Boss Bar API

[pepperoni21]

Description

Hey, I started working on this issue #337.

So far:

• I created a crate "valence_boss_bar" and I moved this packet there

  valence/crates/valence_core/src/protocol/packet.rs

  Line 612 in 2ed5a88

  pub mod boss_bar {

• I initialized the plugin and added a system that removes the players when a boss bar is despawned.
• I created/moved the boss bar components (BossBarTitle, BossBarHealth, BossBarStyle, BossBarFlags and BossBarViewers)
• I added systems that handle the update of boss bar attributes and player disconnection
• I documented the code
• I made unit tests

Playground

I've tested the API in playground and it works fine.

mp4.mp4.online-video-cutter.com.mp4

[Bafbi]

I tried to store Client objects directly inside the BossBarViewers struct but I realized it was a bad idea, now I just store bevy entities, is it how I should do?

Yes it's like in a db you put the id of what you want to ref.

How should I manage to add/remove viewers or update titles/health/style in a BossBar? I implemented methods for the BossBar struct to make these actions but I can't figure out how to send packets to the clients because I don't know how to turn my vector of bevy entities into Client objects.

When you use write_packet on the client, it's being put on a buffer to be send.

I basically forked my test file from the world_border's one, is it how I should spawn a BossBar?

No, BossBar are not link to the instance, but you should spawn a new bevy_entity

commands.spawn(BossBarBundle::new(...));

[dyc3]

Regarding your questions

I tried to store Client objects directly inside the BossBarViewers struct but I realized it was a bad idea, now I just store bevy entities, is it how I should do?

Yes, that's how you should do it. Otherwise, you would be attempting to violate rust's aliasing rules.

How should I manage to add/remove viewers or update titles/health/style in a BossBar? I implemented methods for the BossBar struct to make these actions but I can't figure out how to send packets to the clients because I don't know how to turn my vector of bevy entities into Client objects.

You need to query for clients separately, and then you can use the Entity to look up the Client.

fn foo(clients: Query<Client>) {
    // Then you can look up the client using the entity
    clients.get(entity)

I basically forked my test file from the world_border's one, is it how I should spawn a BossBar?

For unit tests, operating directly on app.world is fine, but otherwise use bevy's Commands. You'll probably want to create a new entity instead of using an existing one.

[pepperoni21]

I tried to store Client objects directly inside the BossBarViewers struct but I realized it was a bad idea, now I just store bevy entities, is it how I should do?

Yes it's like in a db you put the id of what you want to ref.

How should I manage to add/remove viewers or update titles/health/style in a BossBar? I implemented methods for the BossBar struct to make these actions but I can't figure out how to send packets to the clients because I don't know how to turn my vector of bevy entities into Client objects.

When you use write_packet on the client, it's being put on a buffer to be send.

I basically forked my test file from the world_border's one, is it how I should spawn a BossBar?

No, BossBar are not link to the instance, but you should spawn a new bevy_entity

commands.spawn(BossBarBundle::new(...));

Hey thanks for your help! The problem I have is that I don't know how to modify something in the Bundle. I could simply make a method to change a property but how am I supposed to send the packets then? Because since it's not a system I can't query anything right?

[pepperoni21]

Hey thanks a lot for your help!

You need to query for clients separately, and then you can use the Entity to look up the Client.

fn foo(clients: Query<Client>) {
    // Then you can look up the client using the entity
    clients.get(entity)

So I have to do that in a system? But isn't a system supposed to be executed every tick? Or I should use something like an event?

For unit tests, operating directly on app.world is fine, but otherwise use bevy's Commands. You'll probably want to create a new entity instead of using an existing one.

Fine I will do that!

[Bafbi]

So I have to do that in a system? But isn't a system supposed to be executed every tick? Or I should use something like an event?

You want to send the packet when the bossbar is created or that an component change for that you can use changeDetection

fn foo(clients: Query<Client>, bossbar: Query<(UniqueId, ...), Added<BossBarBundle>>) { // not sure if you can put a bundle here, but if you can't use a component that uniquely identify a bossbar
    // you generates packets for each bossbar
    // Then you can look up each client of the bossbar to send them like you did before
}

[Bafbi]

Hey thanks for your help! The problem I have is that I don't know how to modify something in the Bundle. I could simply make a method to change a property but how am I supposed to send the packets then? Because since it's not a system I can't query anything right?

you don't make method to modify the component.
When someone use your plugin they can make system to modify what they want :
// Someone server code

fn update_bossbar(mob: Query<&Hp, &BossBarLink, Change<Hp>>, bossbar: Query<&mut BossBarHealth>) {
    for (hp, link) in mob {
        if let Ok(bossbar_health) = bossbar.get(link) {
            bossbat_health -= hp;
        }
    }
}

That will trigger a change detection on BossBarHealth that you can use to send the updatede packet

[pepperoni21]

So I have to do that in a system? But isn't a system supposed to be executed every tick? Or I should use something like an event?

You want to send the packet when the bossbar is created or that an component change for that you can use changeDetection

fn foo(clients: Query<Client>, bossbar: Query<(UniqueId, ...), Added<BossBarBundle>>) { // not sure if you can put a bundle here, but if you can't use a component that uniquely identify a bossbar
    // you generates packets for each bossbar
    // Then you can look up each client of the bossbar to send them like you did before
}

That's exactly what I was looking for, thanks

[rj00a]

Graph in crates/README.md needs an update.

[rj00a]

valence_boss_bar needs to be exported as boss_bar in the main valence crate. Also, please add an example to examples/.

[rj00a]

Looks good, thanks.