Музыка:	VNV Nation - When is the Future?
Entry tags:	computing

Entity Relations
Apparently the right way to implement relations is the by creating a relation table dynamically and adding there all ids satisfying the relation:

https://ajmmertens.medium.com/building-games-in-ecs-with-entity-relationships-657275ba2c6c

Basically we do

  ComponentTables["[Relation] [What]"].[EntityId] != NULL

For example

  ComponentTables["is mortal"].[Socrates] != NULL

In SQL people usually introduce secondary keys for that.

But yeah, that requires very efficient and adaptive hash table implementation, since we can have millions of relations, having just a few elements each. I.e. doing unordered_map<int,int> won't cut it.

(define-relation 'is 'mortal 'socrates)