Cycle channel node

Creates cycles.

All Parameters Example files

See also: Shift

This CHOP creates cycles. It can repeat the channels any number of times before and after the original. It can also make a single cycle have a smooth transition from its end to its beginning, so it loops smoothly.

Since channels may not naturally loop well, the Cycle CHOP provides three different methods of blending between the cycles.

Parameters

Cycle

Cycles Before

The number of cycles to loop before the input CHOP. This parameter can be fractional.

Cycles After

The number of cycles to loop after the input CHOP. This parameter can be fractional.

Mirror Cycles

If on, consecutive cycles are mirror images (reversed) of one another. The first cycle is never mirrored.

Blend Start to End

If on, the end of the CHOP is blended into the start of the CHOP to produce a smooth loop. If Cycles Before and Cycles After are 0, Region is non-zero, and Extend Conditions are “Cycle”, it loops smoothly forever.

Blend

Method

How to blend between cycles.

Preserve Length

Keeps the total length of each cycle the same as the length of the input CHOP.

Overlap Sequences

Overlaps each cycle with with the previous cycle.

Insert Blend Region

Inserts a region between the cycles where blending is done.

Shape

The shape of the blending function.

Linear

Linear shape.

Ease in

Smooth on entry.

Ease out

Smooth on exit.

Ease in Ease out

Smooth on entry and exit.

Cubic

For Insert Blend Region, cubic interpolation fills the region between the cycles.

Add

The overlapped region has the overlapping samples simply added.

Region

The size of the blend region, in either seconds, samples or frames (set in “Units” in the Common page).

Bias

The bias of the blend. -1 biases the blend toward the beginning, 0 is no bias and +1 biases towards the end.

Step

If set to 1, the next cycle will be shifted in value up or down so that it begins where the last cycle ended. Suitable for root object of walk cycles.

Step Scope

The names of those channels that will be affected by the Step parameter.

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

Cycle

$HFS/houdini/help/examples/nodes/chop/cycle/Cycle.cmd

Load | Launch

This example demonstrates how the Cycle CHOP seamlessly loops input channels. The Cycle is customized by setting the amount of repetitions before and after the input channel, and by setting up the orientation.

Usages in other examples

Example name Example for