add documentation and satisfy clippy

crates/bevy_openxr/examples/3d_scene.rs

@@ -1,11 +1,7 @@
 //! A simple 3D scene with light shining over a cube sitting on a plane.
 
-use bevy::{
-    prelude::*,
-    render::camera::{ManualTextureViewHandle, RenderTarget},
-};
-use bevy_openxr::{add_xr_plugins, render::XR_TEXTURE_INDEX};
-use bevy_xr::camera::XrCameraBundle;
+use bevy::prelude::*;
+use bevy_openxr::add_xr_plugins;
 
 fn main() {
     App::new()

crates/bevy_openxr/src/init.rs

@@ -1,4 +1,4 @@
-use bevy::app::{App, First, Plugin, PreUpdate};
+use bevy::app::{App, First, Plugin};
 use bevy::ecs::event::EventWriter;
 use bevy::ecs::schedule::common_conditions::{not, on_event};
 use bevy::ecs::schedule::IntoSystemConfigs;
@@ -6,7 +6,6 @@ use bevy::ecs::system::{Commands, Res, ResMut, Resource};
 use bevy::ecs::world::World;
 use bevy::log::{error, info};
 use bevy::math::{uvec2, UVec2};
-use bevy::render::camera::ManualTextureViews;
 use bevy::render::extract_resource::ExtractResourcePlugin;
 use bevy::render::renderer::{
     RenderAdapter, RenderAdapterInfo, RenderDevice, RenderInstance, RenderQueue,
@@ -48,14 +47,14 @@ pub fn session_created(status: Option<Res<XrStatus>>) -> bool {
     status.is_some_and(|status| status.session_created)
 }
 
-pub fn session_running(status: Option<Res<XrStatus>>) -> bool {
-    status.is_some_and(|status| status.session_running)
-}
-
 pub fn session_ready(status: Option<Res<XrStatus>>) -> bool {
     status.is_some_and(|status| status.session_ready)
 }
 
+pub fn session_running(status: Option<Res<XrStatus>>) -> bool {
+    status.is_some_and(|status| status.session_running)
+}
+
 impl Plugin for XrInitPlugin {
     fn build(&self, app: &mut App) {
         if let Err(e) = init_xr(&self, app) {
@@ -74,6 +73,7 @@ fn xr_entry() -> Result<XrEntry> {
     Ok(XrEntry(entry))
 }
 
+/// This is called from [`XrInitPlugin::build()`]. Its a separate function so that we can return a [Result] and control flow is cleaner.
 fn init_xr(config: &XrInitPlugin, app: &mut App) -> Result<()> {
     let entry = xr_entry()?;
 
@@ -165,7 +165,8 @@ fn init_xr(config: &XrInitPlugin, app: &mut App) -> Result<()> {
             begin_xr_session
                 .run_if(session_ready)
                 .run_if(on_event::<BeginXrSession>()),
-        ),
+        )
+            .chain(),
     )
     .sub_app_mut(RenderApp)
     .insert_resource(instance)
@@ -208,12 +209,13 @@ pub fn create_xr_session(world: &mut World) {
         return;
     };
 
-    if let Err(e) = init_xr_session(world, instance, *system_id, create_info) {
+    if let Err(e) = create_xr_session_inner(world, instance, *system_id, create_info) {
         error!("Failed to initialize XrSession: {e}");
     }
 }
 
-fn init_xr_session(
+/// This is called from [create_xr_session]. It is a separate function to allow us to return a [Result] and make control flow cleaner.
+fn create_xr_session_inner(
     world: &mut World,
     instance: XrInstance,
     system_id: openxr::SystemId,
@@ -378,6 +380,7 @@ struct XrRenderResources {
     stage: XrStage,
 }
 
+/// This system transfers important render resources from the main world to the render world when a session is created.
 pub fn transfer_xr_resources(mut commands: Commands, mut world: ResMut<MainWorld>) {
     let Some(XrRenderResources {
         session,
@@ -399,6 +402,7 @@ pub fn transfer_xr_resources(mut commands: Commands, mut world: ResMut<MainWorld
     commands.insert_resource(stage);
 }
 
