Orbits

main.rs

use bevy::prelude::*;

#[derive(Component, Debug)]
struct SectorPosition(Vec3);

#[derive(Component, Debug)]
struct ShipVelocity(Vec3);

#[derive(Component)]
struct ShipFactionHuman;

#[derive(Component)]
struct ShipFactionAlien;

#[derive(Default, Reflect, GizmoConfigGroup)]
struct MyRoundGizmos {}

fn main() {
	App::new()
		.add_plugins(DefaultPlugins)
		.init_gizmo_group::<MyRoundGizmos>()
		.add_systems(Startup, setup_map)
		.add_systems(Update, ship_combat)
		.add_systems(Update, ship_move)
		.run();
}

fn setup_map(mut commands: Commands) {
	commands.spawn(Camera3dBundle {
		transform: Transform::from_xyz(10., 20.0, 10.0).looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
		..default()
	});

	/// Ships
	commands.spawn((
		ShipFactionHuman,
		SectorPosition(Vec3::new(1.0, 0.0, 1.0)),
		ShipVelocity(Vec3::ZERO)
	));
	commands.spawn((
		ShipFactionAlien,
		SectorPosition(Vec3::new(0.0, 0.0, 0.0)),
		ShipVelocity(Vec3::ZERO)
	));
}

fn ship_move(
	mut query: Query<(&ShipVelocity, &mut SectorPosition)>,
	mut gizmos: Gizmos,
	mut my_gizmos: Gizmos<MyRoundGizmos>,
	time: Res<Time>
) {

	let mut col = Color::ORANGE;
	for (velo, mut pos) in &mut query {
		pos.0 += velo.0 * time.delta_seconds();

		my_gizmos
			.sphere(pos.0, Quat::IDENTITY, 1.0, col)
			.circle_segments(64);

		col = Color::NAVY;
	}
}

fn ship_combat(
	mut human_query: Query<(&SectorPosition, &mut ShipVelocity), (With<ShipFactionHuman>, Without<ShipFactionAlien>)>,
	mut alien_query: Query<(&SectorPosition, &mut ShipVelocity), (With<ShipFactionAlien>, Without<ShipFactionHuman>)>,
) {
	for (human_position, mut human_velocity) in &mut human_query {
		for (alien_position, mut alien_velocity) in &mut alien_query {
			let pos_diff = human_position.0 - alien_position.0;
			let cross = pos_diff.normalize().cross(Vec3::Y);
			human_velocity.0 = cross.normalize() * 20.0;

			let pos_diff = alien_position.0 - human_position.0;
			let cross = pos_diff.normalize().cross(Vec3::Y);
			alien_velocity.0 = cross.normalize() * 20.0;
		}
	}
}