Roguelike In Rust 04: 地图与行走

接着上一节的内容，这一节将创建地图，然后玩家可以在地图中行走。地图分为可行走区域和不可行走区域。我们可以认为地图是由一个一个的格子组成。

先看一下最终的效果

首先定义地图格子类型，这里使用枚举，我们定义了两种类型的格子，一种是墙，也就是不可走的格子，另一个就是地板，可以走的格子。

#[derive(PartialEq, Copy, Clone)]
enum TileType {
    Wall, Floor
}

写一个函数，将地图的 x, y 坐标，转换为一维数组索引，这里定义地图的宽度为 80 个格子。

pub fn xy_idx(x: i32, y: i32) -> usize {
    (y as usize * 80) + x as usize
}

再写一个函数，用于生成地图数据

fn new_map() -> Vec<TileType> {
    let mut map = vec![TileType::Floor; 80*50];
    // 下面和上面的墙
    for x in 0..80 {
        map[xy_idx(x, 0)] = TileType::Wall;
        map[xy_idx(x, 49)] = TileType::Wall;
    }

    // 左边和右边的墙
    for y in 0..50 {
        map[xy_idx(0, y)] = TileType::Wall;
        map[xy_idx(79, y)] = TileType::Wall;
    }

    let mut rng = rltk::RandomNumberGenerator::new();
    for _i in 0..400 {
        let x = rng.roll_dice(1, 79);
        let y = rng.roll_dice(1, 49);
        let idx = xy_idx(x, y);

        // 地图的中心不能为墙，因为角色出生在那里
        if idx != xy_idx(40, 25) {
            map[idx] = TileType::Wall;
        }
    }

    map
}

在 main 函数中，将地图数据插入到世界中。放在 gs.ecs.register ... 下面

gs.ecs.insert(new_map());

然后是绘制地图函数

fn draw_map(map: &[TileType], ctx: &mut Rltk) {
    let mut y = 0;
    let mut x = 0;
    for tile in map.iter() {
        match tile {
            TileType::Floor => {
                ctx.set(x, y, RGB::from_f32(0.5, 0.5, 0.5), RGB::from_f32(0.0, 0.0, 0.0), rltk::to_cp437('.'));
            }
            TileType::Wall => {
                ctx.set(x, y, RGB::from_f32(0.0, 1.0, 0.0), RGB::from_f32(0.0, 0.0, 0.0), rltk::to_cp437('#'));
            }
        }

        x += 1;
        if x > 79 {
            x = 0;
            y += 1;
        }
    }
}

接下来需要的每一帧中调用地图回执函数，也就是在 tick 函数中 self.run_systems(); 这一行的下面，插入代码。

let map = self.ecs.fetch::<Vec<TileType>>();
draw_map(&map, ctx);

self.ecs.fetch ... 是从 ecs 中读取之前插入的地图数据。

如果现在运行 cargo run，就已经可以显示地图了，不过我们没并有限制玩家的移动，也就是在任何格子都可以行走，接下来需要在玩家行走时判断下一个格子是墙还是地板，如果是墙，则无法行走。

修改 try_move_player 函数，同样使用 self.ecs.fetch 拿出地图数据，然后检查对应格子的类型

fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
    let mut positions = ecs.write_storage::<Position>();
    let mut players = ecs.write_storage::<Player>();
    let map = ecs.fetch::<Vec<TileType>>();

    for (_player, pos) in (&mut players, &mut positions).join() {
        let destination_idx = xy_idx(pos.x + delta_x, pos.y + delta_y);
        if map[destination_idx] != TileType::Wall {
            pos.x = min(79 , max(0, pos.x + delta_x));
            pos.y = min(49, max(0, pos.y + delta_y));
        }
    }
}

使用 cargo run 运行，效果如下

本节完整代码如下

#[macro_use]
use rltk::{GameState, Rltk, RGB, VirtualKeyCode};
use specs::prelude::*;
use specs_derive::Component;
use std::cmp::{max, min};

// 定义一个 Position Component
#[derive(Component, Debug)]
struct Position {
    x: i32,
    y: i32,
}

#[derive(Component, Debug)]
struct Renderable {
    glyph: rltk::FontCharType,
    fg: RGB,
    bg: RGB,
}

