public static void getGeometriesInCamFrustum(GeometryList inputGeometryList,
            Camera camera,
            GeometryList outputGeometryList) {
        for (int i = 0; i < inputGeometryList.size(); i++) {
            Geometry g = inputGeometryList.get(i);
            int planeState = camera.getPlaneState();
            camera.setPlaneState(0);
            if (camera.contains(g.getWorldBound()) != Camera.FrustumIntersect.Outside) {
                outputGeometryList.add(g);
            }
            camera.setPlaneState(planeState);
        }

    }
Populates the outputGeometryList with the geometry of the
inputGeometryList that are in the frustum of the given camera

@param inputGeometryList The list containing all geometries to check
against the camera frustum
@param camera the camera to check geometries against
@param outputGeometryList the list of all geometries that are in the
camera frustum
jme3-core/src/main/java/com/jme3/shadow/ShadowUtil.java