public static void getLitGeometriesInViewPort(Spatial rootScene, Camera vpCamera, Camera[] cameras, RenderQueue.ShadowMode mode, GeometryList outputGeometryList) {
        if (rootScene != null && rootScene instanceof Node) {
            addGeometriesInCamFrustumAndViewPortFromNode(vpCamera, cameras, rootScene, mode, outputGeometryList);
        }
    }
Populates the outputGeometryList with the geometries of the children
of OccludersExtractor.rootScene node that are both in the frustum of the given vpCamera and some camera inside cameras array.
The array of cameras must be initialized to represent the light viewspace of some light like pointLight or spotLight

@param rootScene the root of the scene to traverse (may be null)
@param vpCamera the viewPort camera
@param cameras the camera array to check geometries against, representing the light viewspace
@param mode the ShadowMode to test for
@param outputGeometryList the output list of all geometries that are in the camera frustum
jme3-core/src/main/java/com/jme3/shadow/ShadowUtil.java