From cb83511eabc1d4af64904c154ee06deed4560c21 Mon Sep 17 00:00:00 2001
From: Amatsugu <khamraj@kaisei.app>
Date: Fri, 1 Mar 2024 00:06:56 -0500
Subject: [PATCH] working-ish boids

---
 Cargo.lock   |  14 ++---
 src/boids.rs | 145 +++++++++++++++++++++++++++++++++++++++++++--------
 src/main.rs  |  20 ++++++-
 3 files changed, 148 insertions(+), 31 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 9996460..59129db 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2957,6 +2957,13 @@ dependencies = [
  "serde_derive",
 ]
 
+[[package]]
+name = "rust-boids"
+version = "0.1.0"
+dependencies = [
+ "bevy",
+]
+
 [[package]]
 name = "rustc-hash"
 version = "1.1.0"
@@ -3174,13 +3181,6 @@ dependencies = [
  "winapi-util",
 ]
 
-[[package]]
-name = "test-game"
-version = "0.1.0"
-dependencies = [
- "bevy",
-]
-
 [[package]]
 name = "thiserror"
 version = "1.0.57"
diff --git a/src/boids.rs b/src/boids.rs
index 7bee559..abef83d 100644
--- a/src/boids.rs
+++ b/src/boids.rs
@@ -1,43 +1,142 @@
-use bevy::prelude::*;
+use bevy::{
+	prelude::*,
+	sprite::{MaterialMesh2dBundle, Mesh2dHandle},
+	window::PrimaryWindow,
+};
 pub struct Boids;
 
 impl Plugin for Boids {
 	fn build(&self, app: &mut App) {
-		app.insert_resource(PrintTimer(Timer::from_seconds(2.0, TimerMode::Repeating)))
-			.add_systems(Startup, add_boids)
-			.add_systems(Update, (update_boid, print_boid).chain());
+		app.insert_resource(ClearColor(Color::rgb(0.09, 0., 0.0390625)))
+			.add_systems(Startup, init)
+			.add_systems(Update, (update_boid_vel, wrap_boids, simulate_boids));
 	}
 }
 
-fn print_boid(time: Res<Time>, mut timer: ResMut<PrintTimer>, query: Query<&Name, With<Boid>>) {
-	if !timer.0.tick(time.delta()).just_finished() {
-		return;
+fn simulate_boids(time: Res<Time>, mut boids: Query<(&Transform, &mut Vel), With<Boid>>) {
+	let mut combos = boids.iter_combinations_mut();
+	while let Some([mut a, mut b]) = combos.fetch_next() {
+		let mut a_total_vel = a.1.value;
+		let mut b_total_vel = b.1.value;
+		//Match Speed
+		let avg_vel = (a.1.value + b.1.value) / 2.;
+		a_total_vel += ((avg_vel - a_total_vel) / 8.) * time.delta_seconds();
+		b_total_vel -= ((avg_vel - b_total_vel) / 8.) * time.delta_seconds();
+
+		//Collision Avoidance
+		let dist = a.0.translation - b.0.translation;
+		if dist.length_squared() < 50. * 50. {
+			a_total_vel += dist * time.elapsed_seconds();
+			b_total_vel += -dist * time.elapsed_seconds();
+		} else {
+			//Flocking
+			let avg = (a.0.translation + b.0.translation) / 2.;
+			a_total_vel -= avg * 0.05 * time.elapsed_seconds();
+			b_total_vel += avg * 0.05 * time.elapsed_seconds();
+		}
+
+		// println!("{}", a_total_vel.length());
+		a.1.value = a_total_vel;
+		b.1.value = b_total_vel;
 	}
-	for name in &query {
-		println!("{}", name.0);
+
+	for (t, mut v) in &mut boids {
+		//Tend to Center
+		if t.translation.length_squared() > 500. * 500. {
+			v.value += -t.translation * time.elapsed_seconds() * 0.3;
+		}
+
+		//Limit Velocity
+		if v.value == Vec3::ZERO {
+			continue;
+		}
+		v.value = limit_velocity(&v);
 	}
 }
 
