@Override
    protected void getReceivers(GeometryList lightReceivers) {
        if (lightReceivers.size()==0) {
            for (Spatial scene : viewPort.getScenes()) {
                ShadowUtil.getGeometriesInCamFrustum(scene, viewPort.getCamera(), RenderQueue.ShadowMode.Receive, lightReceivers);
            }
        }
    }
Sets the light to use to cast shadows
@param light a DirectionalLight
jme3-vr/src/main/java/com/jme3/shadow/DirectionalLightShadowRendererVR.java