fix: timestamp predicted Touch poses

docs/development/quest-openxr.md

@@ -321,6 +321,10 @@ thumbrest and face-button touch actions in previously unused button bits, keepin
 the 296-byte tracking layout and existing low click bits compatible. Inactive
 hands clear every input; invalid analog values are sanitized. The flat Cardboard
 gamepad path retains its existing Vive profile and mappings.
+Hand poses now carry the converted OpenXR prediction timestamp relative to
+SteamVR's clock, matching the headset instead of reporting a future hand pose
+as a present-time sample. The common timestamp conversion is host-tested for
+future, past and unavailable prediction times.
 
 Host tests cover the input decoder's independent clicks, touch-versus-press,
 handed menu, analog ranges and inactive reset. The Android native frontend and

tools/vr/src/driver_droiddeck.cpp

@@ -431,7 +431,7 @@ public:
     DriverPose_t GetPose() override { return pose_; }
     VRInputComponentHandle_t HapticHandle() const { return haptic_; }
 
-    void UpdateXr(const DroidDeckXrHand &hand) {
+    void UpdateXr(const DroidDeckXrHand &hand, int64_t predicted) {
         if (id_ == k_unTrackedDeviceIndexInvalid) return;
         DriverPose_t pose{};
         pose.qWorldFromDriverRotation.w = pose.qDriverFromHeadRotation.w = 1;
@@ -441,6 +441,7 @@ public:
         if (pose.poseIsValid) {
             pose.qRotation = {hand.pose.orientation[3], hand.pose.orientation[0], hand.pose.orientation[1], hand.pose.orientation[2]};
             for (int axis = 0; axis < 3; axis++) pose.vecPosition[axis] = hand.pose.position[axis];
+            pose.poseTimeOffset = XrTrackingFile::PoseTimeOffset(predicted, XrTrackingFile::Now());
         }
         pose.result = pose.poseIsValid ? TrackingResult_Running_OK : TrackingResult_Running_OutOfRange;
         pose_ = pose;
@@ -611,7 +612,7 @@ public:
             if (p.poseIsValid) {
                 p.qRotation = {xr.head.orientation[3], xr.head.orientation[0], xr.head.orientation[1], xr.head.orientation[2]};
                 for (int axis = 0; axis < 3; axis++) p.vecPosition[axis] = xr.head.position[axis];
-                if (xr.predicted_ns > 0) p.poseTimeOffset = (xr.predicted_ns - XrTrackingFile::Now()) / 1000000000.0;
+                p.poseTimeOffset = XrTrackingFile::PoseTimeOffset(xr.predicted_ns, XrTrackingFile::Now());
             }
             return p;
         }
@@ -678,7 +679,7 @@ private:
                 VRServerDriverHost()->TrackedDevicePoseUpdated(id_, head, sizeof(head));
                 for (int hand = 0; hand < 2; hand++) if (hands_[hand]) {
                     DroidDeckXrHand state = fresh ? xr.hands[hand] : DroidDeckXrHand{};
-                    hands_[hand]->UpdateXr(state);
+                    hands_[hand]->UpdateXr(state, fresh ? xr.predicted_ns : 0);
                 }
                 VRDriverInput()->UpdateBooleanComponent(proximity_, fresh, 0);
                 std::this_thread::sleep_for(std::chrono::milliseconds(2));

tools/vr/src/xr_tracking_file.h

@@ -42,6 +42,9 @@ public:
         timespec now{}; clock_gettime(CLOCK_MONOTONIC, &now);
         return (int64_t)now.tv_sec * 1000000000LL + now.tv_nsec;
     }
+    static double PoseTimeOffset(int64_t predicted, int64_t now) {
+        return predicted > 0 ? (static_cast<double>(predicted) - static_cast<double>(now)) / 1000000000.0 : 0;
+    }
     static bool Fresh(const DroidDeckXrTracking &packet) {
         int64_t age = Now() - packet.sampled_ns;
         return packet.active && age >= 0 && age < 500000000LL && packet.period_ns >= 1000000LL

tools/vr/tests/test_xr_tracking.cpp

@@ -5,6 +5,10 @@
 #include <limits>
 
 int main(int argc, char **argv) {
+    assert(XrTrackingFile::PoseTimeOffset(1010000000LL, 1000000000LL) == 0.01);
+    assert(XrTrackingFile::PoseTimeOffset(990000000LL, 1000000000LL) == -0.01);
+    assert(XrTrackingFile::PoseTimeOffset(0, 1000000000LL) == 0);
+    assert(XrTrackingFile::PoseTimeOffset(-1, 1000000000LL) == 0);
     char filename[256];
     std::snprintf(filename, sizeof(filename), "%s/droiddeck-xr-test-XXXXXX", argc > 1 ? argv[1] : "/tmp");
     int descriptor = mkstemp(filename);