add support for hand tracking and configurable reference spaces

crates/bevy_openxr/src/openxr/reference_space.rs

@@ -0,0 +1,60 @@
+use std::sync::Arc;
+
+use bevy::{
+    prelude::*,
+    render::extract_resource::{ExtractResource, ExtractResourcePlugin},
+};
+use bevy_xr::session::{status_changed_to, XrStatus};
+
+use crate::{init::OxrPreUpdateSet, resources::OxrSession};
+
+pub struct OxrReferenceSpacePlugin {
+    default_primary_ref_space: openxr::ReferenceSpaceType,
+}
+impl Default for OxrReferenceSpacePlugin {
+    fn default() -> Self {
+        Self {
+            default_primary_ref_space: openxr::ReferenceSpaceType::LOCAL_FLOOR_EXT,
+        }
+    }
+}
+
+#[derive(Resource)]
+struct OxrPrimaryReferenceSpaceType(openxr::ReferenceSpaceType);
+// TODO: this will keep the session alive so we need to remove this in the render world too
+/// The Default Reference space used for locating things
+#[derive(Resource, Deref, ExtractResource, Clone)]
+pub struct OxrPrimaryReferenceSpace(pub Arc<openxr::Space>);
+
+/// The Reference space used for locating spaces on this entity
+#[derive(Component)]
+pub struct OxrReferenceSpace(pub openxr::Space);
+
+impl Plugin for OxrReferenceSpacePlugin {
+    fn build(&self, app: &mut App) {
+        app.insert_resource(OxrPrimaryReferenceSpaceType(self.default_primary_ref_space));
+        app.add_plugins(ExtractResourcePlugin::<OxrPrimaryReferenceSpace>::default());
+        app.add_systems(
+            PreUpdate,
+            set_primary_ref_space
+                .run_if(status_changed_to(XrStatus::Ready))
+                .in_set(OxrPreUpdateSet::UpdateCriticalComponents),
+        );
+    }
+}
+
+fn set_primary_ref_space(
+    session: Res<OxrSession>,
+    space_type: Res<OxrPrimaryReferenceSpaceType>,
+    mut cmds: Commands,
+) {
+    match session.create_reference_space(space_type.0, openxr::Posef::IDENTITY) {
+        Ok(space) => {
+            cmds.insert_resource(OxrPrimaryReferenceSpace(Arc::new(space)));
+        }
+        Err(openxr::sys::Result::ERROR_EXTENSION_NOT_PRESENT) => {
+            error!("Required Extension for Reference Space not loaded");
+        }
+        Err(err) => error!("Error while creating reference space: {}", err.to_string()),
+    };
+}