Add system to let bystanders move around

src/bystander_ai_system.rs

@@ -0,0 +1,71 @@
+use ::rltk::RandomNumberGenerator;
+use specs::prelude::*;
+
+use super::{Map, RunState};
+use crate::components::{Bystander, EntityMoved, Position, Viewshed};
+
+pub struct BystanderAI {}
+
+impl<'a> System<'a> for BystanderAI {
+    #[allow(clippy::type_complexity)]
+    type SystemData = (
+        WriteExpect<'a, Map>,
+        ReadExpect<'a, RunState>,
+        Entities<'a>,
+        WriteStorage<'a, Viewshed>,
+        ReadStorage<'a, Bystander>,
+        WriteStorage<'a, Position>,
+        WriteStorage<'a, EntityMoved>,
+        WriteExpect<'a, RandomNumberGenerator>,
+    );
+
+    fn run(&mut self, data: Self::SystemData) {
+        let (
+            mut map,
+            runstate,
+            entities,
+            mut viewshed,
+            bystander,
+            mut position,
+            mut entity_moved,
+            mut rng,
+        ) = data;
+
+        if *runstate != RunState::MonsterTurn {
+            return;
+        }
+
+        for (entity, mut viewshed, _bystander, mut pos) in
+            (&entities, &mut viewshed, &bystander, &mut position).join()
+        {
+            // Try to move randomly
+            let mut x = pos.x;
+            let mut y = pos.y;
+            match rng.roll_dice(1, 5) {
+                1 => x -= 1,
+                2 => x += 1,
+                3 => y -= 1,
+                4 => y += 1,
+                _ => {}
+            }
+
+            if x > 0 && x < map.width - 1 && y > 0 && y < map.height - 1 {
+                let dest_idx = map.xy_idx(x, y);
+
+                if !map.blocked[dest_idx] {
+                    let idx = map.xy_idx(pos.x, pos.y);
+                    map.blocked[idx] = false;
+
+                    pos.x = x;
+                    pos.y = y;
+                    entity_moved
+                        .insert(entity, EntityMoved {})
+                        .expect("Unable to insert moved flag component");
+
+                    map.blocked[dest_idx] = true;
+                    viewshed.dirty = true;
+                }
+            }
+        }
+    }
+}

src/main.rs

@@ -1,3 +1,4 @@
+mod bystander_ai_system;
 pub mod camera;
 mod components;
 mod damage_system;
@@ -27,6 +28,7 @@ extern crate lazy_static;
 use ::rltk::{GameState, Point, RandomNumberGenerator, Rltk};
 use ::specs::prelude::*;
 use ::specs::saveload::{SimpleMarker, SimpleMarkerAllocator};
+use bystander_ai_system::BystanderAI;
 use components::*;
 use damage_system::DamageSystem;
 pub use game_log::GameLog;
@@ -111,6 +113,9 @@ impl State {
         let mut mapindex = MapIndexingSystem {};
         mapindex.run_now(&self.ecs);
 
+        let mut bystander = BystanderAI {};
+        bystander.run_now(&self.ecs);
+
         let mut melee = MeleeCombatSystem {};
         melee.run_now(&self.ecs);