Extend channel node

Only sets the “extend conditions” of a chop, which determines what values you get when sampling the CHOP before or after its interval.

All

Parameters

Example files

See also: Trim

This CHOP only sets the “extend conditions” of a chop, which determines what values you get when sampling the CHOP before or after its interval.

The Extend CHOP has separate menus to control both the pre-interval and the post-interval. For example, before the interval, you may want to hold a constant value, and after the interval you may want to cycle or repeat the curves in the interval.

To shorten or lengthen the interval (the start or end of the chop), use the Trim chop.

You can see the state of Extend Conditions in the pop-up info of any CHOP ( on the chop tile).

Parameters

Extend

Left Behavior

The extend condition before the CHOP interval.

Hold	Hold first or last value.
Slope	Continue slope at begin or end of channel.
Cycle	Cycle channel repeatedly.
Mirror	Cycle channel repeatedly, mirror every other cycle.
Default Value	Use constant value in Default Value parameter.

Right Behavior

The extend condition after the CHOP interval.

Hold	Hold first or last value.
Slope	Continue slope at begin or end of channel.
Cycle	Cycle channel repeatedly.
Mirror	Cycle channel repeatedly, mirror every other cycle.
Default Value	Use constant value in Default Value parameter.

Default Value

Value used for the Default Value extend condition.

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.

Example files

Extend

$HFS/houdini/help/examples/nodes/chop/extend/Extend.cmd

Load | Launch

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

Usages in other examples

Example name	Example for