Wave CHOP
Summary[edit]
The Wave CHOP makes repeating waves with a variety of shapes. It is by default 10-seconds of 1-second sine waves, a total of 600 frames. You can adjust period (frequency), phase, shape, amplitude and offset.
The Wave CHOP gives a set of waves in channels of a specifiable time-range. It is superceded by the LFO CHOP which gives an endless stream of waves that is Time Sliced, and the Pattern CHOP that has more control over shaping waveform samples (and is time-independent). The Audio Oscillator CHOP also creates waveforms that are continually repeated, but its defaults are for higher-frequency waves at higher (audio) sample rates.
Because the Extend Conditions of the Wave CHOP are set to Repeat, the wave will repeat outside the 10-second range.
Applied to the actual waveform can be an offset, decay and ramp.
Multiple channels can be generated in the Channel Name parameter using Pattern Expansion. A few examples of name pattern name expansion:
tx ty tzt[xyz]- expands totx ty tzchan[1-4]- expands tochan1 chan2 chan3 chan4c[xyz][1-5:2]- expands tocx1 cx3 cx5 cy1 cy3 cy5 cz1 cz3 cz5
See also: LFO CHOP, Pattern CHOP, Audio Oscillator CHOP.
Parameters - Wave Page
Type wavetype - ⊞ - There is a choice of waveforms shapes:
- Constant
const-
(1) A constant-valued "wave".
- Sine
sin-
(-1 to 1) A Sine wave.
- Gaussian
normal-
(0 to 1) A Gaussian (also known as a bell or normal) curve.
- Triangle
tri-
(-1 to 1) A ramp-up to 1 and ramp-down to 0 that can be shaped with the Bias parameter.
- Ramp
ramp-
(0 to 1) A ramp from 0 to 1.
- Square
square-
(-1 to 1) Step-up/step-down, with Bias control to make it rectangular.
- Pulse
pulse-
(0 to 1) Produces a 1 for one sample, 0 otherwise.
- Expression
expr- A user defined expression.
The Sine formula is:
out = Amplitude * (Offset + sin ((Period*index - Phase)*360))
Period period - The period is the number of seconds, frames or samples that the waveform repeats in. It is expressed in the chop's Units (default is Seconds), found on the Common page.
Period Unit periodunit -
Phase phase - The phase shifts the waveform in time, and is expressed as a fraction of a period, usually between 0 and 1.
Bias bias - You can vary the shape of some of the waveform types by changing the bias within the range -1 to +1.
Offset offset - The waveform's value can be offset. A sine wave can remain always positive by setting Offset to 1.
Amplitude amp - The wave's value can be scaled.
Decay Rate decay - The wave's amplitude can be reduced over time with an "exponential decay". For example, if the Decay is 0.2 and the Units are seconds, then the amplitude will decay to 0.8 after 1 second, and 0.8 of 0.8 (or 0.64) after 2 seconds.
Decay Rate Unit decayunit -
Ramp Slope ramp - Then a ramp is added to the result with a slope of Ramp. The channel increases by the Ramp Slope value every Unit of time. For example, if Ramp is 1.2, the channel increases by 1.2 every second, in addition to the shape of the wave.
Ramp Slope Unit rampunit -
Expression exprs - If the waveform type is Expression, the Expression parameter is used to input a math expression. Some local variables are available: $I (Index), $L (the loop variable over the period 0 to 1), $C (the cycle variable, the integer number of cycles the waveform has passed at the current index).
Parameters - Channel Page
Channel Names channelname - You can creates many channels with simple patterns like "chan[1-20]", which generates 20 channels from chan1 to chan20. See the section, Common CHOP Parameters for a description of this and all Options. See Scope and Channel Name Matching Options.
Start start - Start of the interval, expressed in Units (seconds, frames or samples).
Start Unit startunit -
End end - End of the interval, expressed in Units (seconds, frames or samples).
