use crate::components::{Velocity, Position};
use crate::game::MyGame;

use specs::RunNow;

struct Physics;

impl <'a> specs::System<'a> for Physics {
    type SystemData = (
        specs::ReadStorage<'a, Velocity>,
        specs::WriteStorage<'a, Position>,
    );

    fn run(&mut self, (velocity, mut position): Self::SystemData) {
        use specs::Join;

        for (vel, pos) in (&velocity, &mut position).join() {
            pos.x += vel.dx;
            pos.y += vel.dy;
        }
    }
}


pub fn systems(game: &mut MyGame) {
    Physics.run_now(&game.world.res);
}