-fn update_boid(mut query: Query<&mut Name, With<Boid>>) {
-	for mut name in &mut query {
-		if name.0 == "B1" {
-			name.0 = "B1.Updated".to_string();
-			break;
+fn limit_velocity(v: &Vel) -> Vec3 {
+	let max_speed = 200.;
+	if v.value.length_squared() > max_speed * max_speed {
+		return v.value.normalize() * max_speed;
+	}
+	return v.value;
+}
+
+fn update_boid_vel(time: Res<Time>, mut query: Query<(&mut Transform, &Vel), With<Boid>>) {
+	for (mut t, v) in &mut query {
+		t.translation += v.value * time.delta_seconds();
+		if v.value == Vec3::ZERO {
+			continue;
+		}
+		t.rotation = Quat::from_rotation_arc(Vec3::Y, v.value.normalize());
+	}
+}
+
+fn wrap_boids(
+	cam_query: Query<(&Camera, &GlobalTransform)>,
+	window: Query<&Window, With<PrimaryWindow>>,
+	mut boids: Query<(&mut Transform, &mut Vel), With<Boid>>,
+) {
+	let (cam, cam_pos) = cam_query.single();
+	let w = window.single();
+	let (min, max) = (
+		cam.viewport_to_world_2d(cam_pos, (0., w.height()).into())
+			.unwrap(),
+		cam.viewport_to_world_2d(cam_pos, (w.width(), 0.).into())
+			.unwrap(),
+	);
+
+	for (mut t, mut v) in &mut boids {
+		if t.translation.x < min.x || t.translation.x > max.x {
+			v.value.x = -v.value.x;
+		}
+		if t.translation.y < min.y || t.translation.y > max.y {
+			v.value.y = -v.value.y;
+		}
+
+		t.translation = t.translation.min(max.extend(0.)).max(min.extend(0.));
+	}
+}
+
+fn init(
+	mut commands: Commands,
+	mut meshes: ResMut<Assets<Mesh>>,
+	mut materials: ResMut<Assets<ColorMaterial>>,
+) {
+	commands.spawn(Camera2dBundle::default());
+
+	let size = 20;
+
+	for x in 0..size {
+		for y in 0..size {
+			let shape = Mesh2dHandle(meshes.add(Triangle2d::new(
+				Vec2::Y * 5.0,
+				Vec2::new(-5.0, -5.0),
+				Vec2::new(5.0, -5.0),
+			)));
+			let color = Color::hsl(360.0 * x as f32 / 10.0, 0.75, 0.7);
+			commands.spawn((
+				Boid,
+				Vel { value: Vec3::ZERO },
+				Name(format!("B{x}").into()),
+				MaterialMesh2dBundle {
+					mesh: shape,
+					material: materials.add(color),
+					transform: Transform::from_xyz(x as f32 * 8.0, y as f32 * 8.0, 0.0),
+					..default()
+				},
+			));
 		}
 	}
 }
 
-fn add_boids(mut commands: Commands) {
-	commands.spawn((Boid, Name("B1".to_string())));
-	commands.spawn((Boid, Name("B2".to_string())));
-	commands.spawn((Boid, Name("B3".to_string())));
-}
-
-#[derive(Resource)]
-struct PrintTimer(Timer);
-
 #[derive(Component)]
 struct Boid;
 
 #[derive(Component)]
 struct Name(String);
+
+#[derive(Component)]
+struct Vel {
+	pub value: Vec3,
+}
diff --git a/src/main.rs b/src/main.rs
index 496d2e4..a6caf80 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,5 +2,23 @@ use bevy::prelude::*;
 mod boids;
 
 fn main() {
-	App::new().add_plugins((DefaultPlugins, boids::Boids)).run();
+	App::new()
+		.add_plugins((
+			DefaultPlugins.set(WindowPlugin {
+				primary_window: Some(Window {
+					title: "Boids".into(),
+					name: Some("rest.boids".into()),
+					resolution: (1920.0, 1080.0).into(),
+					resizable: false,
+					enabled_buttons: bevy::window::EnabledButtons{
+						maximize: false,
+						..Default::default()
+					},
+					..default()
+				}),
+				..default()
+			}),
+			boids::Boids,
+		))
+		.run();
 }