@Override
    public boolean interpolate(double t) {
        if (t < 0) {
            return true;
        }

        // Scale t to be between 0 and 1 for our length
        if (length == 0) {
            t = 1;
        } else {
            t = t / length;
        }

        boolean done = false;
        if (t >= 1.0) {
            t = 1.0;
            done = true;
        }
        doInterpolate(t);
        return !done;
    }
Default implementation clamps the time value, converts
it to 0 to 1.0 based on getLength(), and calls doInterpolate().
jme3-core/src/main/java/com/jme3/anim/tween/AbstractTween.java