Added breakout example code

Plus ability to swtich

src/breakout.rs

@@ -0,0 +1,423 @@
+
+//! A simplified implementation of the classic game "Breakout".
+
+use bevy::{
+    prelude::*,
+    sprite::collide_aabb::{collide, Collision},
+    sprite::MaterialMesh2dBundle,
+};
+
+// Defines the amount of time that should elapse between each physics step.
+const TIME_STEP: f32 = 1.0 / 60.0;
+
+// These constants are defined in `Transform` units.
+// Using the default 2D camera they correspond 1:1 with screen pixels.
+const PADDLE_SIZE: Vec3 = Vec3::new(120.0, 20.0, 0.0);
+const GAP_BETWEEN_PADDLE_AND_FLOOR: f32 = 60.0;
+const PADDLE_SPEED: f32 = 500.0;
+// How close can the paddle get to the wall
+const PADDLE_PADDING: f32 = 10.0;
+
+// We set the z-value of the ball to 1 so it renders on top in the case of overlapping sprites.
+const BALL_STARTING_POSITION: Vec3 = Vec3::new(0.0, -50.0, 1.0);
+const BALL_SIZE: Vec3 = Vec3::new(30.0, 30.0, 0.0);
+const BALL_SPEED: f32 = 400.0;
+const INITIAL_BALL_DIRECTION: Vec2 = Vec2::new(0.5, -0.5);
+
+const WALL_THICKNESS: f32 = 10.0;
+// x coordinates
+const LEFT_WALL: f32 = -450.;
+const RIGHT_WALL: f32 = 450.;
+// y coordinates
+const BOTTOM_WALL: f32 = -300.;
+const TOP_WALL: f32 = 300.;
+
+const BRICK_SIZE: Vec2 = Vec2::new(100., 30.);
+// These values are exact
+const GAP_BETWEEN_PADDLE_AND_BRICKS: f32 = 270.0;
+const GAP_BETWEEN_BRICKS: f32 = 5.0;
+// These values are lower bounds, as the number of bricks is computed
+const GAP_BETWEEN_BRICKS_AND_CEILING: f32 = 20.0;
+const GAP_BETWEEN_BRICKS_AND_SIDES: f32 = 20.0;
+
+const SCOREBOARD_FONT_SIZE: f32 = 40.0;
+const SCOREBOARD_TEXT_PADDING: Val = Val::Px(5.0);
+
+const BACKGROUND_COLOR: Color = Color::rgb(0.9, 0.9, 0.9);
+const PADDLE_COLOR: Color = Color::rgb(0.3, 0.3, 0.7);
+const BALL_COLOR: Color = Color::rgb(1.0, 0.5, 0.5);
+const BRICK_COLOR: Color = Color::rgb(0.5, 0.5, 1.0);
+const WALL_COLOR: Color = Color::rgb(0.8, 0.8, 0.8);
+const TEXT_COLOR: Color = Color::rgb(0.5, 0.5, 1.0);
+const SCORE_COLOR: Color = Color::rgb(1.0, 0.5, 0.5);
+
+pub fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .insert_resource(Scoreboard { score: 0 })
+        .insert_resource(ClearColor(BACKGROUND_COLOR))
+        .add_startup_system(setup)
+        .add_event::<CollisionEvent>()
+        // Add our gameplay simulation systems to the fixed timestep schedule
+        .add_systems(
+            (
+                check_for_collisions,
+                apply_velocity.before(check_for_collisions),
+                move_paddle
+                    .before(check_for_collisions)
+                    .after(apply_velocity),
+                play_collision_sound.after(check_for_collisions),
+            )
+                .in_schedule(CoreSchedule::FixedUpdate),
+        )
+        // Configure how frequently our gameplay systems are run
+        .insert_resource(FixedTime::new_from_secs(TIME_STEP))
+        .add_system(update_scoreboard)
+        .add_system(bevy::window::close_on_esc)
+        .run();
+}
+
+#[derive(Component)]
+struct Paddle;
+
+#[derive(Component)]
+struct Ball;
+
+#[derive(Component, Deref, DerefMut)]
+struct Velocity(Vec2);
+
+#[derive(Component)]
+struct Collider;
+
+#[derive(Default)]
+struct CollisionEvent;
+
+#[derive(Component)]
+struct Brick;
+
+#[derive(Resource)]
+struct CollisionSound(Handle<AudioSource>);
+
+// This bundle is a collection of the components that define a "wall" in our game
+#[derive(Bundle)]
+struct WallBundle {
+    // You can nest bundles inside of other bundles like this
+    // Allowing you to compose their functionality
+    sprite_bundle: SpriteBundle,
+    collider: Collider,
+}
+
+/// Which side of the arena is this wall located on?
+enum WallLocation {
+    Left,
+    Right,
+    Bottom,
+    Top,
+}
+
+impl WallLocation {
+    fn position(&self) -> Vec2 {
+        match self {
