add android-openxr support

Author: matthewjberger

AndroidManifest.openxr.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.wgpu_android_xr">
+
+    <uses-feature android:glEsVersion="0x00030000" android:required="true" />
+    <uses-feature android:name="android.hardware.vr.headtracking" android:required="true" />
+    <uses-permission android:name="android.permission.INTERNET" />
+
+    <application
+        android:allowBackup="false"
+        android:icon="@mipmap/ic_launcher"
+        android:label="Wgpu OpenXR Example"
+        android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
+        android:hasCode="false">
+
+        <meta-data android:name="com.oculus.supportedDevices" android:value="quest2|questpro|quest3|quest3s" />
+
+        <activity
+            android:name="android.app.NativeActivity"
+            android:exported="true"
+            android:excludeFromRecents="true"
+            android:configChanges="density|keyboard|keyboardHidden|navigation|orientation|screenLayout|screenSize|uiMode"
+            android:launchMode="singleTask"
+            android:screenOrientation="landscape">
+            <meta-data
+                android:name="android.app.lib_name"
+                android:value="app_core" />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+                <category android:name="com.oculus.intent.category.VR" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

Cargo.lock

@@ -19,7 +19,7 @@ nalgebra-glm = { version = "0.20.0", features = [
     "convert-bytemuck",
     "serde-serialize",
 ] }
-openxr = { version = "0.19", features = ["static", "loaded"], optional = true }
+openxr = { version = "0.19", features = ["loaded"], optional = true }
 web-time = "1.1.0"
 wgpu = { version = "27.0.1", default-features = false }
 winit = "0.30.12"
@@ -43,6 +43,7 @@ wasm-bindgen-futures = "0.4.56"
 android-activity = { version = "0.6", features = ["native-activity"] }
 android_logger = "0.15"
 egui-winit = { version = "0.33.3", default-features = false }
+ndk-context = "0.1"
 ndk-sys = "0.6"
 
 [features]
@@ -51,3 +52,4 @@ openxr = ["dep:openxr", "dep:ash", "dep:wgpu-hal", "dep:gpu-allocator"]
 webgl = ["wgpu/webgl"]
 webgpu = ["wgpu/webgpu"]
 android = ["wgpu/vulkan"]
+android-openxr = ["android", "openxr"]

Cargo.toml

@@ -24,7 +24,8 @@ Other languages (experimental):
 | WebGL | `trunk serve --features webgl --open` |
 | Android | `just run-android DEVICE_ID` |
 | Steam Deck | `just build-steamdeck && just deploy-steamdeck` |
-| OpenXR VR | `just run-openxr` |
+| OpenXR VR (Desktop) | `just run-openxr` |
+| OpenXR VR (Quest) | `just build-android-openxr` |
 
