ez-roguelike/ch5/src/systems.rs

use crate::components::{Motion, Player, Renderable};
use crate::map::{Map, Viewshed};

system_impl! {
    Draw(
        resource mut game_board: carpet::GameBoard<carpet::CP437>,
        resource map: Map,
        resource vs: Viewshed,
        renderable: Renderable,
        pos: carpet::Coord,
    ) {
        game_board.clear();
        for (x, y, t) in map.tiles.iter() {
            if vs.vs.visibility([x, y]) {
                game_board.set([x, y], t.glyph());
            }
        }
        for (p, r) in (&pos, &renderable).join() {
            game_board.set_with_color([p.x, p.y], r.glyph, r.color);
        }
    }
}

system! {
    Move (
        resource map: Map,
        resource mut viewshed: Viewshed,
        mut motion: Motion,
        mut pos: carpet::Coord,
    ) {
        let tgt_x = (pos.x as i8 + motion.right) as usize;
        let tgt_y = (pos.y as i8 + motion.down) as usize;
        if map.passable((tgt_x, tgt_y)) {
            viewshed.dirty = true;
            pos.x = tgt_x;
            pos.y = tgt_y;
        }
    } finally {
        motion.clear();
    }
}

system! {
    Visibility(
        resource map: Map,
        resource mut viewshed: Viewshed,
        pos: carpet::Coord,
        _player: Player,
    ) {
        if viewshed.dirty {
            viewshed.vs.calculate_from(&map.tiles, *pos);
            viewshed.dirty = false;
        }
    }
}