Entity Relationships

[HexDecimal]

Just a quick issue in case I lose track of these articles:

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

Semi-related (Hierarchies):
https://skypjack.github.io/2019-06-25-ecs-baf-part-4/
https://skypjack.github.io/2019-08-20-ecs-baf-part-4-insights/

[HexDecimal]

Done adding many-to-many and many-to-one relations.
Done adding named components.

[HexDecimal]

There might be more to do with relations using components, or more details with queries.

[HexDecimal]

So named components are similar to a type related to an entity, so it might be a good idea to access named components by type:

@attrs.define(frozen=True)
class Slot:
    body: str

class Equipment:
    pass

entity.components[(Slot("arms"), Equipment)] = Equipment()
entity.components[(Slot("head"), Equipment)] = Equipment()

# Iterate over all (Slot, Type[Equipment]) named component keys
key: tuple[Slots, Type[Equipment]]
for key in entity.components.by_named_type(Slot, Component):
    assert isinstance(entity.components[key], Equipment)

# Query that an entity has one or more named components associated with a specific type of name
assert entity in entity.world.Q.all_of((Slot, Component))

[HexDecimal]

The main article has advanced examples of chaining relation queries. It'd be nice to support these types of queries.

all_stars = world.Q.all_of(tags=["IsStar"]))
objects_in_orbit_of_stars = world.Q.all_of(relations=[("OrbitOf", all_stars])

[HexDecimal]

I think I've actually did it. This seems to be the full system as described by the article.