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This CHOP allows you to create channels that replicate the values of its parameters through time. Each channel can be named and assigned a different value. The parameter is then evaluated for each frame in the scene file.
This operator can be created from existing channel groups by clicking RMB the name in the Channel Groups list and choosing Motion Effects > Create Clip.
Show All Parameters
Disabling this toggle simplifies the interface to make the parameters and the values easier to work with. Disable this after the channels have been setup to remove controls that are no longer needed.
Copy to Exports
Copies the animation from the value parameters to the channel export parameters.
Copy from Exports
Copies the animation to the value parameters from the channel export parameters.
Channel Names from Exports
Sets the names of the value parameters to the names of the channel export parameters.
Sort all the channel by their name.
Reset All Channels
Removes the animation on all the channel values and reset everything to zero.
One Key Per Sample
Instead of evaluating the value parameter every frame, create the channel such that each sample corresponds to a key on the value parameter. This is only meaningful if the value parameter is animated.
Add Node Name Dependencies
If set, this will cause the names specified in the Name parameter to be treated as real parameter paths and have name dependencies built for them. Then if the referenced nodes are renamed, the paths in the Name parameter will update accordingly.
Number of Channels
Number of channels to create.
Name of the channel to create. If the size is greater than 1, then the letter x,y,z, or w is appended to the channel name depending on if it is the first, second, third, or fourth component of the value parameter respectively.
Type of channel to create.
Regular float parameter
A quaternion attribute is added to the three generated channels.
If the type is Euler Rotation, this parameter specifies the order of rotation.
Number of components. If the type is Euler Rotation, this parameter has no effect since 3 components must be generated.
The values of the channels.
Specifies the range of data to generate.
Use Full Animation Range
All of the animated range.
Use Current Frame
Only the sample at the current frame.
The range is specified from the Start and End parameters.
Use Value Animation
The range is taken from range of keys available in the evaluated Value parameters.
Ignore Sampling Rate
Ignore the Sampling Rate the Channel Range is set to Use Current Frame. This ensures the sample start time is exactly and the current cook time instead of being restricted to a sample matching the sampling rate.
The start time of the channel range.
The end time of the channel range.
The sample rate of the CHOP.
The left extend condition (before the CHOP’s start).
The right extend condition (after the CHOP’s end).
The value to use for the “Default Value” extend condition type.
Some of these parameters may not be available on all CHOP nodes.
To determine which channels get affected, some CHOPs have a scope string. Patterns can be used in the scope, for example
* (match all), and
? (match single character).
The following are examples of possible channel name matching options:
Matches a single channel name.
chan3 tx ty tz
Matches four channel names, separated by spaces.
Matches each channel that starts with
Matches each channel that has
foot in it.
? matches a single character.
t? matches two-character channels starting with t.
Matches number ranges giving
[xyz]matches three characters, giving channels
Sample Rate Match
The Sample Rate Match Options handle cases where multiple input CHOPs’ sample rates are different.
Resample At First Input’s Rate
Use rate of first input to resample others.
Resample At Maximum Rate
Resample to highest sample rate.
Resample At Minimum Rate
Resample to the lowest sample rate.
Error if Rates Differ
Does not accept conflicting sample rates.
The units for which time parameters are specified.
For example, you can specify the amount of time a lag should last for in seconds (default), frames (at the Houdini FPS), or samples (in the CHOP’s sample rate).
When you change the Units parameter, it does not convert the existing parameters to the new units.
Time Slicing is a feature which boosts cooking performance and reduces memory usage. Traditionally, CHOPs calculate the channel over its entire frame range. If the channel does need to be evaluated every frame, then cooking the entire range of the channel is unnecessary. It is more efficient to calculate only the fraction of the channel that is needed. This fraction is known as a Time Slice.
Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.
The Export prefix is prepended to CHOP channel names to determine where to export to.
For example, if the CHOP channel was named
geo1:tx, and the prefix was
/obj, the channel would be exported to
You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as
Every CHOP has this option. Each CHOP gets a default color assigned for display in the Graph port, but you can override the color in the Common page under Graph Color. There are 36 RGB color combinations in the Palette.
Graph Color Step
When the graph displays the animation curves and a CHOP has two or more channels, this defines the difference in color from one channel to the next, giving a rainbow spectrum of colors.
Current channel index.
Total number of channels.
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.