Lookup CHOP

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The Lookup CHOP outputs values from a lookup table. The first input (the Index Channel) is an index into the second input (the Lookup Table). Lookup outputs interpolated values from the lookup table.

Both the Index and Lookup Tables can contain any number of channels.

An Index sample with value 0 maps to the beginning (first sample) of the lookup table, and an index sample with value of 1 maps to the end (last sample) of the lookup table.

The output CHOP is the same length as the Index input. It is the same number of channels as the Lookup Table input, and has the same channel names as the Lookup Table input. The output is filled with the data extracted from the lookup tables. Indexes that fall between two lookup table samples are interpolated. The lookup table can be sampled outside its range.

NOTE: The Extend Conditions of the lookup table are used in this case where the index is less than 0 or greater than 1.

The sample rate of the output is the sample rate of the Index input.

The Lookup CHOP can be used to fetch values from a color lookup table, where a single index produces red, green and blue channels. It can also be used for rolloff or decay tables, where it specifies how much a parameter drops with distance.


Parameters - Lookup Page

Index Range index - - The Index Range maps the index channel's values to the lookup table's start and end and defaults to 0 and 1. The first parameter represents the start of the lookup table. When the index channel has this value, it will index the start of the lookup table. The second parameter represents the end of the lookup table and behaves in the same way.

  • index1 -
  • index2 -

Cyclic Range cyclic - - Adapts the range of the Lookup Table (2nd input) for cyclic or non-cyclic input indices. When using a cyclic input index (1st input), the lookup value for index 0.0 and 1.0 result in the same value. To avoid this, set Cyclic Range to Yes and the lookup will cycle smoothly.

  • Automatic auto - Checks the right extend condition of each channel (Assumes type cycle and mirror are cyclic lookups).
  • Yes yes - For looking up a cyclic output (oscillator, beat driven output etc).
  • No no - For looking up a single wave (slider mapping, etc).

Per Index Channel chanmatch - - Determines how index channels are mapped to lookup Channel tables.

  • One Lookup Table Channel onetoone - The first index channel is matched to the full lookup table.
  • All Lookup Table Channels onetomany - Each index channel is matched with every lookup table.

Match by match - - Determines how index channels are matched with a lookup channel in 'One Lookup Table Channel' mode.

  • Channel Number index - An index channel is matched to a lookup table by its index within the clip. Lookup tables are cycled if there are few of them than index channels.
  • Channel Name name - An index channel is matched to a lookup table by name. Unmatched index channels are left "as is".

Interpolate interp - When on, the input can be interpolated between samples. When off, the nearest sample is used.

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 has geo1/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).

Operator Inputs

  • Input 0 -
  • Input 1 -

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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.

A CHOP outputs one or more channels, where a channel is simply a sequence of numbers, representing motion, audio, etc. Channels are passed between CHOPs in TouchDesigner networks. See also Export.

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.

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.

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.

The location of an operator within the TouchDesigner environment, for example, /geo1/torus1, a node called torus1 in a component called geo1. The path / is called Root. To refer instead to a filesystem folder, directory, disk file or http: address, see Folder.

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.