💎 destroy minions that are too old (avoid leak)

Author: fabienjuif

src/minions.rs

@@ -1,25 +1,28 @@
 use crate::common::*;
 use bevy::{
     prelude::{
-        trace, App, Color, Commands, Component, DespawnRecursiveExt, Entity, Plugin, Query, Res,
+        trace, App, Commands, Component, DespawnRecursiveExt, Entity, Plugin, Query, Res,
         Transform, Update, Vec2, With, Without,
     },
     sprite::{Sprite, SpriteBundle},
-    time::Time,
+    time::{Time, Timer},
     utils::default,
 };
 use rand::Rng;
 
 const MINION_SCALE: f32 = 100.;
+const DESTROY_MINIONS_AFTER_SECS: f32 = 120.;
 
 pub struct MinionsPlugin;
 
 #[derive(Component)]
-struct Minion;
+struct Minion {
+    destroy_timer: Timer,
+}
 
 impl Plugin for MinionsPlugin {
     fn build(&self, app: &mut App) {
-        app.add_systems(Update, update_move_minions);
+        app.add_systems(Update, (update_move_minions, destroy_minions));
     }
 }
 
@@ -42,7 +45,14 @@ pub fn spawn_minion(commands: &mut Commands, transform: &Transform, team: Team)
                 ),
                 ..default()
             },
-            Minion {},
+            Minion {
+                // to avoid leaks
+                // maybe a better option on top of that is to leach health every seconds on minions and make them die!
+                destroy_timer: Timer::from_seconds(
+                    DESTROY_MINIONS_AFTER_SECS,
+                    bevy::time::TimerMode::Once,
+                ),
+            },
             team,
         ))
         .id();
@@ -51,24 +61,14 @@ pub fn spawn_minion(commands: &mut Commands, transform: &Transform, team: Team)
 }
 
 fn update_move_minions(
-    mut commands: Commands,
     time: Res<Time>,
     // if we want minion to move over other minions later, maybe we want something like this instead of having 2 queries
     //      let mut combinations = query.iter_combinations_mut();
     //      while let Some([mut a, mut b]) = combinations.fetch_next() {
-    mut query: Query<(&mut Transform, Entity, &Team), With<Minion>>,
+    mut query: Query<(&mut Transform, &Team), With<Minion>>,
     query_targets: Query<(&mut Transform, &Team), Without<Minion>>,
 ) {
-    for (mut transform, entity, team) in &mut query {
-        // unspawn minions time to time
-        if transform.translation.x.abs() >= GAME_MAX_WIDTH / 2.
-            || transform.translation.y.abs() >= GAME_MAX_HEIGHT / 2.
-        {
-            trace!("Unspawning Minion: {:?}", entity);
-            commands.entity(entity).despawn_recursive();
-            continue;
-        }
-
+    for (mut transform, team) in &mut query {
         // acquire new target
         let mut closer_target: &Transform = &Transform::from_xyz(0., 0., 0.);
         let mut found_target = false;
@@ -105,3 +105,21 @@ fn update_move_minions(
             time.delta_seconds() * MINION_SCALE * normalized_target_position.y;
     }
 }
+
+fn destroy_minions(
+    time: Res<Time>,
+    mut commands: Commands,
+    mut query: Query<(&mut Minion, &Transform, Entity)>,
+) {
+    for (mut minion, transform, entity) in &mut query {
+        let escape_edges_of_the_world = transform.translation.x.abs() >= GAME_MAX_WIDTH / 2.
+            || transform.translation.y.abs() >= GAME_MAX_HEIGHT / 2.;
+        let too_old = minion.destroy_timer.tick(time.delta()).just_finished();
+
+        if escape_edges_of_the_world || too_old {
+            trace!("Unspawning Minion: {:?}", entity);
+            commands.entity(entity).despawn_recursive();
+            continue;
+        }
+    }
+}