From 63fab851acf1fdd10b160b5b32428d2c40405659 Mon Sep 17 00:00:00 2001
From: "Elijah C. Voigt" <elijah.caine.mv@gmail.com>
Date: Fri, 28 Jun 2024 20:56:39 -0700
Subject: [PATCH] Editor fly camera

---
 src/camera.rs     | 127 ++++++++++++++++++++++++++++++++++++++++++++++
 src/conditions.rs |   5 +-
 src/editor.rs     |   5 +-
 src/main.rs       |   5 +-
 src/prelude.rs    |   1 +
 5 files changed, 137 insertions(+), 6 deletions(-)
 create mode 100644 src/camera.rs

diff --git a/src/camera.rs b/src/camera.rs
new file mode 100644
index 0000000..95d19af
--- /dev/null
+++ b/src/camera.rs
@@ -0,0 +1,127 @@
+use crate::prelude::*;
+
+/// Menu Plugin; empty struct for Plugin impl
+pub(crate) struct CameraPlugin;
+
+impl Plugin for CameraPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_systems(
+            Update,
+            move_editor_fly_camera.run_if(any_with_component::<FlyCamera>),
+        );
+        app.add_systems(
+            Update,
+            rotate_editor_fly_camera.run_if(any_with_component::<FlyCamera>),
+        );
+    }
+}
+
+#[derive(Component)]
+pub(crate) struct FlyCamera;
+
+/// Fly camera system for moving around like a drone
+/// TODO: Only if key is pressed!
+fn move_editor_fly_camera(
+    mut cameras: Query<(&Camera, &mut Transform), With<FlyCamera>>,
+    windows: Query<&Window>,
+    primary_window: Query<Entity, With<PrimaryWindow>>,
+    keys: Res<ButtonInput<KeyCode>>,
+    time: Res<Time>,
+) {
+    (keys.any_pressed([
+        KeyCode::KeyW,
+        KeyCode::KeyS,
+        KeyCode::KeyA,
+        KeyCode::KeyD,
+        KeyCode::KeyQ,
+        KeyCode::KeyE,
+    ]))
+    .then(|| {
+        // Iterate over all cameras
+        cameras.iter_mut().for_each(|(c, mut t)| {
+            // Determine which window this camera is attached to
+            let target_window = match c.target {
+                RenderTarget::Window(wr) => match wr {
+                    WindowRef::Entity(e) => Some(e),
+                    WindowRef::Primary => Some(primary_window.get_single().unwrap()),
+                },
+                _ => None,
+            };
+            let window = windows.get(target_window.unwrap()).unwrap();
+
+            // If the target window is focused
+            window.focused.then(|| {
+                let move_speed = if keys.pressed(KeyCode::ShiftLeft) {
+                    16.0
+                } else {
+                    4.0
+                };
+                let mut delta = Vec3::ZERO;
+                if keys.pressed(KeyCode::KeyW) {
+                    delta += t.forward() * move_speed * time.delta_seconds()
+                }
+                if keys.pressed(KeyCode::KeyS) {
+                    delta += t.back() * move_speed * time.delta_seconds()
+                }
+                if keys.pressed(KeyCode::KeyA) {
+                    delta += t.left() * move_speed * time.delta_seconds()
+                }
+                if keys.pressed(KeyCode::KeyD) {
+                    delta += t.right() * move_speed * time.delta_seconds()
+                }
+                if keys.pressed(KeyCode::KeyE) {
+                    delta += Vec3::Y * move_speed * time.delta_seconds()
+                }
+                if keys.pressed(KeyCode::KeyQ) {
+                    delta += Vec3::NEG_Y * move_speed * time.delta_seconds()
+                }
+                t.translation += delta;
+            });
+        });
+    });
+}
+
+fn rotate_editor_fly_camera(
+    mut cameras: Query<(&Camera, &mut Transform), With<FlyCamera>>,
+    windows: Query<&Window>,
+    primary_window: Query<Entity, With<PrimaryWindow>>,
+    mouse: Res<ButtonInput<MouseButton>>,
+    mut cursor_events: EventReader<CursorMoved>,
+) {
+    (cursor_events.len() > 0).then(|| {
+        // Iterate over all cameras
+        cameras.iter_mut().for_each(|(c, mut t)| {
+            // Determine which window this camera is attached to
+            let target_window = match c.target {
+                RenderTarget::Window(wr) => match wr {
+                    WindowRef::Entity(e) => Some(e),
+                    WindowRef::Primary => Some(primary_window.get_single().unwrap()),
+                },
+                _ => None,
+            };
+            let window = windows.get(target_window.unwrap()).unwrap();
+            if mouse.pressed(MouseButton::Middle) {
+                cursor_events
+                    .read()
+                    .filter_map(|CursorMoved { delta, window, .. }| {
+                        (*window == target_window.unwrap()).then_some(delta)
+                    })
+                    .for_each(|delta| {
+                        if let Some(Vec2 { x, y }) = delta {
+                            // Cribbing from bevy_flycam
+                            // Link: https://github.com/sburris0/bevy_flycam/blob/baffe50e0961ad1491d467fa6ab5551f9f21db8f/src/lib.rs#L145-L151
+                            let (mut yaw, mut pitch, _) = t.rotation.to_euler(EulerRot::YXZ);
+                            let window_scale = window.height().min(window.width());
+                            let sensitivity = 0.00012;
+                            pitch -= (sensitivity * y * window_scale).to_radians();
+                            yaw -= (sensitivity * x * window_scale).to_radians();
+                            t.rotation = Quat::from_axis_angle(Vec3::Y, yaw)
+                                * Quat::from_axis_angle(Vec3::X, pitch);
+                        }
+                    });
+            } else {
+                cursor_events.clear();
+            }
+        });
+    });
+}
diff --git a/src/conditions.rs b/src/conditions.rs
index 0dc608a..5635065 100644
--- a/src/conditions.rs
+++ b/src/conditions.rs
@@ -1,5 +1,8 @@
 use bevy::prelude::*;
 
