healing particle effect

src/abilities/healing.rs

@@ -6,7 +6,7 @@ use crate::{
 };
 
 #[derive(Component)]
-struct Healing(Entity);
+pub struct Healing(pub Entity);
 
 #[derive(Event, Debug)]
 pub enum HealingStateChanged {

src/abilities/mod.rs

@@ -4,6 +4,8 @@ mod healing;
 mod missile;
 mod thrown;
 
+pub use healing::Healing;
+
 use crate::{
     GameState,
     aim::AimTarget,

src/heal_effect.rs

@@ -0,0 +1,99 @@
+use crate::{
+    GameState, abilities::Healing, loading_assets::GameAssets, utils::billboards::Billboard,
+};
+use bevy::prelude::*;
+use rand::{Rng, thread_rng};
+
+#[derive(Component, Default)]
+#[require(Transform, InheritedVisibility)]
+struct HealParticleEffect {
+    next_spawn: f32,
+}
+
+#[derive(Component)]
+struct HealParticle {
+    start_scale: f32,
+    end_scale: f32,
+    start_pos: Vec3,
+    end_pos: Vec3,
+    start_time: f32,
+    life_time: f32,
+}
+
+pub fn plugin(app: &mut App) {
+    app.add_systems(
+        Update,
+        (on_added, update_effects, update_particles).run_if(in_state(GameState::Playing)),
+    );
+}
+
+fn on_added(mut cmds: Commands, query: Query<&Healing, Added<Healing>>) {
+    for healing in query.iter() {
+        cmds.entity(healing.0).insert((
+            Name::new("heal-particle-effect"),
+            HealParticleEffect::default(),
+        ));
+    }
+}
+
+fn update_effects(
+    mut cmds: Commands,
+    mut query: Query<(&mut HealParticleEffect, Entity)>,
+    time: Res<Time>,
+    assets: Res<GameAssets>,
+) {
+    const DISTANCE: f32 = 4.;
+    let mut rng = thread_rng();
+
+    let now = time.elapsed_secs();
+    for (mut effect, e) in query.iter_mut() {
+        if effect.next_spawn < now {
+            let start_pos = Vec3::new(
+                rng.gen_range(-DISTANCE..DISTANCE),
+                2.,
+                rng.gen_range(-DISTANCE..DISTANCE),
+            );
+            let max_distance = start_pos.length().max(0.8);
+            let end_pos =
+                start_pos + (start_pos.normalize() * -1.) * rng.gen_range(0.5..max_distance);
+            let start_scale = rng.gen_range(0.7..1.0);
+            let end_scale = rng.gen_range(0.1..start_scale);
+
+            cmds.entity(e).with_child((
+                Name::new("heal-particle"),
+                SceneRoot(assets.mesh_heal_particle.clone()),
+                Billboard,
+                Transform::from_translation(start_pos),
+                HealParticle {
+                    start_scale,
+                    end_scale,
+                    start_pos,
+                    end_pos,
+                    start_time: now,
+                    life_time: rng.gen_range(0.3..1.0),
+                },
+            ));
+
+            effect.next_spawn = now + rng.gen_range(0.1..0.5);
+        }
+    }
+}
+
+fn update_particles(
+    mut cmds: Commands,
+    mut query: Query<(&mut Transform, &HealParticle, Entity)>,
+    time: Res<Time>,
+) {
+    for (mut transform, particle, e) in query.iter_mut() {
+        if particle.start_time + particle.life_time < time.elapsed_secs() {
+            cmds.entity(e).despawn();
+            continue;
+        }
+
+        let t = (time.elapsed_secs() - particle.start_time) / particle.life_time;
+
+        // info!("particle[{e:?}] t: {t}");
+        transform.translation = particle.start_pos.lerp(particle.end_pos, t);
+        transform.scale = Vec3::splat(particle.start_scale.lerp(particle.end_scale, t));
+    }
+}

src/loading_assets.rs

@@ -100,6 +100,9 @@ pub struct GameAssets {
     #[asset(path = "models/cash.glb#Scene0")]
     pub mesh_cash: Handle<Scene>,
 
+    #[asset(path = "models/medic_particle.glb#Scene0")]
+    pub mesh_heal_particle: Handle<Scene>,
+
     #[asset(path = "models/projectiles", collection(mapped, typed))]
     pub projectiles: HashMap<AssetFileName, Handle<Gltf>>,
 

src/main.rs

@@ -14,6 +14,7 @@ mod head;
 mod head_drop;
 mod heads;
 mod heads_database;
+mod heal_effect;
 mod hitpoints;
 mod keys;
 mod loading_assets;
@@ -165,6 +166,7 @@ fn main() {
     app.add_plugins(water::plugin);
     app.add_plugins(head_drop::plugin);
     app.add_plugins(trail::plugin);
+    app.add_plugins(heal_effect::plugin);
 
     app.init_state::<GameState>();