@Override
    protected void initFilter(AssetManager manager, RenderManager renderManager, ViewPort vp, int w, int h) {
        shadowRenderer.needsfallBackMaterial = true;
        shadowRenderer.initialize(renderManager, vp);
        this.viewPort = vp;
    }
Get the {@link Material material} used by this filter.
@return the {@link Material material} used by this filter.
jme3-vr/src/main/java/com/jme3/shadow/AbstractShadowFilterVR.java