Example files
Channel node examples
Area with one input
Example for Area channel node
$HFS/houdini/help/examples/nodes/chop/area/Area01.cmd
This example demonstrates the Area CHOP used with one input.
A Wave CHOP is used as a first input source channel for the Area CHOP.
Area with two inputs
Example for Area channel node
$HFS/houdini/help/examples/nodes/chop/area/Area02.cmd
This is a demonstration of the Area CHOP using two inputs, where a single Wave CHOP is input into the first and second inputs of the Area CHOP.
Area with three inputs
Example for Area channel node
$HFS/houdini/help/examples/nodes/chop/area/Area03.cmd
This example contains a demonstration of the Area CHOP using all three inputs.
A single Wave CHOP is used in the first and second input as a source and as a range modifier. Then another Wave CHOP is used in the third input to modify the length of the output channel of the Area CHOP.
Blend
Example for Composite channel node
$HFS/houdini/help
You can chain the Composite CHOP together to take two or more channels and do an ordered sequence blend. The Composite CHOP takes a control curve and uses it to determine which channel to use with each Composite CHOP working on two channels at a time, creating a sequence blend. The first Composite node processes the first and second channel, the second Composite node processes the result from the first node and the third channel, and so on.
A key component of this network is the Limit CHOP. It processes the control curve so the range is valid for the pair of channels being processed by the associated Composite node.
ExtractTransforms
Example for Dynamics channel node
$HFS/houdini/help/examples/nodes/chop/dynamics/ExtractTransforms.cmd
This example demonstrates the use of the Dynamics CHOP to pull transformation information out of a DOP simulation and apply it to Objects.
Slope
Example for Slope channel node
$HFS/houdini/help/examples/nodes/chop/slope/Slope.cmd
This example demonstrates how the Slope CHOP calculates the slope (or derivative) of the input channels.
If the input CHOP represents position, the slope can be interpreted as speed.
By default, the Slope CHOP converts position to speed.
ChannelBasic
Example for Channel channel node
$HFS/houdini/help/examples/nodes/chop/channel/ChannelBasic.cmd
This is a simple example of using the Channel CHOP along with a Noise CHOP to add some variety to keyframed animation that can still be easily tweaked as keyframe animation. Notice that the object can be manipulated as usual in the viewport transparently. The values will be modified in the Channel CHOP.
ObjectBasic
Example for Object channel node
$HFS/houdini/help/examples/nodes/chop/object/ObjectBasic.cmd
This file demonstrates the Object CHOP.
The CHOP is used to bring in the channel information from a Object.
This data can then be manipulated within CHOPs and exported back into the Object, or even a different Operator.
Cycle
Example for Cycle channel node
$HFS/houdini/help/examples/nodes/chop/cycle/Cycle.cmd
This example demonstrates how the Cycle CHOP seamlessly loops input channels. The Cycle is customized by setting the amount of repetitions before and after the input channel, and by setting up the orientation.
SimpleInverseKin
Example for InverseKin channel node
$HFS/houdini/help/examples/nodes/chop/inversekin/SimpleInverseKin.otl
This example demonstrates how to manually use the InverseKin CHOP. To create bone chains with inverse kinematics, it is easiest to use the Character > Bones shelf tool.
Geometry
Example for Geometry channel node
$HFS/houdini/help/examples/nodes/chop/geometry/Geometry.cmd
This is an example of how the Geometry CHOP can fetch data from a SOP and turn that data into channels.
In this case, the Geometry CHOP pulls in the position of every point in a Superquad SOP and creates channels from that data.
Stretch
Example for Stretch channel node
$HFS/houdini/help/examples/nodes/chop/stretch/Stretch.cmd
This example demonstrates how the Stretch CHOP changes the Start and/or End interval. It then resamples the input channel, preserving the shape of the channel. The sample rate remains the same, however, the interval changes.
Rename
Example for Rename channel node
$HFS/houdini/help/examples/nodes/chop/rename/Rename.cmd
The Rename CHOP renames the channel names in a CHOP.
To visualize the channels in this demonstration, please enter the CHOP network.
For a complete list of the types of renaming possible, please see the Houdini documentation.
Lookup
Example for Lookup channel node
$HFS/houdini/help/examples/nodes/chop/lookup/LookupCHOPExample.otl
This example demonstrates how to use the Lookup CHOP to play animation based on an event, or trigger.
LimitBasic
Example for Limit channel node
$HFS/houdini/help/examples/nodes/chop/limit/LimitBasic.cmd
This example file uses the Limit CHOP both to limit the height and to “quantize” the values of a channel.
By limiting the height the Limit CHOP can keep data values from going to high or from falling to low. To “quantize” the data, the curve is broken into steps rather than a smooth curve.
Delay
Example for Delay channel node
$HFS/houdini/help/examples/nodes/chop/delay/Delay.cmd
This example demonstrates how the Delay CHOP copies and layers input channels. The Delay (timing) and Gain (Scale) values of each copy are added together to output a single channel.
Shift
Example for Shift channel node
$HFS/houdini/help/examples/nodes/chop/shift/Shift.cmd
This example demonstrates how the Shift CHOP changes the interval of a CHOP wave, keeping its content and length the same.
The Reference parameter chooses whether the Start or the End is being redefined.
The Unit Values parameter sets whether the new Start/End frame is Relative to its original position, or an Absolute frame number.
Delete02
Example for Delete channel node
$HFS/houdini/help/examples/nodes/chop/delete/Delete02.cmd
This example demonstrates how the Delete CHOP can remove or extract input channels by selecting channel names.
