From 68430ee8e50ff618044c62425ef93d6f6773c615 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Thu, 10 Mar 2016 16:35:08 +0000
Subject: [PATCH] Added a local implementation of
 SlideEventHandler::checkNeedToDoFrame() so that Present3D can toggle on/off
 the need for continuous rendering to only slides that require it, enabling
 slides with no animation to sit iddle rather keeping rendering, reducing
 CPU/GPU overhead and saving power.

---
 applications/present3D/present3D.cpp      |  2 +-
 include/osgPresentation/SlideEventHandler |  3 ++
 include/osgViewer/ViewerBase              | 12 ++++---
 src/osgPresentation/SlideEventHandler.cpp | 38 +++++++++++++++++++++++
 4 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/applications/present3D/present3D.cpp b/applications/present3D/present3D.cpp
index 80620ada6..cab9fbafc 100644
--- a/applications/present3D/present3D.cpp
+++ b/applications/present3D/present3D.cpp
@@ -865,7 +865,7 @@ int main( int argc, char **argv )
         {
             osg::Timer_t startFrameTick = osg::Timer::instance()->tick();
 
-            if (viewer.getRunFrameScheme()!=osgViewer::ViewerBase::ON_DEMAND || viewer.checkNeedToDoFrame())
+            if (viewer.getRunFrameScheme()!=osgViewer::ViewerBase::ON_DEMAND || seh->checkNeedToDoFrame())
             {
                 // do the normal frame.
 
diff --git a/include/osgPresentation/SlideEventHandler b/include/osgPresentation/SlideEventHandler
index aa27edeb4..6f41310dd 100644
--- a/include/osgPresentation/SlideEventHandler
+++ b/include/osgPresentation/SlideEventHandler
@@ -344,6 +344,7 @@ public:
 
     osg::Switch* getPresentationSwitch() { return _presentationSwitch.get(); }
 
+
     enum WhichPosition
     {
         FIRST_POSITION = 0,
@@ -405,6 +406,8 @@ public:
 
     double getReferenceTime() const { return _referenceTime; }
 
+    virtual bool checkNeedToDoFrame();
+
 protected:
 
     ~SlideEventHandler() {}
diff --git a/include/osgViewer/ViewerBase b/include/osgViewer/ViewerBase
index e221e9581..9e31a4492 100644
--- a/include/osgViewer/ViewerBase
+++ b/include/osgViewer/ViewerBase
@@ -224,7 +224,7 @@ class OSGVIEWER_EXPORT ViewerBase : public virtual osg::Object
 
         /** check to see if the new frame is required, called by run(..) when FrameScheme is set to ON_DEMAND.*/
         virtual bool checkNeedToDoFrame() = 0;
-        
+
         /** check to see if events have been received, return true if events are now available.*/
         virtual bool checkEvents() = 0;
 
@@ -277,7 +277,11 @@ class OSGVIEWER_EXPORT ViewerBase : public virtual osg::Object
         /** Get the keyboard and mouse usage of this viewer.*/
         virtual void getUsage(osg::ApplicationUsage& usage) const = 0;
 
-    protected:
+        bool getRequestRedraw() const { return _requestRedraw; }
+        
+        bool getRequestContinousUpdate() const { return _requestContinousUpdate; }
+
+protected:
 
         void viewerBaseInit();
 
@@ -335,9 +339,9 @@ class OSGVIEWER_EXPORT ViewerBase : public virtual osg::Object
         osg::ref_ptr<osgUtil::IncrementalCompileOperation>  _incrementalCompileOperation;
 
         osg::observer_ptr<osg::GraphicsContext>             _currentContext;
-        
+
     private:
-        
+
         // Define private copy constructor
         // otherwsie VS2015 will construct it's own which will call the private copy operator from osg::Object resulting in an compile error.
         ViewerBase& operator = (const ViewerBase&) { return *this; }
diff --git a/src/osgPresentation/SlideEventHandler.cpp b/src/osgPresentation/SlideEventHandler.cpp
index 551c355dc..61f24ff99 100644
--- a/src/osgPresentation/SlideEventHandler.cpp
+++ b/src/osgPresentation/SlideEventHandler.cpp
@@ -1655,3 +1655,41 @@ void SlideEventHandler::setRequestReload(bool flag)
     _requestReload = flag;
 }
 
+bool SlideEventHandler::checkNeedToDoFrame()
+{
+    if (_viewer.valid())
+    {
+        if (_viewer->getRequestRedraw()) return true;
+        if (_viewer->getRequestContinousUpdate()) return true;
+
+        // If the database pager is going to update the scene the render flag is
+        // set so that the updates show up
+        if(_viewer->getDatabasePager()->requiresUpdateSceneGraph() || _viewer->getDatabasePager()->getRequestsInProgress()) return true;
+
+        // if there update callbacks then we need to do frame.
+        if (_viewer->getCamera()->getUpdateCallback()) return true;
+
+        if (!_pause)
+        {
+            if (_slideSwitch.valid() && _activeLayer<static_cast<int>(_slideSwitch->getNumChildren()))
+            {
+                if (_slideSwitch->getChild(_activeLayer)->getNumChildrenRequiringUpdateTraversal()>0) return true;
+            }
+            else if (_viewer->getSceneData()!=0 && _viewer->getSceneData()->getNumChildrenRequiringUpdateTraversal()>0) return true;
+        }
+
+        // check if events are available and need processing
+        if (_viewer->checkEvents()) return true;
+
+        // now check if any of the event handles have prompted a redraw.
+        if (_viewer->getRequestRedraw()) return true;
+        if (_viewer->getRequestContinousUpdate()) return true;
+
+        return false;
+    }
+    else
+    {
+        return true;
+    }
+}
+