FIX: Corrected behaviour of TrackedPoseDriver when no device is connected.

Assets/Tests/InputSystem/Plugins/XRTests.cs

@@ -728,6 +728,35 @@ public void Components_TrackedPoseDriver_RetainsPoseWhenTrackedDeviceRemoved()
         }
     }
 
+    [Test]
+    [Category("Components")]
+    public void Components_TrackedPoseDriver_RetainsPoseWhenNoTrackedDeviceIsConnected()
+    {
+        // Tests/reproduces the scenario described in https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-699
+        // i.e. that rotation and/or position is not updated if device is not connected and track state isn't ignored.
+
+        var position = new Vector3(1f, 2f, 3f);
+        var rotation = new Quaternion(0.09853293f, 0.09853293f, 0.09853293f, 0.9853293f);
+
+        var go = new GameObject();
+        go.transform.position = position;
+        go.transform.rotation = rotation;
+
+        var tpd = go.AddComponent<TrackedPoseDriver>();
+        tpd.updateType = TrackedPoseDriver.UpdateType.Update;
+        tpd.trackingType = TrackedPoseDriver.TrackingType.RotationAndPosition;
+        tpd.ignoreTrackingState = false;
+        var transform = tpd.transform;
+
+        Assert.That(transform.position, Is.EqualTo(position));
+        Assert.That(transform.rotation, Is.EqualTo(rotation));
+
+        InputSystem.Update(InputUpdateType.Dynamic);
+
+        Assert.That(transform.position, Is.EqualTo(position));
+        Assert.That(transform.rotation, Is.EqualTo(rotation));
+    }
+
     [Test]
     [Category("Layouts")]
     public void Layouts_PoseControlsCanBeCreatedBySubcontrols()

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -16,6 +16,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed arrow key navigation of Input Actions after Action rename. [ISXB-1024](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1024)
 - Fixed gamepad navigation in UI Toolkit TextField when using InputSystemUIInputModule. [UUM-77364](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-77364)
 - Fixed issue where asset editor window splitter positions were not persisted [ISXB-1316]
+- Fixed a bug that would case `TrackedPoseDriver` to update position and rotation when no HMD device is connected [ISXB-699](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-699) instead of keeping it unchanged.
 
 ### Changed
 - Changed default input action asset name from New Controls to New Actions.

Packages/com.unity.inputsystem/InputSystem/Plugins/XR/TrackedPoseDriver.cs

@@ -500,7 +500,27 @@ void ReadTrackingState()
             {
                 // Treat an Input Action Reference with no reference the same as
                 // an enabled Input Action with no authored bindings, and allow driving the Transform pose.
-                m_CurrentTrackingState = TrackingStates.Position | TrackingStates.Rotation;
+                // TODO Remove if suggested fix seems valid. m_CurrentTrackingState = TrackingStates.Position | TrackingStates.Rotation;
+
+                // Check if we have transform and rotation controls to drive the pose.
+                var positionInputAction = m_PositionInput.action;
+                var rotationInputAction = m_RotationInput.action;
+                if (positionInputAction != null && positionInputAction.m_BindingsCount > 0 && rotationInputAction != null && rotationInputAction.m_BindingsCount > 0)
+                {
+                    m_CurrentTrackingState = TrackingStates.Position | TrackingStates.Rotation;
+                }
+                else if (positionInputAction != null && positionInputAction.m_BindingsCount > 0)
+                {
+                    m_CurrentTrackingState = TrackingStates.Position;
+                }
+                else if (rotationInputAction != null && rotationInputAction.m_BindingsCount > 0)
+                {
+                    m_CurrentTrackingState = TrackingStates.Rotation;
+                }
+                else
+                {
+                    m_CurrentTrackingState = TrackingStates.None;
+                }
                 return;
             }