@Override
    public boolean intersectsFrustum(Camera camera, TempVars vars) {
        if (this.radius == 0) {
            return true;
        } else {
            return Intersection.intersect(camera, position, radius);
        }
    }
for internal use only
@return the inverse of the radius
jme3-core/src/main/java/com/jme3/light/PointLight.java