请教拾取的问题，谢谢

qushi

有哪位大侠在mfc下做过osg的拾取，小弟在osgMFC那个例子里增加拾取功能，老是报错，请指点一二，不胜感激！！！

下面是CPickHandler的代码
//////h文件
#pragma once
#include <osgGA/GUIEventHandler>
#include <osgViewer/View>

class CPickHandler :
        public osgGA::GUIEventHandler
{
public:
        CPickHandler(void);
        virtual ~CPickHandler(void);

public:
        float m_fMouseX;
        float m_fMouseY;

public:

        bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa);

        void pick( osg::ref_ptr<osgViewer::View> view, float x, float y);


};

/////////cpp文件
#include "StdAfx.h"
#include "ickHandler.h"
#include <osgUtil/LineSegmentIntersector>

CPickHandler::CPickHandler(void)
{
        m_fMouseX = 0;
        m_fMouseY = 0;
}

CPickHandler::~CPickHandler(void)
{
}
bool CPickHandler::handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)
{
        osg::ref_ptr<osgViewer::View> view = dynamic_cast<osgViewer::View*>(&aa);

        if ( !view )
        {
                return false;
        }

        switch(ea.getEventType())
        {
        case osgGA::GUIEventAdapter:USH:
                {
                        m_fMouseX = ea.getX();
                        m_fMouseY = ea.getY();
                        break;
                }

        case osgGA::GUIEventAdapter::RELEASE:
                {
                        if ( m_fMouseX==ea.getX() && m_fMouseY == ea.getY() )
                        {
                                pick(view.get(), m_fMouseX, m_fMouseY);
                        }
                        break;
                }

        default:

                break;
        }
        return false;
}

void CPickHandler::pick( osg::ref_ptr<osgViewer::View> view, float x, float y)
{
        osg::ref_ptr<osg::Node> node = new osg::Node();
        osg::ref_ptr<osg::Group> parent = new osg::Group();

        osgUtil:ineSegmentIntersector::Intersections intersections;
        if ( view->computeIntersections(x,y,intersections))
        {
                osgUtil::LineSegmentIntersector::Intersection intersection = *intersections.begin();
                osg::NodePath& nodepath = intersection.nodePath;

                node = (nodepath.size()>=1)?nodepath[nodepath.size()-1]:0;
                parent = (nodepath.size()>=2)?dynamic_cast<osg::Group*>(nodepath[nodepath.size()-2]):0;

                CString ss;
                std::string str = node->getName();
                ss = str.c_str();
                AfxMessageBox(ss);
        }
}

在osg类中增加事件处理器
void cOSG::InitCameraConfig(void)
{
    // Local Variable to hold window size data
    RECT rect;

    // Create the viewer for this window
    mViewer = new osgViewer::Viewer();
       
     //这句注释掉就不报错，打开就报错
   mViewer->addEventHandler(new CPickHandler());
    // Add a Stats Handler to the viewer
    //mViewer->addEventHandler(new osgViewer::StatsHandler);
   
    // Get the current window size
    ::GetWindowRect(m_hWnd, &rect);

   ………………以下省略……………………
}

qushi

补充一下，就是把handle函数改为
bool CPickHandler::handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)
{
        osg::ref_ptr<osgViewer::View> view = dynamic_cast<osgViewer::View*>(&aa);

         return false;
}

同样报错。。。

qushi

哪位大侠给指点下啊，谢谢了

liuzhiyu123

bool CPickHandler::handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)
{
        osg::ref_ptr<osgViewer::View> view = dynamic_cast<osgViewer::View*>(&aa);

         return false;
}

这样也能出错 比较奇怪

array

既然错误指向的地址是0，那么您肯定在什么地方用到了空指针，如是

qushi

谢谢回复，我跟了一下，报错的位置在void cOSG::Render(void* ptr)中的viewer->frame();

qushi

是怎么回事呢？