OSG例程(1) - 交互(Pick)

OSG程序设计教程 第五章 交互的Pick实例

 

#include <iostream>
#include <osgDB/ReadFile>
#include <osgViewer/Viewer>
#include <osg/Group>
#include <osg/Node>
#include <osgFX/Scribe>
#include <osgGA/GUIEventHandler>
#include <osgUtil/LineSegmentIntersector>

class CPickHandler:public osgGA::GUIEventHandler
{
public:
    CPickHandler(osgViewer::Viewer * viewer):mViewer(viewer){};
    virtual bool handle(const osgGA::GUIEventAdapter &ea, osgGA::GUIActionAdapter &&aa)
    {
        switch(ea.getEventType())
        {
            // PUSH, button down
        case osgGA::GUIEventAdapter::PUSH:
            // 1,left button push
            if (ea.getButton()==1)
            {
                Pick(ea.getX(),ea.getY());
            }
            return true;
        }
        return false;
    }
protected:
    void Pick(float x, float y)
    {
        osgUtil::LineSegmentIntersector::Intersections intersections;
        if (mViewer->computeIntersections(x,y,intersections))
        {
            for (osgUtil::LineSegmentIntersector::Intersections::iterator hitr = intersections.begin();
                hitr != intersections.end();
                ++ hitr)
            {
                if (! hitr->nodePath.empty() && ! (hitr->nodePath.back()->getName().empty()))
                {
                    const osg::NodePath &np = hitr->nodePath;
                    for(int i = np.size()-1;i>=0;--i)
                    {
                        osgFX::Scribe *sc = dynamic_cast<osgFX::Scribe *> (np[i]);
                        if(sc!=NULL)
                        {
                            if(sc->getNodeMask()!=0)
                                sc->setNodeMask(0);
                        }
                    }
                }

            }
        }
    }
    osgViewer::Viewer *mViewer;
};


// argc: the number of argv
// argv: an array of arguments,
//       args[0] always is the path and name of the program itself.
int main(int argc, char** argv)
{

    osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer();

    osg::ref_ptr<osg::Group>  root = new osg::Group();
    root->addChild(osgDB::readNodeFile("cessna.osg"));
    osg::ref_ptr<osg::Node> cow = osgDB::readNodeFile("cow.osg");

    osg::ref_ptr<osgFX::Scribe> sc = new osgFX::Scribe();
    sc->addChild(cow.get());
    
    root->addChild(cow.get());
    root->addChild(sc.get());
    
    viewer->setSceneData(root.get());

    viewer->addEventHandler(new CPickHandler(viewer.get()));

    viewer->realize();
    viewer->run();


}