From 34de4d67d80f6e9337d3f28ce6bc3dcf29ffcfba Mon Sep 17 00:00:00 2001
From: Howard Stearns <howard@highfidelity.io>
Date: Mon, 7 Dec 2015 09:32:12 -0800
Subject: [PATCH] DisplayPlugin::getLastSynchronizedElapsed

---
 .../src/display-plugins/OpenGLDisplayPlugin.cpp             | 6 ++++++
 .../src/display-plugins/OpenGLDisplayPlugin.h               | 4 ++++
 libraries/plugins/src/plugins/DisplayPlugin.h               | 1 +
 3 files changed, 11 insertions(+)

diff --git a/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.cpp b/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.cpp
index d306c23dc0..4668f8ba1a 100644
--- a/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.cpp
+++ b/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.cpp
@@ -156,8 +156,10 @@ OpenGLDisplayPlugin::OpenGLDisplayPlugin() {
         _container->releaseOverlayTexture(texture);
     });
 
+    _synchronizedTimer.start();
     connect(&_timer, &QTimer::timeout, this, [&] {
         if (_active && _sceneTextureEscrow.depth() <= 1) {
+            _synchronizedTimer.start();
             emit requestRender();
         }
     });
@@ -279,6 +281,10 @@ void OpenGLDisplayPlugin::submitOverlayTexture(GLuint sceneTexture, const glm::u
 }
 
 void OpenGLDisplayPlugin::updateTextures() {
+    const qint64 elapsed =_synchronizedTimer.elapsed();
+    if (elapsed != 0) {
+        _lastSynchronizedElapsed = elapsed;
+    }
     _currentSceneTexture = _sceneTextureEscrow.fetchAndRelease(_currentSceneTexture);
     _currentOverlayTexture = _overlayTextureEscrow.fetchAndRelease(_currentOverlayTexture);
 }
diff --git a/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.h b/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.h
index ef78374994..4577777034 100644
--- a/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.h
+++ b/libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.h
@@ -10,6 +10,7 @@
 #include "DisplayPlugin.h"
 
 #include <QtCore/QTimer>
+#include <QElapsedTimer>
 
 #include <GLMHelpers.h>
 #include <SimpleMovingAverage.h>
@@ -30,6 +31,7 @@ public:
     virtual void submitSceneTexture(uint32_t frameIndex, uint32_t sceneTexture, const glm::uvec2& sceneSize) override;
     virtual void submitOverlayTexture(uint32_t overlayTexture, const glm::uvec2& overlaySize) override;
     virtual float presentRate() override;
+    virtual qint64 getLastSynchronizedElapsed() { return _lastSynchronizedElapsed; }
 
     virtual glm::uvec2 getRecommendedRenderSize() const override {
         return getSurfacePixels();
@@ -68,6 +70,8 @@ protected:
     virtual void internalPresent();
 
     mutable QTimer _timer;
+    QElapsedTimer _synchronizedTimer;
+    qint64 _lastSynchronizedElapsed { 0 };
     ProgramPtr _program;
     ShapeWrapperPtr _plane;
 
diff --git a/libraries/plugins/src/plugins/DisplayPlugin.h b/libraries/plugins/src/plugins/DisplayPlugin.h
index 83afbc9402..6fc6062214 100644
--- a/libraries/plugins/src/plugins/DisplayPlugin.h
+++ b/libraries/plugins/src/plugins/DisplayPlugin.h
@@ -58,6 +58,7 @@ public:
     /// By default, all HMDs are stereo
     virtual bool isStereo() const { return isHmd(); }
     virtual bool isThrottled() const { return false; }
+    virtual qint64 getLastSynchronizedElapsed() { return 0; }
 
     // Rendering support