Merge channel node

Takes multiple inputs and merges them into the output.

All

Parameters

Example files

See also: Switch

This CHOP takes multiple inputs and merges them into the output. All the channels of the input appear in the output. The channel order is the channels of the first input followed by the channels of the second input, and so on.

Channel names may conflict, but a channel is renamed according to the Duplicate Names menu.

Parameters

Merge

Align

The alignment option to use.

Extend to Min/Max	Find the earliest start and latest end, and extend all inputs to that range using the extend conditions.
Stretch to Min/Max	Find the earliest start and latest end, and stretch every channel’s start and end to that range.
Shift to Minimum	Find the earliest start and shift all channels so they all start at that index. All channels are extended to the length of the longest one.
Shift to Maximum	Find the latest end and shift all channels so they all end at that index. Extend all channels to the length of the longest one.
Shift to First Interval	Shift all channels to the start of the first channel and sample all inputs using the first input’s range.
Trim to First Interval	Trim all channels to first channel’s range.
Stretch to First Interval	Stretch all channels to the first channel’s range.
Trim to Smallest Interval	Trim all channels to the smallest start/end interval. The start and end values may not come from the same channel.
Stretch to Smallest Interval	Stretch all channels to the smallest start/end interval. The start and end values may not come from the same channel.

Duplicate Names

What to do when channels of input CHOPs have same name.

Unique Names	Include all input channels, make conflict names unique.
Keep First	Include only channel of the first CHOP name appears in.
Keep Last	Include only channel of the last CHOP name appears in.

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

MergeBasic

$HFS/houdini/help/examples/nodes/chop/merge/MergeBasic.cmd

Load | Launch

This example file demonstrates the Merge CHOP.

Two CHOPs are read in with the Merge CHOP and then combined in a variety of different ways. The curves can either be stretched or cut off depending on the chosen settings.

Usages in other examples

Example name	Example for
SimpleIKSolver	IKSolver channel node	Load \| Launch
Constant02	Constant channel node	Load \| Launch
Lookup	Lookup channel node	Load \| Launch