Rust 实现的飞机游戏

简介

一个使用 bevy 引擎制作的飞机游戏。

原视频教程地址,github 地址。

因为 bevy 已经升级到 0.10.1 了，所以重新做一遍。顺带手出个教程。

下面是做的部分变动：

• 将激光以及玩家的移动模块进行了拆分。
• 新增了背景图片。
• 新增了游戏状态管理 Welcome/InGame/Paused。
• 新增了声音播放模块。
• 新增了游戏记分板。

通过左右方向键进行控制，使用空格发射激光。
按 P 暂停游戏，按 S 恢复游戏。
更新后的GitHub地址

代码结构

·
├── assets/
│   ├──audios/
│   ├──images/
├── src/
│   ├──enemy/
│   │  ├── formation.rs
│   │  └── mod.rs
│   ├── components.rs
│   ├── constants.rs
│   ├── main.rs
│   ├── player.rs
│   ├── resource.rs
│   └── state.rs
├── Cargo.lock
└── Cargo.toml

• assets/audios 声音资源文件。
• assets/images 图片资源文件。
• enemy/formation.rs 敌人阵型系统的实现。
• enemy/mod.rs 敌人插件，生成、移动、攻击的实现。
• components.rs 负责游戏的逻辑、控制、等内容。
• constants.rs 负责存储游戏中用到的常量。
• main.rs 负责游戏的逻辑、控制、等内容。
• player.rs 玩家角色插件，生成、移动、攻击、键盘处理的实现。
• resource.rs 游戏资源定义。
• state.rs 游戏组件定义。

两点间的距离公式 \(|AB|=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}\)

enemy/formation.rs

use bevy::prelude::{Component, Resource};
use rand::{thread_rng, Rng};

use crate::{WinSize, BASE_SPEED, FORMATION_MEMBER_MAX};

/// 敌人阵型
#[derive(Component, Clone)]
pub struct Formation {
    /// 启始位置
    pub start: (f32, f32),
    /// 半径
    pub radius: (f32, f32),
    /// 原点
    pub pivot: (f32, f32),
    /// 速度
    pub speed: f32,
    /// 角度
    pub angle: f32,
}

/// 阵型资源
#[derive(Resource, Default)]
pub struct FormationMaker {
    /// 当前阵型
    current_template: Option<Formation>,
    /// 当前数量
    current_members: u32,
}

impl FormationMaker {
    pub fn make(&mut self, win_size: &WinSize) -> Formation {
        match (
            &self.current_template,
            self.current_members >= FORMATION_MEMBER_MAX,
        ) {
            // 当前阵型还有空位 直接加入
            (Some(template), false) => {
                self.current_members += 1;
                template.clone()
            }
            // 当前阵型没有空位，或还没有阵型，需要创建新的阵型
            _ => {
                let mut rng = thread_rng();

                // 生成 起点坐标
                let w_spawn = win_size.w / 2. + 100.;
                let h_spawn = win_size.h / 2. + 100.;
                let x = if rng.gen_bool(0.5) { w_spawn } else { -w_spawn };
                let y = rng.gen_range(-h_spawn..h_spawn);
                let start = (x, y);

                // 生成原点坐标
                let w_spawn = win_size.w / 4.;
                let h_spawn = win_size.h / 3. + 50.;
                let pivot = (
                    rng.gen_range(-w_spawn..w_spawn),
                    rng.gen_range(0. ..h_spawn),
                );

                // 生成半径
                let radius = (rng.gen_range(80. ..150.), 100.);

                // 计算初始角度
                let angle = (y - pivot.1).atan2(x - pivot.0);

                // 速度
                let speed = BASE_SPEED;

                let formation = Formation {
                    start,
                    pivot,
                    radius,
                    angle,
                    speed,
                };

                self.current_template = Some(formation.clone());
                self.current_members = 1;
                formation
            }
        }
    }
}

enemy/mod.rs

use std::{f32::consts::PI, time::Duration};

use crate::{
    components::{Enemy, FromEnemy, Laser, Movable, SpriteSize, Velocity},
    resource::GameState,
    GameTextures, MaxEnemy, WinSize, ENEMY_LASER_SIZE, ENEMY_SIZE, MAX_ENEMY, SPRITE_SCALE,
    TIME_STEP,
};

use bevy::{prelude::*, time::common_conditions::on_timer};
use rand::{thread_rng, Rng};

use self::formation::{Formation, FormationMaker};

mod formation;

#[derive(Component)]
pub struct EnemyPlugin;

impl Plugin for EnemyPlugin {
    fn build(&self, app: &mut App) {
        // 间隔执行
        app.insert_resource(FormationMaker::default())
            .add_system(
                enemy_spawn_system
                    .run_if(on_timer(Duration::from_secs_f32(0.5)))
                    .in_set(OnUpdate(GameState::InGame)),
            )
            .add_system(
                enemy_fire_system
                    .run_if(enemy_fire_criteria)
                    .in_set(OnUpdate(GameState::InGame)),
            )
            .add_system(enemy_movement_system.in_set(OnUpdate(GameState::InGame)));
    }
}

