Represents part of the world geometry that is a result of a SceneQuery.
Since world geometry is normally vast and sprawling, we need a way of retrieving parts of it based on a query. That is what this struct is for; note there are potentially as many data structures for world geometry as there are SceneManagers, however this structure includes a few common abstractions as well as a more general format.
The type of world fragment that is returned from a query depends on the SceneManager, and the fragment types are supported on the query.
