complete switch from character id to Player component as 'tag'

src/game.rs

@@ -6,7 +6,7 @@ use crate::AppState;
 use bevy::{
 	input::{keyboard::KeyCode, Input},
 	prelude::{shape::Quad, *},
-	sprite::Mesh2dHandle,
+	sprite::Mesh2dHandle, ecs::system::EntityCommands,
 };
 use bevy_rapier2d::prelude::*;
 use std::collections::BTreeSet;
@@ -34,13 +34,14 @@ impl Plugin for GamePlugin {
 			.add_system_set(
 				SystemSet::on_update(AppState::Game)
 					.with_system(crate::levels::post_setup_level)
-					.with_system(keyboard_input_system)
+					.with_system(player_movement_system)
 					.with_system(move_camera)
 					.with_system(character_particle_effect_system),
 			)
 			.add_system_set(
 				SystemSet::on_update(AppState::Win)
-					.with_system(keyboard_input_system)
+					.with_system(change_character_system)
+					.with_system(player_movement_system)
 					.with_system(move_camera)
 					.with_system(character_particle_effect_system),
 			)
@@ -79,18 +80,12 @@ impl FromWorld for CharacterMeshes {
 #[derive(Component)]
 pub struct Level;
 
-#[derive(Clone, Component, Copy, Eq, Hash, Ord, PartialEq, PartialOrd)]
-pub struct CharacterId(pub u32);
-
-#[derive(Clone, Component, Copy, Eq, Hash, PartialEq)]
-pub struct SelectedCharacterId(pub Option<CharacterId>);
-
-#[derive(Component)]
-pub struct CharacterIdList(pub BTreeSet<CharacterId>);
-
 #[derive(Clone, Component, PartialEq)]
 pub struct CharacterColor(pub Color);
 
+#[derive(Component)]
+pub struct Player;
+
 // Systems
 
 fn setup(
@@ -109,36 +104,60 @@ fn setup(
 	);
 }
 
+pub fn spawn_characters(
+	commands: &mut Commands,
+	character_meshes: &Res<CharacterMeshes>,
+	materials: &mut ResMut<Assets<ColorMaterial>>,
+	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,
+
+	transforms: &mut Vec<Transform>,
+	colors: &Vec<Color>,
+) {
+	spawn_character(
+		commands,
+		character_meshes,
+		materials,
+		audio,
+		transforms[0],
+		colors[0],
+		true,
+	);
+
+	for c in 1 .. transforms.len() {
+		spawn_character(
+			commands,
+			character_meshes,
+			materials,
+			audio,
+			transforms[c],
+			colors[c],
+			false,
+		);
+	}
+}
+
 pub fn spawn_character(
 	commands: &mut Commands,
 	character_meshes: &Res<CharacterMeshes>,
 	materials: &mut ResMut<Assets<ColorMaterial>>,
-	selected_character_id: &mut Mut<SelectedCharacterId>,
-	character_id_list: &mut Mut<CharacterIdList>,
 	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,
 	mut transform: Transform,
 	color: Color,
+	is_player: bool,
 ) {
 	transform.translation.z = transform.translation.z.max(1.0);
 
-	let character_id = CharacterId(
+	let color_mesh_2d_bundle: ColorMesh2dBundle = ColorMesh2dBundle {
-		character_id_list
+		mesh: character_meshes.square.clone(),
-			.0
+		material: materials.add(ColorMaterial::from(color)),
-			.iter()
+		transform,
-			.last()
+		..default()
-			.map_or(0, |last_character_id| last_character_id.0 + 1),
+	};
-	);
-	character_id_list.0.insert(character_id);
 
-	commands
+	let mut entity_commands: EntityCommands = commands.spawn_bundle(color_mesh_2d_bundle);
-		.spawn_bundle(ColorMesh2dBundle {
+
-			mesh: character_meshes.square.clone(),
+	entity_commands
-			material: materials.add(ColorMaterial::from(color)),
-			transform,
-			..default()
-		})
 		.insert(Level)
-		.insert(character_id)
 		.insert(CharacterColor(color))
 		.insert(RigidBody::Dynamic)
 		.insert(Collider::cuboid(32., 32.))
@@ -154,9 +173,8 @@ pub fn spawn_character(
 		.insert(ExternalImpulse::default())
 		.insert(ActiveEvents::COLLISION_EVENTS);
 
