Added osgoccluder demo, it creates a single quad occluder, but the culling

code is not complete yet, so it won't actually do any occlusion culling,
the demo is here so I can test the evolving occlusion culling code.

src/Demos/osgoccluder/Makefile

@@ -0,0 +1,16 @@
+TOPDIR = ../../..
+include $(TOPDIR)/Make/makedefs 
+
+CXXFILES =\
+	osgoccluder.cpp\
+
+LIBS     += $(OSG_LIBS) $(GLUT_LIB) $(GL_LIBS) $(X_LIBS) $(OTHER_LIBS) 
+
+INSTFILES = \
+	$(CXXFILES)\
+	Makefile.inst=Makefile
+
+EXEC = osgoccluder
+
+include $(TOPDIR)/Make/makerules 
+

src/Demos/osgoccluder/Makefile.inst

@@ -0,0 +1,12 @@
+TOPDIR = ../..
+include $(TOPDIR)/Make/makedefs
+
+CXXFILES =\
+	osgoccluder.cpp\
+
+LIBS     += $(OSG_LIBS) $(GLUT_LIB) $(GL_LIBS) $(X_LIBS) $(OTHER_LIBS) 
+
+EXEC = osgoccluder
+
+
+include $(TOPDIR)/Make/makerules

src/Demos/osgoccluder/osgoccluder.cpp

@@ -0,0 +1,181 @@
+#include <osg/GL>
+#include <osgGLUT/glut>
+#include <osgGLUT/Viewer>
+
+#include <osg/Transform>
+#include <osg/Billboard>
+#include <osg/Geode>
+#include <osg/Group>
+#include <osg/Notify>
+
+#include <osgDB/Registry>
+#include <osgDB/ReadFile>
+
+#include <osgUtil/TrackballManipulator>
+#include <osgUtil/FlightManipulator>
+#include <osgUtil/DriveManipulator>
+
+#include <osgUtil/Optimizer>
+
+#include <osg/OccluderNode>
+#include <osg/GeoSet>
+
+void write_usage(std::ostream& out,const std::string& name)
+{
+    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;
+}
+
+osg::Node* createOccludersAroundModel(osg::Node* model)
+{
+    osg::Group* scene = osgNew osg::Group;
+
+    // add the loaded model into a the scene group.
+    scene->addChild(model);
+
+
+    // create and occluder which will site along side the loadmodel model.
+    osg::OccluderNode* occluderNode = osgNew osg::OccluderNode;
+
+    // get the bounding volume of the model.
+    const osg::BoundingSphere& bs = model->getBound();
+    
+    // create a bounding box around the sphere.
+    osg::BoundingBox bb;
+    bb.expandBy(bs);
+
+    
+    osg::ConvexPlanerOccluder* cpo = osgNew osg::ConvexPlanerOccluder;
+    
+    // set the occluder up for the front face of the bounding box.
+    osg::ConvexPlanerPolygon& occluder = cpo->getOccluder();
+    occluder.add(osg::Vec3(bb.xMin(),bb.yMin(),bb.zMin()));
+    occluder.add(osg::Vec3(bb.xMax(),bb.yMin(),bb.zMin()));
+    occluder.add(osg::Vec3(bb.xMax(),bb.yMin(),bb.zMax()));
+    occluder.add(osg::Vec3(bb.xMin(),bb.yMin(),bb.zMax()));
+    
+    occluderNode->setOccluder(cpo);
+    
+
+    // create a drawable for occluder.
+    osg::GeoSet* geoset = osgNew osg::GeoSet;
+    
+    osg::Vec3* coords = osgNew osg::Vec3[occluder.getVertexList().size()];
+    std::copy(occluder.getVertexList().begin(),occluder.getVertexList().end(),coords);
+    geoset->setCoords(coords);
+    
+    osg::Vec4* color = osgNew osg::Vec4[1];
+    color[0].set(1.0f,1.0f,1.0f,0.5f);
+    geoset->setColors(color);
+    geoset->setColorBinding(osg::GeoSet::BIND_OVERALL);
+    
+    geoset->setPrimType(osg::GeoSet::QUADS);
+    geoset->setNumPrims(1);
+    
+    osg::Geode* geode = osgNew osg::Geode;
+    geode->addDrawable(geoset);
+    
+    osg::StateSet* stateset = osgNew osg::StateSet;
+    stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
+    stateset->setMode(GL_BLEND,osg::StateAttribute::ON);
+    stateset->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
+    
+    geoset->setStateSet(stateset);
+    
+    // add the occluder geode as a child of the occluder,
+    // as the occluder can't self occlude its subgraph the
+    // geode will never be occluder by this occluder.
+    occluderNode->addChild(geode);    
+    
+    // add the occluder node into the scene.
+    scene->addChild(occluderNode);
+
+    return scene;
+} 
+
+
+int main( int argc, char **argv )
+{
+
+    // initialize the GLUT
+    glutInit( &argc, argv );
+
+    if (argc<2)
+    {
+        write_usage(std::cout,argv[0]);
+        return 0;
+    }
+    
+    // create the commandline args.
+    std::vector<std::string> commandLine;
+    for(int i=1;i<argc;++i) commandLine.push_back(argv[i]);
+    
+
+    // initialize the viewer.
+    osgGLUT::Viewer viewer;
+    viewer.setWindowTitle(argv[0]);
+
+    // configure the viewer from the commandline arguments, and eat any
+    // parameters that have been matched.
+    viewer.readCommandLine(commandLine);
+    
+    // configure the plugin registry from the commandline arguments, and 
+    // eat any parameters that have been matched.
+    osgDB::readCommandLine(commandLine);
+
+    // load the nodes from the commandline arguments.
+    osg::Node* loadedmodel = osgDB::readNodeFiles(commandLine);
+    if (!loadedmodel)
+    {
+//        write_usage(osg::notify(osg::NOTICE),argv[0]);
+        return 1;
+    }
+    
+    // add the occluders to the loaded model.
+    osg::Node* rootnode = createOccludersAroundModel(loadedmodel);
+    
+    // run optimization over the scene graph
+    osgUtil::Optimizer optimzer;
+    optimzer.optimize(rootnode);
+     
+    // add a viewport to the viewer and attach the scene graph.
+    viewer.addViewport( rootnode );
+    
+    // register trackball, flight and drive.
+    viewer.registerCameraManipulator(new osgUtil::TrackballManipulator);
+    viewer.registerCameraManipulator(new osgUtil::FlightManipulator);
+    viewer.registerCameraManipulator(new osgUtil::DriveManipulator);
+
+    // open the viewer window.
+    viewer.open();
+    
+    // fire up the event loop.
+    viewer.run();
+
+    return 0;
+}