Implement world border (#364)

## Description

Basic implementation of world border
World border is not enabled by default. It can be enabled by inserting
`WorldBorderBundle` bundle. Currently, this PR only implements world
borders per instance, I'm considering expanding this per client.
However, the same functionality can be achieved by Visibility Layers
#362

<details>
<summary>Playground:</summary>

```rust
fn border_controls(
    mut events: EventReader<ChatMessageEvent>,
    mut instances: Query<(Entity, &WorldBorderDiameter, &mut WorldBorderCenter), With<Instance>>,
    mut event_writer: EventWriter<SetWorldBorderSizeEvent>,
) {
    for x in events.iter() {
        let parts: Vec<&str> = x.message.split(' ').collect();
        match parts[0] {
            "add" => {
                let Ok(value) = parts[1].parse::<f64>() else {
                    return;
                };

                let Ok(speed) = parts[2].parse::<i64>() else {
                    return;
                };

                let Ok((entity, diameter, _)) = instances.get_single_mut() else {
                    return;
                };

                event_writer.send(SetWorldBorderSizeEvent {
                    instance: entity,
                    new_diameter: diameter.diameter() + value,
                    speed,
                })
            }
            "center" => {
                let Ok(x) = parts[1].parse::<f64>() else {
                    return;
                };

                let Ok(z) = parts[2].parse::<f64>() else {
                    return;
                };

                instances.single_mut().2 .0 = DVec2 { x, y: z };
            }
            _ => (),
        }
    }
}
``` 
</details>

example: `cargo run --package valence --example world_border`
tests: `cargo test --package valence --lib -- tests::world_border`


**Related**
part of #210

Cargo.toml

@@ -89,7 +89,9 @@ valence_nbt = { path = "crates/valence_nbt", features = ["uuid"] }
 valence_network.path = "crates/valence_network"
 valence_player_list.path = "crates/valence_player_list"
 valence_registry.path = "crates/valence_registry"
+valence_world_border.path = "crates/valence_world_border"
 valence.path = "crates/valence"
+
 zip = "0.6.3"
 
 [profile.dev.package."*"]

