@Override
    public Plane.Side whichSide(Plane plane) {
        float distance = plane.pseudoDistance(center);

        if (distance <= -radius) {
            return Plane.Side.Negative;
        } else if (distance >= radius) {
            return Plane.Side.Positive;
        } else {
            return Plane.Side.None;
        }
    }
<code>whichSide</code> takes a plane (typically provided by a view
frustum) to determine which side this bound is on.

@param plane
           the plane to check against.
@return side
jme3-core/src/main/java/com/jme3/bounding/BoundingSphere.java