public RenderState extract(final Stack<? extends RenderState> stack, final Spatial spat) {
if (spat == null) {
return stack.peek();
}
final LightCombineMode mode = spat.getSceneHints().getLightCombineMode();
final Mesh mesh = (Mesh) spat;
LightState lightState = mesh.getLightState();
if (lightState == null) {
lightState = new LightState();