1 files changed, 39 insertions, 42 deletions

diff --git a/components/script/dom/xrsession.rs b/components/script/dom/xrsession.rs
index 3451bb55467..41f8392acfb 100644
--- a/components/script/dom/xrsession.rs
+++ b/components/script/dom/xrsession.rs
@@ -119,6 +119,7 @@ impl XRSession {
         );
         input_sources.set_initial_inputs(&ret);
         ret.attach_event_handler();
+        ret.setup_raf_loop();
         ret
     }
 
@@ -131,6 +132,43 @@ impl XRSession {
         self.ended.get()
     }
 
+    fn setup_raf_loop(&self) {
+        assert!(
+            self.raf_sender.borrow().is_none(),
+            "RAF loop already set up"
+        );
+        let this = Trusted::new(self);
+        let global = self.global();
+        let window = global.as_window();
+        let (task_source, canceller) = window
+            .task_manager()
+            .dom_manipulation_task_source_with_canceller();
+        let (sender, receiver) = ipc::channel(global.time_profiler_chan().clone()).unwrap();
+        *self.raf_sender.borrow_mut() = Some(sender);
+        ROUTER.add_route(
+            receiver.to_opaque(),
+            Box::new(move |message| {
+                let this = this.clone();
+                let _ = task_source.queue_with_canceller(
+                    task!(xr_raf_callback: move || {
+                        this.root().raf_callback(message.to().unwrap());
+                    }),
+                    &canceller,
+                );
+            }),
+        );
+
+        self.request_new_xr_frame();
+    }
+
+    /// Requests a new https://immersive-web.github.io/webxr/#xr-animation-frame
+    ///
+    /// This happens regardless of the presense of rAF callbacks
+    fn request_new_xr_frame(&self) {
+        let sender = self.raf_sender.borrow().clone().unwrap();
+        self.session.borrow_mut().request_animation_frame(sender);
+    }
+
     fn attach_event_handler(&self) {
         let this = Trusted::new(self);
         let global = self.global();
@@ -291,6 +329,7 @@ impl XRSession {
 
         frame.set_active(false);
         self.session.borrow_mut().render_animation_frame();
+        self.request_new_xr_frame();
 
         // If the canvas element is attached to the DOM, it is now dirty,
         // and we need to trigger a reflow.
@@ -368,9 +407,6 @@ impl XRSessionMethods for XRSession {
 
     /// https://immersive-web.github.io/webxr/#dom-xrsession-requestanimationframe
     fn RequestAnimationFrame(&self, callback: Rc<XRFrameRequestCallback>) -> i32 {
-        // We only need to send a message once, until a raf callback executes.
-        let should_send = self.raf_callback_list.borrow().is_empty();
-
         // queue up RAF callback, obtain ID
         let raf_id = self.next_raf_id.get();
         self.next_raf_id.set(raf_id + 1);
@@ -378,45 +414,6 @@ impl XRSessionMethods for XRSession {
             .borrow_mut()
             .push((raf_id, Some(callback)));
 
-        // set up listener for response, if necessary
-        if self.raf_sender.borrow().is_none() {
-            let this = Trusted::new(self);
-            let global = self.global();
-            let window = global.as_window();
-            let (task_source, canceller) = window
-                .task_manager()
-                .dom_manipulation_task_source_with_canceller();
-            let (sender, receiver) = ipc::channel(global.time_profiler_chan().clone()).unwrap();
-            *self.raf_sender.borrow_mut() = Some(sender);
-            ROUTER.add_route(
-                receiver.to_opaque(),
-                Box::new(move |message| {
-                    let this = this.clone();
-                    let _ = task_source.queue_with_canceller(
-                        task!(xr_raf_callback: move || {
-                            this.root().raf_callback(message.to().unwrap());
-                        }),
-                        &canceller,
-                    );
-                }),
-            );
-        }
-
-        if should_send {
-            // If our callback list is empty, it either means this is the first request,
-            // or raf_callback executed, in which case we should
-            // send a message to request an animation frame.
-            //
-            // This prevents multiple messages being sent for a single call to raf_callback,
-            // and multiple message are unnecessary,
-            // since one call will already deal with multiple potentially enqueued callbacks.
-            //
-            // Allowing multiple messages could keep the main-thread,
-            // where the session thread might be running, looping on incoming messages.
-            let sender = self.raf_sender.borrow().clone().unwrap();
-            self.session.borrow_mut().request_animation_frame(sender);
-        }
-
         raf_id
     }