Merge pull request #6601 from howard-stearns/fix-sync-period-calc

Fix sync period calc, restoring avatar render distance

interface/src/Application.cpp

@@ -1124,29 +1124,6 @@ void Application::paintGL() {
     _inPaint = true;
     Finally clearFlagLambda([this] { _inPaint = false; });
 
-    // Some LOD-like controls need to know a smoothly varying "potential" frame rate that doesn't
-    // include time waiting for vsync, and which can report a number above target if we've got the headroom.
-    // For example, if we're shooting for 75fps and paintWait is 3.3333ms (= 75% * 13.33ms), our deducedNonVSyncFps
-    // would be 100fps. In principle, a paintWait of zero would have deducedNonVSyncFps=75.
-    // Here we make a guess for deducedNonVSyncFps = 1 / deducedNonVSyncPeriod.
-    //
-    // Time between previous paintGL call and this one, which can vary not only with vSync misses, but also with QT timing.
-    // We're using this as a proxy for the time between vsync and displayEnd, below. (Not exact, but tends to be the same over time.)
-    // This is not the same as update(deltaTime), because the latter attempts to throttle to 60hz and also clamps to 1/4 second.
-    const float actualPeriod = diff / (float)USECS_PER_SECOND; // same as 1/instantaneousFps but easier for compiler to optimize
-    // Note that _lastPaintWait (stored at end of last call) is for the same paint cycle.
-    float deducedNonVSyncPeriod = actualPeriod - _lastPaintWait + _marginForDeducedFramePeriod; // plus a some non-zero time for machinery we can't measure
-    // We don't know how much time to allow for that, but if we went over the target period, we know it's at least the portion
-    // of paintWait up to the next vSync. This gives us enough of a penalty so that when actualPeriod crosses two cycles,
-    // the key part (and not an exagerated part) of _lastPaintWait is accounted for.
-    const float targetPeriod = getTargetFramePeriod();
-    if (_lastPaintWait > EPSILON && actualPeriod > targetPeriod) {
-        // Don't use C++ remainder(). It's authors are mathematically insane.
-        deducedNonVSyncPeriod += fmod(actualPeriod, _lastPaintWait);
-    }
-    _lastDeducedNonVSyncFps = 1.0f / deducedNonVSyncPeriod;
-    _lastInstantaneousFps = instantaneousFps;
-
     auto displayPlugin = getActiveDisplayPlugin();
     // FIXME not needed anymore?
     _offscreenContext->makeCurrent();
@@ -1403,7 +1380,6 @@ void Application::paintGL() {
         Q_ASSERT(!_lockedFramebufferMap.contains(finalTexture));
         _lockedFramebufferMap[finalTexture] = scratchFramebuffer;
 
-        uint64_t displayStart = usecTimestampNow();
         Q_ASSERT(isCurrentContext(_offscreenContext->getContext()));
         {
             PROFILE_RANGE(__FUNCTION__ "/pluginSubmitScene");
@@ -1412,9 +1388,6 @@ void Application::paintGL() {
         }
         Q_ASSERT(isCurrentContext(_offscreenContext->getContext()));
 
-        uint64_t displayEnd = usecTimestampNow();
-        const float displayPeriodUsec = (float)(displayEnd - displayStart); // usecs
-        _lastPaintWait = displayPeriodUsec / (float)USECS_PER_SECOND;
     }
 
     {
@@ -1425,6 +1398,14 @@ void Application::paintGL() {
             batch.resetStages();
         });
     }
+
+    // Some LOD-like controls need to know a smoothly varying "potential" frame rate that doesn't
+    // include time waiting for sync, and which can report a number above target if we've got the headroom.
+    // In my tests, the following is mostly less than 0.5ms, and never more than 3ms. I don't think its worth measuring during runtime.
+    const float paintWaitAndQTTimerAllowance = 0.001f; // seconds
+    // Store both values now for use by next cycle.
+    _lastInstantaneousFps = instantaneousFps;
+    _lastUnsynchronizedFps = 1.0f / (((usecTimestampNow() - now) / (float)USECS_PER_SECOND) + paintWaitAndQTTimerAllowance);
 }
 
 void Application::runTests() {

interface/src/Application.h

@@ -163,11 +163,8 @@ public:
     float const HMD_TARGET_FRAME_RATE = 75.0f;
     float const DESKTOP_TARGET_FRAME_RATE = 60.0f;
     float getTargetFrameRate() { return isHMDMode() ? HMD_TARGET_FRAME_RATE : DESKTOP_TARGET_FRAME_RATE; }
-    float getTargetFramePeriod() { return isHMDMode() ? 1.0f / HMD_TARGET_FRAME_RATE : 1.0f / DESKTOP_TARGET_FRAME_RATE; } // same as 1/getTargetFrameRate, but w/compile-time division
     float getLastInstanteousFps() const { return _lastInstantaneousFps; }
-    float getLastPaintWait() const { return _lastPaintWait; };
-    float getLastDeducedNonVSyncFps() const { return _lastDeducedNonVSyncFps; }
-    void setMarginForDeducedFramePeriod(float newValue) { _marginForDeducedFramePeriod = newValue; }
+    float getLastUnsynchronizedFps() const { return _lastUnsynchronizedFps; }
 
     float getFieldOfView() { return _fieldOfView.get(); }
     void setFieldOfView(float fov);
@@ -443,9 +440,7 @@ private:
     QElapsedTimer _timerStart;
     QElapsedTimer _lastTimeUpdated;
     float _lastInstantaneousFps { 0.0f };
-    float _lastPaintWait { 0.0f };
-    float _lastDeducedNonVSyncFps { 0.0f };
-    float _marginForDeducedFramePeriod{ 0.002f }; // 2ms, adjustable
+    float _lastUnsynchronizedFps { 0.0f };
 
     ShapeManager _shapeManager;
     PhysicalEntitySimulation _entitySimulation;

interface/src/avatar/AvatarManager.cpp

@@ -111,7 +111,6 @@ void AvatarManager::init() {
     _renderDistanceController.setKP(0.0008f); // Usually about 0.6 of largest that doesn't oscillate when other parameters 0.
     _renderDistanceController.setKI(0.0006f); // Big enough to bring us to target with the above KP.
     _renderDistanceController.setKD(0.000001f); // A touch of kd increases the speed by which we get there.
-
 }
 
 void AvatarManager::updateMyAvatar(float deltaTime) {
@@ -151,7 +150,7 @@ void AvatarManager::updateOtherAvatars(float deltaTime) {
     // The measured value is frame rate. When the controlled value (1 / render cutoff distance)
     // goes up, the render cutoff distance gets closer, the number of rendered avatars is less, and frame rate
     // goes up.
-    const float deduced = qApp->getLastDeducedNonVSyncFps();
+    const float deduced = qApp->getLastUnsynchronizedFps();
     const float distance = 1.0f / _renderDistanceController.update(deduced, deltaTime);
     _renderDistanceAverage.updateAverage(distance);
     _renderDistance = _renderDistanceAverage.getAverage();

libraries/shared/src/PIDController.cpp

@@ -65,7 +65,7 @@ void PIDController::updateHistory(float measuredValue, float dt, float error, fl
     }
 }
 void PIDController::reportHistory() {
-    qCDebug(shared) << _label << "measured dt FIXME || error accumulated changed || p i d controlled";
+    qCDebug(shared) << _label << "measured dt || error accumulated changed || p i d controlled";
     for (int i = 0; i < _history.size(); i++) {
         Row& row = _history[i];
         qCDebug(shared) << row.measured << row.dt <<