commit c7e8a483c9bdd48dde327fcd0dd2c4b1d900a65c
author Ytai Ben-Tsvi <ytai@google.com> Mon Dec 20 13:26:34 2021 -0800
committer Ytai Ben-tsvi <ytai@google.com> Thu Dec 23 20:32:59 2021 +0000
tree 10b5d2348c968bfc15e37e6ef4a2020f978eca75
parent 44e7c3dbd402f5763d1657c6276f1a92b59f7666

Switch to static mode and recenter whenever screen moves

This logic intends to solve issues related to using head-tracking
while moving (e.g. being in a moving vehicle of walking).

We do so by switching to static mode and recentering whenever we
detect a significant motion of the screen.

Test: Manual verification via the SpatialAudioDemo app.
Test: atest --host libheadtracking-test
Change-Id: Iae5090c5a315d31ff89ada8d8a13694ea68ccf8e

media/libheadtracking/ModeSelector.cpp

diff --git a/media/libheadtracking/ModeSelector.cpp b/media/libheadtracking/ModeSelector.cpp
index 16e1712..cb3a27f 100644
--- a/media/libheadtracking/ModeSelector.cpp
+++ b/media/libheadtracking/ModeSelector.cpp
@@ -41,11 +41,18 @@
     mWorldToHeadTimestamp = timestamp;
 }
 
+void ModeSelector::setScreenStable(int64_t timestamp, bool stable) {
+    mScreenStable = stable;
+    mScreenStableTimestamp = timestamp;
+}
+
 void ModeSelector::calculateActualMode(int64_t timestamp) {
     bool isValidScreenToHead = mScreenToHead.has_value() &&
                                timestamp - mScreenToHeadTimestamp < mOptions.freshnessTimeout;
     bool isValidWorldToHead = mWorldToHead.has_value() &&
                               timestamp - mWorldToHeadTimestamp < mOptions.freshnessTimeout;
+    bool isValidScreenStable = mScreenStable.has_value() &&
+                              timestamp - mScreenStableTimestamp < mOptions.freshnessTimeout;
 
     HeadTrackingMode mode = mDesiredMode;
 
@@ -58,7 +65,7 @@
 
     // Optional downgrade from world-relative to static.
     if (mode == HeadTrackingMode::WORLD_RELATIVE) {
-        if (!isValidWorldToHead) {
+        if (!isValidWorldToHead || !isValidScreenStable || !mScreenStable.value()) {
             mode = HeadTrackingMode::STATIC;
         }
     }