Add anthilll + ants spawning from it over time

src/systems/anthill.rs

@@ -0,0 +1,72 @@
+use bevy::prelude::*;
+use rand::Rng;
+
+use crate::{
+    components::{
+        ant::AntBundle,
+        anthill::{AntCapacity, GroupSize, SpawnTimer},
+        common::AnimationIndices,
+    },
+    ANT_COUNT, ANT_SCALE,
+};
+
+#[allow(clippy::needless_pass_by_value)]
+pub fn leave_anthill_system(
+    mut query: Query<(&mut AntCapacity, &GroupSize, &mut SpawnTimer)>,
+    mut commands: Commands,
+    time: Res<Time>,
+    asset_server: Res<AssetServer>,
+    mut texture_atlas_layouts: ResMut<Assets<TextureAtlasLayout>>,
+) {
+    for (mut capacity, group_size, mut timer) in &mut query {
+        timer.0.tick(time.delta());
+
+        // Anthill empty :(
+        if capacity.0 == 0 {
+            continue;
+        }
+
+        // Each timer period we want to spawn between 1 and group_size ants
+        if timer.0.just_finished() {
+            let num_ants: u32 = rand::thread_rng()
+                .gen_range(1..group_size.0)
+                .clamp(1, capacity.0);
+
+            for _ in 0..num_ants {
+                spawn_cute_ant(&mut commands, &asset_server, &mut texture_atlas_layouts);
+            }
+
+            capacity.0 -= num_ants;
+            println!(
+                "Spawned {} cute ants 😍, {} ants are still at home 🏠",
+                num_ants, capacity.0
+            );
+        }
+    }
+}
+
+fn spawn_cute_ant(
+    commands: &mut Commands,
+    asset_server: &Res<AssetServer>,
+    texture_atlas_layouts: &mut ResMut<Assets<TextureAtlasLayout>>,
+) {
+    // https://github.com/bevyengine/bevy/blob/latest/examples/2d/sprite_sheet.rs
+    let texture: Handle<Image> = asset_server.load("sprites/ant_walk_anim.png");
+    let layout = TextureAtlasLayout::from_grid(UVec2::new(202, 248), 8, 8, None, None);
+    let texture_atlas_layout = texture_atlas_layouts.add(layout);
+    let animation_indices = AnimationIndices { first: 0, last: 61 };
+    let texture_atlas = TextureAtlas {
+        layout: texture_atlas_layout,
+        index: rand::thread_rng().gen_range(animation_indices.first..=animation_indices.last),
+    };
+
+    commands.spawn(AntBundle::new(
+        Vec2::ZERO,
+        texture,
+        texture_atlas,
+        animation_indices,
+        Vec2::splat(ANT_SCALE),
+    ));
+}
+
+pub fn enter_anthill_system() {}