crates/README.md

@@ -22,4 +22,5 @@ graph TD
 	anvil --> instance
 	entity --> block
 	advancement --> client
+	world_border --> client
 ```

crates/valence/Cargo.toml

@@ -11,12 +11,13 @@ keywords = ["minecraft", "gamedev", "server", "ecs"]
 categories = ["game-engines"]
 
 [features]
-default = ["network", "player_list", "inventory", "anvil", "advancement"]
+default = ["network", "player_list", "inventory", "anvil", "advancement", "world_border"]
 network = ["dep:valence_network"]
 player_list = ["dep:valence_player_list"]
 inventory = ["dep:valence_inventory"]
 anvil = ["dep:valence_anvil"]
 advancement = ["dep:valence_advancement"]
+world_border = ["dep:valence_world_border"]
 
 [dependencies]
 bevy_app.workspace = true
@@ -37,6 +38,8 @@ valence_player_list = { workspace = true, optional = true }
 valence_inventory = { workspace = true, optional = true }
 valence_anvil = { workspace = true, optional = true }
 valence_advancement = { workspace = true, optional = true }
+valence_world_border = { workspace = true, optional = true }
+
 
 [dev-dependencies]
 anyhow.workspace = true

crates/valence/examples/world_border.rs

@@ -0,0 +1,161 @@
+use std::time::Duration;
+
+use bevy_app::App;
+use valence::client::chat::ChatMessageEvent;
+use valence::client::despawn_disconnected_clients;
+use valence::inventory::HeldItem;
+use valence::prelude::*;
+use valence::world_border::*;
+
+const SPAWN_Y: i32 = 64;
+
+fn main() {
+    tracing_subscriber::fmt().init();
+
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .add_startup_system(setup)
+        .add_system(init_clients)
+        .add_system(despawn_disconnected_clients)
+        .add_system(border_center_avg)
+        .add_system(border_expand)
+        .add_system(border_controls)
+        .run();
+}
+
+fn setup(
+    mut commands: Commands,
+    server: Res<Server>,
+    biomes: Res<BiomeRegistry>,
+    dimensions: Res<DimensionTypeRegistry>,
+) {
+    let mut instance = Instance::new(ident!("overworld"), &dimensions, &biomes, &server);
+
+    for z in -5..5 {
+        for x in -5..5 {
+            instance.insert_chunk([x, z], Chunk::default());
+        }
+    }
+
+    for z in -25..25 {
+        for x in -25..25 {
+            instance.set_block([x, SPAWN_Y, z], BlockState::MOSSY_COBBLESTONE);
+        }
+    }
+
+    commands
+        .spawn(instance)
+        .insert(WorldBorderBundle::new([0.0, 0.0], 1.0));
+}
+
+fn init_clients(
+    mut clients: Query<
+        (
+            &mut Client,
+            &mut Location,
+            &mut Position,
+            &mut Inventory,
+            &HeldItem,
+        ),
+        Added<Client>,
+    >,
+    instances: Query<Entity, With<Instance>>,
+) {
+    for (mut client, mut loc, mut pos, mut inv, main_slot) in &mut clients {
+        loc.0 = instances.single();
+        pos.set([0.5, SPAWN_Y as f64 + 1.0, 0.5]);
+        let pickaxe = Some(ItemStack::new(ItemKind::WoodenPickaxe, 1, None));
+        inv.set_slot(main_slot.slot(), pickaxe);
+        client.send_message("Break block to increase border size!");
+    }
+}
+
+fn border_center_avg(
+    clients: Query<(&Location, &Position)>,
+    mut instances: Query<(Entity, &mut WorldBorderCenter), With<Instance>>,
+) {
+    for (entity, mut center) in instances.iter_mut() {
+        let new_center = {
+            let (count, x, z) = clients
+                .iter()
+                .filter(|(loc, _)| loc.0 == entity)
+                .fold((0, 0.0, 0.0), |(count, x, z), (_, pos)| {
+                    (count + 1, x + pos.0.x, z + pos.0.z)
+                });
+
+            DVec2 {
+                x: x / count.max(1) as f64,
+                y: z / count.max(1) as f64,
+            }
+        };
+
+        center.0 = new_center;
+    }
+}
+
+fn border_expand(
+    mut events: EventReader<DiggingEvent>,
+    clients: Query<&Location, With<Client>>,
+    wbs: Query<&WorldBorderDiameter, With<Instance>>,
+    mut event_writer: EventWriter<SetWorldBorderSizeEvent>,
+) {
+    for digging in events.iter().filter(|d| d.state == DiggingState::Stop) {
+        let Ok(loc) = clients.get(digging.client) else {
+            continue;
+        };
+
+        let Ok(size) = wbs.get(loc.0) else {
+            continue;
+        };
+
+        event_writer.send(SetWorldBorderSizeEvent {
+            instance: loc.0,
+            new_diameter: size.get() + 1.0,
+            duration: Duration::from_secs(1),
+        });
+    }
+}
+
+// Not needed for this demo, but useful for debugging
+fn border_controls(
+    mut events: EventReader<ChatMessageEvent>,
+    mut instances: Query<(Entity, &WorldBorderDiameter, &mut WorldBorderCenter), With<Instance>>,
+    mut event_writer: EventWriter<SetWorldBorderSizeEvent>,
+) {
+    for x in events.iter() {
+        let parts: Vec<&str> = x.message.split(' ').collect();
+        match parts[0] {
+            "add" => {
+                let Ok(value) = parts[1].parse::<f64>() else {
+                    return;
+                };
+
+                let Ok(speed) = parts[2].parse::<i64>() else {
+                    return;
+                };
+
+                let Ok((entity, diameter, _)) = instances.get_single_mut() else {
+                    return;
+                };
+
+                event_writer.send(SetWorldBorderSizeEvent {
+                    instance: entity,
