ECS

While comfy does not mandate the use of ECS, it does include hecs along with a few useful components and helpers. If you don't like hecs and would want to use something else, you are 100% able to do so. Currently there is no way to turn off hecs with a feature flag, mainly because it hasn't been a priority for us, but is something that we're not opposed to doing.

Everything ECS related that comfy does builds on the existing public APIs, which means any of the ECS features that are built in could just as well be implemented by the user.

Notably comfy provides a Sprite (example) and AnimatedSprite (example) components, as well as a Transform component which supports child transforms. Note this isn't something we really use to build complex scene trees, but it may come in handy from time to time.

You can think of Sprite as simply "something that makes comfy call draw_sprite" every frame. The AnimatedSprite is similar, but it also handles all of the animation timing and state updates, and it is probably the main reason why you'd want to use ECS with comfy.

Note that there is nothing inherently magical about AnimatedSprite being tied to ECS, and you could very well instantiate it yourself, store it in your own data structures, and use the provided methods to draw it manually with draw_sprite.

Comfy does include a few other components with builtin functionality, but as some of the APIs aren't the most stable we're not going to document them here for the v0.1 release. If you're feeling adventurous, browse around the codebase and see what you can find. Note that almost nothing in comfy is hidden from the user, and all internal state/fields are exposed. This is something we've done intentionally to make comfy a bit more flexible without having to build complex render graphs and other modular data structures.

The builtin EngineContext exposes a few helper methods:

• c.world() for immutable access to &World
• c.world_mut() for mutable access to &mut World
• c.commands() for mutable access to the CommandBuffer

If you're not sure what these do or how to use them, the hecs documentation is a great place to learn! Out of all the ECS libraries we've tried hecs has been the best and simplest by far, and would 100% recommend it to everyone. It's not as comfy as bevy's automagic resource injection, but we've found the more explicit nature of it to be a great productivity boost.

Notably, comfy does run the CommandBuffer's run_on(...) every frame, which means you can just queue commands and have comfy run them on the builtin ECS world.