crates/border-wars/src/camera.rs

@@ -0,0 +1,123 @@
+//! This module contains the camera systems responsible for movement and
+//! scaling.
+
+use bevy::input::mouse::{MouseScrollUnit, MouseWheel};
+use bevy::prelude::*;
+
+use crate::CurrentScene;
+
+/// The speed of camera movement.
+#[derive(Resource)]
+struct CameraSpeedMouvement(f32);
+
+/// The speed of camera scaling.
+#[derive(Resource)]
+struct CameraSpeedScale(f32);
+
+/// The minimum scale of the camera.
+#[derive(Resource)]
+struct MinimumScale(f32);
+
+/// The maximum scale of the camera.
+#[derive(Resource)]
+struct MaximumScale(f32);
+
+/// Key settings for camera movement.
+#[derive(Resource)]
+pub struct KeysMovementSettings {
+    /// Key to move the camera up.
+    pub up: KeyCode,
+
+    /// Key to move the camera down.
+    pub down: KeyCode,
+
+    /// Key to move the camera right.
+    pub right: KeyCode,
+
+    /// Key to move the camera left.
+    pub left: KeyCode,
+}
+
+/// A Bevy plugin for the camera.
+/// Allows camera movement with the keyboard and scaling with the mouse.
+pub struct CameraPlugin;
+
+impl Plugin for CameraPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_systems(Startup, init_camera)
+            .add_systems(Startup, init_resources_for_camera)
+            .add_systems(Update, movement_system.run_if(in_state(CurrentScene::Game)))
+            .add_systems(Update, scale_system.run_if(in_state(CurrentScene::Game)));
+    }
+}
+
+/// Initializes the camera.
+fn init_camera(mut commands: Commands) {
+    commands.spawn(Camera2dBundle::default());
+}
+
+/// Initializes the resources related to the camera.
+///
+/// - [KeysMovementSettings]: The key settings for camera movement.
+/// - [CameraSpeedMouvement]: The speed of camera movement.
+/// - [CameraSpeedScale]: The speed of camera scaling.
+/// - [MinimumScale]: The minimum scale of the camera.
+/// - [MaximumScale]: The maximum scale of the camera.
+fn init_resources_for_camera(mut commands: Commands) {
+    commands.insert_resource(KeysMovementSettings {
+        up: KeyCode::Z,
+        down: KeyCode::S,
+        right: KeyCode::D,
+        left: KeyCode::Q,
+    });
+
+    commands.insert_resource(CameraSpeedMouvement(10.0));
+    commands.insert_resource(CameraSpeedScale(0.1));
+    commands.insert_resource(MinimumScale(0.1));
+    commands.insert_resource(MaximumScale(10.0));
+}
+
+/// Moves the camera with keyboard input.
+fn movement_system(
+    mut query: Query<&mut Transform, With<Camera>>,
+    keys: Res<Input<KeyCode>>,
+    keys_settings: Res<KeysMovementSettings>,
+    movement_speed: Res<CameraSpeedMouvement>,
+) {
+    for mut transform in query.iter_mut() {
+        let mut target = Vec3::ZERO;
+        for key in keys.get_pressed() {
+            match *key {
+                value if value == keys_settings.up => target.y += movement_speed.0,
+                value if value == keys_settings.down => target.y -= movement_speed.0,
+                value if value == keys_settings.right => target.x += movement_speed.0,
+                value if value == keys_settings.left => target.x -= movement_speed.0,
+                _ => continue,
+            }
+        }
+
+        transform.translation += target;
+    }
+}
+
+/// Scales the view with mouse input.
+fn scale_system(
+    mut scroll_event: EventReader<MouseWheel>,
+    mut query: Query<&mut OrthographicProjection, With<Camera>>,
+    min_scale: Res<MinimumScale>,
+    max_scale: Res<MaximumScale>,
+    scale_speed: Res<CameraSpeedScale>,
+) {
+    for event in scroll_event.read() {
+        for mut projection in query.iter_mut() {
+            if event.unit != MouseScrollUnit::Line {
+                return;
+            }
+
+            let future_scale = event.y.mul_add(scale_speed.0, projection.scale);
+            if min_scale.0 < future_scale && future_scale < max_scale.0 {
+                projection.scale = future_scale;
+            }
+        }
+    }
+}

crates/border-wars/src/lib.rs

@@ -2,6 +2,7 @@
 
 use bevy::prelude::*;
 
+pub mod camera;
 pub mod map;
 pub mod scenes;
 

crates/border-wars/src/main.rs

@@ -4,6 +4,7 @@ use bevy::prelude::*;
 use border_wars::map::generation::{EndMapGeneration, MapGenerationPlugin, StartMapGeneration};
 use border_wars::map::renderer::RendererPlugin;
 use border_wars::map::Tile;
+use border_wars::camera::CameraPlugin;
 use border_wars::scenes::ScenesPlugin;
 
 fn setup(mut writer: EventWriter<StartMapGeneration>) {
@@ -37,5 +38,6 @@ fn main() {
             Update,
             update.run_if(in_state(border_wars::CurrentScene::Game)),
         )
+        .add_plugins(CameraPlugin)
         .run();
 }