Make camera move with player

src/main.rs

@@ -5,6 +5,7 @@ use bevy::input::system::exit_on_esc_system;
 use bevy::input::Input;
 use bevy::math::Vec3;
 use bevy::prelude::*;
+use bevy::render::primitives::Frustum;
 use bevy::sprite::{Sprite, SpriteBundle};
 use bevy::text::Text;
 use bevy::window::Windows;
@@ -264,8 +265,11 @@ fn expiration_date_system(
 
 fn arnold_movement_system(
     keyboard_input: Res<Input<KeyCode>>,
-    mut query: Query<(&mut Arnold, &mut Sprite, &mut Transform)>,
+    mut query: Query<(&mut Arnold, &mut Sprite, &mut Transform), Without<Camera>>,
+    // Hack to get exactly the right camera (the one for the given 2d scene, not the UI one)
+    mut cam_query: Query<(&Camera, &mut Transform), With<Frustum>>,
 ) {
+    let (_cam, mut cam_transform) = cam_query.single_mut();
     let (mut arnold, mut sprite, mut transform) = query.single_mut();
 
     let mut velocity = Vec3::new(0.0, 0.0, 0.0);
@@ -293,6 +297,7 @@ fn arnold_movement_system(
     }
 
     transform.translation += velocity;
+    cam_transform.translation += velocity;
 }
 
 fn arnold_attack_system(
@@ -332,6 +337,7 @@ fn enemy_spawner_system(
     windows: Res<Windows>,
     time: Res<Time>,
     mut query: Query<&mut EnemySpawner>,
+    query_player: Query<&Transform, With<Arnold>>,
 ) {
     let mut enemy_spawner = query.single_mut();
 
@@ -349,7 +355,8 @@ fn enemy_spawner_system(
         .spawn_bundle(SpriteBundle {
             texture: assets.load("monster.png"),
             transform: Transform {
-                translation: Vec3::new(phi.cos() * spawn_distance, phi.sin() * spawn_distance, 0.0),
+                translation: query_player.single().translation
+                    + Vec3::new(phi.cos() * spawn_distance, phi.sin() * spawn_distance, 0.0),
                 ..Default::default()
             },
             ..Default::default()