1 files changed, 147 insertions, 0 deletions
diff --git a/azalea-entity/src/plugin/mod.rs b/azalea-entity/src/plugin/mod.rs
new file mode 100644
index 00000000..7b514fcc
--- /dev/null
+++ b/azalea-entity/src/plugin/mod.rs
@@ -0,0 +1,147 @@
+pub mod indexing;
+mod relative_updates;
+
+use std::collections::HashSet;
+
+use azalea_core::{BlockPos, Vec3};
+use azalea_world::{InstanceContainer, InstanceName, MinecraftEntityId};
+use bevy_app::{App, Plugin, PostUpdate, PreUpdate, Update};
+use bevy_ecs::prelude::*;
+use derive_more::{Deref, DerefMut};
+use log::debug;
+
+use crate::{
+    metadata::Health, Dead, EyeHeight, FluidOnEyes, Local, LookDirection, Physics, Position,
+};
+
+use indexing::EntityUuidIndex;
+pub use relative_updates::RelativeEntityUpdate;
+
+/// A Bevy [`SystemSet`] for various types of entity updates.
+#[derive(SystemSet, Debug, Hash, Eq, PartialEq, Clone)]
+pub enum EntityUpdateSet {
+    /// Remove ECS entities that refer to an entity that was already in the ECS
+    /// before.
+    Deduplicate,
+    /// Create search indexes for entities.
+    Index,
+    /// Remove despawned entities from search indexes.
+    Deindex,
+}
+
+/// Plugin handling some basic entity functionality.
+pub struct EntityPlugin;
+impl Plugin for EntityPlugin {
+    fn build(&self, app: &mut App) {
+        // entities get added pre-update
+        // added to indexes during update (done by this plugin)
+        // modified during update
+        // despawned post-update (done by this plugin)
+        app.add_systems(
+            PreUpdate,
+            indexing::remove_despawned_entities_from_indexes.in_set(EntityUpdateSet::Deindex),
+        )
+        .add_systems(
+            PostUpdate,
+            (
+                indexing::deduplicate_entities,
+                indexing::deduplicate_local_entities,
+            )
+                .in_set(EntityUpdateSet::Deduplicate),
+        )
+        .add_systems(
+            Update,
+            (
+                (
+                    indexing::update_entity_chunk_positions,
+                    indexing::update_uuid_index,
+                    indexing::update_entity_by_id_index,
+                )
+                    .in_set(EntityUpdateSet::Index),
+                (
+                    relative_updates::add_updates_received,
+                    relative_updates::debug_detect_updates_received_on_local_entities,
+                    debug_new_entity,
+                    add_dead,
+                    update_bounding_box,
+                    clamp_look_direction,
+                    update_fluid_on_eyes,
+                ),
+            ),
+        )
+        .init_resource::<EntityUuidIndex>();
+    }
+}
+
+fn debug_new_entity(query: Query<(Entity, Option<&Local>), Added<MinecraftEntityId>>) {
+    for (entity, local) in query.iter() {
+        if local.is_some() {
+            debug!("new local entity: {:?}", entity);
+        } else {
+            debug!("new entity: {:?}", entity);
+        }
+    }
+}
+
+/// System that adds the [`Dead`] marker component if an entity's health is set
+/// to 0 (or less than 0). This will be present if an entity is doing the death
+/// animation.
+///
+/// Entities that are dead can not be revived.
+/// TODO: fact check this in-game by setting an entity's health to 0 and then
+/// not 0
+pub fn add_dead(mut commands: Commands, query: Query<(Entity, &Health), Changed<Health>>) {
+    for (entity, health) in query.iter() {
+        if **health <= 0.0 {
+            commands.entity(entity).insert(Dead);
+        }
+    }
+}
+
+pub fn update_fluid_on_eyes(
+    mut query: Query<(&mut FluidOnEyes, &Position, &EyeHeight, &InstanceName)>,
+    instance_container: Res<InstanceContainer>,
+) {
+    for (mut fluid_on_eyes, position, eye_height, instance_name) in query.iter_mut() {
+        let Some(instance) = instance_container.get(instance_name) else {
+            continue;
+        };
+
+        let adjusted_eye_y = position.y + (**eye_height as f64) - 0.1111111119389534;
+        let eye_block_pos = BlockPos::from(Vec3::new(position.x, adjusted_eye_y, position.z));
+        let fluid_at_eye = instance
+            .read()
+            .get_fluid_state(&eye_block_pos)
+            .unwrap_or_default();
+        let fluid_cutoff_y = eye_block_pos.y as f64 + (fluid_at_eye.height as f64 / 16f64);
+        if fluid_cutoff_y > adjusted_eye_y {
+            **fluid_on_eyes = fluid_at_eye.fluid;
+        } else {
+            **fluid_on_eyes = azalea_registry::Fluid::Empty;
+        }
+    }
+}
+
+/// A component that lists all the local player entities that have this entity
+/// loaded. If this is empty, the entity will be removed from the ECS.
+#[derive(Component, Clone, Deref, DerefMut)]
+pub struct LoadedBy(pub HashSet<Entity>);
+
+pub fn clamp_look_direction(mut query: Query<&mut LookDirection>) {
+    for mut look_direction in &mut query {
+        look_direction.y_rot %= 360.0;
+        look_direction.x_rot = look_direction.x_rot.clamp(-90.0, 90.0) % 360.0;
+    }
+}
+
+/// Sets the position of the entity. This doesn't update the cache in
+/// azalea-world, and should only be used within azalea-world!
+///
+/// # Safety
+/// Cached position in the world must be updated.
+pub fn update_bounding_box(mut query: Query<(&Position, &mut Physics), Changed<Position>>) {
+    for (position, mut physics) in query.iter_mut() {
+        let bounding_box = physics.dimensions.make_bounding_box(position);
+        physics.bounding_box = bounding_box;
+    }
+}