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12.2.2 Summary

An Alpha class is very simple—it converts a time value in milliseconds to a value between 0 and 1. The built−in Alpha class defines all the parameters for an Alpha function to implement a common class of onset, peak, offset activation functions.

A custom Alpha function, such as FileAlpha, is a very powerful mechanism to feed application−specific data into one of the Interpolator−derived classes. An application might define an Alpha class that samples data straight from a communications port, or reads precomputed data from a file. The output from the custom Alpha class can then be used to parameterize a wide variety of Interpolators.

Alpha classes are used in conjunction with Interpolators, but they do not do anything visible themselves. Their prime purpose in Java 3D is to provide input to the Interpolator classes.

Interpolators are the subjects of section 12.3, so read on.