Added new osgspacewarp example which demonstrates how to create a star

field which becomes lines as one accelerates, similar to the effect seen
in star trek's warp drive.

examples/osgspacewarp/GNUmakefile

@@ -0,0 +1,18 @@
+TOPDIR = ../..
+include $(TOPDIR)/Make/makedefs 
+
+CXXFILES =\
+	osgspacewarp.cpp\
+
+LIBS     += -losgProducer -lProducer -losgText -losgGA -losgDB -losgUtil -losg $(GL_LIBS) $(X_LIBS) $(OTHER_LIBS) 
+
+INSTFILES = \
+	$(CXXFILES)\
+	GNUmakefile.inst=GNUmakefile
+
+EXEC = osgspacewarp
+
+INC +=  $(X_INC) 
+
+include $(TOPDIR)/Make/makerules 
+

examples/osgspacewarp/GNUmakefile.inst

@@ -0,0 +1,13 @@
+TOPDIR = ../..
+include $(TOPDIR)/Make/makedefs
+
+CXXFILES =\
+	osgspacewarp.cpp\
+
+LIBS     += -losgProducer -lProducer -losgDB -losgText -losgUtil -losg $(GL_LIBS) $(X_LIBS) $(OTHER_LIBS) 
+
+EXEC = osgspacewarp
+
+INC += $(X_INC)
+
+include $(TOPDIR)/Make/makerules