+/// Poll any OpenXR events and handle them accordingly
 pub fn poll_events(
     instance: Res<XrInstance>,
     session: Option<Res<XrSession>>,

crates/bevy_openxr/src/render.rs

@@ -9,8 +9,8 @@ use bevy::{
 use bevy_xr::camera::{XrCameraBundle, XrProjection, XrView};
 use openxr::CompositionLayerFlags;
 
-use crate::layer_builder::*;
 use crate::resources::*;
+use crate::{init::begin_xr_session, layer_builder::*};
 
 use crate::init::session_running;
 
@@ -19,11 +19,12 @@ pub struct XrRenderPlugin;
 impl Plugin for XrRenderPlugin {
     fn build(&self, app: &mut App) {
         app.add_systems(
-            PreUpdate,
+            First,
             (
                 init_views.run_if(resource_added::<XrGraphicsInfo>),
                 wait_frame.run_if(session_running),
-            ),
+            )
+                .after(begin_xr_session),
         );
         // .add_systems(Startup, init_views);
         app.sub_app_mut(RenderApp).add_systems(
@@ -42,6 +43,7 @@ impl Plugin for XrRenderPlugin {
 
 pub const XR_TEXTURE_INDEX: u32 = 3383858418;
 
+// TODO: have cameras initialized externally and then recieved by this function.
 /// This is needed to properly initialize the texture views so that bevy will set them to the correct resolution despite them being updated in the render world.
 pub fn init_views(
     graphics_info: Res<XrGraphicsInfo>,
@@ -73,6 +75,8 @@ pub fn init_views(
 
 pub fn wait_frame(mut frame_waiter: ResMut<XrFrameWaiter>, mut commands: Commands) {
     let state = frame_waiter.wait().expect("Failed to wait frame");
+    // Here we insert the predicted display time for when this frame will be displayed.
+    // TODO: don't add predicted_display_period if pipelined rendering plugin not enabled
     commands.insert_resource(XrTime(openxr::Time::from_nanos(
         state.predicted_display_time.as_nanos() + state.predicted_display_period.as_nanos(),
     )));
@@ -227,31 +231,6 @@ pub fn insert_texture_views(
     for i in 0..2 {
         add_texture_view(&mut manual_texture_views, image, &graphics_info, i);
     }
-    // let left = image.create_view(&wgpu::TextureViewDescriptor {
-    //     dimension: Some(wgpu::TextureViewDimension::D2),
-    //     array_layer_count: Some(1),
-    //     ..Default::default()
-    // });
-    // let right = image.create_view(&wgpu::TextureViewDescriptor {
-    //     dimension: Some(wgpu::TextureViewDimension::D2),
-    //     array_layer_count: Some(1),
-    //     base_array_layer: 1,
-    //     ..Default::default()
-    // });
-    // let resolution = graphics_info.resolution;
-    // let format = graphics_info.format;
-    // let left = ManualTextureView {
-    //     texture_view: left.into(),
-    //     size: resolution,
-    //     format: format,
-    // };
-    // let right = ManualTextureView {
-    //     texture_view: right.into(),
-    //     size: resolution,
-    //     format: format,
-    // };
-    // manual_texture_views.insert(LEFT_XR_TEXTURE_HANDLE, left);
-    // manual_texture_views.insert(RIGHT_XR_TEXTURE_HANDLE, right);
 }
 
 pub fn add_texture_view(

crates/bevy_xr/src/session.rs

@@ -49,15 +49,15 @@ pub fn handle_xr_events(
     }
 }
 
-/// Event sent to backends to create an XR session
+/// Event sent to backends to create an XR session. Should only be called after [`XrInstanceCreated`] is recieved.
 #[derive(Event, Clone, Copy, Default)]
 pub struct CreateXrSession;
 
-/// Event sent to backends to begin an XR session
+/// Event sent to backends to begin an XR session. Should only be called after [`XrSessionState::Ready`] is recieved.
 #[derive(Event, Clone, Copy, Default)]
 pub struct BeginXrSession;
 
-/// Event sent to backends to end an XR session.
+/// Event sent to backends to end an XR session. Should only be called after [`XrSessionState::Running`] is recieved.
 #[derive(Event, Clone, Copy, Default)]
 pub struct EndXrSession;