Examples

Area

Area with one input Example for Area channel node

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

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

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

Blend Example for Blend channel node

This example demonstrates how the Blend CHOP combines several channels together using an interpolated blend weight control.

BlendPose

BlendPoseBasic Example for BlendPose channel node

This is a simple example of using the BlendPose CHOP to deform some geometry using random tracker point positions.

Channel

ChannelBasic Example for Channel channel node

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.

Composite

BlendLimit Example for Composite channel node

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.

Composite Example for Composite channel node

This example demonstrates how the Composite CHOP blends channels together where the first input is the base channel and the second input is the layer channel.

Constant

Constant01 Example for Constant channel node

This example demonstrates the most common use of the Constant CHOP by creating channels which have one unchanging value.

Constant02 Example for Constant channel node

This example demonstrates how the Constant CHOP can import channels through the first input by adopting their names and values at the current frame.

Constraint Lookat

LookAtTargetAndOffset Example for Constraint Lookat channel node

The first example shows a LookAt constraint with a global Y axis up vector. The second example shows a LookAt constraint with its up vector driven by an object. The third example shows a LookAt constraint applied with Keep Position turned on. The CHOP Offset node, after the constraint, makes the object keep its orientation when the constraint is applied. You can use the LookAt Shelf Tool to recreate the examples.

Copy

CopyAnimation Example for Copy channel node

This file demonstrates how the Copy CHOP can be used to copy channels and apply them to geometry.

CopyChannels Example for Copy channel node

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

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.

Count

CountImpacts Example for Count channel node

This example demonstrates how to count impacts from a DOPs simulation using the Count CHOP. Then, using the values from the Count CHOP, we generate copies of a teapot.

Cycle

Cycle Example for Cycle channel node

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.

Delay

Delay Example for Delay channel node

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.

DelayPosition Example for Delay channel node

This example demonstrates how to take the position of an object, and delay the animation using the Delay CHOP.

Delete

Delete01 Example for Delete channel node

This example demonstrates how the Delete CHOP can remove or extract input channels by index number and pattern.

Delete02 Example for Delete channel node

This example demonstrates how the Delete CHOP can remove or extract input channels by selecting channel names.

Dynamics

DynamicLights Example for Dynamics channel node

This example demonstrates how to use the Dynamics CHOP to extract impact data from a DOPs simulation, and then modify the data to control lights in the scene.

DynamicPops Example for Dynamics channel node

This example demonstrates using the Dynamics CHOP to birth particles where an impact occurs, as well as controlling the birth rate based in impulse.

ExtractTransforms Example for Dynamics channel node

This example demonstrates the use of the Dynamics CHOP to pull transformation information out of a DOP simulation and apply it to Objects.

Envelope

Envelope Example for Envelope channel node

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.

Export

Export Example for Export channel node

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.

Expression

ExpressionLine Example for Expression channel node

This example demonstrates how to use an expression in an Expression CHOP.

Extend

Extend Example for Extend channel node

This is an example of how the Extend CHOP determines the values that are computed when sampling outside the interval.

Feedback

feedbackloop Example for Feedback channel node

In this example, we demonstrate how a feedback node can be used to get the state of a CHOP as it was one frame or time slice ago.

Fetch Parameters

Fetch Example for Fetch Parameters channel node

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.

Geometry

Geometry Example for Geometry channel node

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.

GeometryMethods Example for Geometry channel node

This example demonstrates using the different methods of the Geometry CHOP - Animated and Static.

Hold

HoldLight Example for Hold channel node

This example uses the Hold CHOP in conjunction with the Dynamics CHOP to hold a light at the position of an impact from a DOPs simulation until a new impact occurs.

IKSolver

SimpleIKSolver Example for IKSolver channel node

This example demonstrates how to use the IKSolver CHOP.

Interpolate

InterpolateBasic Example for Interpolate channel node

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.

InverseKin

SimpleInverseKin Example for InverseKin channel node

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.

Lag

LagBasic Example for Lag channel node

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.

Limit

LimitBasic Example for Limit channel node

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.

Lookup

Lookup Example for Lookup channel node

This example demonstrates how to use the Lookup CHOP to play animation based on an event, or trigger.

Math

MathBasic Example for Math channel node

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.

Merge

MergeBasic Example for Merge channel node

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.

MIDI Out

Keyboard Example for MIDI Out channel node

This example demonstrates how to write MIDI data using the MIDI Out CHOP, and read it in using the MIDI In CHOP. The MIDI that is written out is based on geometry, and the MIDI that is read in is controlling other geometry.

Noise

NoiseBasic Example for Noise channel node

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.

NoiseTransform Example for Noise channel node

This example demonstrates using the Noise CHOP to generate animation and apply it to geometry.

Object

ObjectBasic Example for Object channel node

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.

Rename

Rename Example for Rename channel node

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.

Sequence

AnimationSequence Example for Sequence channel node

This example demonstrates how to take the animation from three separate objects, and sequence their animation into one animation on a fourth object.

Sequence Example for Sequence channel node

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.

Shift

Shift Example for Shift channel node

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.

Slope

Slope Example for Slope channel node

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.

Stretch

Stretch Example for Stretch channel node

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.

TransformChain

SimpleTransformChain Example for TransformChain channel node

This example demonstrates an example usage of the TransformChain CHOP.

Vector

AverageSpeed Example for Vector channel node

This example shows you how to calculate the average speed for each particle over a given time interval using CHOP nodes such as Vector, Trim, and Math.

Warp

WarpSpeed Example for Warp channel node

This example demonstrates how to retime a particle simulation using the Warp CHOP.

Wave

WaveGrid Example for Wave channel node

This example demonstrates how to warp geometry using a Wave CHOP.

Node examples

Examples by node type