ez-roguelike/ch2/src/main.rs

#[macro_use]
extern crate specs_derive;
#[macro_use]
extern crate specs_system_macro;

use ggez::GameError;
use specs::prelude::*;

#[derive(Component)]
pub struct Pos {
    x: usize,
    y: usize,
}

#[derive(Component)]
pub struct Renderable {
    glyph: carpet::CP437,
    color: carpet::Color,
}

#[derive(Component)]
pub struct MoveLeft;

#[derive(Component)]
pub struct Player;

impl Player {
    fn get_entity(world: &mut specs::World) -> Entity {
        let storage = (&world.read_component::<Player>(), &world.entities());
        storage
            .join()
            .next()
            .expect("No entities tagged as Player")
            .1
    }
}

#[derive(Component)]
pub struct Motion {
    down: i8,
    right: i8,
}

impl Motion {
    fn move_player(world: &mut specs::World, down: i8, right: i8) {
        let player = Player::get_entity(world);
        world
            .write_component::<Motion>()
            .insert(player, Motion { down, right })
            .unwrap();
    }
}

system_impl! {
    Draw(
        resource mut board: carpet::GameBoard<carpet::CP437>,
        renderable: Renderable,
        pos: Pos,
    ) {
        board.clear();
        for (p, r) in (&pos, &renderable).join() {
            board.set_with_color([p.x, p.y], r.glyph, r.color);
        }
    }
}

system! {
    Leftward (
        _left: MoveLeft,
        mut pos: Pos,
    ) {
        if pos.x == 0 {
            pos.x = 79;
        } else {
            pos.x -= 1;
        }
    }
}

system! {
    Move (
        mut motion: Motion,
        mut pos: Pos,
    ) {
        pos.x = (pos.x as i8 + motion.right) as usize;
        pos.y = (pos.y as i8 + motion.down) as usize;
    } finally {
        motion.clear();
    }
}

fn main() -> Result<(), GameError> {
    let mut game = carpet::GameBuilder::new()
        .name("game")
        .author("me")
        .resource_path({
            let base = std::env::var("CARGO_MANIFEST_DIR").unwrap();
            let mut path = std::path::PathBuf::from(base);
            path.pop();
            path.push("resources");
            path
        })
        .tileset("/haberdash.gif", [12, 12])
        .map_size(80, 50)
        .build()?;

    game.register::<Pos>();
    game.register::<Renderable>();
    game.register::<MoveLeft>();
    game.register::<Motion>();
    game.register::<Player>();
    game.world.print([1, 1], "Hello, world!");

    game.create_entity()
        .with(Pos { x: 40, y: 25 })
        .with(Player)
        .with(Renderable {
            glyph: carpet::CP437::from_char('A'),
            color: carpet::Color::Blue,
        })
        .build();

    for i in 0..10 {
        game.create_entity()
            .with(Pos { x: i * 7, y: 20 })
            .with(Renderable {
                glyph: carpet::CP437::from_char('X'),
                color: carpet::Color::Red,
            })
            .with(MoveLeft)
            .build();
    }

    game.on_key(
        (carpet::VirtualKeyCode::W, carpet::KeyMods::NONE),
        |world| {
            Motion::move_player(world, -1, 0);
        },
    );

    game.on_key(
        (carpet::VirtualKeyCode::A, carpet::KeyMods::NONE),
        |world| {
            Motion::move_player(world, 0, -1);
        },
    );

    game.on_key(
        (carpet::VirtualKeyCode::S, carpet::KeyMods::NONE),
        |world| {
            Motion::move_player(world, 1, 0);
        },
    );

    game.on_key(
        (carpet::VirtualKeyCode::D, carpet::KeyMods::NONE),
        |world| {
            Motion::move_player(world, 0, 1);
        },
    );

    game.run_with_systems(|world| {
        Draw.run_now(&world);
        Leftward.run_now(&world);
        Move.run_now(&world);
    })
}