roguelike-game/src/map_indexing_system.rs

use specs::prelude::*;

use crate::{BlocksTile, Map, Position};

pub struct MapIndexingSystem {}

impl<'a> System<'a> for MapIndexingSystem {
    type SystemData = (
        WriteExpect<'a, Map>,
        ReadStorage<'a, Position>,
        ReadStorage<'a, BlocksTile>,
        Entities<'a>,
    );

    fn run(&mut self, data: Self::SystemData) {
        let (mut map, position, blockers, entities) = data;

        map.populate_blocked();
        map.clear_content_index();

        for (entity, position) in (&entities, &position).join() {
            let idx = map.xy_idx(position.x, position.y);

            // If it's a blocking entity, note that in the map object
            if let Some(_p) = blockers.get(entity) {
                map.blocked[idx] = true;
            }

            // Push a copy of the entity to the indexed slot
            map.tile_content[idx].push(entity);
        }
    }
}