examples/osgspacewarp/osgspacewarp.cpp

@@ -0,0 +1,194 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
+ *
+ * This application is open source and may be redistributed and/or modified   
+ * freely and without restriction, both in commericial and non commericial applications,
+ * as long as this copyright notice is maintained.
+ * 
+ * This application is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+*/
+
+#include <osg/Group>
+#include <osg/Geometry>
+
+#include <osgDB/ReadFile>
+#include <osgUtil/Optimizer>
+#include <osgProducer/Viewer>
+
+float random(float min,float max) { return min + (max-min)*(float)rand()/(float)RAND_MAX; }
+
+
+struct DrawCallback : public osg::Drawable::DrawCallback
+{
+
+    DrawCallback():
+        _firstTime(true) {}
+
+    virtual void drawImplementation(osg::State& state,const osg::Drawable* drawable) const
+    {
+    
+        if (!_firstTime)
+        {
+            _previousModelViewMatrix = _currentModelViewMatrix;
+            _currentModelViewMatrix = state.getModelViewMatrix();
+            _inverseModelViewMatrix.invert(_currentModelViewMatrix);
+            
+            osg::Matrix T(_previousModelViewMatrix*_inverseModelViewMatrix);
+
+            osg::Geometry* geometry = dynamic_cast<osg::Geometry*>(const_cast<osg::Drawable*>(drawable));
+            osg::Vec3Array* vertices = dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray());
+            for(unsigned int i=0;i+1<vertices->size();i+=2)
+            {
+                (*vertices)[i+1] = (*vertices)[i]*T;
+            }
+        }
+        else
+        {
+            _currentModelViewMatrix = state.getModelViewMatrix();
+        }
+                
+        _firstTime = false;
+
+        drawable->drawImplementation(state);
+    }
+    
+    mutable bool _firstTime;
+    mutable osg::Matrix _currentModelViewMatrix;
+    mutable osg::Matrix _inverseModelViewMatrix;
+    mutable osg::Matrix _previousModelViewMatrix;
+};
+
+
+
+
+osg::Node* createScene(unsigned int noStars)
+{
+    
+    osg::Geometry* geometry = new osg::Geometry;
+    
+    // set up vertices
+    osg::Vec3Array* vertices = new osg::Vec3Array(noStars*2);
+    geometry->setVertexArray(vertices);
+    
+    float min = -1.0f;
+    float max = 1.0f;
+    unsigned int j = 0;
+    unsigned int i = 0;
+    for(i=0;i<noStars;++i,j+=2)
+    {
+        (*vertices)[j].set(random(min,max),random(min,max),random(min,max));
+        (*vertices)[j+1] = (*vertices)[j]+osg::Vec3(0.0f,0.0f,0.001f);
+    }    
+
+    // set up colours
+    osg::Vec4Array* colours = new osg::Vec4Array(1);
+    geometry->setColorArray(colours);
+    geometry->setColorBinding(osg::Geometry::BIND_OVERALL);
+    (*colours)[0].set(1.0f,1.0f,1.0f,1.0f);
+
+    // set up the primitive set to draw lines
+    geometry->addPrimitiveSet(new osg::DrawArrays(GL_LINES,0,noStars*2));
+
+    // set up the points for the stars.
+    osg::DrawElementsUShort* points = new osg::DrawElementsUShort(GL_POINTS,noStars);
+    geometry->addPrimitiveSet(points);
+    for(i=0;i<noStars;++i)
+    {
+        (*points)[i] = i*2;
+    }
+
+    geometry->setUseDisplayList(false);
+    geometry->setDrawCallback(new DrawCallback);
+    
+    osg::Geode* geode = new osg::Geode;
+    geode->addDrawable(geometry);
+
+    osg::Group* group = new osg::Group;
+    group->addChild(geode);        
+    
+    return group;
+}
+
+int main( int argc, char **argv )
+{
+
+    // use an ArgumentParser object to manage the program arguments.
+    osg::ArgumentParser arguments(&argc,argv);
+    
+    // set up the usage document, in case we need to print out how to use this program.
+    arguments.getApplicationUsage()->setApplicationName(arguments.getApplicationName());
+    arguments.getApplicationUsage()->setDescription(arguments.getApplicationName()+" is the standard OpenSceneGraph example which loads and visualises 3d models.");
+    arguments.getApplicationUsage()->setCommandLineUsage(arguments.getApplicationName()+" [options] filename ...");
+    arguments.getApplicationUsage()->addCommandLineOption("-h or --help","Display this information");
+    
+
+    // construct the viewer.
+    osgProducer::Viewer viewer(arguments);
+
+    // set up the value with sensible default event handlers.
+    viewer.setUpViewer(osgProducer::Viewer::STANDARD_SETTINGS);
+
+    // get details on keyboard and mouse bindings used by the viewer.
+    viewer.getUsage(*arguments.getApplicationUsage());
+
+    // if user request help write it out to cout.
+    if (arguments.read("-h") || arguments.read("--help"))
+    {
+        arguments.getApplicationUsage()->write(std::cout);
+        return 1;
+    }
+
+    // report any errors if they have occured when parsing the program aguments.
+    if (arguments.errors())
+    {
+        arguments.writeErrorMessages(std::cout);
+        return 1;
+    }
+    
+
+    // read the scene from the list of file specified commandline args.
+    osg::ref_ptr<osg::Node> loadedModel = createScene(50000);
+
+    // if no model has been successfully loaded report failure.
+    if (!loadedModel) 
+    {
+        std::cout << arguments.getApplicationName() <<": No data loaded" << std::endl;
+        return 1;
+    }
+
+    // any option left unread are converted into errors to write out later.
+    arguments.reportRemainingOptionsAsUnrecognized();
+
+    // report any errors if they have occured when parsing the program aguments.
+    if (arguments.errors())
+    {
+        arguments.writeErrorMessages(std::cout);
+    }
+
+    // set the scene to render
+    viewer.setSceneData(loadedModel.get());
+
+    // create the windows and run the threads.
+    viewer.realize();
+
+    while( !viewer.done() )
+    {
+        // wait for all cull and draw threads to complete.
+        viewer.sync();
+
+        // update the scene by traversing it with the the update visitor which will
+        // call all node update callbacks and animations.
+        viewer.update();
+         
+        // fire off the cull and draw traversals of the scene.
+        viewer.frame();
+        
+    }
+    
+    // wait for all cull and draw threads to complete before exit.
+    viewer.sync();
+
+    return 0;
+}
+