@Override
    public void read(JmeImporter im) throws IOException {
        super.read(im);
        InputCapsule ic = im.getCapsule(this);

    }
get the length over which the shadow will fade out when using a shadowZextend
@return the fade length in world units
jme3-core/src/main/java/com/jme3/shadow/PssmShadowFilter.java