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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.
Parameters ¶
Waveform ¶
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 Rate
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.
Expression
Expression to use for “Expression” Type.
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.
Extend Left
The left extend conditions.
Extend Right
The right extend conditions.
Default Value
The default value for extend conditions.
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 ¶
I
The current index.
L
The current loop index, which is reset every period.
N
The current period count, starting at zero.
C
The current channel (0 to NC-1).
NC
The total number of channels.
P
The period of the wave (from the Period parameter).
PH
The phase of the wave (from the Phase parameter).
B
The bias of the wave (from the Bias parameter).
Examples ¶
See also |