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This CHOP generates pulses at regular intervals of one channel. The amplitude of each pulse can be edited with the chop sliders or with handles on the graph.
The Pulse chop can be used as triggers to the Copy CHOP, and can represent regularly-timed events.
By default, the pulses are a single sample long, but you can increase the Pulse Width so that the pulses are steps to the next pulse. You can also interpolate the values between pulses, as Linear, Ease In Ease Out, Cubic or other curves.
The pulses can be restricted to a minimum / maximum limit. If the Limit Type is Clamp, the graph has additional convenient handles at the minimum and maximum for each pulse.
The Pulse CHOP generates a single channel of up to 32 pulses, and you can merge several Pulse chops into a multi-channel CHOP.
The Pulse CHOP uses its optional second input as a start/end reference, so a number of Pulse chops can be stretched to the same interval.
In order to set the value at the last sample, the option, Last Pulse at Last Sample is provided. Otherwise, the last pulse is prior to the last sample.
Number of Pulses
Total number of pulses in the channel.
How to interpolate between pulse values.
The width of each pulse, in Units.
Pulse values can be clamped into a range given by the minimum and maximum parameters listed below.
The minimum pulse value.
The maximum pulse value.
Last Pulse at Last Sample
If on, the last sample will contain the last pulse, with pulses at the start of intervals of length "Channel Length / (#Pulses -1)". Otherwise the pulses will be at the start of intervals of length "Channel Length / #Pulses".
0, 8, 16, 24
The value of each pulse.
The start time of the desired interval.
The end time of the desired interval.
The left extend conditions.
The right extend conditions.
The default value for extend conditions.
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 current channel (0 to NC-1).
The total number of channels.
The following examples include this node.
This file demonstrates how the Copy CHOP can be used to copy channels and apply them to geometry.