-	// If no character is selected, then select this one
+	if is_player {
-	if selected_character_id.0.is_none() {
+		entity_commands.insert(Player);
-		selected_character_id.0 = Some(character_id);
 		audio
 			.send(AudioMsg::Color([color.r(), color.g(), color.b()]))
 			.ok();
@@ -168,23 +186,16 @@ fn collision_event_system(
 	character_meshes: Res<CharacterMeshes>,
 	mut materials: ResMut<Assets<ColorMaterial>>,
 	mut collision_events: EventReader<CollisionEvent>,
-	character_query: Query<(&CharacterId, &CharacterColor, &Transform)>,
+	character_query: Query<(&CharacterColor, &Transform)>,
-	mut level_query: Query<(&mut SelectedCharacterId, &mut CharacterIdList)>,
 	mut app_state: ResMut<State<AppState>>,
 	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
 ) {
 	for collision_event in collision_events.iter() {
 		if let CollisionEvent::Started(e1, e2, flags) = collision_event {
 			if flags.is_empty() {
-				if let (Ok((c1_id, c1_color, c1_transform)), Ok((c2_id, c2_color, _c2_transform))) =
+				if let (Ok((c1_color, c1_transform)), Ok((c2_color, _c2_transform))) =
 					(character_query.get(*e1), character_query.get(*e2))
 				{
-					let (mut selected_character_id, mut character_id_list) =
-						level_query.single_mut();
-					character_id_list.0.remove(c1_id);
-					character_id_list.0.remove(c2_id);
-					selected_character_id.0 = None;
-
 					// TODO completely remove particles
 					commands.entity(*e1).despawn_recursive();
 					commands.entity(*e2).despawn_recursive();
@@ -203,11 +214,10 @@ fn collision_event_system(
 						&mut commands,
 						&character_meshes,
 						&mut materials,
-						&mut selected_character_id,
-						&mut character_id_list,
 						&audio,
 						*c1_transform,
 						new_color.into(),
+						true,
 					);
 				}
 			}
@@ -215,56 +225,67 @@ fn collision_event_system(
 	}
 }
 
-fn keyboard_input_system(
+fn change_character_system(
+	mut commands: Commands,
+
 	keyboard_input: Res<Input<KeyCode>>,
-	mut characters: Query<(&CharacterId, &mut Velocity, &CharacterColor)>,
+	characters: Query<(Entity, &Transform, &CharacterColor, Option<&Player>)>,
-	mut level_query: Query<(&mut SelectedCharacterId, &CharacterIdList)>,
+	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
+) {
+	if !keyboard_input.just_pressed(KeyCode::Tab) { return; }
+
+    let mut player_idx: usize = 0;
+    let mut player_count: usize = 0;
+
+	// find player idx
+	for (_entity, _transform, _color, player) in characters.iter() {
+		if let Some(_player) = player {
+			player_idx = player_count;
+		}
+		player_count += 1;
+	}
+
+	// calculate next player index
+	let next_player_idx = (player_idx + 1) % player_count;
+	player_count = 0;
+
+	// exchange `Player` component from old `player_idx` to new `next_player_idx`
+	for (entity, _transform, color, _player) in characters.iter() {
+		if player_count == player_idx {
+			commands.entity(entity).remove::<Player>();
+		}
+
+		if player_count == next_player_idx {
+			commands.entity(entity).insert(Player);
+			audio
+				.send(AudioMsg::Color([color.0.r(), color.0.g(), color.0.b()]))
+				.ok();
+		}
+
+		player_count += 1;
+	}
+}
+
+fn player_movement_system(
+	keyboard_input: Res<Input<KeyCode>>,
+	mut characters: Query<&mut Velocity, With<Player>>,
 	mut app_state: ResMut<State<AppState>>,
 	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
 ) {
-	if let Ok((mut selected_character_id, character_id_list)) = level_query.get_single_mut() {
-		if keyboard_input.just_pressed(KeyCode::Tab) {
-			let selected = if let Some(selected_character_id) = &mut selected_character_id.0 {
-				*selected_character_id = *character_id_list
-					.0
-					.range(*selected_character_id..)
-					.nth(1)
-					.unwrap_or_else(|| character_id_list.0.iter().next().unwrap());
-				*selected_character_id
-			} else {
-				selected_character_id.0 = Some(CharacterId(0));
-				CharacterId(0)
-			};
 
-			if let Some((_character_id, _velocity, color)) = characters
+    let right_pressed: bool =
-				.iter_mut()
+        keyboard_input.pressed(KeyCode::Right) || keyboard_input.pressed(KeyCode::D);
-				.find(|(character_id, _velocity, _color)| **character_id == selected)
+    let left_pressed: bool =
-			{
+        keyboard_input.pressed(KeyCode::Left) || keyboard_input.pressed(KeyCode::A);
-				audio
-					.send(AudioMsg::Color([color.0.r(), color.0.g(), color.0.b()]))
-					.ok();
-			}
-		}
 
