osg點選pick物體

本文轉載自查看原文 2013-04-21 17:07 2980 OSG

osg已經實現了通過屏幕坐標直接與物體求交的方法。

能得到pick的物體，也能得到坐標。

我希望點擊大地形，根據點擊的點畫出直線。

屏幕坐標與世界坐標的轉換都會了，隨后實現這個功能。

#pragma once

#include <osgGA/GUIEventHandler>
#include <osgUtil/LineSegmentIntersector>
#include <osgViewer/Viewer>

class CPickHandler : public osgGA::GUIEventHandler
{
public:
    CPickHandler(osgViewer::Viewer *viewer);
    ~CPickHandler( void);

    osgViewer::Viewer *m_pViewer;

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

     void pick( float fX, float fY);
};

#include " StdAfx.h "
#include " PickHandler.h "

CPickHandler::CPickHandler(osgViewer::Viewer *viewer):m_pViewer(viewer)
{
}

CPickHandler::~CPickHandler( void)
{
}

bool CPickHandler::handle( const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& aa )
{
     switch (ea.getEventType())
    {
     case(osgGA::GUIEventAdapter::PUSH):
        {
             if (ea.getButton() == 1)
            {
                pick(ea.getX(),ea.getY());
            }
             return true;
        }
    }

     return false;
}

void CPickHandler::pick( float fX, float fY )
{
    osgUtil::LineSegmentIntersector::Intersections intersections;
     if (m_pViewer->computeIntersections(fX,fY,intersections))
    {
         for (auto itr=intersections.begin();itr!=intersections.end();++itr)
        {
             if (!itr->nodePath.empty())
            {
                 const osg::NodePath& np = itr->nodePath;
                 for ( int i=np.size()- 1;i>= 0;--i)
                {
                    osg::ref_ptr<osg::Node> node = dynamic_cast<osg::Node *>(np[i]);
                     if (NULL != node && node->getName().compare( " cow ") == 0)
                    {
                        node->setNodeMask( 0);
                         // itr->getWorldIntersectPoint(); // 得到坐標
                    }
                }
            }
        }
    }
}

屏幕坐標與世界坐標轉換

osg::Vec3 DrawCallback::getPoint()
{
    osg::Vec3 vec3;

    osg::ref_ptr<osgViewer::Viewer> viewer = dynamic_cast<osgViewer::Viewer *>(m_pAA);
    osg::ref_ptr<osg::Camera> camera = viewer->getCamera();
    osgViewer::Renderer *render = dynamic_cast<osgViewer::Renderer *>(camera->getRenderer());
    osgUtil::SceneView *sceneView = render->getSceneView( 0);

    osg::Vec3 vScreen(m_pEA->getX(),m_pEA->getY(), 0);
    osg::Vec3 window;
    sceneView->projectWindowIntoObject(vScreen,window);

    osg::Matrix mVPW = camera->getViewMatrix() * camera->getProjectionMatrix() * camera->getViewport()->computeWindowMatrix();
    osg::Matrix invertVPW;
    invertVPW.invert(mVPW);

    vec3 = window * invertVPW;

     return vec3;
}

1.配置MD

2.配置x64

3.找到mfc example

4.寫callback

5.創建一個節點掛到根節點下，為這個節點設置一個回調器。

響應事件改變節點。
url: http://greatverve.cnblogs.com/archive/2013/04/21/osg-pick.html

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