3 ms·

I think originally it was primarily about developer ergonomics - here's the first thing I ever read about them in 2007 where they tested it on Tony Hawk Pro Ska

I think originally it was primarily about developer ergonomics - here's the first thing I ever read about them in 2007 where they tested it on Tony Hawk Pro Skater (http://cowboyprogramming.com/2007/01/05/evolve-your-heirachy/ http://cowboyprogramming.com/2007/01/05/evolve-your-heirachy...). The CPU/memory management has been an on-going discussion ever since! Being able to process domains as flat arrays helps with cache misses - but there is a lot of other overhead, depending on how you designed everything. Making it performant was one of the big problems initially, and it seems like the `Component Graph System` this thread is about trying to answer "how do systems efficiently process components?"... But I don't really get how it answers that actually.

gmueckl 5y ago
As far as I understand it this is about the ECS equivalent of an INNER JOIN, that is, some variation on "iterate over all entities that possess instances of component A and B". Iterating over single component types in a system is trivial if they are separated into pools by types. When you have a system requiring more than one component, it isn't that easy to do better than iterating over all entities and checking whether they possess each required component. You can decide to maintain back references from components to their entities, but this means that you incur that management overhead pretty much globally. This essay says that doing away with entities altogether and just keeping direct links between your components is better. And it probably is when it comes to handling related components. However, I believe (without having actually tried it) that this proposal has its own drawbacks. it's harder to thoroughly clean up all components that form a single entity. My suspicion is that it's easier to produce bugs like keeping e.g. a stray collision shape or sound source around while the other parts of an entity are removed. All you need for that to happen is an incomplete graph traversal.
- Kinrany 5y ago
  I think CGS boils down to smart links between components, which may include SQL-like automatic checks: deleting components that refer to deleted components or components owned by the deleted component.
  - gmueckl 5y ago
    When this has to deal with a myriad of different component types individually while staying reasonably performant, this can easily become convoluted. This makes me believe that maintaining it becomes a bit of a error prone chore.
jmiskovic 5y ago
My reading of CGS is that it also means to boost ergonomics. Without "entity" concept of ECS triad, it should be 33% easier to understand how everything works, and what pitfalls exist.

gmueckl 5y ago

As far as I understand it this is about the ECS equivalent of an INNER JOIN, that is, some variation on "iterate over all entities that possess instances of component A and B". Iterating over single component types in a system is trivial if they are separated into pools by types. When you have a system requiring more than one component, it isn't that easy to do better than iterating over all entities and checking whether they possess each required component. You can decide to maintain back references from components to their entities, but this means that you incur that management overhead pretty much globally. This essay says that doing away with entities altogether and just keeping direct links between your components is better. And it probably is when it comes to handling related components. However, I believe (without having actually tried it) that this proposal has its own drawbacks. it's harder to thoroughly clean up all components that form a single entity. My suspicion is that it's easier to produce bugs like keeping e.g. a stray collision shape or sound source around while the other parts of an entity are removed. All you need for that to happen is an incomplete graph traversal.

Kinrany 5y ago
I think CGS boils down to smart links between components, which may include SQL-like automatic checks: deleting components that refer to deleted components or components owned by the deleted component.
- gmueckl 5y ago
  When this has to deal with a myriad of different component types individually while staying reasonably performant, this can easily become convoluted. This makes me believe that maintaining it becomes a bit of a error prone chore.

jmiskovic 5y ago

My reading of CGS is that it also means to boost ergonomics. Without "entity" concept of ECS triad, it should be 33% easier to understand how everything works, and what pitfalls exist.