void checkDoBoundUpdate() {
        if ((refreshFlags & RF_BOUND) == 0) {
            return;
        }

        checkDoTransformUpdate();

        // Go to children recursively and update their bound
        if (this instanceof Node) {
            Node node = (Node) this;
            int len = node.getQuantity();
            for (int i = 0; i < len; i++) {
                Spatial child = node.getChild(i);
                child.checkDoBoundUpdate();
            }
        }

        // All children's bounds have been updated. Update my own now.
        updateWorldBound();
    }
Computes this Spatial's world bounding volume in the most efficient
manner possible.
jme3-core/src/main/java/com/jme3/scene/Spatial.java