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Callbacks can be used for handling lots of different events in TouchDesigner, everything from starting whole processes to changing parameters. Let’s see how this works with a simple Timer CHOP example.
The first thing our time does with the
onReady callback is to set the text for our Text TOP to be “Ready”. When the timer starts it changes the text to read “Start”. Next, on each cycle we update the text of our Text TOP to be the cycle number, and we also update the seed value for our Noise TOP. While this is a very simple example, this idea can be used to trigger any number of events based on callbacks. You might use this same technique to countdown to taking a photo in a photo booth, or to send an email from an installation.