Pulse channel node

Generates pulses at regular intervals of one channel.

All

Parameters

Local variables

See also: Copy

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.

Parameters

Pulse

Number of Pulses	Total number of pulses in the channel.
Interpolate	How to interpolate between pulse values.
Pulse Width	The width of each pulse, in Units.
Limit Type	Pulse values can be clamped into a range given by the minimum and maximum parameters listed below.
Minimum	The minimum pulse value.
Maximum	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

Pulse x

The value of each pulse.

Channel

Start	The start time of the desired interval.
End	The end time of the desired interval.
Extend Left	The left extend conditions.
Extend Right	The right extend conditions.
Default Value	The default value for extend conditions.

Common

Some of these parameters may not be avaiable on all CHOP nodes.

Scope

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:

`chan2`	Matches a single channel name.
`chan3 tx ty tz`	Matches four channel names, separated by spaces.
`chan*`	Matches each channel that starts with `chan`.
`foot`	Matches each channel that has `foot` in it.
`t?`	The `?` matches a single character. `t?` matches two-character channels starting with t.
`r[xyz]`	Matches channels `rx`, `ry` and `rz`.
`blend[3-7:2]`	Matches number ranges giving `blend3`, `blend5`, and `blend7`.
`blend[2-3,5,13]`	Matches channels `blend2`, `blend3`, `blend5`, `blend13`.
`t[xyz]`	`[xyz]`matches three characters, giving channels `tx`, `ty` and `tz`.

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.

Units

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).

Note

When you change the Units parameter, it does not convert the existing parameters to the new units.

Time Slice

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.

Unload

Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.

Export Prefix

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 /obj/geo1/tx.

Note

You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as obj:geo1:tx.

Graph Color

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.

Local variables

C	The current channel (0 to NC-1).
NC	The total number of channels.

Usages in other examples

Example name	Example for