2 files changed, 142 insertions, 0 deletions
diff --git a/engine/src/camera.rs b/engine/src/camera.rs
index 640c1f4..5b71e2f 100644
--- a/engine/src/camera.rs
+++ b/engine/src/camera.rs
@@ -3,6 +3,8 @@ use ecs::Component;
 use crate::projection::{Perspective, Projection};
 use crate::vector::Vec3;
 
+pub mod fly;
+
 #[derive(Debug, Component)]
 pub struct Camera
 {
diff --git a/engine/src/camera/fly.rs b/engine/src/camera/fly.rs
new file mode 100644
index 0000000..7fa435b
--- /dev/null
+++ b/engine/src/camera/fly.rs
@@ -0,0 +1,140 @@
+use ecs::component::local::Local;
+use ecs::sole::Single;
+use ecs::system::{Into, System};
+use ecs::{Component, Query};
+use glfw::window::{Key, KeyState};
+
+use crate::camera::Camera;
+use crate::delta_time::DeltaTime;
+use crate::event::Update as UpdateEvent;
+use crate::input::{Cursor, Keys};
+use crate::vector::{Vec2, Vec3};
+
+/// Fly camera extension.
+pub struct Extension(pub Options);
+
+impl ecs::extension::Extension for Extension
+{
+    fn collect(self, mut collector: ecs::extension::Collector<'_>)
+    {
+        collector.add_system(
+            UpdateEvent,
+            update.into_system().initialize((
+                CursorState {
+                    current_yaw: -90.0,
+                    ..Default::default()
+                },
+                self.0,
+            )),
+        );
+    }
+}
+
+#[derive(Debug, Component)]
+pub struct Options
+{
+    pub camera_speed: f32,
+    pub mouse_sensitivity: f32,
+}
+
+fn update(
+    camera_query: Query<(Camera,)>,
+    keys: Single<Keys>,
+    cursor: Single<Cursor>,
+    delta_time: Single<DeltaTime>,
+    mut cursor_state: Local<CursorState>,
+    options: Local<Options>,
+)
+{
+    let Some((mut camera,)) = camera_query.iter().next() else {
+        #[cfg(feature = "debug")]
+        tracing::warn!("No camera");
+
+        return;
+    };
+
+    if cursor.has_moved && cursor_state.first_mouse {
+        println!("First cursor move");
+
+        cursor_state.last_pos = cursor.position;
+        cursor_state.first_mouse = false;
+    }
+
+    let delta_time = delta_time.duration;
+
+    let mut x_offset = cursor.position.x - cursor_state.last_pos.x;
+    let mut y_offset = cursor_state.last_pos.y - cursor.position.y;
+
+    cursor_state.last_pos = cursor.position;
+
+    x_offset *= f64::from(options.mouse_sensitivity);
+    y_offset *= f64::from(options.mouse_sensitivity);
+
+    cursor_state.current_yaw += x_offset;
+    cursor_state.current_pitch += y_offset;
+
+    if cursor_state.current_pitch > 89.0 {
+        cursor_state.current_pitch = 89.0;
+    } else if cursor_state.current_pitch < -89.0 {
+        cursor_state.current_pitch = -89.0;
+    }
+
+    // TODO: This casting to a f32 from a f64 is horrible. fix it
+    #[allow(clippy::cast_possible_truncation)]
+    let direction = Vec3 {
+        x: (cursor_state.current_yaw.to_radians().cos()
+            * cursor_state.current_pitch.to_radians().cos()) as f32,
+        y: cursor_state.current_pitch.to_radians().sin() as f32,
+        z: (cursor_state.current_yaw.to_radians().sin()
+            * cursor_state.current_pitch.to_radians().cos()) as f32,
+    }
+    .normalize();
+
+    let cam_right = direction.cross(&Vec3::UP).normalize();
+
+    camera.global_up = cam_right.cross(&direction).normalize();
+
+    if matches!(keys.get_key_state(Key::W), KeyState::Pressed) {
+        camera.position += direction * options.camera_speed * delta_time.as_secs_f32();
+    }
+
+    if matches!(keys.get_key_state(Key::S), KeyState::Pressed) {
+        camera.position -= direction * options.camera_speed * delta_time.as_secs_f32();
+    }
+
+    if matches!(keys.get_key_state(Key::A), KeyState::Pressed) {
+        let cam_left = -direction.cross(&Vec3::UP).normalize();
+
+        camera.position += cam_left * options.camera_speed * delta_time.as_secs_f32();
+    }
+
+    if matches!(keys.get_key_state(Key::D), KeyState::Pressed) {
+        let cam_right = direction.cross(&Vec3::UP).normalize();
+
+        camera.position += cam_right * options.camera_speed * delta_time.as_secs_f32();
+    }
+
+    camera.target = camera.position + direction;
+}
+
+#[derive(Debug, Component)]
+struct CursorState
+{
+    last_pos: Vec2<f64>,
+    current_pitch: f64,
+    current_yaw: f64,
+    first_mouse: bool,
+}
+
+impl Default for CursorState
+{
+    fn default() -> Self
+    {
+        Self {
+            last_pos: Vec2::default(),
+            current_pitch: 0.0,
+            current_yaw: 0.0,
+            first_mouse: true,
+        }
+    }
+}