/// 敌人生成系统
fn enemy_spawn_system(
    mut commands: Commands,
    mut max_enemy: ResMut<MaxEnemy>,
    mut formation_maker: ResMut<FormationMaker>,
    game_textures: Res<GameTextures>,
    win_size: Res<WinSize>,
) {
    // 如果当前的敌人数量大于等于最大敌人数量，则不再产生新的敌人
    if max_enemy.0 >= MAX_ENEMY {
        return;
    }

    // 随机生成
    // let mut rng = thread_rng();
    // let w_span = win_size.w / 2. - 100.;
    // let h_span = win_size.h / 2. - 100.;
    // let x = rng.gen_range(-w_span..w_span);
    // let y = rng.gen_range(-h_span..h_span);

    // 使用 阵型
    let formation = formation_maker.make(&win_size);
    let (x, y) = formation.start;

    commands
        .spawn(SpriteBundle {
            texture: game_textures.enemy.clone(),
            transform: Transform {
                // 坐标
                translation: Vec3::new(x, y, 10.),
                // 缩放
                scale: Vec3::new(SPRITE_SCALE, SPRITE_SCALE, 1.),
                // 旋转
                rotation: Quat::IDENTITY,
            },
            ..Default::default()
        })
        .insert(Enemy)
        .insert(formation)
        .insert(SpriteSize::from(ENEMY_SIZE));
    max_enemy.0 += 1;
}

/// 敌人射击系统
fn enemy_fire_system(
    mut commands: Commands,
    game_textures: Res<GameTextures>,
    query: Query<&Transform, With<Enemy>>,
) {
    for &enemy_tf in query.iter() {
        let (x, y) = (enemy_tf.translation.x, enemy_tf.translation.y);

        commands
            .spawn(SpriteBundle {
                texture: game_textures.enemy_laser.clone(),
                transform: Transform {
                    translation: Vec3::new(x, y, 1.),
                    scale: Vec3::new(SPRITE_SCALE, SPRITE_SCALE, 1.),
                    rotation: Quat::from_rotation_x(PI),
                },
                ..Default::default()
            })
            .insert(Laser)
            .insert(SpriteSize::from(ENEMY_LASER_SIZE))
            .insert(FromEnemy)
            .insert(Movable { auto_despawn: true })
            .insert(Velocity::new(0., -1.));
    }
}

/// 是否发射攻击
fn enemy_fire_criteria() -> bool {
    if thread_rng().gen_bool(1. / 60.) {
        true
    } else {
        false
    }
}

/// 敌人移动系统
///
/// 两点间的距离公式 $|AB|=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$
fn enemy_movement_system(mut query: Query<(&mut Transform, &mut Formation), With<Enemy>>) {
    // 当前时间
    // let now = time.elapsed_seconds();
    for (mut transform, mut formation) in query.iter_mut() {
        // 当前坐标
        let (x_org, y_org) = (transform.translation.x, transform.translation.y);
        // let (x_org, y_org) = formation.start;

        // 单位时间内最大移动距离
        // let max_distance = BASE_SPEED * TIME_STEP;
        let max_distance = formation.speed * TIME_STEP;

        // 方向 1 顺时针 -1 逆时针
        // let dir = -1.;
        let dir = if formation.start.0 < 0. { 1. } else { -1. };
        // 中心点
        // let (x_pivot, y_pivot) = (0., 0.);
        let (x_pivot, y_pivot) = formation.pivot;
        // 半径
        // let (x_radius, y_radius) = (200., 130.);
        let (x_radius, y_radius) = formation.radius;

        // 基于当前时间计算的角度
        // let angel = dir * BASE_SPEED * TIME_STEP * now % 360. / PI;
        let angel = formation.angle
            + dir * formation.speed * TIME_STEP / (x_radius.min(y_radius) * PI / 2.);

        // 计算目标点位
        let x_dst = x_radius * angel.cos() + x_pivot;
        let y_dst = y_radius * angel.sin() + y_pivot;

        // 计算距离
        // 两点间的距离公式 根号下 a.x - b.x
        let dx = x_org - x_dst;
        let dy = y_org - y_dst;

        let distance = (dx * dx + dy * dy).sqrt();
        let distance_radio = if distance != 0. {
            max_distance / distance
        } else {
            0.
        };

        // 计算 x y 的最终坐标
        let x = x_org - dx * distance_radio;
        let x = if dx > 0. { x.max(x_dst) } else { x.min(x_dst) };
        let y = y_org - dy * distance_radio;
        let y = if dy > 0. { y.max(y_dst) } else { y.min(y_dst) };

