@Override
    protected void preFrame(float tpf) {
        shadowRenderer.preFrame(tpf);
        material.setMatrix4("ViewProjectionMatrixInverse", viewPort.getCamera().getViewProjectionMatrix().invert());
        Matrix4f m = viewPort.getCamera().getViewProjectionMatrix();
        material.setVector4("ViewProjectionMatrixRow2", tmpv.set(m.m20, m.m21, m.m22, m.m23));
    }
Abstract class constructor

@param manager the application asset manager
@param shadowMapSize the size of the rendered shadowmaps (512,1024,2048,
etc...)
@param shadowRenderer the shadowRenderer to use for this Filter
jme3-core/src/main/java/com/jme3/shadow/AbstractShadowFilter.java