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This time-shifts a CHOP, changing the start and end of the CHOP’s interval. However, the contents of the channels remain the same.
Each channel can be shifted a different amount by using the
$C variable in the Scroll parameter.
An optional second input, the Start/End Reference, is used to align the first input CHOP relative to another reference CHOP. This outputs the channels of the first CHOP only, and the shifts are based on the interval of the second CHOP. It is useful for making several CHOPs match up to the same time.
The start or the end of the channels can be used as the reference position. The channels are shifted by altering the reference position.
Uses the start of the CHOP to do the aligning.
Uses the end of the CHOP to do the aligning.
Determines how the Start and End parameters are are to be interpreted.
The Start/End parameters are the actual start/end position.
It is used to shift the CHOP to start at
0 seconds, for
Relative to Start/End
The Start/End parameters are a shift relative to the input CHOP’s start/end position.
Use Current Frame
Ignore the start/end parameters and use the current frame as the new start position.
The start of the interval, absolute or relative to the input CHOP.
The end of the interval, absolute or relative to the input CHOP.
The amount to shift the channel.
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.
The start of the input clip, in samples.
The end of the input clip, in samples.
The length of the input clip, in samples.
The current channel (0 to NC-1).
With this variable, channels can be shifted relative to one another.
The total number of channels.
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.