Fix VR player orientation and controls

The VR player was not oriented to the earth surface, but to the global coordinate system

Cargo.toml

@@ -33,7 +33,7 @@ web-sys = { version = "0.3.22", default-features = false, features = [
 ] }
 
 [target.'cfg(not(any(target_os="macos", target_arch = "wasm32")))'.dependencies]
-bevy_oxr = { git = "https://github.com/awtterpip/bevy_openxr", optional = true }
+bevy_oxr = { git = "https://github.com/oli-obk/vrtest", branch = "arbitrary_up", optional = true }
 
 [features]
 xr = ["dep:bevy_oxr"]

src/lib.rs

@@ -4,14 +4,14 @@ use bevy::{
     diagnostic::{DiagnosticsStore, FrameTimeDiagnosticsPlugin},
     prelude::*,
 };
-use bevy_flycam::FlyCam;
+use bevy_flycam::{FlyCam, MovementSettings};
 #[cfg(all(feature = "xr", not(any(target_os = "macos", target_arch = "wasm32"))))]
 use bevy_oxr::xr_input::trackers::OpenXRTrackingRoot;
 use bevy_screen_diagnostics::{
     Aggregate, ScreenDiagnostics, ScreenDiagnosticsPlugin, ScreenEntityDiagnosticsPlugin,
     ScreenFrameDiagnosticsPlugin,
 };
-use geopos::GeoPos;
+use geopos::{GeoPos, EARTH_RADIUS};
 use http_assets::HttpAssetReaderPlugin;
 use sun::Sky;
 use tilemap::TileMap;
@@ -53,13 +53,16 @@ pub fn main() {
         lon: 11.55741,
     };
 
+    let mut xr = false;
+
     for arg in args {
         let (k, v) = arg
             .split_once('=')
             .expect("arguments must be `key=value` pairs");
         match k {
             "lat" => pos.lat = v.parse().unwrap(),
             "lon" => pos.lon = v.parse().unwrap(),
+            "xr" => xr = v.parse().unwrap(),
             other => panic!("unknown key `{other}`"),
         }
     }
@@ -69,9 +72,10 @@ pub fn main() {
     app.add_plugins(HttpAssetReaderPlugin {
         base_url: "gltiles.osm2world.org/glb/".into(),
     });
-    if std::env::args().any(|arg| arg == "xr") {
+    if xr {
         #[cfg(all(feature = "xr", not(any(target_os = "macos", target_arch = "wasm32"))))]
         app.add_plugins(xr::Plugin);
+        app.add_systems(Update, pull_to_ground);
     } else {
         app.add_plugins(DefaultPlugins);
     }
@@ -86,6 +90,7 @@ pub fn main() {
         .add_plugins(flycam::Plugin)
         .add_systems(Startup, setup)
         .add_systems(Update, (load_next_tile, TileMap::update))
+        .add_systems(Update, update_camera_orientations)
         .run();
 }
 
@@ -190,3 +195,35 @@ fn load_next_tile(
         radius,
     );
 }
+
+fn update_camera_orientations(
+    mut movement_settings: ResMut<MovementSettings>,
+    fly_cam: Query<&Transform, (With<FlyCam>, Without<TileMap>)>,
+    tilemap: Query<&Transform, (With<TileMap>, Without<FlyCam>)>,
+) {
+    movement_settings.up =
+        (fly_cam.single().translation - tilemap.single().translation).normalize();
+}
+
+fn pull_to_ground(
+    time: Res<Time>,
+    mut tracking_root_query: Query<&mut Transform, (With<OpenXRTrackingRoot>, Without<TileMap>)>,
+    tilemap: Query<&Transform, (With<TileMap>, Without<OpenXRTrackingRoot>)>,
+) {
+    let Ok(mut root) = tracking_root_query.get_single_mut() else {
+        return;
+    };
+    let tilemap = tilemap.single();
+
+    let adjustment_rate = (time.delta_seconds() * 10.0).min(1.0);
+
+    // Lower player onto sphere
+    let real_pos = root.translation.as_dvec3() - tilemap.translation.as_dvec3();
+    let up = real_pos.normalize();
+    let diff = up * EARTH_RADIUS as f64 - real_pos;
+    root.translation += diff.as_vec3() * adjustment_rate;
+
+    // Rotate player to be upright on sphere
+    let angle_diff = Quat::from_rotation_arc(root.up(), up.as_vec3());
+    root.rotate(Quat::IDENTITY.slerp(angle_diff, adjustment_rate));
+}

src/xr.rs

@@ -14,7 +14,6 @@ use bevy_oxr::xr_input::prototype_locomotion::{
 };
 use bevy_oxr::xr_input::trackers::{
     AimPose, OpenXRController, OpenXRLeftController, OpenXRRightController, OpenXRTracker,
-    OpenXRTrackingRoot,
 };
 use bevy_oxr::xr_input::Hand;
 use bevy_oxr::xr_input::{
@@ -29,7 +28,6 @@ impl bevy::prelude::Plugin for Plugin {
     fn build(&self, app: &mut App) {
         app.add_plugins(DefaultXrPlugins)
             .add_systems(Update, proto_locomotion)
-            .add_systems(Startup, setup_initial_position)
             .insert_resource(PrototypeLocomotionConfig {
                 locomotion_speed: 10.0,
                 rotation_type: RotationType::Snap,
@@ -61,16 +59,6 @@ impl bevy::prelude::Plugin for Plugin {
     }
 }
 
-fn setup_initial_position(
-    mut tracking_root_query: Query<&mut Transform, With<OpenXRTrackingRoot>>,
-) {
-    tracking_root_query.single_mut().translation.x = 3.;
-    tracking_root_query.single_mut().translation.z = 400.0;
-    // FIXME: attach the camera bundle to the world, so when we move the world, the player is automatically moved with it.
-    // We'll need this when the player moves very far or teleports to another place, as we need to ensure we don't go into
-    // regions where the floating point numbers become imprecise.
-}
-
 fn spawn_controllers_example(mut commands: Commands) {
     //left hand
     commands.spawn((