Anchored Main Menu Quad

runtime/include/runtime_config.h

@@ -386,11 +386,11 @@ inline void EnsureConfigFile() {
               "# model of your kart, the vehicle included.\n"
               "first_person_hidden_model = 0\n"
               "# Keyboard shortcut that recenters the VR view, naming the key the\n"
-              "# way SDL does (F9, Home, Keypad 5, ...). It moves the view to where\n"
-              "# you are sitting now and nothing else: forward and the horizon come\n"
-              "# from the headset's own reference space, so recentering cannot tilt\n"
-              "# the game. Applies during an immersive race; the menu screen is\n"
-              "# head-locked already. Rebindable from the F10 menu under VR. Leave\n"
+              "# way SDL does (F9, Home, Keypad 5, ...). It moves the race view to\n"
+              "# where you are sitting now and brings the menu screen back upright in\n"
+              "# front of you. The race view moves in position only: forward and the\n"
+              "# horizon come from the headset's own reference space, so recentering\n"
+              "# cannot tilt the game. Rebindable from the F10 menu under VR. Leave\n"
               "# empty to unbind.\n"
               "recenter_key = \"F9\"\n"
               "# Fixed pitch of the game camera, in degrees, for a player sitting\n"

runtime/include/vr/openxr_d3d12.h

@@ -41,10 +41,17 @@ struct OpenXRD3D12GraphicsRequirements {
 struct OpenXRD3D12Presentation {
     OpenXRD3D12FrameMode mode = OpenXRD3D12FrameMode::ImmersiveProjection;
 
-    // Used only by VirtualScreen. The quad is head-locked in XR_VIEW_SPACE
-    // and centered straight ahead at -Z.
+    // Used only by VirtualScreen.
     float quad_distance_meters = 2.0f;
     float quad_width_meters = 2.4f;
+
+    // When quad_anchored is set, the quad is placed at quad_pose in the
+    // application reference space and stays put as the player looks around.
+    // Otherwise it falls back to being head-locked in XR_VIEW_SPACE, centered
+    // straight ahead at -Z, which is what happens until tracking has produced a
+    // head pose good enough to anchor against.
+    bool quad_anchored = false;
+    XrPosef quad_pose{{0.0f, 0.0f, 0.0f, 1.0f}, {0.0f, 0.0f, 0.0f}};
 };
 
 struct OpenXRD3D12Frame {
@@ -96,8 +103,9 @@ public:
 
     // Releases acquired images and calls xrEndFrame. submit_layer must only be
     // true after WaitForSubmission returned Success. Immersive frames submit
-    // XrCompositionLayerProjection; virtual-screen frames submit a head-locked
-    // XrCompositionLayerQuad using the single mono target.
+    // XrCompositionLayerProjection; virtual-screen frames submit an
+    // XrCompositionLayerQuad using the single mono target, placed as the
+    // presentation's quad_anchored/quad_pose describe.
     bool FinishFrame(OpenXRD3D12Frame& frame, bool submit_layer);
 
     // Call on the XR owner thread after Aurora's worker is idle and before

runtime/include/vr/openxr_integration.h

@@ -36,12 +36,13 @@ void OpenXRServiceProducerFrameBoundary() noexcept;
 bool OpenXRIsRunning() noexcept;
 std::string OpenXRLastError();
 
-// Recenters the view on where the player is sitting now. Position only: the
-// forward direction and the horizon come from the OpenXR reference space and
-// are never relatched from the headset, so recentering cannot tilt the game's
-// horizon. Use the runtime's own recenter gesture to change forward. Callable
-// from any thread; serviced on the XR pacing thread and ignored outside an
-// immersive race, where the head-locked menu screen has no origin to recenter.
+// Recenters on where the player is sitting now: it moves the immersive race
+// view's origin, and re-places the anchored menu screen upright in front of
+// them. Position only for the race view: the forward direction and the horizon
+// come from the OpenXR reference space and are never relatched from the
+// headset, so recentering cannot tilt the game's horizon. Use the runtime's own
+// recenter gesture to change forward. Callable from any thread; serviced once
+// per frame on the XR pacing thread.
 void OpenXRRequestRecenter() noexcept;
 
 // Sets a fixed pitch of the game camera for a player sitting reclined, in