Created nearest_entity system param (#102)

* Created nearest_entity system param

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

* Added nearby item iterators.

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

* Export bot.rs (#101)

* Removed .vscode settings (#104)

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

* raycasting not raytracing

* don't panic if TranslatableComponent::to_string fails

* Food/saturation component support (#97)

* modified for food stuff

* moved food/saturation to a separate file

* hunger component

* simplify some logic

---------

Co-authored-by: mat <git@matdoes.dev>

* Created nearest_entity system param

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

* Added nearby item iterators.

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

* Applied tweaks from PR review

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

* Fixed doctests

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>

---------

Signed-off-by: TheDudeFromCI <thedudefromci@gmail.com>
Co-authored-by: mat <git@matdoes.dev>
Co-authored-by: Luuk van Oijen <lazyluuk.channel@gmail.com>

3 files changed, 263 insertions, 0 deletions

diff --git a/azalea/examples/nearest_entity.rs b/azalea/examples/nearest_entity.rs
new file mode 100644
index 00000000..9ac6331b
--- /dev/null
+++ b/azalea/examples/nearest_entity.rs
@@ -0,0 +1,73 @@
+use azalea::nearest_entity::EntityFinder;
+use azalea::ClientBuilder;
+use azalea::{Bot, LookAtEvent};
+use azalea_client::Account;
+use azalea_entity::metadata::{ItemItem, Player};
+use azalea_entity::{EyeHeight, Local, Position};
+use bevy_app::{FixedUpdate, Plugin};
+use bevy_ecs::{
+    prelude::{Entity, EventWriter},
+    query::With,
+    system::Query,
+};
+
+#[tokio::main]
+async fn main() {
+    let account = Account::offline("bot");
+
+    ClientBuilder::new()
+        .add_plugins(LookAtStuffPlugin)
+        .start(account, "localhost")
+        .await
+        .unwrap();
+}
+
+pub struct LookAtStuffPlugin;
+impl Plugin for LookAtStuffPlugin {
+    fn build(&self, app: &mut bevy_app::App) {
+        app.add_systems(FixedUpdate, (look_at_everything, log_nearby_item_drops));
+    }
+}
+
+fn look_at_everything(
+    bots: Query<Entity, (With<Local>, With<Player>)>,
+    entities: EntityFinder,
+    entity_positions: Query<(&Position, Option<&EyeHeight>)>,
+    mut look_at_event: EventWriter<LookAtEvent>,
+) {
+    for bot_id in bots.iter() {
+        let Some(entity) = entities.nearest_to_entity(bot_id, 16.0) else {
+            continue;
+        };
+
+        let (position, eye_height) = entity_positions.get(entity).unwrap();
+
+        let mut look_target = **position;
+        if let Some(eye_height) = eye_height {
+            look_target.y += **eye_height as f64;
+        }
+
+        look_at_event.send(LookAtEvent {
+            entity: bot_id,
+            position: look_target,
+        });
+    }
+}
+
+fn log_nearby_item_drops(
+    bots: Query<Entity, With<Bot>>,
+    entities: EntityFinder<With<ItemItem>>,
+    item_drops: Query<&ItemItem>,
+) {
+    for bot_id in bots.iter() {
+        for (entity, distance) in entities.nearby_entities_to_entity(bot_id, 8.0) {
+            let item_drop = item_drops.get(entity).unwrap();
+            let kind = item_drop.kind();
+
+            println!(
+                "Bot {:?} can see an {:?} {:.1} meters away.",
+                bot_id, kind, distance
+            );
+        }
+    }
+}
diff --git a/azalea/src/lib.rs b/azalea/src/lib.rs
index 9a8dc560..52551ea3 100644
--- a/azalea/src/lib.rs
+++ b/azalea/src/lib.rs
@@ -7,6 +7,7 @@
 mod auto_respawn;
 mod bot;
 pub mod container;
+pub mod nearest_entity;
 pub mod pathfinder;
 pub mod prelude;
 pub mod swarm;
diff --git a/azalea/src/nearest_entity.rs b/azalea/src/nearest_entity.rs
new file mode 100644
index 00000000..b9db6adb
--- /dev/null
+++ b/azalea/src/nearest_entity.rs
@@ -0,0 +1,189 @@
+use azalea_entity::Position;
+use azalea_world::{InstanceName, MinecraftEntityId};
+use bevy_ecs::{
+    prelude::Entity,
+    query::{ReadOnlyWorldQuery, With},
+    system::{Query, SystemParam},
+};
+
+/// This system parameter can be used as a shorthand for quickly finding an
+/// entity, (or several) close to a given position.
+///
+/// This system parameter allows for additional filtering of entities based off
+/// of ECS marker components, such as `With<>`, `Without<>`, or `Added<>`, etc.
+/// All functions used by this system parameter instance will respect the
+/// applied filter.
+///
+/// ```
+/// use azalea::chat::SendChatEvent;
+/// use azalea::nearest_entity::EntityFinder;
+/// use azalea_entity::metadata::{Player, AbstractMonster};
+/// use azalea_entity::Local;
+/// use bevy_ecs::system::Query;
+/// use bevy_ecs::prelude::{Entity, EventWriter};
+/// use bevy_ecs::query::With;
+///
+/// /// All bots near aggressive mobs will scream in chat.
+/// pub fn bots_near_aggressive_mobs(
+///     bots: Query<Entity, (With<Local>, With<Player>)>,
+///     entity_finder: EntityFinder<With<AbstractMonster>>,
+///     mut chat_events: EventWriter<SendChatEvent>,
+/// ) {
+///     for bot_id in bots.iter() {