Delete01
Example for Delete channel node
$HFS/houdini/help/examples/nodes/chop/delete/Delete01.cmd
This example demonstrates how the Delete CHOP can remove or extract input channels by index number and pattern.
Fetch
Example for Fetch channel node
$HFS/houdini/help/examples/nodes/chop/fetch/Fetch.cmd
This is an example of the Fetch CHOP. Here the Fetch CHOP is used to import the tx, ty and tz channels from a null node.
NoiseBasic
Example for Noise channel node
$HFS/houdini/help/examples/nodes/chop/noise/NoiseBasic.cmd
This example demonstrates the Noise CHOP.
The Noise CHOP makes an irregular wave that never repeats, with values approximately in the range -1 to +1. Or using the “Time Slice” option a single noise value can be returned.
Envelope
Example for Envelope channel node
$HFS/houdini/help/examples/nodes/chop/envelope/Envelope.cmd
This example illustrates how the Envelope CHOP outputs the maximum amplitude of a channel in the vicinity of each sample of the input. Here, envelope1 and envelope2 try to follow the maximum amplitude of the noisy curve they use as input.
To visualize the channels in this demonstration, please enter the CHOP network and use the default CHOPs desktop.
Sequence
Example for Sequence channel node
$HFS/houdini/help/examples/nodes/chop/sequence/Sequence.cmd
The Sequence CHOP is used to combine multiple waves into a single wave.
This CHOP takes all its input CHOPs and appends one wave after another. It is expected the input CHOPs all have the same channels.
The end section of the first CHOP is overlapped with the start section of the second CHOP, and so on for the rest of the input CHOPs. The second input is shifted to line up with the end of the first.
To visualize the channels in this demonstration, please enter the CHOP network.
Export
Example for Export channel node
$HFS/houdini/help/examples/nodes/chop/export/Export.cmd
This is an example of the Export CHOP. The Export CHOP is a convenient tool for exporting channels. It allows you to match a CHOP’s channels with different destination channels, without needing to rename the channels. This demonstrates a method to export channels from CHOPs to the ty parameter of a model.
SimpleTransformChain
Example for TransformChain channel node
$HFS/houdini/help/examples/nodes/chop/transformchain/SimpleTransformChain.otl
This example demonstrates an example usage of the TransformChain CHOP.
Blend
Example for Blend channel node
$HFS/houdini/help/examples/nodes/chop/blend/Blend.cmd
This example demonstrates how the Blend CHOP combines several channels together using an interpolated blend weight control.
MathBasic
Example for Math channel node
$HFS/houdini/help/examples/nodes/chop/math/MathBasic.cmd
These examples demonstrate the ability of the Math CHOP to combine multiple channels together.
The first example shows two different methods of controlling the amplitude of a sine wave. The second example shows three different channels combined into one.
Extend
Example for Extend channel node
$HFS/houdini/help/examples/nodes/chop/extend/Extend.cmd
This is an example of how the Extend CHOP determines the values that are computed when sampling outside the interval.
InterpolateBasic
Example for Interpolate channel node
$HFS/houdini/help/examples/nodes/chop/interp/InterpolateBasic.cmd
This example file uses the Interpolate CHOP to read in multiple frames.
These Key Frames are interpolated to create a new Channel. Different settings in the Interpolate CHOP can creat curves, such a cubic, linear, ease, and so on.
Constant02
Example for Constant channel node
$HFS/houdini/help/examples/nodes/chop/constant/Constant02.cmd
This example demonstrates how the Constant CHOP can import channels through the first input by adopting their names and values at the current frame.
Constant01
Example for Constant channel node
$HFS/houdini/help/examples/nodes/chop/constant/Constant01.cmd
This example demonstrates the most common use of the Constant CHOP by creating channels which have one unchanging value.
SimpleIKSolver
Example for IKSolver channel node
$HFS/houdini/help/examples/nodes/chop/iksolver/SimpleIKSolver.otl
This example demonstrates how to use the IKSolver CHOP.
MergeBasic
Example for Merge channel node
$HFS/houdini/help/examples/nodes/chop/merge/MergeBasic.cmd
This example file demonstrates the Merge CHOP.
Two CHOPs are read in with the Merge CHOP and then combined in a variety of different ways. The curves can either be stretched or cut off depending on the chosen settings.
BlendPoseBasic
Example for BlendPose channel node
$HFS/houdini/help/examples/nodes/chop/blendpose/BlendPoseBasic.cmd
This is a simple example of using the BlendPose CHOP to deform some geometry using random tracker point positions.
LagBasic
Example for Lag channel node
$HFS/houdini/help/examples/nodes/chop/lag/LagBasic.cmd
This file demonstrates the Lag CHOP.
The Lag CHOP can apply a lag, or overshoot an input channel. It can also limit the velocity and acceleration of input channels. The result of modifying channels in this way is similar to the effect of the Spring CHOP, yet not as naturalistic.
CopyChannels
Example for Copy channel node
$HFS/houdini/help/examples/nodes/chop/copy/CopyChannels.cmd
This example demonstrates how the Copy CHOP additively copies the values of a channel onto the time line of another to create a new channel.
CopyStamping
Example for Copy channel node
$HFS/houdini/help/examples/nodes/chop/copy/CopyStamping.cmd
This example demonstrates how to use the CopyStamp feature of the Copy CHOP. Custom variables are created within the Copy CHOP and used to modify the geometry.
In the file, geometry is imported into CHOPS. The Alpha attribute is scoped and manipulated using the Copy Stamping technique.
The new Alpha data is then brought back to the SOP level, and applied to the geometry’s Position.