Add some comments and deduplicate or simplify logic

examples/globe.rs

@@ -78,7 +78,7 @@ fn setup(
  mut materials: ResMut<Assets<StandardMaterial>>,
  mut images: ResMut<Assets<Image>>,
 ) {
- // plane
+ // globe
  let radius = 5.0;
  commands.spawn((
  PbrBundle {

src/xr_input/prototype_locomotion.rs

@@ -66,109 +66,70 @@ pub fn proto_locomotion(
  session: Res<XrSession>,
  views: ResMut<XrViews>,
  mut gizmos: Gizmos,
- config_option: Option<ResMut<PrototypeLocomotionConfig>>,
+ mut config: ResMut<PrototypeLocomotionConfig>,
  action_sets: Res<XrActionSets>,
 ) {
- let mut config = match config_option {
- Some(c) => c,
- None => {
- info!("no locomotion config");
- return;
- }
- };
  //get controller
  let controller = oculus_controller.get_ref(&session, &frame_state, &xr_input, &action_sets);
- let root = tracking_root_query.get_single_mut();
- match root {
- Ok(mut position) => {
- //get the stick input and do some maths
- let stick = controller.thumbstick(Hand::Left);
- let input = stick.x * *position.right() + stick.y * *position.forward();
- let reference_quat;
- match config.locomotion_type {
- LocomotionType::Head => {
- let views = views.first();
- match views {
- Some(view) => {
- reference_quat = view.pose.orientation.to_quat();
- }
- None => return,
- }
- }
- LocomotionType::Hand => {
- let grip = controller.grip_space(Hand::Left);
- reference_quat = grip.0.pose.orientation.to_quat();
- }
- }
- let (yaw, _pitch, _roll) = reference_quat.to_euler(EulerRot::YXZ);
- let reference_quat = Quat::from_axis_angle(*position.up(), yaw);
- let locomotion_vec = reference_quat.mul_vec3(input);
- position.translation += locomotion_vec * config.locomotion_speed * time.delta_seconds();
+ let mut position = tracking_root_query
+ .get_single_mut()
+ .expect("too many tracking roots");
+ let Some(view) = views.first() else {
+ info!("locomotion found no head to use for relative movement");
+ return;
+ };
+ // Get the stick input
+ let stick = controller.thumbstick(Hand::Left);
+ let input = stick.x * *position.right() + stick.y * *position.forward();
+ let reference_quat = match config.locomotion_type {
+ LocomotionType::Head => view.pose,
+ LocomotionType::Hand => {
+ let (loc, _vel) = controller.grip_space(Hand::Left);
+ loc.pose
+ }
+ }
+ .orientation
+ .to_quat();
+ // Get rotation around "up" axis (y).
+ let (yaw, _pitch, _roll) = reference_quat.to_euler(EulerRot::YXZ);
+ // A quat representing the global position and rotation, ignoring pitch and roll
+ let reference_quat = Quat::from_axis_angle(*position.up(), yaw);
+ // Direction to move towards, in global orientation.
+ let locomotion_vec = reference_quat.mul_vec3(input);
+ // Actually move the player
+ position.translation += locomotion_vec * config.locomotion_speed * time.delta_seconds();
 
-  //now time for rotation
+ // Now rotate the player
 
- match config.rotation_type {
- RotationType::Smooth => {
- //once again with the math
- let control_stick = controller.thumbstick(Hand::Right);
- let rot_input = -control_stick.x; //why is this negative i dont know
- if rot_input.abs() <= config.rotation_stick_deadzone {
- return;
- }
- let smoth_rot = Quat::from_axis_angle(
- *position.up(),
- rot_input * config.smooth_rotation_speed * time.delta_seconds(),
- );
- //apply rotation
- let views = views.first();
- match views {
- Some(view) => {
- let mut hmd_translation = view.pose.position.to_vec3();
- hmd_translation.y = 0.0;
- let local = position.translation;
- let global = position.rotation.mul_vec3(hmd_translation) + local;
- gizmos.circle(global, position.up(), 0.1, Color::GREEN);
- position.rotate_around(global, smoth_rot);
- }
- None => return,
- }
- }
- RotationType::Snap => {
- //tick the timer
- config.rotation_timer.timer.tick(time.delta());
- if config.rotation_timer.timer.finished() {
- //now we can snap turn?
- //once again with the math
- let control_stick = controller.thumbstick(Hand::Right);
- let rot_input = -control_stick.x;
- if rot_input.abs() <= config.rotation_stick_deadzone {
- return;
- }
- let dir: f32 = match rot_input > 0.0 {
- true => 1.0,
- false => -1.0,
- };
- let smoth_rot =
- Quat::from_axis_angle(*position.up(), config.snap_angle * dir);
- //apply rotation
- let v = views;
- let views = v.first();
- match views {
- Some(view) => {
- let mut hmd_translation = view.pose.position.to_vec3();
- hmd_translation.y = 0.0;
- let local = position.translation;
- let global = position.rotation.mul_vec3(hmd_translation) + local;
- gizmos.circle(global, position.up(), 0.1, Color::GREEN);
- position.rotate_around(global, smoth_rot);
- }
- None => return,
- }
- config.rotation_timer.timer.reset();
- }
- }
+ // Get controller direction and "turning strength"
+ let control_stick = controller.thumbstick(Hand::Right);
+ let rot_input = -control_stick.x; //why is this negative i dont know
+ if rot_input.abs() <= config.rotation_stick_deadzone {
+ return;
+ }
+ let angle = match config.rotation_type {
+ RotationType::Smooth => rot_input * config.smooth_rotation_speed * time.delta_seconds(),
+ RotationType::Snap => {
+ // The timer is needed so we don't move by the snap amount every frame.
+ // FIXME: use no timer at all and require moving the controller stick back to the default
+ // location. This is what most VR games do.
+ config.rotation_timer.timer.tick(time.delta());
+ if config.rotation_timer.timer.finished() {
+ config.rotation_timer.timer.reset();
+ return;
+ } else {
+ config.snap_angle * rot_input.signum()
  }
  }
- Err(_) => info!("too many tracking roots"),
- }
+ };
+
+ // Rotate around the body, not the head
+ let smoth_rot = Quat::from_axis_angle(*position.up(), angle);
+ // Apply rotation
+ let mut hmd_translation = view.pose.position.to_vec3();
+ hmd_translation.y = 0.0;
+ let local = position.translation;
+ let global = position.rotation.mul_vec3(hmd_translation) + local;
+ gizmos.circle(global, position.up(), 0.1, Color::GREEN);
+ position.rotate_around(global, smoth_rot);
 }