This addon enables you to get the ratio of the elapsed time to the duration time.
1.Instantiation ofxTimedInterpolation
ofxTimedInterpolation timedInterpolation
2.Just Bang with the duration
timedInterpolation.bang(1000)
3.Then you will get the ratio of elapsed time to the duration
float ratio = timedInterpolation.get() //if reached, the value is 1.0
For more details, please check the example.