        // 图片资源在椭圆上 或接近椭圆时开始加入旋转
        if distance < max_distance * formation.speed / 20. {
            formation.angle = angel;
        }

        let translation = &mut transform.translation;
        (translation.x, translation.y) = (x, y);
    }
}

components.rs

use bevy::{
    prelude::{Component, Vec2, Vec3},
    time::{Timer, TimerMode},
};

// 通用控制组件
#[derive(Component)]
pub struct Velocity {
    pub x: f32,
    pub y: f32,
}
impl Velocity {
    pub fn new(x: f32, y: f32) -> Self {
        Self { x, y }
    }
}

/// 移动能力组件
#[derive(Component)]
pub struct Movable {
    /// 自动销毁
    pub auto_despawn: bool,
}

/// 玩家组件
#[derive(Component)]
pub struct Player;

/// 玩家信息组件
#[derive(Component)]
pub struct FromPlayer;

/// 敌人组件
#[derive(Component)]
pub struct Enemy;

/// 敌人信息组件
#[derive(Component)]
pub struct FromEnemy;

/// 激光组件
#[derive(Component)]
pub struct Laser;

/// 图片大小组件
#[derive(Component)]
pub struct SpriteSize(pub Vec2);

/// 实现 (f32,f32) 转 SpritSize
impl From<(f32, f32)> for SpriteSize {
    fn from(value: (f32, f32)) -> Self {
        Self(Vec2::new(value.0, value.1))
    }
}

/// 爆炸组件
#[derive(Component)]
pub struct Explosion;

/// 产生爆炸组件
#[derive(Component)]
pub struct ExplosionToSpawn(pub Vec3);

/// 爆炸事件组件
#[derive(Component)]
pub struct ExplosionTimer(pub Timer);

impl Default for ExplosionTimer {
    fn default() -> Self {
        Self(Timer::from_seconds(0.05, TimerMode::Once))
    }
}

/// 分数显示组件
#[derive(Component)]
pub struct DisplayScore;

/// 欢迎组件
#[derive(Component)]
pub struct WelcomeText;

/// 暂停组件
#[derive(Component)]
pub struct PausedText;

constants.rs

/// 游戏背景图片路径
pub const BACKGROUND_SPRITE: &str = "images/planet05.png";

/// 玩家图片路径
pub const PLAYER_SPRITE: &str = "images/player_a_01.png";
/// 玩家大小
pub const PLAYER_SIZE: (f32, f32) = (144., 75.);
/// 玩家攻击图片路径
pub const PLAYER_LASER_SPRITE: &str = "images/laser_a_01.png";
/// 玩家攻击图片大小
pub const PLAYER_LASER_SIZE: (f32, f32) = (9., 54.);

/// 敌人图片路径
pub const ENEMY_SPRITE: &str = "images/enemy_a_01.png";
/// 敌人大小
pub const ENEMY_SIZE: (f32, f32) = (144., 75.);
/// 敌人攻击图片路径
pub const ENEMY_LASER_SPRITE: &str = "images/laser_b_01.png";
/// 敌人攻击图片大小
pub const ENEMY_LASER_SIZE: (f32, f32) = (17., 55.);

/// 爆炸图片路径
pub const EXPLOSION_SHEET: &str = "images/explosion_a_sheet.png";
/// 爆炸图片大小
pub const EXPLOSION_SIZE: (f32, f32) = (64., 64.);
/// 爆炸画面帧数
pub const EXPLOSION_ANIMATION_LEN: usize = 16;

/// 图片缩放比例
pub const SPRITE_SCALE: f32 = 0.5;

/// 步长 (帧数)
pub const TIME_STEP: f32 = 1. / 60.;
/// 基础速度
pub const BASE_SPEED: f32 = 500.;
/// 敌人最大数量
pub const MAX_ENEMY: u32 = 2;
/// 玩家自动重生时间
pub const PLAYER_RESPAWN_DELAY: f64 = 2.;
/// 阵型内敌人最大数量
pub const FORMATION_MEMBER_MAX: u32 = 2;

/// 敌人被摧毁声音
pub const ENEMY_EXPLOSION_AUDIO: &str = "audios/enemy_explosion.ogg";
/// 玩家被摧毁的声音
pub const PLAYER_EXPLOSION_AUDIO: &str = "audios/player_explosion.ogg";
/// 玩家发射激光的声音
pub const PLAYER_LASER_AUDIO: &str = "audios/player_laser.ogg";