+            WallLocation::Left => Vec2::new(LEFT_WALL, 0.),
+            WallLocation::Right => Vec2::new(RIGHT_WALL, 0.),
+            WallLocation::Bottom => Vec2::new(0., BOTTOM_WALL),
+            WallLocation::Top => Vec2::new(0., TOP_WALL),
+        }
+    }
+
+    fn size(&self) -> Vec2 {
+        let arena_height = TOP_WALL - BOTTOM_WALL;
+        let arena_width = RIGHT_WALL - LEFT_WALL;
+        // Make sure we haven't messed up our constants
+        assert!(arena_height > 0.0);
+        assert!(arena_width > 0.0);
+
+        match self {
+            WallLocation::Left | WallLocation::Right => {
+                Vec2::new(WALL_THICKNESS, arena_height + WALL_THICKNESS)
+            }
+            WallLocation::Bottom | WallLocation::Top => {
+                Vec2::new(arena_width + WALL_THICKNESS, WALL_THICKNESS)
+            }
+        }
+    }
+}
+
+impl WallBundle {
+    // This "builder method" allows us to reuse logic across our wall entities,
+    // making our code easier to read and less prone to bugs when we change the logic
+    fn new(location: WallLocation) -> WallBundle {
+        WallBundle {
+            sprite_bundle: SpriteBundle {
+                transform: Transform {
+                    // We need to convert our Vec2 into a Vec3, by giving it a z-coordinate
+                    // This is used to determine the order of our sprites
+                    translation: location.position().extend(0.0),
+                    // The z-scale of 2D objects must always be 1.0,
+                    // or their ordering will be affected in surprising ways.
+                    // See https://github.com/bevyengine/bevy/issues/4149
+                    scale: location.size().extend(1.0),
+                    ..default()
+                },
+                sprite: Sprite {
+                    color: WALL_COLOR,
+                    ..default()
+                },
+                ..default()
+            },
+            collider: Collider,
+        }
+    }
+}
+
+// This resource tracks the game's score
+#[derive(Resource)]
+struct Scoreboard {
+    score: usize,
+}
+
+// Add the game's entities to our world
+fn setup(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<ColorMaterial>>,
+    asset_server: Res<AssetServer>,
+) {
+    // Camera
+    commands.spawn(Camera2dBundle::default());
+
+    // Sound
+    let ball_collision_sound = asset_server.load("sounds/breakout_collision.ogg");
+    commands.insert_resource(CollisionSound(ball_collision_sound));
+
+    // Paddle
+    let paddle_y = BOTTOM_WALL + GAP_BETWEEN_PADDLE_AND_FLOOR;
+
+    commands.spawn((
+        SpriteBundle {
+            transform: Transform {
+                translation: Vec3::new(0.0, paddle_y, 0.0),
+                scale: PADDLE_SIZE,
+                ..default()
+            },
+            sprite: Sprite {
+                color: PADDLE_COLOR,
+                ..default()
+            },
+            ..default()
+        },
+        Paddle,
+        Collider,
+    ));
+
+    // Ball
+    commands.spawn((
+        MaterialMesh2dBundle {
+            mesh: meshes.add(shape::Circle::default().into()).into(),
+            material: materials.add(ColorMaterial::from(BALL_COLOR)),
+            transform: Transform::from_translation(BALL_STARTING_POSITION).with_scale(BALL_SIZE),
+            ..default()
+        },
+        Ball,
+        Velocity(INITIAL_BALL_DIRECTION.normalize() * BALL_SPEED),
+    ));
+
+    // Scoreboard
+    commands.spawn(
+        TextBundle::from_sections([
+            TextSection::new(
+                "Score: ",
+                TextStyle {
+                    font: asset_server.load("fonts/FiraSans-Bold.ttf"),
+                    font_size: SCOREBOARD_FONT_SIZE,
+                    color: TEXT_COLOR,
+                },
+            ),
+            TextSection::from_style(TextStyle {