 ## Platform Setup
 
@@ -75,8 +76,9 @@ The build uses `--features android` which enables wgpu's Vulkan backend.
 <summary><strong>Additional Android Commands</strong></summary>
 
 ```bash
-just build-android              # Build only
+just build-android              # Build only (windowed app)
 just build-android-all          # Build for arm64 and x64
+just build-android-openxr       # Build for Meta Quest VR
 just install-android DEVICE_ID  # Install without running
 just connect-android IP:PORT    # Connect over wireless ADB
 just list-android               # List connected devices
@@ -108,16 +110,50 @@ cd ~/Downloads && ./app
 
 The `Cross.toml` file configures system libraries for graphics and windowing support.
 
-### OpenXR VR Mode
+### OpenXR VR Mode (Desktop)
 
-Renders the spinning triangle with an infinite grid, procedural skybox, and hand tracking in VR.
+Renders the spinning triangle with an infinite grid, procedural skybox, and hand tracking in VR via PCVR streaming.
 
 **Setup:**
 1. Install [SteamVR](https://store.steampowered.com/app/250820/SteamVR/)
 2. Install [Virtual Desktop](https://www.vrdesktop.net/) or another OpenXR-compatible runtime
 3. Start Virtual Desktop and stream your desktop to your VR headset
 4. Run `just run-openxr` on your desktop
 
+### OpenXR VR Mode (Meta Quest)
+
+Native standalone VR for Meta Quest 2, Quest Pro, Quest 3, and Quest 3S.
+
+**Prerequisites:**
+- All Android prerequisites (see above)
+- Meta Quest device with Developer Mode enabled
+
+**Build:**
+```bash
+just build-android-openxr
+```
+
+This produces an APK at `target/x/release/android/app.apk`.
+
+**Install on Quest:**
+```bash
+adb install -r target/x/release/android/app.apk
+```
+
+Or use [SideQuest](https://sidequestvr.com) to drag and drop the APK onto your Quest.
+
+The app appears in your Quest library under "Unknown Sources".
+
+<details>
+<summary><strong>Technical Notes</strong></summary>
+
+- Uses the `android-openxr` feature which combines `android` and `openxr` features
+- Bundles Meta's OpenXR loader from `libs/arm64-v8a/libopenxr_loader.so`
+- Manifest includes `com.oculus.intent.category.VR` for proper VR app handling
+- Supports Quest hand tracking and controller input
+- Requires `manifest.yaml` with `runtime_libs` configuration for library bundling
+</details>
+
 ## Screenshots
 
 <img width="1665" height="1287" alt="webgl" src="https://github.com/user-attachments/assets/d8771e73-4b0b-459a-baf2-5ce1f79f943e" />

README.md

@@ -107,6 +107,22 @@ build-android-all:
     x build --release --platform android --arch x64 --features android
     Copy-Item -Force target/x/release/android/x64/cargo/x86_64-linux-android/release/libapp_core.so target/x/release/android/x64/cargo/x86_64-linux-android/release/libapp.so
 
+# Build the app for Android with OpenXR (arm64) for Meta Quest
+[unix]
+build-android-openxr:
+    mv AndroidManifest.xml AndroidManifest.xml.bak
+    cp AndroidManifest.openxr.xml AndroidManifest.xml
+    x build --release --platform android --arch arm64 --features android-openxr || (mv AndroidManifest.xml.bak AndroidManifest.xml && exit 1)
+    mv AndroidManifest.xml.bak AndroidManifest.xml
+    cp -f target/x/release/android/arm64/cargo/aarch64-linux-android/release/libapp_core.so target/x/release/android/arm64/cargo/aarch64-linux-android/release/libapp.so
+
+[windows]
+build-android-openxr:
+    Move-Item AndroidManifest.xml AndroidManifest.xml.bak
+    Copy-Item AndroidManifest.openxr.xml AndroidManifest.xml
+    x build --release --platform android --arch arm64 --features android-openxr; $r = $LASTEXITCODE; Move-Item -Force AndroidManifest.xml.bak AndroidManifest.xml; if ($r -ne 0) { exit $r }
+    Copy-Item -Force target/x/release/android/arm64/cargo/aarch64-linux-android/release/libapp_core.so target/x/release/android/arm64/cargo/aarch64-linux-android/release/libapp.so
+
 # Install the app on connected Android device
 install-android device:
     x build --release --arch arm64 --features android --device adb:{{device}}

justfile

@@ -0,0 +1,27 @@
+android:
+  runtime_libs:
+    - libs
+  manifest:
+    package: com.example.wgpu_android_xr
+    uses_feature:
+      - name: android.hardware.vulkan.level
+        required: true
+        version: 1
+    application:
+      meta_data:
+        - name: com.oculus.supportedDevices
+          value: quest2|questpro|quest3|quest3s
+      activities:
+        - name: android.app.NativeActivity
+          exported: true
+          orientation: landscape
+          config_changes: "orientation|keyboardHidden|screenSize|screenLayout|uiMode|density"
+          meta_data:
+            - name: android.app.lib_name
+              value: app
+          intent_filters:
+            - actions:
+                - android.intent.action.MAIN
+              categories:
+                - android.intent.category.LAUNCHER
+                - com.oculus.intent.category.VR

libs/arm64-v8a/libopenxr_loader.so

