From 0f492a3950f16a23012d806a2277b0ff40a5b5d5 Mon Sep 17 00:00:00 2001
From: ouv <ouv@opencascade.com>
Date: Fri, 23 Apr 2010 14:10:35 +0000
Subject: [PATCH] Bug IPAL21715 : TC5.1.4: Application hangs up after calling
 of context menu in VTK viewer

---
 src/OpenGLUtils/OpenGLUtils_FrameBuffer.cxx | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/OpenGLUtils/OpenGLUtils_FrameBuffer.cxx b/src/OpenGLUtils/OpenGLUtils_FrameBuffer.cxx
index c976e7d0a..62f5687d1 100755
--- a/src/OpenGLUtils/OpenGLUtils_FrameBuffer.cxx
+++ b/src/OpenGLUtils/OpenGLUtils_FrameBuffer.cxx
@@ -22,6 +22,10 @@
 //
 #include "OpenGLUtils_FrameBuffer.h"
 
+#include <utilities.h>
+
+#include <string>
+
 #ifndef WNT
 # ifndef GLX_GLXEXT_LEGACY
 #  define GLX_GLXEXT_LEGACY
@@ -124,8 +128,13 @@ OpenGLUtils_FrameBuffer::~OpenGLUtils_FrameBuffer()
 
 bool OpenGLUtils_FrameBuffer::init( const GLsizei& xSize, const GLsizei& ySize )
 {
-  if( !IsEXTInitialized )
+  char* ext = (char*)glGetString( GL_EXTENSIONS );
+  if( !IsEXTInitialized ||
+      strstr( ext, "GL_EXT_framebuffer_object" ) == NULL )
+  {
+    MESSAGE( "Initializing OpenGL FrameBuffer extension failed" );
     return false;
+  }
 
   // create a texture object
   glEnable( GL_TEXTURE_2D );
-- 
2.39.2