+                font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+                font_size: SCOREBOARD_FONT_SIZE,
+                color: SCORE_COLOR,
+            }),
+        ])
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            position: UiRect {
+                top: SCOREBOARD_TEXT_PADDING,
+                left: SCOREBOARD_TEXT_PADDING,
+                ..default()
+            },
+            ..default()
+        }),
+    );
+
+    // Walls
+    commands.spawn(WallBundle::new(WallLocation::Left));
+    commands.spawn(WallBundle::new(WallLocation::Right));
+    commands.spawn(WallBundle::new(WallLocation::Bottom));
+    commands.spawn(WallBundle::new(WallLocation::Top));
+
+    // Bricks
+    // Negative scales result in flipped sprites / meshes,
+    // which is definitely not what we want here
+    assert!(BRICK_SIZE.x > 0.0);
+    assert!(BRICK_SIZE.y > 0.0);
+
+    let total_width_of_bricks = (RIGHT_WALL - LEFT_WALL) - 2. * GAP_BETWEEN_BRICKS_AND_SIDES;
+    let bottom_edge_of_bricks = paddle_y + GAP_BETWEEN_PADDLE_AND_BRICKS;
+    let total_height_of_bricks = TOP_WALL - bottom_edge_of_bricks - GAP_BETWEEN_BRICKS_AND_CEILING;
+
+    assert!(total_width_of_bricks > 0.0);
+    assert!(total_height_of_bricks > 0.0);
+
+    // Given the space available, compute how many rows and columns of bricks we can fit
+    let n_columns = (total_width_of_bricks / (BRICK_SIZE.x + GAP_BETWEEN_BRICKS)).floor() as usize;
+    let n_rows = (total_height_of_bricks / (BRICK_SIZE.y + GAP_BETWEEN_BRICKS)).floor() as usize;
+    let n_vertical_gaps = n_columns - 1;
+
+    // Because we need to round the number of columns,
+    // the space on the top and sides of the bricks only captures a lower bound, not an exact value
+    let center_of_bricks = (LEFT_WALL + RIGHT_WALL) / 2.0;
+    let left_edge_of_bricks = center_of_bricks
+        // Space taken up by the bricks
+        - (n_columns as f32 / 2.0 * BRICK_SIZE.x)
+        // Space taken up by the gaps
+        - n_vertical_gaps as f32 / 2.0 * GAP_BETWEEN_BRICKS;
+
+    // In Bevy, the `translation` of an entity describes the center point,
+    // not its bottom-left corner
+    let offset_x = left_edge_of_bricks + BRICK_SIZE.x / 2.;
+    let offset_y = bottom_edge_of_bricks + BRICK_SIZE.y / 2.;
+
+    for row in 0..n_rows {
+        for column in 0..n_columns {
+            let brick_position = Vec2::new(
+                offset_x + column as f32 * (BRICK_SIZE.x + GAP_BETWEEN_BRICKS),
+                offset_y + row as f32 * (BRICK_SIZE.y + GAP_BETWEEN_BRICKS),
+            );
+
+            // brick
+            commands.spawn((
+                SpriteBundle {
+                    sprite: Sprite {
+                        color: BRICK_COLOR,
+                        ..default()
+                    },
+                    transform: Transform {
+                        translation: brick_position.extend(0.0),
+                        scale: Vec3::new(BRICK_SIZE.x, BRICK_SIZE.y, 1.0),
+                        ..default()
+                    },
+                    ..default()
+                },
+                Brick,
+                Collider,
+            ));
+        }
+    }
+}
+
+fn move_paddle(
+    keyboard_input: Res<Input<KeyCode>>,
+    mut query: Query<&mut Transform, With<Paddle>>,
+) {
+    let mut paddle_transform = query.single_mut();
+    let mut direction = 0.0;
+
+    if keyboard_input.pressed(KeyCode::Left) {
+        direction -= 1.0;
+    }
+
+    if keyboard_input.pressed(KeyCode::Right) {
+        direction += 1.0;
+    }
+
+    // Calculate the new horizontal paddle position based on player input
+    let new_paddle_position = paddle_transform.translation.x + direction * PADDLE_SPEED * TIME_STEP;
+
+    // Update the paddle position,
+    // making sure it doesn't cause the paddle to leave the arena
