From dac86dabb599ee8afb1e681487078e1cdbc3def1 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Fri, 18 Apr 2003 08:17:18 +0000
Subject: [PATCH] Added a realize callback for setting up the pbuffer so that
 it definately has a valid graphics context.

---
 examples/osgpbuffer/osgpbuffer.cpp | 52 ++++++++++++------------------
 1 file changed, 20 insertions(+), 32 deletions(-)

diff --git a/examples/osgpbuffer/osgpbuffer.cpp b/examples/osgpbuffer/osgpbuffer.cpp
index 95f10346e..79e06a550 100644
--- a/examples/osgpbuffer/osgpbuffer.cpp
+++ b/examples/osgpbuffer/osgpbuffer.cpp
@@ -548,36 +548,24 @@ texture->setWrap(osg::Texture2D::WRAP_T,osg::Texture2D::CLAMP);
     return parent;
 }
 
-void write_usage(std::ostream& out,const std::string& name)
+class InitializePbufferCallback : public osgProducer::OsgCameraGroup::RealizeCallback
 {
-    out << std::endl;
-    out <<"usage:"<< std::endl;
-    out <<"    "<<name<<" [options] infile1 [infile2 ...]"<< std::endl;
-    out << std::endl;
-    out <<"options:"<< std::endl;
-    out <<"    -l libraryName      - load plugin of name libraryName"<< std::endl;
-    out <<"                          i.e. -l osgdb_pfb"<< std::endl;
-    out <<"                          Useful for loading reader/writers which can load"<< std::endl;
-    out <<"                          other file formats in addition to its extension."<< std::endl;
-    out <<"    -e extensionName    - load reader/wrter plugin for file extension"<< std::endl;
-    out <<"                          i.e. -e pfb"<< std::endl;
-    out <<"                          Useful short hand for specifying full library name as"<< std::endl;
-    out <<"                          done with -l above, as it automatically expands to"<< std::endl;
-    out <<"                          the full library name appropriate for each platform."<< std::endl;
-    out <<std::endl;
-    out <<"    -stereo             - switch on stereo rendering, using the default of,"<< std::endl;
-    out <<"                          ANAGLYPHIC or the value set in the OSG_STEREO_MODE "<< std::endl;
-    out <<"                          environmental variable. See doc/stereo.html for "<< std::endl;
-    out <<"                          further details on setting up accurate stereo "<< std::endl;
-    out <<"                          for your system. "<< std::endl;
-    out <<"    -stereo ANAGLYPHIC  - switch on anaglyphic(red/cyan) stereo rendering."<< std::endl;
-    out <<"    -stereo QUAD_BUFFER - switch on quad buffered stereo rendering."<< std::endl;
-    out <<std::endl;
-    out <<"    -stencil            - use a visual with stencil buffer enabled, this "<< std::endl;
-    out <<"                          also allows the depth complexity statistics mode"<< std::endl;
-    out <<"                          to be used (press 'p' three times to cycle to it)."<< std::endl;
-    out << std::endl;
-}
+    public:
+        InitializePbufferCallback() {}
+        
+        virtual void operator()( osgProducer::OsgCameraGroup&, osgProducer::OsgSceneHandler& sh, const Producer::RenderSurface& )
+        { 
+            if (!g_pPixelBuffer)
+            {
+                 g_pPixelBuffer = new PBuffer(512,512);
+                g_pPixelBuffer->initialize();
+            }            
+
+            // now safe to continue
+            sh.init();
+        }
+        
+};
 
 int main( int argc, char **argv )
 {
@@ -647,12 +635,12 @@ int main( int argc, char **argv )
     // set the scene to render
     viewer.setSceneData(rootNode);
 
+    // use a realize callback to create and initialize the PBuffer to ensure it has a valid graphics context.
+    viewer.setRealizeCallback(new InitializePbufferCallback());
+
     // create the windows and run the threads.
     viewer.realize();
 
-    g_pPixelBuffer = new PBuffer(512,512);
-    g_pPixelBuffer->initialize();
-
     while( !viewer.done() )
     {
         // wait for all cull and draw threads to complete.