-		let right_pressed: bool =
+    for mut velocity  in characters.iter_mut() {
-			keyboard_input.pressed(KeyCode::Right) || keyboard_input.pressed(KeyCode::D);
+        velocity.linvel.x = 200. * (right_pressed as i8 - left_pressed as i8) as f32;
-		let left_pressed: bool =
-			keyboard_input.pressed(KeyCode::Left) || keyboard_input.pressed(KeyCode::A);
 
-		if let Some(selected_character_id) = &selected_character_id.0 {
+        if keyboard_input.just_pressed(KeyCode::Space) {
-			if let Some((_character_id, mut velocity, _color)) = characters
+            audio.send(AudioMsg::Jump).ok();
-				.iter_mut()
+            velocity.linvel.y = 500.;
-				.find(|(character_id, _velocity, _color)| *character_id == selected_character_id)
+        }
-			{
+    }
-				velocity.linvel.x = 200. * (right_pressed as i8 - left_pressed as i8) as f32;
-
-				if keyboard_input.just_pressed(KeyCode::Space) {
-					audio.send(AudioMsg::Jump).ok();
-					velocity.linvel.y = 500.;
-				}
-			}
-		}
-	}
 
 	if app_state.current() == &AppState::Win && keyboard_input.just_pressed(KeyCode::Return) {
 		app_state.replace(AppState::Game).unwrap();
@@ -272,20 +293,12 @@ fn keyboard_input_system(
 }
 
 fn character_particle_effect_system(
-	mut characters: Query<(&CharacterId, &Transform, &CharacterColor)>,
+	characters: Query<(&Transform, &CharacterColor), With<Player>>,
 	mut particle_effect: ResMut<crate::particle_effect::ParticleEffectResource>,
-	mut level_query: Query<&SelectedCharacterId>,
 ) {
-	if let Ok(selected_character_id) = level_query.get_single_mut() {
+	for (transform, color) in characters.iter() {
-		if let Some(selected_character_id) = &selected_character_id.0 {
+		particle_effect.translation = transform.translation;
-			if let Some((_character_id, transform, color)) = characters
+		particle_effect.color = color.0;
-				.iter_mut()
-				.find(|(character_id, _transform, _color)| *character_id == selected_character_id)
-			{
-				particle_effect.translation = transform.translation;
-				particle_effect.color = color.0;
-			}
-		}
 	}
 }
 
@@ -309,29 +322,25 @@ fn win_setup(mut commands: Commands, asset_server: Res<AssetServer>) {
 
 fn move_camera(
 	mut camera_query: Query<(&Camera, &mut Transform)>,
-	characters: Query<(&CharacterId, &Transform), Without<Camera>>,
+	characters: Query<&Transform, (Without<Camera>, With<Player>)>,
-	level_query: Query<&SelectedCharacterId>,
 	time: Res<Time>,
 ) {
 	const MARGIN: f32 = 300.0;
 	const FOLLOW_SPEED: f32 = std::f32::consts::PI;
 
-	if let Ok(selected_character_id) = level_query.get_single() {
+	for character_transform in characters.iter() {
-		if let Some(selected_character_id) = &selected_character_id.0 {
+		let (camera, mut camera_transform) =
-			if let Some((_character_id, transform)) = characters
+			camera_query.single_mut();
-				.iter()
-				.find(|(character_id, _transform)| *character_id == selected_character_id)
-			{
-				let (camera, mut camera_transform) =
-					camera_query.single_mut();
 
-				let size: Vec2 = camera.logical_viewport_size().unwrap();
+		let size: Vec2 = camera.logical_viewport_size().unwrap();
-				let half_height: f32 = size.y * 0.5;
+		let half_height: f32 = size.y * 0.5;
-				camera_transform.translation = camera_transform.translation.lerp(transform.translation, time.delta_seconds() * FOLLOW_SPEED);
+		camera_transform.translation = camera_transform.translation.lerp(
-				// prevent camera from going too low
+			character_transform.translation, time.delta_seconds() * FOLLOW_SPEED
-				camera_transform.translation.y = camera_transform.translation.y.max(half_height-MARGIN);
+		);
-				camera_transform.translation.z = 999.0;
+
-			}
+		// prevent camera from going too low
-		}
+		camera_transform.translation.y = camera_transform.translation.y.max(half_height-MARGIN);
+		// always make sure that camera is away from the object in order to render them
+		camera_transform.translation.z = 999.0;
 	}
 }

src/levels.rs

@@ -7,7 +7,6 @@ mod level1;
 use crate::game::*;
 
 use bevy::prelude::*;
-use std::collections::BTreeSet;
 
 pub fn setup_level(
 	commands: &mut Commands,
@@ -19,8 +18,6 @@ pub fn setup_level(
 	let level_entity = commands
 		.spawn()
 		.insert(Level)
-		.insert(SelectedCharacterId(None))
-		.insert(CharacterIdList(BTreeSet::new()))
 		.id();
 	current_level.0 = Some(level_id);
 
