@Override
    public float getInterpolation(float input) {
        return (float) (0.5f + 0.5f * Math.sin(input * Math.PI - Math.PI / 2.f));
    }
Interpolator which, when drawn from 0 to 1, looks like half a sine-wave. Used for smoother opening/closing when
peeking at the drawer.
menudrawer/src/net/simonvt/menudrawer/SinusoidalInterpolator.java