boundary conditions

src/main.rs

@@ -8,7 +8,7 @@ fn main() {
         .init_resource::<BoidMesh>()
         .add_plugins(DefaultPlugins)
         .add_systems(Startup, (boid_mesh::build_boid_mesh, setup).chain())
-        .add_systems(Update, move_boids)
+        .add_systems(Update, (move_boids, boid_border_teleport).chain())
         .run();
 }
 
@@ -31,6 +31,40 @@ fn move_boids(mut boids: Query<(&mut Transform, &Velocity), With<Boid>>, time: R
     }
 }
 
+fn boid_border_teleport(mut boids: Query<&mut Transform, With<Boid>>, windows: Query<&Window>) {
+    let window = windows.get_single().unwrap();
+    let width = window.resolution.width();
+    let height = window.resolution.height();
+
+    let half_width = width / 2.;
+    let half_height = height / 2.;
+
+    let left_bound = -half_width;
+    let right_bound = half_width;
+    let top_bound = half_height;
+    let bottom_bound = -half_height;
+
+    for boid_transform in &mut boids {
+        let mut translation = boid_transform.translation;
+
+        if translation.y > top_bound {
+            translation.y = bottom_bound;
+        }
+
+        if translation.y < bottom_bound {
+            translation.y = top_bound;
+        }
+
+        if translation.x < left_bound {
+            translation.x = right_bound;
+        }
+
+        if translation.x > right_bound {
+            translation.x = left_bound;
+        }
+    }
+}
+
 fn setup(
     mut commands: Commands,
     mut materials: ResMut<Assets<ColorMaterial>>,