@@ -41,35 +38,26 @@ pub fn post_setup_level(
 	character_meshes: Res<CharacterMeshes>,
 	mut materials: ResMut<Assets<ColorMaterial>>,
 	current_level: Res<CurrentLevel>,
-	mut level_query: Query<(&mut SelectedCharacterId, &mut CharacterIdList)>,
 	mut level_startup_event: EventReader<LevelStartupEvent>,
 	asset_server: Res<AssetServer>,
 	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
 ) {
 	for LevelStartupEvent(level_entity) in level_startup_event.iter() {
-		if let Ok((mut selected_character_id, mut character_id_list)) =
+		if let Some(level_id) = current_level.0 {
-			level_query.get_mut(*level_entity)
+			match level_id.0 {
-		{
+				0 => level0::setup(
-			if let Some(level_id) = current_level.0 {
+					&mut commands,
-				match level_id.0 {
+					&character_meshes,
-					0 => level0::setup(
+					&mut materials,
-						&mut commands,
+					&audio,
-						&character_meshes,
+				),
-						&mut materials,
+				1 => level1::setup(
-						&mut selected_character_id,
+					&mut commands,
-						&mut character_id_list,
+					&character_meshes,
-						&audio,
+					&mut materials,
-					),
+					&audio,
-					1 => level1::setup(
+				),
-						&mut commands,
+				_ => game_over::setup(&mut commands, &asset_server),
-						&character_meshes,
-						&mut materials,
-						&mut selected_character_id,
-						&mut character_id_list,
-						&audio,
-					),
-					_ => game_over::setup(&mut commands, &asset_server),
-				}
 			}
 		}
 	}

src/levels/level0.rs

@@ -7,8 +7,8 @@ pub fn setup(
 	commands: &mut Commands,
 	character_meshes: &Res<CharacterMeshes>,
 	materials: &mut ResMut<Assets<ColorMaterial>>,
-	selected_character_id: &mut Mut<SelectedCharacterId>,
+	// selected_character_id: &mut Mut<SelectedCharacterId>,
-	character_id_list: &mut Mut<CharacterIdList>,
+	// character_id_list: &mut Mut<CharacterIdList>,
 	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,
 ) {
 	commands
@@ -20,30 +20,27 @@ pub fn setup(
 		commands,
 		character_meshes,
 		materials,
-		selected_character_id,
-		character_id_list,
 		audio,
 		Transform::from_xyz(-128., -64., 0.),
 		Color::RED,
+        true,
 	);
 	spawn_character(
 		commands,
 		character_meshes,
 		materials,
-		selected_character_id,
-		character_id_list,
 		audio,
 		Transform::from_xyz(0., -64., 0.),
 		Color::GREEN,
+		false,
 	);
 	spawn_character(
 		commands,
 		character_meshes,
 		materials,
-		selected_character_id,
-		character_id_list,
 		audio,
 		Transform::from_xyz(128., -64., 0.),
 		Color::BLUE,
+		false,
 	);
 }

src/levels/level1.rs

@@ -7,8 +7,6 @@ pub fn setup(
 	commands: &mut Commands,
 	character_meshes: &Res<CharacterMeshes>,
 	materials: &mut ResMut<Assets<ColorMaterial>>,
-	selected_character_id: &mut Mut<SelectedCharacterId>,
-	character_id_list: &mut Mut<CharacterIdList>,
 	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,
 ) {
 	commands
@@ -26,30 +24,27 @@ pub fn setup(
 		commands,
 		character_meshes,
 		materials,
-		selected_character_id,
-		character_id_list,
 		audio,
 		Transform::from_xyz(128., 64., 0.),
 		Color::BLUE,
+        true,
 	);
 	spawn_character(
 		commands,
 		character_meshes,
 		materials,
-		selected_character_id,
-		character_id_list,
 		audio,
 		Transform::from_xyz(-128., -128., 0.),
 		Color::RED,
+		false,
 	);
 	spawn_character(
 		commands,
 		character_meshes,
 		materials,
-		selected_character_id,
-		character_id_list,
 		audio,
 		Transform::from_xyz(0., -128., 0.),
 		Color::GREEN,
+		false,
 	);
 }