Add paddle acceleration (inertia) (#4)

* Refactor game structure: move paddle logic to game module and update viewport constants for default values

* Bump version to 0.3.0 in Cargo.toml

Author: Vianpyro

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "Breakout"
-version = "0.2.0"
+version = "0.3.0"
 authors = ["Vianpyro"]
 edition = "2024"
 

src/player/mod.rs src/game/mod.rssrc/player/mod.rs renamed to src/game/mod.rs

@@ -0,0 +1,68 @@
+use crate::viewport::{DEFAULT_VIRTUAL_HEIGHT, DEFAULT_VIRTUAL_WIDTH};
+use bevy::prelude::*;
+
+const PADDLE_START_Y: f32 = -DEFAULT_VIRTUAL_HEIGHT / 2.0 + PADDLE_SIZE.y * 2.0;
+const PADDLE_SIZE: Vec2 = Vec2::new(DEFAULT_VIRTUAL_WIDTH / 15.0, DEFAULT_VIRTUAL_HEIGHT / 40.0);
+const PADDLE_COLOR: Color = Color::srgb(1.0, 1.0, 1.0);
+const PADDLE_SPEED: f32 = 650.0;
+const PADDLE_ACCELERATION: f32 = 2000.0;
+
+#[derive(Component)]
+pub struct Paddle {
+    pub velocity: f32,
+}
+
+pub fn create_paddle(mut commands: Commands, mut meshes: ResMut<Assets<Mesh>>, mut materials: ResMut<Assets<ColorMaterial>>) {
+    let paddle_mesh = meshes.add(Rectangle::new(PADDLE_SIZE.x, PADDLE_SIZE.y));
+    let paddle_material = materials.add(ColorMaterial::from(PADDLE_COLOR));
+    commands.spawn((
+        Mesh2d(paddle_mesh),
+        MeshMaterial2d(paddle_material),
+        Transform::from_translation(Vec3::new(0.0, PADDLE_START_Y, 0.0)),
+        Paddle { velocity: 0.0 },
+    ));
+}
+
+pub fn paddle_movement_system(
+    keyboard_input: Res<ButtonInput<KeyCode>>,
+    time: Res<Time>,
+    viewport: Res<crate::viewport::WindowViewport>,
+    mut query: Query<(&mut Transform, &mut Paddle), With<Paddle>>,
+) {
+    let half_world_width = viewport.half_width;
+    let delta_time = time.delta_secs();
+
+    for (mut transform, mut paddle) in query.iter_mut() {
+        let mut direction = 0.0;
+        if keyboard_input.pressed(KeyCode::ArrowLeft) {
+            direction -= 1.0;
+        }
+        if keyboard_input.pressed(KeyCode::ArrowRight) {
+            direction += 1.0;
+        }
+
+        // Apply acceleration when input is held
+        if direction != 0.0 {
+            paddle.velocity += direction * PADDLE_ACCELERATION * delta_time;
+            paddle.velocity = paddle.velocity.clamp(-PADDLE_SPEED, PADDLE_SPEED);
+        } else {
+            // Decelerate towards 0 when no input (simple friction)
+            let deceleration = PADDLE_ACCELERATION * delta_time;
+            if paddle.velocity.abs() <= deceleration {
+                paddle.velocity = 0.0;
+            } else {
+                paddle.velocity -= paddle.velocity.signum() * deceleration;
+            }
+        }
+
+        // Move by current velocity
+        transform.translation.x += paddle.velocity * delta_time;
+
+        // Clamp to world bounds
+        let half_paddle_width = PADDLE_SIZE.x / 2.0;
+        transform.translation.x = transform
+            .translation
+            .x
+            .clamp(-half_world_width + half_paddle_width, half_world_width - half_paddle_width);
+    }
+}

src/game/paddle.rs

@@ -1,6 +1,6 @@
 #![windows_subsystem = "windows"]
 
-mod player;
+mod game;
 mod viewport;
 use bevy::app::AppExit;
 use bevy::prelude::*;
@@ -9,7 +9,7 @@ use viewport::{VirtualResolution, WindowViewport};
 
 fn main() {
     App::new()
-        .insert_resource(VirtualResolution { width: 1280.0, height: 720.0 })
+        .insert_resource(VirtualResolution::default())
         .insert_resource(viewport::ScalingStrategy::AutoMin)
         .insert_resource(WindowViewport::default())
         .add_plugins(DefaultPlugins.set(WindowPlugin {
@@ -30,7 +30,7 @@ fn main() {
         )
         .add_systems(PreUpdate, exit_on_esc_system)
         .add_systems(Update, (viewport::maybe_update_window_viewport, viewport::update_camera_on_resize))
-        .add_systems(Update, player::paddle::paddle_movement_system)
+        .add_systems(Update, game::paddle::paddle_movement_system)
         .run();
 }
 
@@ -46,5 +46,5 @@ fn spawn_camera(mut commands: Commands) {
 }
 
 fn spawn_map(mut _commands: Commands, mut _meshes: ResMut<Assets<Mesh>>, mut _materials: ResMut<Assets<ColorMaterial>>) {
-    player::paddle::create_paddle(_commands, _meshes, _materials);
+    game::paddle::create_paddle(_commands, _meshes, _materials);
 }

src/main.rs

@@ -1,5 +1,10 @@
 use bevy::prelude::*;
 
+const DEFAULT_VIEWPORT_WIDTH: f32 = 1920.0;
+const DEFAULT_VIEWPORT_HEIGHT: f32 = 1080.0;
+pub const DEFAULT_VIRTUAL_WIDTH: f32 = 1280.0;
+pub const DEFAULT_VIRTUAL_HEIGHT: f32 = 720.0;
+
 // Virtual resolution (in world units) that should be visible on screen regardless
 // of the physical pixel resolution. For example, a height of 720 means the camera
 // will display 720 world units vertically; the projection scale is adjusted so
@@ -12,7 +17,10 @@ pub struct VirtualResolution {
 
 impl Default for VirtualResolution {
     fn default() -> Self {
-        Self { width: 1280.0, height: 720.0 }
+        Self {
+            width: DEFAULT_VIRTUAL_WIDTH,
+            height: DEFAULT_VIRTUAL_HEIGHT,
+        }
     }
 }
 
@@ -46,10 +54,10 @@ pub struct WindowViewport {
 impl Default for WindowViewport {
     fn default() -> Self {
         Self {
-            half_width: 1920.0 / 2.0,
-            half_height: 1080.0 / 2.0,
-            pixel_width: 1920.0,
-            pixel_height: 1080.0,
+            half_width: DEFAULT_VIEWPORT_WIDTH / 2.0,
+            half_height: DEFAULT_VIEWPORT_HEIGHT / 2.0,
+            pixel_width: DEFAULT_VIEWPORT_WIDTH,
+            pixel_height: DEFAULT_VIEWPORT_HEIGHT,
             scale: 1.0,
         }
     }