set up visibility system

src/components.rs

@@ -1,4 +1,4 @@
-use rltk::RGB;
+use rltk::{RGB,Point};
 
 use specs::prelude::*;
 
@@ -20,3 +20,9 @@ pub struct LeftMover {}
 
 #[derive(Component, Debug)]
 pub struct Player {}
+
+#[derive(Component)]
+pub struct Viewshed {
+    pub visible_tiles : Vec<Point>,
+    pub range : i32
+}

src/main.rs

@@ -7,6 +7,8 @@ mod map;
 pub use map::*;
 mod components;
 pub use components::*;
+mod visibility_system;
+pub use visibility_system::VisibilitySystem;
 
 #[macro_use]
 extern crate specs_derive;
@@ -69,8 +71,8 @@ impl<'a> System<'a> for LeftWalker {
 
 impl State {
     fn run_systems(&mut self) {
-        let mut lw = LeftWalker {};
-        lw.run_now(&self.ecs);
+        let mut vis = VisibilitySystem {};
+        vis.run_now(&self.ecs);
         self.ecs.maintain();
     }
 }
@@ -104,6 +106,7 @@ fn main() {
     gs.ecs.register::<Renderable>();
     gs.ecs.register::<LeftMover>();
     gs.ecs.register::<Player>();
+    gs.ecs.register::<Viewshed>();
 
     gs.ecs
         .create_entity()
@@ -117,6 +120,10 @@ fn main() {
             bg: RGB::named(rltk::BLACK),
         })
         .with(Player {})
+        .with(Viewshed {
+            visible_tiles: Vec::new(),
+            range: 8,
+        })
         .build();
 
     for i in 0..10 {

src/visibility_system.rs

@@ -0,0 +1,15 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Viewshed, Position};
+
+pub struct VisibilitySystem {}
+
+impl<'a> System<'a> for VisibilitySystem {
+    type SystemData = ( WriteStorage<'a, Viewshed>, 
+                        WriteStorage<'a, Position>);
+
+    fn run(&mut self, (mut viewshed, pos) : Self::SystemData) {
+        for (viewshed,pos) in (&mut viewshed, &pos).join() {
+        }
+    }
+}