From 9aba89c88d02d3b9d72eb4fd4f22291bbeca7240 Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Sun, 6 Dec 2015 14:08:49 +0100
Subject: [PATCH] Check for presence of occlusion query extension

---
 src/osg/OcclusionQueryNode.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/osg/OcclusionQueryNode.cpp b/src/osg/OcclusionQueryNode.cpp
index cc3a7627f..2af3a1b31 100644
--- a/src/osg/OcclusionQueryNode.cpp
+++ b/src/osg/OcclusionQueryNode.cpp
@@ -243,7 +243,7 @@ public:
     virtual void deleteGLObject(GLuint globj)
     {
         const GLExtensions* extensions = GLExtensions::Get(_contextID,true);
-        if (extensions->isGlslSupported) extensions->glDeleteQueries( 1L, &globj );
+        if (extensions->isOcclusionQuerySupported || extensions->isARBOcclusionQuerySupported) extensions->glDeleteQueries( 1L, &globj );
     }
 };
 
@@ -285,6 +285,10 @@ QueryGeometry::drawImplementation( osg::RenderInfo& renderInfo ) const
 {
     unsigned int contextID = renderInfo.getState()->getContextID();
     osg::GLExtensions* ext = renderInfo.getState()->get<GLExtensions>();
+
+    if (!ext->isARBOcclusionQuerySupported && !ext->isOcclusionQuerySupported)
+        return;
+
     osg::Camera* cam = renderInfo.getCurrentCamera();
 
     // Add callbacks if necessary.