/// 字体路径
pub const KENNEY_BLOCK_FONT: &str = "fonts/kenney_blocks.ttf";

main.rs

use bevy::{math::Vec3Swizzles, prelude::*, sprite::collide_aabb::collide, utils::HashSet};
use components::*;

use constants::*;
use enemy::EnemyPlugin;
use player::PlayerPlugin;
use resource::{GameAudio, GameData, GameState, GameTextures, MaxEnemy, PlayerState, WinSize};
use state::StatePlugin;

mod components;
mod constants;
mod enemy;
mod player;
mod resource;
mod state;

fn main() {
    // add_startup_system 启动生命周期时只运行一次 ，
    // add_system 每帧都会被调用方法
    App::new()
        .add_state::<GameState>()
        .insert_resource(ClearColor(Color::rgb(0.04, 0.04, 0.04)))
        .add_plugins(DefaultPlugins.set(WindowPlugin {
            primary_window: Some(Window {
                title: "Invaders".to_owned(),
                resolution: (598., 676.).into(),
                position: WindowPosition::At(IVec2::new(2282, 0)),
                ..Window::default()
            }),
            ..WindowPlugin::default()
        }))
        .add_plugin(PlayerPlugin)
        .add_plugin(EnemyPlugin)
        .add_plugin(StatePlugin)
        .add_startup_system(setup_system)
        // InGame 状态下执行的函数
        .add_systems(
            (
                laser_movable_system,
                player_laser_hit_enemy_system,
                explosion_to_spawn_system,
                explosion_animation_system,
                enemy_laser_hit_player_system,
                score_display_update_system,
            )
                .in_set(OnUpdate(GameState::InGame)),
        )
        // 启动 esc 键退出程序
        .add_system(bevy::window::close_on_esc)
        .run();
}

/// 资源加载
fn setup_system(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut texture_atlases: ResMut<Assets<TextureAtlas>>,
    mut windows: Query<&mut Window>,
) {
    // 创建2d镜头
    commands.spawn(Camera2dBundle::default());

    // 获取当前窗口
    let window = windows.single_mut();
    let win_w = window.width();
    let win_h = window.height();

    //  添加 WinSize 资源
    let win_size = WinSize { w: win_w, h: win_h };
    commands.insert_resource(win_size);

    // 创建爆炸动画
    let texture_handle = asset_server.load(EXPLOSION_SHEET);
    let texture_atlas =
        TextureAtlas::from_grid(texture_handle, Vec2::from(EXPLOSION_SIZE), 4, 4, None, None);
    let explosion = texture_atlases.add(texture_atlas);

    // 添加 GameTextures
    let game_texture = GameTextures {
        background: asset_server.load(BACKGROUND_SPRITE),
        player: asset_server.load(PLAYER_SPRITE),
        player_laser: asset_server.load(PLAYER_LASER_SPRITE),
        enemy: asset_server.load(ENEMY_SPRITE),
        enemy_laser: asset_server.load(ENEMY_LASER_SPRITE),
        font: asset_server.load(KENNEY_BLOCK_FONT),
        explosion,
    };

    // 声音资源引入
    let game_audio = GameAudio {
        player_laser: asset_server.load(PLAYER_LASER_AUDIO),
        player_explosion: asset_server.load(PLAYER_EXPLOSION_AUDIO),
        enemy_explosion: asset_server.load(ENEMY_EXPLOSION_AUDIO),
    };

    // 背景图片
    commands.spawn(SpriteBundle {
        texture: game_texture.background.clone(),
        sprite: Sprite {
            custom_size: Some(Vec2 { x: win_w, y: win_h }),
            ..Default::default()
        },
        transform: Transform::from_scale(Vec3::new(1.5, 1.5, 0.0)),
        ..Default::default()
    });

    // 字体引入
    let font = game_texture.font.clone();
    let text_style = TextStyle {
        font: font.clone(),
        font_size: 32.,
        color: Color::ANTIQUE_WHITE,
    };
    let text_alignment = TextAlignment::Center;

    // 分数展示控件
    commands.spawn((
        Text2dBundle {
            text: Text::from_section("SCORE:0", text_style).with_alignment(text_alignment),
            transform: Transform {
                translation: Vec3 {
                    x: 0.,
                    y: win_h / 2. - 20.,
                    z: 11.,
                },
                ..Default::default()
            },
            ..Default::default()
        },
        DisplayScore,
    ));

    let game_data = GameData::new();
    commands.insert_resource(game_data);
    commands.insert_resource(game_audio);
    commands.insert_resource(game_texture);
    commands.insert_resource(MaxEnemy(0));
}

/// 激光移动系统
fn laser_movable_system(
    mut commands: Commands,
    win_size: Res<WinSize>,
    mut query: Query<(Entity, &Velocity, &mut Transform, &Movable), With<Laser>>,
) {
    for (entity, velocity, mut transform, movable) in query.iter_mut() {
        // 移动位置
        let translation = &mut transform.translation;
        translation.x += velocity.x * BASE_SPEED * TIME_STEP;
        translation.y += velocity.y * BASE_SPEED * TIME_STEP;

