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The Delete CHOP removes channels coming from its input. The channels are selected by a variety of methods, which may be layered. The first method uses a text string to select channels by name or index. The second method uses a value range to select channels with samples within or outside the range. The third method selects constant-valued channels.
An option selects whether to delete or output the selected channels.
Determines whether the selected channels should be deleted or retained.
The selected channels are deleted. The rest are output.
The selected channels are output. The rest are deleted.
Chooses channel selection by name or by index.
The names of the channels to delete or extract. See the possible scope patterns below.
The indices of the channels to delete or extract. See possible number patterns below.
Chooses the type of value range selection:
Do not perform range selection.
Channel Completely Within Range
All the channel’s samples must be within the specified range for it to be selected.
Channel Partially Within Range
At least one of the channel’s samples must be in the range for it to be selected.
Channel Completely Outside Range
None of the channel’s samples can be in the range for it to be selected.
The lower and upper values of the range used for Range Selection.
Select Constant Valued Channels
Select channels which have the same value for all samples.
Some of these parameters may not be available on all CHOP nodes.
To determine the channels that are affected, some CHOPs have a scope string. Patterns can be used in 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 the rate of the first input to resample the others.
Resample At Maximum Rate
Resample to the 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 of the time parameters.
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, the existing parameters are not converted to the new units.
Time slicing is a feature that boosts cooking performance and reduces memory usage. Traditionally, CHOPs calculate the channel over its entire frame range. If the channel needs 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 the 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 to it for display in the graph, but you can override the color with the 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.
This example demonstrates how the Delete CHOP can remove or extract input channels by index number and pattern.