Add chapter 2.6

src/map_indexing_system.rs

@@ -0,0 +1,34 @@
+use specs::prelude::*;
+
+use crate::{
+    components::{BlocksTile, Position},
+    map::Map,
+};
+
+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);
+
+            let _p: Option<&BlocksTile> = blockers.get(entity);
+            if let Some(_p) = _p {
+                map.blocked[idx] = true;
+            }
+
+            map.tile_content[idx].push(entity);
+        }
+    }
+}