ECS

src/components.rs

@@ -8,3 +8,6 @@ pub struct Render {
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct Player;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Enemy;

src/main.rs

@@ -34,8 +34,14 @@ impl State {
         let mut resources = Resources::default();
         let mut rng = RandomNumberGenerator::new();
         let map_builder = MapBuilder::new(&mut rng);
-        spawn_player(&mut ecs, map_builder.player_start);
 
+        spawn_player(&mut ecs, map_builder.player_start);
+        map_builder
+            .rooms
+            .iter()
+            .skip(1)
+            .map(|r| r.center())
+            .for_each(|pos| spawn_monster(&mut ecs, &mut rng, pos));
         resources.insert(map_builder.map);
         resources.insert(Camera::new(map_builder.player_start));
 

src/spawners.rs

@@ -10,3 +10,19 @@ pub fn spawn_player(ecs: &mut World, pos: Point) {
         },
     ));
 }
+
+pub fn spawn_monster(ecs: &mut World, rng: &mut RandomNumberGenerator, pos: Point) {
+    ecs.push((
+        Enemy,
+        pos,
+        Render {
+            color: ColorPair::new(WHITE, BLACK),
+            glyph: match rng.range(0, 4) {
+                0 => to_cp437('E'), // Ettin
+                1 => to_cp437('O'), // Ogre
+                2 => to_cp437('o'), // Orc
+                _ => to_cp437('g'), // goblin
+            },
+        },
+    ));
+}

src/systems/collisions.rs

@@ -0,0 +1,19 @@
+use crate::prelude::*;
+
+#[system]
+#[read_component(Point)]
+#[read_component(Player)]
+#[read_component(Enemy)]
+pub fn collisions(ecs: &mut SubWorld, commands: &mut CommandBuffer) {
+    let mut player_pos = Point::zero();
+    let mut players = <&Point>::query().filter(component::<Player>());
+    players.iter(ecs).for_each(|pos| player_pos = *pos);
+
+    let mut enemies = <(Entity, &Point)>::query().filter(component::<Enemy>());
+    enemies
+        .iter(ecs)
+        .filter(|(_, pos)| **pos == player_pos)
+        .for_each(|(entity, _)| {
+            commands.remove(*entity);
+        });
+}

src/systems/mod.rs

@@ -1,4 +1,5 @@
 use crate::prelude::*;
+mod collisions;
 mod entity_render;
 mod map_render;
 mod player_input;
@@ -6,6 +7,7 @@ mod player_input;
 pub fn build_scheduler() -> Schedule {
     Schedule::builder()
         .add_system(player_input::player_input_system())
+        .add_system(collisions::collisions_system())
         .add_system(map_render::map_render_system())
         .add_system(entity_render::entity_render_system())
         .build()