        // 自动销毁
        if movable.auto_despawn {
            const MARGIN: f32 = 200.;
            if translation.y > win_size.h / 2. + MARGIN
                || translation.y < -win_size.h / 2. - MARGIN
                || translation.x > win_size.w / 2. + MARGIN
                || translation.x < -win_size.w / 2. - MARGIN
            {
                commands.entity(entity).despawn();
            }
        }
    }
}

/// 敌人激光攻击玩家判定系统
fn enemy_laser_hit_player_system(
    mut commands: Commands,
    mut player_state: ResMut<PlayerState>,
    time: Res<Time>,
    audio_source: Res<GameAudio>,
    audio: Res<Audio>,
    mut game_data: ResMut<GameData>,
    mut next_state: ResMut<NextState<GameState>>,
    laser_query: Query<(Entity, &Transform, &SpriteSize), (With<Laser>, With<FromEnemy>)>,
    player_query: Query<(Entity, &Transform, &SpriteSize), With<Player>>,
) {
    if let Ok((player_entity, player_tf, player_size)) = player_query.get_single() {
        let player_scale = Vec2::from(player_tf.scale.xy());

        for (laser, laser_tf, laser_size) in laser_query.into_iter() {
            let laser_scale = Vec2::from(laser_tf.scale.xy());

            let collision = collide(
                player_tf.translation,
                player_size.0 * player_scale,
                laser_tf.translation,
                laser_size.0 * laser_scale,
            );

            if let Some(_) = collision {
                // 播放音乐
                audio.play(audio_source.player_explosion.clone());
                // 重置分数
                game_data.reset_score();
                next_state.set(GameState::Welcome);
                // 销毁角色
                commands.entity(player_entity).despawn();
                // 记录被命中的时刻
                player_state.shot(time.elapsed_seconds_f64());
                // 销毁激光
                commands.entity(laser).despawn();
                // 产生爆炸动画
                commands.spawn(ExplosionToSpawn(player_tf.translation.clone()));
                break;
            }
        }
    }
}

/// 玩家攻击敌人判定系统
fn player_laser_hit_enemy_system(
    mut commands: Commands,
    audio_source: Res<GameAudio>,
    audio: Res<Audio>,
    mut max_enemy: ResMut<MaxEnemy>,
    mut game_data: ResMut<GameData>,
    laser_query: Query<(Entity, &Transform, &SpriteSize), (With<Laser>, With<FromPlayer>)>,
    enemy_query: Query<(Entity, &Transform, &SpriteSize), With<Enemy>>,
) {
    // 重复删除检测
    let mut despawn_entities: HashSet<Entity> = HashSet::new();
    // 玩家激光
    for (laser_entity, laser_tf, laser_size) in laser_query.iter() {
        if despawn_entities.contains(&laser_entity) {
            continue;
        }

        // 玩家激光的坐标
        let laser_scale = Vec2::from(laser_tf.scale.xy());

        // 敌人
        for (enemy_entity, enemy_tf, enemy_size) in enemy_query.iter() {
            if despawn_entities.contains(&enemy_entity) || despawn_entities.contains(&laser_entity)
            {
                continue;
            }

            // 敌人坐标
            let enemy_scale = Vec2::from(enemy_tf.scale.xy());

            // collide 定义两个元素的碰撞，a 点坐标，a 的大小，b 点坐标，b 的大小,如果未发生碰撞返回 None
            let collision = collide(
                laser_tf.translation,
                laser_size.0 * laser_scale,
                enemy_tf.translation,
                enemy_size.0 * enemy_scale,
            );

            // 碰撞检测
            if let Some(_) = collision {
                // 敌人数量 -1
                if max_enemy.0 != 0 {
                    max_enemy.0 -= 1;
                }
                game_data.add_score();

                audio.play(audio_source.enemy_explosion.clone());
                // 销毁敌人
                commands.entity(enemy_entity).despawn();
                despawn_entities.insert(enemy_entity);
                // 销毁激光
                commands.entity(laser_entity).despawn();
                despawn_entities.insert(laser_entity);

                // 播放爆炸动画
                commands.spawn(ExplosionToSpawn(enemy_tf.translation.clone()));
            }
        }
    }
}

