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use std::any::Any;

trait Component {
    fn as_any(&self) -> &Any;
}

#[derive(Debug, Clone, Copy)]
struct Health {
    hp: i32,
}
impl Component for Health {
    fn as_any(&self) -> &Any {
        self
    }
}

#[derive(Debug, Clone, Copy)]
struct Position {
    x: i32,
    y: i32,
}
impl Component for Position {
    fn as_any(&self) -> &Any {
        self
    }
}
impl Position {
    fn set(&mut self, x: i32, y: i32) {
        self.x = x;
        self.y = y;
    }
}

#[derive(Debug, Clone, Copy)]
struct Motion {
    // velocity
    v_x: f32,
    v_y: f32,
    // acceleration
    a_x: f32,
    a_y: f32,
}
impl Component for Motion {
    fn as_any(&self) -> &Any {
        self
    }
}
impl Motion {
    fn new() -> Motion {
        return Motion {
            v_x: 0.0, v_y: 0.0,
            a_x: 0.0, a_y: 0.0,
        };
    }
    fn set_v(&mut self, a_x: f32, a_y: f32)  {
        self.a_x = a_x;
        self.a_y = a_y;
    }
    fn set_a(&mut self, v_x: f32, v_y: f32) {
        self.v_x = v_x;
        self.v_y = v_y;
    }
}

#[derive(Debug, Clone, Copy)]
struct Draw {

}

fn get_cmpnt<'a, T>(v: &'a Components) -> Option<T>
    where T: Component + Copy + 'static {
    for boxed_cmpnt in v {
        match boxed_cmpnt.as_any().downcast_ref::<T>() {
            Some(t) => return Some(*t),
            None => continue,
        }
    }
    return None;
}

fn set_cmpnt<T>(v: &mut Components, val: T)
    where T: Component + Copy + 'static {
    for boxed_cmpnt in v.iter_mut() {
        if let Some(_) = boxed_cmpnt.as_any().downcast_ref::<T>() {
            *boxed_cmpnt = Box::new(val);
        }
    }
}

type Components = Vec<Box<Component>>;

struct Screen {
    w: i32,
    h: i32,
}

fn moving(entity: &Components) {
    let motion = get_cmpnt::<Motion>(entity);
    let position = get_cmpnt::<Position>(entity);
    if let Some(m) = motion {
        if let Some(p) = position {
            let mut new_p = p;

        }
    }
}

fn rendering(screen: &Screen, entity: &Components) {
    for y in 0..screen.h {
        for x in 0..screen.w {
            let position = get_cmpnt::<Position>(entity);
            if let Some(p) = position {
                if p.x == x && p.y == y {
                    print!(".");
                } else {
                    print!(" ");
                }
            }
        }
        println!("");
    }
}

fn main() {
    let screen = Screen {w: 20, h: 20};
    let mut entity: Components = vec![];
    entity.push(Box::new(Health {hp: 0}));
    entity.push(Box::new(Position {x: 0, y: 1}));
    entity.push(Box::new(Motion::new()));

    let health = get_cmpnt::<Health>(&entity);
    if let Some(h) = health {
        println!("health: {:?}", h);
    }

    if let Some(h) = health {
        let mut new_h = h;
        new_h.hp = 20;
        set_cmpnt::<Health>(&mut entity, new_h);
    }

    let health = get_cmpnt::<Health>(&entity);
    if let Some(h) = health {
        println!("health: {:?}", h);
    }

    for i in 0..20 {
        let position = get_cmpnt::<Position>(&entity);
        if let Some(p) = position {
            println!("position: {:?}", p);

            let mut new_p = p;
            new_p.x += 1;
            set_cmpnt::<Position>(&mut entity, new_p);
        }
    }

    // Systems
    moving(&entity);
    rendering(&screen, &entity);
}