-pub(crate) fn any_component_added<T: Component>(q: Query<Entity, Added<T>>) -> bool {
+///
+/// ECS scheduler active when an entity has a given component added
+///
+pub(crate) fn any_component_added<C: Component>(q: Query<Entity, Added<C>>) -> bool {
     !q.is_empty()
 }
diff --git a/src/editor.rs b/src/editor.rs
index 5d13c39..0693850 100644
--- a/src/editor.rs
+++ b/src/editor.rs
@@ -78,6 +78,7 @@ fn init_editor(mut commands: Commands) {
     let editor_camera = commands
         .spawn((
             EditorTag,
+            FlyCamera,
             Camera3dBundle {
                 camera: Camera {
                     target: RenderTarget::Window(WindowRef::Entity(editor_window)),
@@ -180,7 +181,3 @@ fn plane_gizmos(mut gizmos: Gizmos) {
         gizmos.arrow(Vec3::ZERO, Vec3::Z, Color::BLUE);
     }
 }
-
-fn _fly_camera(mut _camera: Query<&mut Transform, (With<Camera>, With<EditorTag>)>) {
-    todo!()
-}
diff --git a/src/main.rs b/src/main.rs
index 9a17ddd..3a67267 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,5 @@
+/// Camera controller
+pub(crate) mod camera;
 /// ECS scheduling `run_if` conditions
 pub(crate) mod conditions;
 /// Editor: debugging and run-time modifications to the game
@@ -19,8 +21,9 @@ fn main() {
             exit_condition: bevy::window::ExitCondition::OnPrimaryClosed,
             ..default()
         }))
-        .add_plugins(menu::MenuPlugin)
+        .add_plugins(camera::CameraPlugin)
         .add_plugins(editor::EditorPlugin)
+        .add_plugins(menu::MenuPlugin)
         .add_plugins(window::WindowPlugin)
         .run();
 }
diff --git a/src/prelude.rs b/src/prelude.rs
index ebb594d..c662a8a 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -6,4 +6,5 @@ pub(crate) use bevy::window::PrimaryWindow;
 pub(crate) use bevy::window::WindowCloseRequested;
 pub(crate) use bevy::window::WindowRef;
 
+pub(crate) use crate::camera::*;
 pub(crate) use crate::conditions::*;