Using time values for a parameter's automation

Using time values is apparently the most commonly used method to automate a parameter. In this approach, a parameter's value is set to be a function depending on the time, and more precisely, the number of seconds measured from some initial point in time.

Tip

Dependency of time can be implemented in many ways—as a mathematical expression, in tabular form, or even by drawing it using a graphics tablet. We will consider the simplest way, which is using mathematical expressions.

To implement dependency of time, we need a function to measure it. In openFrameworks, such a function is ofGetElapsedTime(). It returns the number of seconds elapsed from the project's start. This is a float value and is measured with millisecond precision.

To check this function, add the following command to the end of update():

kangle = ofGetElapsedTimef();

This command sets the value of the kangle slider to the number of seconds elapsed from the project...