Skybox is a wrapper around your entire scene that shows what the world looks
like beyond your geometry. You might use a Skybox to simulate infinite sky,
mountains and other phenomena.
Creating a Skybox:
// create a Skybox object
auto box = Skybox::create();
// set textureCube for Skybox
box->setTexture(_textureCube);
// attached to scene
_scene->addChild(box);