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This function is a sub-set of the waveform CHOP.
Parameters ¶
Waveform ¶
Wave Type
The wave type which is one of the following:
Constant
A constant valued “wave”.
Sine
A sine wave.
Gaussian
A Gaussian wave (also known as bell or normal curve).
Triangle
A triangular sawtooth wave.
Square
A square wave.
Pulse
A periodic one-sample pulse wave.
Expression
A user defined non-periodic expression.
Period
The period of the wave.
Phase
The phase of the wave, from 0
to 1
.
Bias
The bias of the waveform. Only Gaussian, triangle and square waves have biases.
Offset
The value offset of the waveform.
Amplitude
The amplitude of the waveform.
Decay
The decay rate of the waveform, represented as the fraction
of decay after 1
Unit of time (default is one second)
Ramp Slope
A ramp is added the wave: amount per Unit of time.
Channel ¶
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.
Channel Name
The names of the channels to create. Patterns like chan[1-20]
generate multiple channels.
Channel Range
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.
Use Start/End
Specify the range using the Start/End parameters.
Start, End
The start time of the channels.
Sample Rate
The sample rate of the channels.
Edit VEX Function
Opens the Edit Operator Type Properties dialog.
Re-load VEX Functions
Reloads VEX Functions.
Common ¶
Some of these parameters may not be available on all CHOP nodes.
Scope
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:
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.
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 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.
Units
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).
Note
When you change the Units parameter, the existing parameters are not converted to the new units.
Time Slice
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.
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 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.
Locals ¶
C
Current channel index.
I
Current index.
L
Loop variable (1-period-1).
N
Cycle variable (# of current cycle).
P
Period.
PH
Phase.
B
Bias.
NC
Total number of channels.