End Unit endunit -
Sample Rate rate - The sample rate of the channels, in samples per second.
Extend Left left - ⊞ - The left extend conditions (before/after range).
- Hold
hold-
- Slope
slope-
- Cycle
cycle-
- Mirror
mirror-
- Default Value
default-
Extend Right right - ⊞ - The right extend conditions (before/after range).
- Hold
hold-
- Slope
slope-
- Cycle
cycle-
- Mirror
mirror-
- Default Value
default-
Default Value defval - The default value for extend conditions.
Parameters - Common Page
Time Slice timeslice - Turning this on forces the channels to be "Time Sliced". A Time Slice is the time between the last cook frame and the current cook frame.
Scope scope - To determine which channels get affected, some CHOPs use a Scope string on the Common page.
Sample Rate Match srselect - ⊞ - Handle cases where multiple input CHOPs' sample rates are different. When Resampling occurs, the curves are interpolated according to the Interpolation Method Option, or "Linear" if the Interpolate Options are not available.
- Resample At First Input's Rate
first- Use rate of first input to resample others.
- Resample At Maximum Rate
max- Resample to the highest sample rate.
- Resample At Minimum Rate
min- Resample to the lowest sample rate.
- Error If Rates Differ
err- Doesn't accept conflicting sample rates.
Export Method exportmethod - ⊞ - This will determine how to connect the CHOP channel to the parameter. Refer to the Export article for more information.
- DAT Table by Index
datindex- Uses the docked DAT table and references the channel via the index of the channel in the CHOP.
- DAT Table by Name
datname- Uses the docked DAT table and references the channel via the name of the channel in the CHOP.
- Channel Name is Path:Parameter
autoname- The channel is the full destination of where to export to, such hasgeo1/transform1:tx.
Export Root autoexportroot - This path points to the root node where all of the paths that exporting by Channel Name is Path:Parameter are relative to.
Export Table exporttable - The DAT used to hold the export information when using the DAT Table Export Methods (See above).
TouchDesigner Build:
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An Operator Family which operate on Channels (a series of numbers) which are used for animation, audio, mathematics, simulation, logic, UI construction, and many other applications.
To pulse a parameter is to send it a signal from a CHOP or python or a mouse click that causes a new action to occur immediately. A pulse via python is via the .pulse() function on a pulse-type parameter, such as Reset in a Speed CHOP. A pulse from a CHOP is typically a 0 to 1 to 0 signal in a channel.
A text string that contains data (string, float, list, boolean, etc.) and operators (+ * < etc) that are evaluated by the node's language (python or Tscript) and returns a string, float list or boolean, etc. Expressions are used in parameters, DATs and in scripts.
samples-per-second of a CHOP. Each CHOP in your network has a sample rate, whether it is used or not. The overall timeline has a "frame rate", which is the number of animation frames per second, generally your monitor display frequency.
A Time Slice is the time from the last cook frame to the current cook frame. In CHOPs it is the set of short channels that only contain the CHOP channels' samples between the last and the current cook frame.
A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator.
Exporting is the connection of CHOP channels to parameters of operators. The output of each exporting CHOP is one or more channels, active only while the CHOP Viewer is on. The current value of a channel can be exported to a parameter of any operator, overriding that parameter's value. See Parameter.
An Operator Family that manipulates text strings: multi-line text or tables. Multi-line text is often a command Script, but can be any multi-line text. Tables are rows and columns of cells, each containing a text string.
Parameters in TouchDesigner are an operator's settings (numbers, menus, flags, strings, paths) which the user can alter. Parameters for any operator can be opened by right-clicking on the operator and selecting "Parameters..." A currently selected operator's parameters can be viewed in a Network Editor by pressing the keyboard shortcut 'p'.
TouchDesigner is a hierarchy of components. "root" is the top-most network in the hierarchy. The Path is simply /. A typical path is /project1/moviein1.
