VRML
2.0 Interpolator Concepts

Each interpolator node has a set of keys and a set of keyValues

The keys are numbers between 0.0 and 1.0 which represents a fraction
over the interval (0.0..1.0)

Each key must have an associated keyValue of the type of the
interpolator

When a set_fraction eventIn is received, the values are interpolated to
get the correct value_changed eventOut.

Technically this is a piecewise linear interpolator

Think of these interpolators as key frame animators for different fields

There is no integer interpolator in VRML!

The value_changed eventOut is usually routed to a field of a named node
to change something that is drawn, however it could be routed to a
script node for further processing

To achieve a better interpolation than piecewise linear you must write
your own interpolator