@@ -21,10 +21,10 @@ use winit::{
     window::{Theme, Window},
 };
 
-#[cfg(target_os = "android")]
+#[cfg(all(target_os = "android", not(feature = "openxr")))]
 use winit::platform::android::EventLoopBuilderExtAndroid;
 
-#[cfg(target_os = "android")]
+#[cfg(all(target_os = "android", not(feature = "openxr")))]
 #[unsafe(no_mangle)]
 fn android_main(app: AndroidApp) {
     android_logger::init_once(
@@ -43,6 +43,31 @@ fn android_main(app: AndroidApp) {
         .expect("Failed to run app!");
 }
 
+#[cfg(all(target_os = "android", feature = "openxr"))]
+#[unsafe(no_mangle)]
+fn android_main(app: AndroidApp) {
+    android_logger::init_once(
+        android_logger::Config::default().with_max_level(log::LevelFilter::Info),
+    );
+
+    let handle = std::thread::spawn(|| {
+        run_xr().expect("XR session failed");
+    });
+
+    loop {
+        app.poll_events(Some(std::time::Duration::from_millis(100)), |event| {
+            if let android_activity::PollEvent::Main(android_activity::MainEvent::Destroy) = event {
+                std::process::exit(0);
+            }
+        });
+        if handle.is_finished() {
+            break;
+        }
+    }
+
+    handle.join().expect("XR thread panicked");
+}
+
 #[derive(Default)]
 pub struct App {
     window: Option<Arc<Window>>,

manifest.yaml

@@ -48,8 +48,6 @@ pub struct XrContext {
     _views: Vec<xr::ViewConfigurationView>,
     action_set: xr::ActionSet,
     move_action: xr::Action<xr::Vector2f>,
-    left_hand_action: xr::Action<xr::Posef>,
-    right_hand_action: xr::Action<xr::Posef>,
     left_trigger_action: xr::Action<f32>,
     right_trigger_action: xr::Action<f32>,
     left_hand_space: xr::Space,
@@ -64,15 +62,24 @@ pub struct XrContext {
     sky_uniform_buffer: wgpu::Buffer,
     sky_bind_group: wgpu::BindGroup,
     sky_pipeline: wgpu::RenderPipeline,
+    session_running: bool,
 }
 
 impl XrContext {
     pub fn new() -> Result<(Self, wgpu::Device, wgpu::Queue), Box<dyn std::error::Error>> {
-        let xr_entry = xr::Entry::linked();
+        let xr_entry = unsafe { xr::Entry::load()? };
+
+        #[cfg(target_os = "android")]
+        xr_entry.initialize_android_loader()?;
 
         let mut required_extensions = xr::ExtensionSet::default();
         required_extensions.khr_vulkan_enable2 = true;
 
+        #[cfg(target_os = "android")]
+        {
+            required_extensions.khr_android_create_instance = true;
+        }
+
         let xr_instance = xr_entry.create_instance(
             &xr::ApplicationInfo {
                 application_name: "wgpu-xr-example",
@@ -596,8 +603,6 @@ impl XrContext {
                 _views: views,
                 action_set,
                 move_action,
-                left_hand_action,
-                right_hand_action,
                 left_trigger_action,
                 right_trigger_action,
                 left_hand_space,
@@ -612,6 +617,7 @@ impl XrContext {
                 sky_uniform_buffer,
                 sky_bind_group,
                 sky_pipeline,
+                session_running: false,
             },
             wgpu_device,
             wgpu_queue,
@@ -628,13 +634,16 @@ impl XrContext {
                         xr::SessionState::READY => {
                             self.session
                                 .begin(xr::ViewConfigurationType::PRIMARY_STEREO)?;
+                            self.session_running = true;
                             log::info!("XR Session started");
                         }
                         xr::SessionState::STOPPING => {
+                            self.session_running = false;
                             self.session.end()?;
                             log::info!("XR Session ended");
                         }
                         xr::SessionState::EXITING | xr::SessionState::LOSS_PENDING => {
+                            self.session_running = false;
                             log::info!("XR Session exiting");
                             return Ok(false);
                         }
@@ -651,6 +660,10 @@ impl XrContext {
         Ok(true)
     }
 
+    pub fn is_session_running(&self) -> bool {
+        self.session_running
+    }
+
     pub fn wait_frame(&mut self) -> Result<xr::FrameState, Box<dyn std::error::Error>> {
         Ok(self.frame_wait.wait()?)
     }
@@ -1200,6 +1213,7 @@ impl XrContext {
 }
 
 pub fn run_xr() -> Result<(), Box<dyn std::error::Error>> {
+    #[cfg(not(target_os = "android"))]
     env_logger::init();
     log::info!("Initializing OpenXR mode");
 
@@ -1215,6 +1229,11 @@ pub fn run_xr() -> Result<(), Box<dyn std::error::Error>> {
             break;
         }
 
+        if !xr_context.is_session_running() {
+            std::thread::sleep(std::time::Duration::from_millis(10));
+            continue;
+        }
+
         let now = Instant::now();
         let delta_time = (now - last_render_time).as_secs_f32();
         last_render_time = now;