From 906bb27fa0355a69dd15d41350df0070adb1aced Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Tue, 26 May 2015 17:22:05 +0000
Subject: [PATCH] From Farshid Lashkari, "attached a small change to
 osgUtil::SceneView that prevents unnecessary calls to glClear when the split
 stereo separation is 0."

git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14875 16af8721-9629-0410-8352-f15c8da7e697
---
 src/osgUtil/SceneView.cpp | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/osgUtil/SceneView.cpp b/src/osgUtil/SceneView.cpp
index 7510d26bd..b9ab69256 100644
--- a/src/osgUtil/SceneView.cpp
+++ b/src/osgUtil/SceneView.cpp
@@ -1146,14 +1146,15 @@ void SceneView::draw()
                 _renderStageRight->drawPreRenderStages(_renderInfo,previous);
 
                 double separation = _displaySettings->getSplitStereoHorizontalSeparation();
+                if (separation > 0.0)
+                {
+                    double  left_half_width = (getViewport()->width()-separation)/2.0;
 
-                double  left_half_width = (getViewport()->width()-separation)/2.0;
-
-                clearArea(static_cast<int>(getViewport()->x()+left_half_width),
-                          static_cast<int>(getViewport()->y()),
-                          static_cast<int>(separation),
-                          static_cast<int>(getViewport()->height()),_renderStageLeft->getClearColor());
-
+                    clearArea(static_cast<int>(getViewport()->x()+left_half_width),
+                              static_cast<int>(getViewport()->y()),
+                              static_cast<int>(separation),
+                              static_cast<int>(getViewport()->height()),_renderStageLeft->getClearColor());
+                }
 
                 _localStateSet->setAttribute(_viewportLeft.get());
                 _renderStageLeft->draw(_renderInfo,previous);
@@ -1196,14 +1197,16 @@ void SceneView::draw()
                 _renderStageRight->drawPreRenderStages(_renderInfo,previous);
 
                 double separation = _displaySettings->getSplitStereoVerticalSeparation();
+                if (separation > 0.0)
+                {
+                    double bottom_half_height = (getViewport()->height()-separation)/2.0;
 
-                double bottom_half_height = (getViewport()->height()-separation)/2.0;
-
-                clearArea(static_cast<int>(getViewport()->x()),
-                          static_cast<int>(getViewport()->y()+bottom_half_height),
-                          static_cast<int>(getViewport()->width()),
-                          static_cast<int>(separation),
-                          _renderStageLeft->getClearColor());
+                    clearArea(static_cast<int>(getViewport()->x()),
+                              static_cast<int>(getViewport()->y()+bottom_half_height),
+                              static_cast<int>(getViewport()->width()),
+                              static_cast<int>(separation),
+                              _renderStageLeft->getClearColor());
+                }
 
                 _localStateSet->setAttribute(_viewportLeft.get());
                 _renderStageLeft->draw(_renderInfo,previous);