Fix camera getting uneven, clamp top/bottom rotation

src/player.rs

@@ -1,16 +1,17 @@
 use bevy::{
   input::mouse::MouseMotion,
   prelude::*,
-  render::camera::{Camera, PerspectiveProjection, VisibleEntities},
+  render::camera::{PerspectiveProjection, VisibleEntities},
 };
 use bevy_rapier3d::{
-  na::Matrix3x1,
+  na::{clamp, wrap, Matrix3x1},
   physics::RigidBodyHandleComponent,
   rapier::{
     dynamics::{RigidBody, RigidBodyBuilder, RigidBodySet},
     geometry::ColliderBuilder,
   },
 };
+use std::f32::consts::{FRAC_PI_2, PI};
 
 pub struct PlayerPlugin;
 
@@ -32,6 +33,12 @@ struct State {
 #[derive(Default)]
 struct PlayerMarker;
 
+#[derive(Default, Debug)]
+struct CameraData {
+  yaw: f32,
+  pitch: f32,
+}
+
 #[derive(Bundle)]
 pub struct PlayerBundle {
   pub perspective_projection: PerspectiveProjection,
@@ -60,7 +67,7 @@ impl Default for PlayerBundle {
 }
 
 const PLAYER_SPEED: f32 = 320.0;
-const MOUSE_SENSITIVITY: f32 = 1.0;
+const MOUSE_SENSITIVITY: f32 = 0.5;
 const PLAYER_HEIGHT: f32 = 1.8;
 const PLAYER_WIDTH: f32 = 0.25;
 
@@ -68,10 +75,12 @@ fn init_player(commands: &mut Commands) {
   commands
     .spawn(PlayerBundle::default())
     .with_children(|parent| {
-      parent.spawn(Camera3dBundle {
+      parent
+        .spawn(Camera3dBundle {
           transform: Transform::from_translation(Vec3::new(0.0, PLAYER_HEIGHT / 2., 0.0)),
           ..Default::default()
-      });
+        })
+        .with(CameraData::default());
     });
 }
 
@@ -79,19 +88,18 @@ fn player_movement_system(
   time: Res<Time>,
   mut bodies: ResMut<RigidBodySet>,
   keyboard_input: Res<Input<KeyCode>>,
-  // TODO: need to use better queries which filters by parent.player_marker
+  camera_transform_query: Query<&Transform, With<CameraData>>,
-  camera_transform_query: Query<&Transform, With<Camera>>,
   mut player_query: Query<&RigidBodyHandleComponent, With<PlayerMarker>>,
 ) {
   for camera_transform in camera_transform_query.iter() {
     for body_handle in player_query.iter_mut() {
       let body: &mut RigidBody = bodies.get_mut(body_handle.handle()).unwrap();
-      let axis_straight = movement_axis(&keyboard_input, KeyCode::D, KeyCode::A);
+      let axis_strafe = movement_axis(&keyboard_input, KeyCode::D, KeyCode::A);
-      let axis_strafe = movement_axis(&keyboard_input, KeyCode::S, KeyCode::W);
+      let axis_straight = movement_axis(&keyboard_input, KeyCode::S, KeyCode::W);
 
       let rotation = camera_transform.rotation;
       let mut speed_2d: Vec3 =
-        (strafe_vector(&rotation) * axis_straight) + (forward_vector(&rotation) * axis_strafe);
+        (strafe_vector(&rotation) * axis_strafe) + (forward_vector(&rotation) * axis_straight);
       if speed_2d.length() != 0.0 {
         speed_2d = speed_2d.normalize() * PLAYER_SPEED;
       }
@@ -132,7 +140,7 @@ fn player_look_system(
   time: Res<Time>,
   mut state: ResMut<State>,
   mouse_motion_events: Res<Events<MouseMotion>>,
-  mut query: Query<&mut Transform, With<Camera>>,
+  mut query: Query<(&mut Transform, &mut CameraData)>,
 ) {
   let mut delta: Vec2 = Vec2::zero();
   for event in state.mouse_motion_event_reader.iter(&mouse_motion_events) {
@@ -142,15 +150,22 @@ fn player_look_system(
     return;
   }
 
-  // TODO: need to keep the camera level
+  for (mut transform, mut data) in query.iter_mut() {
-  for mut transform in query.iter_mut() {
+    data.yaw -= delta.y * MOUSE_SENSITIVITY * time.delta_seconds();
-    let yaw = -delta.y * MOUSE_SENSITIVITY * time.delta_seconds();
+    data.pitch -= delta.x * MOUSE_SENSITIVITY * time.delta_seconds();
-    let pitch = -delta.x * MOUSE_SENSITIVITY * time.delta_seconds();
+    // NOTE: if we just use FRAC_PI_2 here, for some reason it results in a blank screen when
+    //       looking up/down
+    let half_pi = FRAC_PI_2 - 0.01;
+    data.yaw = clamp(data.yaw, -half_pi, half_pi);
+    data.pitch = wrap(data.pitch, -PI, PI);
 
-    let quat_yaw = Quat::from_axis_angle(Vec3::unit_x(), yaw);
+    let quat_yaw = Quat::from_axis_angle(Vec3::unit_x(), data.yaw);
-    let quat_pitch = Quat::from_axis_angle(Vec3::unit_y(), pitch);
+    let quat_pitch = Quat::from_axis_angle(Vec3::unit_y(), data.pitch);
 
-    let orientation_change: Quat = (quat_pitch * quat_yaw).normalize();
+    let mut orientation = Quat::identity();
-    transform.rotate(orientation_change);
+    orientation = orientation * quat_yaw;
+    orientation = quat_pitch * orientation;
+
+    transform.rotation = orientation.normalize();
   }
 }