or sets of channels.

  • Voice Split

    The Voice Split CHOP takes an audio track and separates words out into different channels.

  • Voice Sync

    The Voice Sync CHOP detects phonemes in an audio channel given some audio phoneme samples and pro…

  • Warp

    Time-warps the channels of the first input (the Pre-Warp Channels) using one warping channel in the second input.

  • Wave

    Creates a waveform that is repeated.