+    let left_bound = LEFT_WALL + WALL_THICKNESS / 2.0 + PADDLE_SIZE.x / 2.0 + PADDLE_PADDING;
+    let right_bound = RIGHT_WALL - WALL_THICKNESS / 2.0 - PADDLE_SIZE.x / 2.0 - PADDLE_PADDING;
+
+    paddle_transform.translation.x = new_paddle_position.clamp(left_bound, right_bound);
+}
+
+fn apply_velocity(mut query: Query<(&mut Transform, &Velocity)>) {
+    for (mut transform, velocity) in &mut query {
+        transform.translation.x += velocity.x * TIME_STEP;
+        transform.translation.y += velocity.y * TIME_STEP;
+    }
+}
+
+fn update_scoreboard(scoreboard: Res<Scoreboard>, mut query: Query<&mut Text>) {
+    let mut text = query.single_mut();
+    text.sections[1].value = scoreboard.score.to_string();
+}
+
+fn check_for_collisions(
+    mut commands: Commands,
+    mut scoreboard: ResMut<Scoreboard>,
+    mut ball_query: Query<(&mut Velocity, &Transform), With<Ball>>,
+    collider_query: Query<(Entity, &Transform, Option<&Brick>), With<Collider>>,
+    mut collision_events: EventWriter<CollisionEvent>,
+) {
+    let (mut ball_velocity, ball_transform) = ball_query.single_mut();
+    let ball_size = ball_transform.scale.truncate();
+
+    // check collision with walls
+    for (collider_entity, transform, maybe_brick) in &collider_query {
+        let collision = collide(
+            ball_transform.translation,
+            ball_size,
+            transform.translation,
+            transform.scale.truncate(),
+        );
+        if let Some(collision) = collision {
+            // Sends a collision event so that other systems can react to the collision
+            collision_events.send_default();
+
+            // Bricks should be despawned and increment the scoreboard on collision
+            if maybe_brick.is_some() {
+                scoreboard.score += 1;
+                commands.entity(collider_entity).despawn();
+            }
+
+            // reflect the ball when it collides
+            let mut reflect_x = false;
+            let mut reflect_y = false;
+
+            // only reflect if the ball's velocity is going in the opposite direction of the
+            // collision
+            match collision {
+                Collision::Left => reflect_x = ball_velocity.x > 0.0,
+                Collision::Right => reflect_x = ball_velocity.x < 0.0,
+                Collision::Top => reflect_y = ball_velocity.y < 0.0,
+                Collision::Bottom => reflect_y = ball_velocity.y > 0.0,
+                Collision::Inside => { /* do nothing */ }
+            }
+
+            // reflect velocity on the x-axis if we hit something on the x-axis
+            if reflect_x {
+                ball_velocity.x = -ball_velocity.x;
+            }
+
+            // reflect velocity on the y-axis if we hit something on the y-axis
+            if reflect_y {
+                ball_velocity.y = -ball_velocity.y;
+            }
+        }
+    }
+}
+
+fn play_collision_sound(
+    mut collision_events: EventReader<CollisionEvent>,
+    audio: Res<Audio>,
+    sound: Res<CollisionSound>,
+) {
+    // Play a sound once per frame if a collision occurred.
+    if !collision_events.is_empty() {
+        // This prevents events staying active on the next frame.
+        collision_events.clear();
+        audio.play(sound.0.clone());
+    }
+}

src/main.rs

@@ -1,3 +1,5 @@
+mod breakout;
+
 use bevy::prelude::*;
 use bevy::sprite::MaterialMesh2dBundle;
 
@@ -39,6 +41,17 @@ fn greetings(query: Query<&Name, With<Person>>, time: Res<Time>, mut timer: ResM
 
 
 fn main() {
+    let args: Vec<String> = std::env::args().collect();
+
+    match args.get(1) {
+        Some(s) if s == "1" => traditional_main(),
+        Some(s) if s == "2" => breakout::main(),
+        _ => panic!("Pick 1 or 2")
+    }
+
+}
+
+fn traditional_main() {
     App::new()
         .add_plugins(DefaultPlugins)
         .add_plugin(GamarjobaPlugin)