+///         let Some(nearest) = entity_finder.nearest_to_entity(bot_id, 16.0) else {
+///             continue;
+///         };
+///
+///         chat_events.send(SendChatEvent {
+///             entity: bot_id,
+///             content: String::from("Ahhh!"),
+///         });
+///     }
+/// }
+/// ```
+#[derive(SystemParam)]
+pub struct EntityFinder<'w, 's, F = ()>
+where
+    F: ReadOnlyWorldQuery + 'static,
+{
+    all_entities:
+        Query<'w, 's, (&'static Position, &'static InstanceName), With<MinecraftEntityId>>,
+
+    filtered_entities: Query<
+        'w,
+        's,
+        (Entity, &'static InstanceName, &'static Position),
+        (With<MinecraftEntityId>, F),
+    >,
+}
+
+impl<'w, 's, 'a, F> EntityFinder<'w, 's, F>
+where
+    F: ReadOnlyWorldQuery + 'static,
+{
+    /// Gets the nearest entity to the given position and world instance name.
+    /// This method will return `None` if there are no entities within range. If
+    /// multiple entities are within range, only the closest one is returned.
+    pub fn nearest_to_position(
+        &'a self,
+        position: &Position,
+        instance_name: &InstanceName,
+        max_distance: f64,
+    ) -> Option<Entity> {
+        let mut nearest_entity = None;
+        let mut min_distance = max_distance;
+
+        for (target_entity, e_instance, e_pos) in self.filtered_entities.iter() {
+            if e_instance != instance_name {
+                continue;
+            }
+
+            let target_distance = position.distance_to(e_pos);
+            if target_distance < min_distance {
+                nearest_entity = Some(target_entity);
+                min_distance = target_distance;
+            }
+        }
+
+        nearest_entity
+    }
+
+    /// Gets the nearest entity to the given entity. This method will return
+    /// `None` if there are no entities within range. If multiple entities are
+    /// within range, only the closest one is returned.
+    pub fn nearest_to_entity(&'a self, entity: Entity, max_distance: f64) -> Option<Entity> {
+        let Ok((position, instance_name)) = self.all_entities.get(entity) else {
+            return None;
+        };
+
+        let mut nearest_entity = None;
+        let mut min_distance = max_distance;
+
+        for (target_entity, e_instance, e_pos) in self.filtered_entities.iter() {
+            if entity == target_entity {
+                continue;
+            };
+
+            if e_instance != instance_name {
+                continue;
+            }
+
+            let target_distance = position.distance_to(e_pos);
+            if target_distance < min_distance {
+                nearest_entity = Some(target_entity);
+                min_distance = target_distance;
+            }
+        }
+
+        nearest_entity
+    }
+
+    /// This function get an iterator over all nearby entities to the given
+    /// position within the given maximum distance. The entities in this
+    /// iterator are not returned in any specific order.
+    ///
+    /// This function returns the Entity ID of nearby entities and their
+    /// distance away.
+    pub fn nearby_entities_to_position(
+        &'a self,
+        position: &'a Position,
+        instance_name: &'a InstanceName,
+        max_distance: f64,
+    ) -> impl Iterator<Item = (Entity, f64)> + '_ {
+        self.filtered_entities
+            .iter()
+            .filter_map(move |(target_entity, e_instance, e_pos)| {
+                if e_instance != instance_name {
+                    return None;
+                }
+
+                let distance = position.distance_to(e_pos);
+                if distance < max_distance {
+                    Some((target_entity, distance))
+                } else {
+                    None
+                }
+            })
+    }
+
+    /// This function get an iterator over all nearby entities to the given
+    /// entity within the given maximum distance. The entities in this iterator
+    /// are not returned in any specific order.
+    ///
+    /// This function returns the Entity ID of nearby entities and their
+    /// distance away.
+    pub fn nearby_entities_to_entity(
+        &'a self,
+        entity: Entity,
+        max_distance: f64,
+    ) -> impl Iterator<Item = (Entity, f64)> + '_ {
+        let position;
+        let instance_name;
+        if let Ok((pos, instance)) = self.all_entities.get(entity) {
+            position = *pos;
+            instance_name = Some(instance);
+        } else {
+            position = Position::default();
+            instance_name = None;
+        };
+
+        self.filtered_entities
+            .iter()
+            .filter_map(move |(target_entity, e_instance, e_pos)| {
+                if entity == target_entity {
+                    return None;
+                }
+
+                if Some(e_instance) != instance_name {
+                    return None;
+                }
+
+                let distance = position.distance_to(e_pos);
+                if distance < max_distance {
+                    Some((target_entity, distance))
+                } else {
+                    None
+                }
+            })
+    }
+}