/// 爆炸画面生成系统
fn explosion_to_spawn_system(
    mut commands: Commands,
    game_textures: Res<GameTextures>,
    query: Query<(Entity, &ExplosionToSpawn)>,
) {
    for (explosion_spawn_entity, explosion_to_spawn) in query.iter() {
        commands
            .spawn(SpriteSheetBundle {
                texture_atlas: game_textures.explosion.clone(),
                transform: Transform {
                    translation: explosion_to_spawn.0,
                    ..Default::default()
                },
                ..Default::default()
            })
            .insert(Explosion)
            .insert(ExplosionTimer::default());

        commands.entity(explosion_spawn_entity).despawn();
    }
}

/// 爆炸动画系统
fn explosion_animation_system(
    mut commands: Commands,
    time: Res<Time>,
    mut query: Query<(Entity, &mut ExplosionTimer, &mut TextureAtlasSprite), With<Explosion>>,
) {
    for (entity, mut timer, mut texture_atlas_sprite) in query.iter_mut() {
        timer.0.tick(time.delta());

        if timer.0.finished() {
            texture_atlas_sprite.index += 1;
            if texture_atlas_sprite.index >= EXPLOSION_ANIMATION_LEN {
                commands.entity(entity).despawn();
            }
        }
    }
}

/// 分数更新系统
fn score_display_update_system(
    game_data: Res<GameData>,
    mut query: Query<&mut Text, With<DisplayScore>>,
) {
    for mut text in &mut query {
        let new_str: String = format!("SCORE:{}", game_data.get_score());
        text.sections[0].value = new_str;
    }
}

player.rs

use bevy::{prelude::*, time::common_conditions::on_timer};
use std::time::Duration;

use crate::{
    components::{FromPlayer, Laser, Movable, Player, SpriteSize, Velocity},
    resource::GameAudio,
    resource::PlayerState,
    resource::WinSize,
    resource::{GameState, GameTextures},
    BASE_SPEED, PLAYER_LASER_SIZE, PLAYER_RESPAWN_DELAY, PLAYER_SIZE, SPRITE_SCALE, TIME_STEP,
};

pub struct PlayerPlugin;

impl Plugin for PlayerPlugin {
    fn build(&self, app: &mut App) {
        // add_startup_system 应用程序生命周期开始时运行一次
        // StartupSet::PostStartup 在 StartupSet::Startup 后运行一次
        // add_startup_system(player_spawn_system.in_base_set(StartupSet::PostStartup))
        // add_system 每帧都运行 , 可以在函数后通过 run_if 传入 bool 类型的条件进行限制
        app.insert_resource(PlayerState::default())
            .add_system(
                player_spawn_system
                    .run_if(on_timer(Duration::from_secs_f32(0.5)))
                    .in_set(OnUpdate(GameState::InGame)),
            )
            .add_systems(
                (
                    player_keyboard_event_system,
                    player_movable_system,
                    player_fire_system,
                )
                    .in_set(OnUpdate(GameState::InGame)),
            );
    }
}

/// 玩家角色生成系统
fn player_spawn_system(
    mut commands: Commands,
    mut player_state: ResMut<PlayerState>,
    time: Res<Time>,
    game_textures: Res<GameTextures>,
    win_size: Res<WinSize>,
) {
    let now = time.elapsed_seconds_f64();
    let last_shot = player_state.last_shot;
    if !player_state.on && (player_state.last_shot == -1. || now - PLAYER_RESPAWN_DELAY > last_shot)
    {
        let bottom = -win_size.h / 2.;

        // 创建组件实体，并返回对应的 EntityCommand
        commands
            .spawn(SpriteBundle {
                texture: game_textures.player.clone(),
                transform: Transform {
                    translation: Vec3::new(
                        0.,
                        bottom + PLAYER_SIZE.1 / 2. * SPRITE_SCALE + 5.0,
                        10.,
                    ),
                    scale: Vec3::new(SPRITE_SCALE, SPRITE_SCALE, 1.0),
                    ..default()
                },
                ..SpriteBundle::default()
            })
            .insert(Velocity::new(0., 0.))
            .insert(Movable {
                auto_despawn: false,
            })
            .insert(SpriteSize::from(PLAYER_SIZE))
            .insert(Player);

        player_state.spawned();
    }
}

/// 玩家攻击系统
fn player_fire_system(
    mut commands: Commands,
    audio_source: Res<GameAudio>,
    audio: Res<Audio>,
    kb: Res<Input<KeyCode>>,
    game_textures: Res<GameTextures>,
    query: Query<&Transform, With<Player>>,
) {
    if let Ok(player_tf) = query.get_single() {
        // just_released 松开按键
        if kb.just_released(KeyCode::Space) {
            audio.play(audio_source.player_laser.clone());
            let (x, y) = (player_tf.translation.x, player_tf.translation.y);

            let x_offset = PLAYER_SIZE.0 / 2. * SPRITE_SCALE - 5.;