+                    new_diameter: diameter.get() + value,
+                    duration: Duration::from_millis(speed as u64),
+                })
+            }
+            "center" => {
+                let Ok(x) = parts[1].parse::<f64>() else {
+                    return;
+                };
+
+                let Ok(z) = parts[2].parse::<f64>() else {
+                    return;
+                };
+
+                instances.single_mut().2 .0 = DVec2 { x, y: z };
+            }
+            _ => (),
+        }
+    }
+}

crates/valence/src/lib.rs

@@ -37,6 +37,8 @@ pub use valence_inventory as inventory;
 pub use valence_network as network;
 #[cfg(feature = "player_list")]
 pub use valence_player_list as player_list;
+#[cfg(feature = "world_border")]
+pub use valence_world_border as world_border;
 pub use {
     bevy_app as app, bevy_ecs as ecs, glam, valence_biome as biome, valence_block as block,
     valence_client as client, valence_dimension as dimension, valence_entity as entity,
@@ -162,6 +164,11 @@ impl PluginGroup for DefaultPlugins {
                 .add(valence_advancement::bevy_hierarchy::HierarchyPlugin);
         }
 
+        #[cfg(feature = "world_border")]
+        {
+            group = group.add(valence_world_border::WorldBorderPlugin);
+        }
+
         group
     }
 }

crates/valence/src/tests.rs

@@ -284,3 +284,4 @@ mod client;
 mod example;
 mod inventory;
 mod weather;
+mod world_border;

crates/valence/src/tests/world_border.rs

@@ -0,0 +1,133 @@
+use std::time::Duration;
+
+use bevy_app::App;
+use valence_entity::Location;
+use valence_instance::Instance;
+use valence_registry::{Entity, Mut};
+use valence_world_border::packet::*;
+use valence_world_border::*;
+
+use super::{create_mock_client, scenario_single_client, MockClientHelper};
+
+#[test]
+fn test_intialize_on_join() {
+    let mut app = App::new();
+    let (_, instance_ent) = prepare(&mut app);
+
+    let (client, mut client_helper) = create_mock_client();
+    let client_ent = app.world.spawn(client).id();
+
+    app.world.get_mut::<Location>(client_ent).unwrap().0 = instance_ent;
+    app.update();
+
+    client_helper
+        .collect_sent()
+        .assert_count::<WorldBorderInitializeS2c>(1);
+}
+
+#[test]
+fn test_resizing() {
+    let mut app = App::new();
+    let (mut client_helper, instance_ent) = prepare(&mut app);
+
+    app.world.send_event(SetWorldBorderSizeEvent {
+        new_diameter: 20.0,
+        duration: Duration::ZERO,
+        instance: instance_ent,
+    });
+
+    app.update();
+    let frames = client_helper.collect_sent();
+    frames.assert_count::<WorldBorderSizeChangedS2c>(1);
+}
+
+#[test]
+fn test_center() {
+    let mut app = App::new();
+    let (mut client_helper, instance_ent) = prepare(&mut app);
+
+    let mut ins_mut = app.world.entity_mut(instance_ent);
+    let mut center: Mut<WorldBorderCenter> = ins_mut
+        .get_mut()
+        .expect("Expect world border to be present!");
+    center.0 = [10.0, 10.0].into();
+
+    app.update();
+    let frames = client_helper.collect_sent();
+    frames.assert_count::<WorldBorderCenterChangedS2c>(1);
+}
+
+#[test]
+fn test_warn_time() {
+    let mut app = App::new();
+    let (mut client_helper, instance_ent) = prepare(&mut app);
+
+    let mut ins_mut = app.world.entity_mut(instance_ent);
+    let mut wt: Mut<WorldBorderWarnTime> = ins_mut
+        .get_mut()
+        .expect("Expect world border to be present!");
+    wt.0 = 100;
+    app.update();
+
+    let frames = client_helper.collect_sent();
+    frames.assert_count::<WorldBorderWarningTimeChangedS2c>(1);
+}
+
+#[test]
+fn test_warn_blocks() {
+    let mut app = App::new();
+    let (mut client_helper, instance_ent) = prepare(&mut app);
+
+    let mut ins_mut = app.world.entity_mut(instance_ent);
+    let mut wb: Mut<WorldBorderWarnBlocks> = ins_mut
+        .get_mut()
+        .expect("Expect world border to be present!");
+    wb.0 = 100;
+    app.update();
+
+    let frames = client_helper.collect_sent();
+    frames.assert_count::<WorldBorderWarningBlocksChangedS2c>(1);
+}
+
+#[test]
+fn test_portal_tp_boundary() {
+    let mut app = App::new();
+    let (mut client_helper, instance_ent) = prepare(&mut app);
+
+    let mut ins_mut = app.world.entity_mut(instance_ent);
+    let mut tp: Mut<WorldBorderPortalTpBoundary> = ins_mut
+        .get_mut()
+        .expect("Expect world border to be present!");
+    tp.0 = 100;
+    app.update();
+
+    let frames = client_helper.collect_sent();
+    frames.assert_count::<WorldBorderInitializeS2c>(1);
+}
+
+fn prepare(app: &mut App) -> (MockClientHelper, Entity) {
+    let (_, mut client_helper) = scenario_single_client(app);
+
+    // Process a tick to get past the "on join" logic.
+    app.update();
+    client_helper.clear_sent();
+
+    // Get the instance entity.
+    let instance_ent = app
+        .world
+        .iter_entities()
+        .find(|e| e.contains::<Instance>())
+        .expect("could not find instance")
+        .id();
+
+    // Insert a the world border bundle to the instance.
+    app.world
+        .entity_mut(instance_ent)
+        .insert(WorldBorderBundle::new([0.0, 0.0], 10.0));
+    for _ in 0..2 {
+        app.update();
+    }
+
+    client_helper.clear_sent();
+    (client_helper, instance_ent)
+}