maybe fixed frame timing??

examples/xr.rs

@@ -1,5 +1,6 @@
 use bevy::core_pipeline::core_3d;
 use bevy::core_pipeline::tonemapping::{DebandDither, Tonemapping};
+use bevy::diagnostic::{LogDiagnosticsPlugin, FrameTimeDiagnosticsPlugin};
 use bevy::ecs::prelude::{Bundle, Component, ReflectComponent};
 
 use bevy::math::Mat4;
@@ -34,6 +35,8 @@ fn main() {
     App::new()
         .add_plugins(DefaultXrPlugins)
         .add_plugins(OpenXrInput::new(XrControllerType::OculusTouch))
+        .add_plugins(LogDiagnosticsPlugin::default())
+        .add_plugins(FrameTimeDiagnosticsPlugin::default())
         .add_systems(Startup, setup)
         .add_systems(Update, hands)
         .run();

src/lib.rs

@@ -157,25 +157,11 @@ impl Plugin for OpenXrPlugin {
                 size: *resolution,
                 format: *format,
             };
+            app.add_systems(PreUpdate, xr_begin_frame);
             let mut manual_texture_views = app.world.resource_mut::<ManualTextureViews>();
             manual_texture_views.insert(LEFT_XR_TEXTURE_HANDLE, left);
             manual_texture_views.insert(RIGHT_XR_TEXTURE_HANDLE, right);
             drop(manual_texture_views);
-            let pipeline_app = app.sub_app_mut(RenderExtractApp);
-            pipeline_app
-                .insert_resource(xr_instance.clone())
-                .insert_resource(session.clone())
-                .insert_resource(blend_mode.clone())
-                .insert_resource(resolution.clone())
-                .insert_resource(format.clone())
-                .insert_resource(session_running.clone())
-                .insert_resource(frame_waiter.clone())
-                .insert_resource(swapchain.clone())
-                .insert_resource(input.clone())
-                .insert_resource(views.clone())
-                .insert_resource(frame_state.clone())
-                .insert_resource(action_sets.clone());
-            drop(pipeline_app);
             let render_app = app.sub_app_mut(RenderApp);
 
             render_app
@@ -195,8 +181,9 @@ impl Plugin for OpenXrPlugin {
             render_app.add_systems(
                 Render,
                 (
-                    begin_frame.before(render_system).after(RenderSet::ExtractCommands),
+                    post_frame
-                    locate_views.before(render_system),
+                        .before(render_system)
+                        .after(RenderSet::ExtractCommands),
                     end_frame.after(render_system),
                 ),
             );
@@ -214,16 +201,15 @@ impl PluginGroup for DefaultXrPlugins {
     }
 }
 
-pub fn begin_frame(
+pub fn xr_begin_frame(
     instance: Res<XrInstance>,
     session: Res<XrSession>,
     session_running: Res<XrSessionRunning>,
-    resolution: Res<XrResolution>,
-    format: Res<XrFormat>,
-    swapchain: Res<XrSwapchain>,
-    frame_waiter: Res<XrFrameWaiter>,
     frame_state: Res<XrFrameState>,
-    mut manual_texture_views: ResMut<ManualTextureViews>,
+    frame_waiter: Res<XrFrameWaiter>,
+    swapchain: Res<XrSwapchain>,
+    views: Res<XrViews>,
+    input: Res<XrInput>,
 ) {
     {
         let _span = info_span!("xr_poll_events");
@@ -263,6 +249,25 @@ pub fn begin_frame(
         let _span = info_span!("xr_begin_frame").entered();
         swapchain.begin().unwrap()
     }
+    {
+        let _span = info_span!("xr_locate_views").entered();
+        *views.lock().unwrap() = session
+            .locate_views(
+                VIEW_TYPE,
+                frame_state.lock().unwrap().predicted_display_time,
+                &input.stage,
+            )
+            .unwrap()
+            .1;
+    }
+}
+
+pub fn post_frame(
+    resolution: Res<XrResolution>,
+    format: Res<XrFormat>,
+    swapchain: Res<XrSwapchain>,
+    mut manual_texture_views: ResMut<ManualTextureViews>,
+) {
     {
         let _span = info_span!("xr_acquire_image").entered();
         swapchain.acquire_image().unwrap()

src/xr_input/mod.rs

@@ -59,7 +59,7 @@ fn action_set_system(action_sets: Res<ActionSets>, session: Res<XrSession>) {
     for i in &action_sets.0 {
         active_action_sets.push(openxr::ActiveActionSet::new(i));
     }
-    info!("action sets: {:#?}", action_sets.0.len());
+    //info!("action sets: {:#?}", action_sets.0.len());
     match session.sync_actions(&active_action_sets) {
         Err(err) => {
             warn!("{}", err);