activateLightOnSubMeshes_1 = function (mesh, light) {
                                        var children = mesh.getChildren();
                                        if (children.length !== 0) {
                                            children.forEach(function (mesh) {
                                                light.includedOnlyMeshes.push(mesh);
                                                activateLightOnSubMeshes_1(mesh, light);
                                            });
                                        }
                                    }
This function is called by the two RIG cameras.
'this' is the left or right camera (and NOT (!!!) the WebVRFreeCamera instance)