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This CHOP produces a variety of waveforms. On top of the actual waveform, an offset, decay and ramp can be applied.
Multiple channels can be generated by using patterns in the Channel Name parameter. A few examples of name pattern generation:
tx ty tz tx ty tz t[xyz] tx ty tz chan[1-4] chan1 chan2 chan3 chan4 c[xyz][1-3:2,15] cx1 cy1 cz1 cx3 cy3 cz3 cx15 cy15 cz15
These parameters are applied in the following order: Offset, Amplitude, Decay, Ramp, and Expression.
The wave type which is one of the following:
A constant valued “wave”.
A sine wave.
A Gaussian wave (also known as bell or normal curve).
A triangular sawtooth wave.
A square wave.
A periodic one-sample pulse wave.
A user defined non-periodic expression.
The period of the wave.
The phase of the wave, from
The bias of the waveform. Only Gaussian, triangle and square waves have biases.
The value offset of the waveform.
The amplitude of the waveform.
The decay rate of the waveform, represented as the fraction
of decay after
1 Unit of time (default is one second)
A ramp is added the wave: amount per Unit of time.
Expression to use for “Expression” Type.
The names of the channels to create. Patterns like
chan[1-20] generate multiple channels.
Indicates how much of the channel to cook.
Use Full Animation Range
All of the current global animation range.
Use Current Frame
Only the sample at the current frame.
Specify the range using the Start/End parameters.
The start time of the channels.
The sample rate of the channels.
The left extend conditions.
The right extend conditions.
The default value for extend conditions.
Some of these parameters may not be available on all CHOP nodes.
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:
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 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.
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).
When you change the Units parameter, it does not convert the existing parameters to the new units.
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.
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 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.
The current index.
The current loop index, which is reset every period.
The current period count, starting at zero.
The current channel (0 to NC-1).
The total number of channels.
The period of the wave (from the Period parameter).
The phase of the wave (from the Phase parameter).
The bias of the wave (from the Bias parameter).