            // 激光生成闭包 因为这里使用了 commands 生成新的包 所以这里的闭包需要定义为 mut 类型
            let mut spawn_laser = |x_offset: f32| {
                commands
                    .spawn(SpriteBundle {
                        texture: game_textures.player_laser.clone(),
                        transform: Transform {
                            translation: Vec3::new(x + x_offset, y + 15., 1.),
                            scale: Vec3::new(SPRITE_SCALE, SPRITE_SCALE, 0.),
                            ..Default::default()
                        },
                        ..Default::default()
                    })
                    .insert(Laser)
                    .insert(FromPlayer)
                    .insert(SpriteSize::from(PLAYER_LASER_SIZE))
                    .insert(Movable { auto_despawn: true })
                    .insert(Velocity::new(0., 1.));
            };
            spawn_laser(x_offset);
            spawn_laser(-x_offset);
        }
    }
}

/// 键盘事件系统
fn player_keyboard_event_system(
    kb: Res<Input<KeyCode>>,
    mut next_state: ResMut<NextState<GameState>>,
    mut query: Query<&mut Velocity, With<Player>>,
) {
    if let Ok(mut velocity) = query.get_single_mut() {
        // pressed 按下按键
        if kb.pressed(KeyCode::Left) {
            velocity.x = -1.
        } else if kb.pressed(KeyCode::Right) {
            velocity.x = 1.
        } else if kb.just_pressed(KeyCode::P) {
            next_state.set(GameState::Paused);
        } else {
            velocity.x = 0.
        }
    };
}

/// 玩家移动系统
fn player_movable_system(
    win_size: Res<WinSize>,
    mut query: Query<(&Velocity, &mut Transform), With<Player>>,
) {
    let max_w = win_size.w / 2.;

    for (velocity, mut transform) in query.iter_mut() {
        let distance = velocity.x * BASE_SPEED * TIME_STEP;
        let new_x = transform.translation.x + distance;
        if -max_w <= new_x && new_x <= max_w {
            // 移动位置
            transform.translation.x += distance;
        }
    }
}

resource.rs

use bevy::{
    prelude::{AudioSource, Handle, Image, Resource, States},
    sprite::TextureAtlas,
    text::Font,
};

/// 游戏窗口大小资源
#[derive(Resource)]
pub struct WinSize {
    pub w: f32,
    pub h: f32,
}

/// 游戏图像资源
#[derive(Resource)]
pub struct GameTextures {
    pub background: Handle<Image>,
    pub player: Handle<Image>,
    pub player_laser: Handle<Image>,
    pub enemy: Handle<Image>,
    pub enemy_laser: Handle<Image>,
    pub explosion: Handle<TextureAtlas>,
    pub font: Handle<Font>,
}

/// 敌人最大数量
#[derive(Resource)]
pub struct MaxEnemy(pub u32);

/// 玩家状态
#[derive(Resource)]
pub struct PlayerState {
    pub on: bool,
    pub last_shot: f64,
}

impl Default for PlayerState {
    fn default() -> Self {
        Self {
            on: false,
            last_shot: -1.,
        }
    }
}

impl PlayerState {
    /// 被命中
    pub fn shot(&mut self, time: f64) {
        self.on = false;
        self.last_shot = time;
    }
    /// 重生
    pub fn spawned(&mut self) {
        self.on = true;
        self.last_shot = -1.;
    }
}

#[derive(Resource)]
pub struct GameAudio {
    pub enemy_explosion: Handle<AudioSource>,
    pub player_explosion: Handle<AudioSource>,
    pub player_laser: Handle<AudioSource>,
}

/// 游戏状态    
#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, Hash, States)]
pub enum GameState {
    /// 欢迎
    #[default]
    Welcome,
    /// 游戏中
    InGame,
    /// 暂停
    Paused,
}

/// 游戏数据
#[derive(Resource)]
pub struct GameData {
    score: u32,
}

impl GameData {
    pub fn new() -> Self {
        Self { score: 0 }
    }

    /// 获取当前得分
    pub fn get_score(&self) -> u32 {
        self.score
    }

    /// 增加得分
    pub fn add_score(&mut self) {
        self.score += 1;
    }

    /// 增加得分
    pub fn reset_score(&mut self) {
        self.score = 0;
    }
}

state.rs

use bevy::{
    prelude::{
        Color, Commands, Entity, Input, IntoSystemAppConfig, IntoSystemConfig, IntoSystemConfigs,
        KeyCode, NextState, OnEnter, OnExit, OnUpdate, Plugin, Query, Res, ResMut, Transform, Vec3,
        With,
    },
    text::{Text, Text2dBundle, TextAlignment, TextSection, TextStyle},
    time::Time,
};

use crate::{
    components::{PausedText, WelcomeText},
    resource::{GameState, GameTextures},
};

