Lookup CHOP

From TouchDesigner 099 Wiki


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. 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.

PythonIcon.png lookupCHOP_Class


Index Range /index1 /index2 - 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.

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

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

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

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

  • Channel Number - 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 - An index channel is matched to a lookup table by name. Unmatched index channels are left "as is".

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

Standard Options and Local Variables

There are no local variables.