#[derive(Component, Debug)]
struct Player {}

#[derive(Component)]
struct LeftMover{}

struct LeftWalker {}

impl<'a> System<'a> for LeftWalker {
    type SystemData = (ReadStorage<'a, LeftMover>, WriteStorage<'a, Position>);
    fn run(&mut self, (lefty, mut pos): Self::SystemData) {
        for(_lefty, pos) in (&lefty, &mut pos).join() {
            pos.x -= 1;
            if pos.x < 0 { pos.x = 79 };
        }
    }
}

struct State {
    ecs: World,
}

#[derive(PartialEq, Copy, Clone)]
enum TileType {
    Wall, Floor
}

pub fn xy_idx(x: i32, y: i32) -> usize {
    (y as usize * 80) + x as usize
}

fn new_map() -> Vec<TileType> {
    let mut map = vec![TileType::Floor; 80*50];
    // 下面和上面的墙
    for x in 0..80 {
        map[xy_idx(x, 0)] = TileType::Wall;
        map[xy_idx(x, 49)] = TileType::Wall;
    }

    // 左边和右边的墙
    for y in 0..50 {
        map[xy_idx(0, y)] = TileType::Wall;
        map[xy_idx(79, y)] = TileType::Wall;
    }

    let mut rng = rltk::RandomNumberGenerator::new();
    for _i in 0..400 {
        let x = rng.roll_dice(1, 79);
        let y = rng.roll_dice(1, 49);
        let idx = xy_idx(x, y);

        // 地图的中心不能为墙，因为角色出生在那里
        if idx != xy_idx(40, 25) {
            map[idx] = TileType::Wall;
        }
    }

    map
}

impl State {
    fn run_systems(&mut self) {
        let mut lw = LeftWalker{};
        lw.run_now(&self.ecs);
        self.ecs.maintain();
    }
}

impl GameState for State {
    fn tick(&mut self, ctx: &mut Rltk){
        ctx.cls();

        player_input(self, ctx);
        self.run_systems();

        let map = self.ecs.fetch::<Vec<TileType>>();
        draw_map(&map, ctx);

        let positions = self.ecs.read_storage::<Position>();
        let renderables = self.ecs.read_storage::<Renderable>();
        for(pos, render) in (&positions, &renderables).join() {
            ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph);
        }
    }
}

fn try_move_player(delta_x: i32, delta_y: i32, ecs:&mut World) {
    let mut positions = ecs.write_storage::<Position>();
    let mut players = ecs.write_storage::<Player>();
    let map = ecs.fetch::<Vec<TileType>>();
    for(_player, pos) in (&mut players, &mut positions).join(){
        let destination_idx = xy_idx(pos.x + delta_x, pos.y + delta_y);
        if map[destination_idx] != TileType::Wall {
            pos.x = min(79, max(0, pos.x + delta_x));
            pos.y = min(49, max(0, pos.y + delta_y));
        }
    }
}

fn player_input(gs: &mut State, ctx: &mut Rltk){
    match ctx.key {
        None => {}
        Some(key) => match key {
            VirtualKeyCode::Left => try_move_player(-1, 0, &mut gs.ecs),
            VirtualKeyCode::Right => try_move_player(1, 0, &mut gs.ecs),
            VirtualKeyCode::Up => try_move_player(0, -1, &mut gs.ecs),
            VirtualKeyCode::Down => try_move_player(0, 1, &mut gs.ecs),
            _ => {}
        }
    }
}

fn draw_map(map: &[TileType], ctx: &mut Rltk) {
    let mut y = 0;
    let mut x = 0;
    for tile in map.iter() {
        match tile {
            TileType::Floor => {
                ctx.set(x, y, RGB::from_f32(0.5, 0.5, 0.5), RGB::from_f32(0.0, 0.0, 0.0), rltk::to_cp437('.'));
            }
            TileType::Wall => {
                ctx.set(x, y, RGB::from_f32(0.0, 1.0, 0.0), RGB::from_f32(0.0, 0.0, 0.0), rltk::to_cp437('#'));
            }
        }

        x += 1;
        if x > 79 {
            x = 0;
            y += 1;
        }
    }
}


fn main() -> rltk::BError {
    use rltk::RltkBuilder;
    let context = RltkBuilder::simple80x50()
                                .with_title("Roguelike Toturial")
                                .build()?;

    let mut gs = State {
        ecs: World::new()
    };

    gs.ecs.register::<Position>();
    gs.ecs.register::<Renderable>();
    gs.ecs.register::<LeftMover>();
    gs.ecs.register::<Player>();

    gs.ecs.insert(new_map());

    gs.ecs
    .create_entity()
    .with(Position { x: 40, y: 25 })
    .with(Renderable {
        glyph: rltk::to_cp437('@'),
        fg: RGB::named(rltk::YELLOW),
        bg: RGB::named(rltk::BLACK),
    })
    .with(Player {})
    .build();

    rltk::main_loop(context, gs)
}

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