pub struct StatePlugin;
impl Plugin for StatePlugin {
    fn build(&self, app: &mut bevy::prelude::App) {
        app
            // 在 CoreSet::StateTransitions 期间,当 AppState::Menu 时，该函数执行，
            //当退出该状态进入下一个状态时，会先执行当前状态的退出函数，再执行下个状态的函数
            // OnEnter 进入时执行、OnUpdate 期间内每帧执行、OnExit 退出时执行
            .add_system(welcome_system.in_schedule(OnEnter(GameState::Welcome)))
            // CoreSet::Update 期间 主函数中的 on_update 将会检查 State 资源的值，并判断是否应该运行
            .add_systems(
                (welcome_input_system, welcome_text_scale_system)
                    .in_set(OnUpdate(GameState::Welcome)),
            )
            .add_system(welcome_exit_system.in_schedule(OnExit(GameState::Welcome)))
            // Paused 状态下执行的函数
            .add_system(paused_system.in_schedule(OnEnter(GameState::Paused)))
            .add_system(paused_input_system.in_set(OnUpdate(GameState::Paused)))
            .add_system(paused_exit_system.in_schedule(OnExit(GameState::Paused)));
    }
}

/// 欢迎状态下运行的系统
pub fn welcome_system(mut commands: Commands, game_textures: Res<GameTextures>) {
    // 字体引入
    let font = game_textures.font.clone();
    let text_style = TextStyle {
        font: font.clone(),
        font_size: 46.,
        color: Color::BLUE,
    };
    let text_alignment = TextAlignment::Center;

    let text = Text {
        sections: vec![
            TextSection::new("PRESS ", text_style.clone()),
            TextSection::new(
                " ENTER ",
                TextStyle {
                    color: Color::RED,
                    ..text_style.clone()
                },
            ),
            TextSection::new("START GAME !\r\n", text_style.clone()),
            TextSection::new("PRESS ", text_style.clone()),
            TextSection::new(
                " P ",
                TextStyle {
                    color: Color::RED,
                    ..text_style.clone()
                },
            ),
            TextSection::new("TO PAUSED GAME !", text_style.clone()),
        ],
        ..Default::default()
    }
    .with_alignment(text_alignment);
    commands.spawn((
        Text2dBundle {
            text,
            transform: Transform {
                translation: Vec3 {
                    x: 0.,
                    y: -20.,
                    z: 11.,
                },
                ..Default::default()
            },
            ..Default::default()
        },
        WelcomeText,
    ));
}

/// 欢迎状态状态下的键盘监听系统
pub fn welcome_input_system(kb: Res<Input<KeyCode>>, mut next_state: ResMut<NextState<GameState>>) {
    if kb.just_pressed(KeyCode::Return) {
        next_state.set(GameState::InGame);
    }
}

/// 欢迎状态字体变化系统
pub fn welcome_text_scale_system(
    time: Res<Time>,
    mut query: Query<&mut Transform, (With<Text>, With<WelcomeText>)>,
) {
    for mut transform in &mut query {
        transform.scale = Vec3::splat(time.elapsed_seconds().sin() / 4. + 0.9);
    }
}

/// 退出欢迎状态时执行的系统
pub fn welcome_exit_system(
    mut commands: Commands,
    query: Query<Entity, (With<Text>, With<WelcomeText>)>,
) {
    for entity in query.iter() {
        commands.entity(entity).despawn();
    }
}

/// 暂停状态下运行的系统
pub fn paused_system(mut commands: Commands, game_textures: Res<GameTextures>) {
    // 字体引入
    let font = game_textures.font.clone();
    let text_style = TextStyle {
        font: font.clone(),
        font_size: 46.,
        color: Color::BLUE,
    };
    let text_alignment = TextAlignment::Center;

    let text = Text {
        sections: vec![
            TextSection::new("GAME PAUSED!\r\nPRESSED", text_style.clone()),
            TextSection::new(
                " R ",
                TextStyle {
                    color: Color::RED,
                    ..text_style.clone()
                },
            ),
            TextSection::new("RETURN GAME!", text_style.clone()),
        ],
        ..Default::default()
    }
    .with_alignment(text_alignment);
    commands.spawn((
        Text2dBundle {
            text,
            transform: Transform {
                translation: Vec3 {
                    x: 0.,
                    y: -20.,
                    z: 11.,
                },
                ..Default::default()
            },
            ..Default::default()
        },
        PausedText,
    ));
}

/// 暂停状态状态下的键盘监听系统
pub fn paused_input_system(kb: Res<Input<KeyCode>>, mut next_state: ResMut<NextState<GameState>>) {
    if kb.pressed(KeyCode::R) {
        next_state.set(GameState::InGame);
    }
}

/// 退出暂停状态时执行的系统
pub fn paused_exit_system(
    mut commands: Commands,
    query: Query<Entity, (With<Text>, With<PausedText>)>,
) {
    for entity in query.iter() {
        commands.entity(entity).despawn();
    }
}

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