Returns the NodeList managed by this class. This should be a reference that remains valid always since it is retained and reused by Systems that use the list. i.e. never recreate the list, always modify it in place.
clean the node (reset component pointers)
An entity has been added to the engine. It may already have components so test the entity for inclusion in this family's NodeList.
An entity has been removed from the engine. If it's in this family's NodeList it should be removed.
A component has been added to an entity. Test whether the entity's inclusion in this family's NodeList should be modified.
A component has been removed from an entity. Test whether the entity's inclusion in this family's NodeList should be modified.
The family is about to be discarded. Clean up all properties as necessary. Usually, you will want to empty the NodeList at this time.