Am I using registry.view<...>().front()) correctly or is this code messy?

[rudiHammad]

hello,
I was wondering if the following is correct: I know that some entities will only have one component. For instance, a camera component entity.
So this is what I am doing

struct InfiniteParallaxSystem
{
    //...
    entt::registry& registry;
    CameraComponent& cameraComponent;
    //
}

InfiniteParallaxSystem::InfiniteParallaxSystem(entt::registry& registry, CameraComponent& cameraComponent):
    registry(registry),
    cameraComponent( registry.get<CameraComponent>(registry.view<CameraComponent>().front()) )
{   
    //... some code that requieres some registry and camera stuff to set
}


void InfiniteParallaxSystem::update(float delta)
{
    auto camPos = cameraComponent.getPosition();
    // ... more code
}

As you can see I have the two references variables (&registry and &cameraComponent). My question is if I am doing something weird
by initializing the cameraComponent using front like this
cameraComponent( registry.get<CameraComponent>(registry.view<CameraComponent>().front()) )

The reason why I am doing this is to be able to access directly the cameraComponent in the update ( auto camPos = cameraComponent.getPosition();) without having to loop the CameraComponent entities, because I know I only have one.

Without storing my cameraComonent as a reference variable I would have to do this in the update

void InfiniteParallaxSystem::update(float delta)
{
    for (auto [entity, cameraComponent]): registry.view<CameraComponent>().each()
    {
        auto camPos = cameraComponent.getPosition();
        // ... more code        
    }
}

which I guess won't have an big impact on performance since it is only one component and it is not doing anything crazy.
Some my question really is if this code is messy or if it is valid to set a reference attribute and initialize it with registry.view<...>().front()) as I am doing.

Thanks

[skypjack]

Not a fan of storing references as members, but what you're doing is fine. At least, as long as you don't add other components of the same type. In that case, the reference can be invalidated due to a reallocation.
To be honest, if you know that you're only going to have a single camera in your game, I wouldn't even use a component for that. Just store some data aside along with the entity to which the camera is attached and you're done. Creating a storage for it doesn't make much sense.

[rudiHammad]

yeah, I am not storing any other components, so I am sure only one exists. I use a reference as member because otherwise without it I thing I would have to pass it as parameter to the update method which I don't like. I might be wrong.

I guess I'll use a component anyway to keep things organized, and because maybe in the future I'll do a MultiCameraSystem that would split the screen that will require two cameras. But for this specific system I know only one cam is needed.

[skypjack]

and because maybe in the future I'll do a MultiCameraSystem that would split the screen that will require two cameras

In this case, I'd implement it as a loop over the camera component from the beginning.
It doesn't hurt and you won't have to change it later on in case. 🤷‍♂️

[rudiHammad]

Got it. Thanks for the feedback