OSG鼠标选择求交

OSG鼠标选择求交

////求交方法一：(用WINDOW坐标值，在相机下求交)

           //osg::ref_ptr< osgUtil::LineSegmentIntersector > picker = new osgUtil::LineSegmentIntersector(

           //  osgUtil::Intersector::WINDOW, ea.getX(), ea.getY());

           //osgUtil::IntersectionVisitor iv( picker.get());

           //cameraMaster->accept( iv);//(从相机往下遍历)

 

//求交方法二：(直接用view求交)

//view->computeIntersections( x, y, intersections);

 

//求交方法三：(用世界坐标值，既可在某个节点node下求交，也可在相机下求交。但需注意，在某个节点node下求交时，需要把该node的有矩阵变换的父节点都用上，比如根节点->MT节点->cow模型节点，则可用MT节点->accept( iv)或根节点->accept( iv)。求交时是根据执行accept( iv)的节点向下遍历，求出节点的真实世界坐标。而如果用cow->accept( iv) ，则会忽略父节点的MT节点，导致求不出真正的世界坐标值，这样求交会产生错误)

           osg::ref_ptr< osgUtil::LineSegmentIntersector > picker =new osgUtil::LineSegmentIntersector(

              nearPoint, farPoint);//线段(真实的世界坐标)

           osgUtil::IntersectionVisitor iv( picker.get());

    g_grpMouse->getParent( 0)->getChild( 0)->asGroup()->getChild( 0)->accept( iv);//模型求交

 

//求最前交点 方法一：

if (picker->containsIntersections())

           {  //获取最前的交点。

              osg::Vec3 ptWorldIntersectPointFirst= picker->getFirstIntersection().getWorldIntersectPoint();

              cout<<"world coords vertex("<< ptWorldIntersectPointFirst.x()<<","

                  << ptWorldIntersectPointFirst.y()<< ","<< ptWorldIntersectPointFirst.z()<<")"<< std::endl;

             

           }

/*下面方法也可以计算求出最前的交点：*/

//求最前交点 方法二：

    /*double dLen2Shortest= DBL_MAX, dLenTmp;           osgUtil::LineSegmentIntersector::Intersections::iterator hitrShortest;

              osgUtil::LineSegmentIntersector::Intersections intersections= picker->getIntersections();

           for( osgUtil::LineSegmentIntersector::Intersections::iterator hitr = intersections.begin();

                  hitr != intersections.end();

                  ++hitr)

              {

                  //求离视点最近的点，即鼠标选择的最前面的点

                  dLenTmp= ( ptEye.x()- hitr->getWorldIntersectPoint().x())*

                     ( ptEye.x()- hitr->getWorldIntersectPoint().x())+

                     ( ptEye.y()- hitr->getWorldIntersectPoint().y())*

                     ( ptEye.y()- hitr->getWorldIntersectPoint().y())+

                     ( ptEye.z()- hitr->getWorldIntersectPoint().z())*

                     ( ptEye.z()- hitr->getWorldIntersectPoint().z());

                  if ( dLen2Shortest> dLenTmp)

                  {

                     dLen2Shortest= dLenTmp;

                     hitrShortest= hitr;                   

                  }

              }

其中ptEye为视点的世界坐标值：

osg::Matrix _inverseMV;

           _inverseMV.invert( cameraMaster->getViewMatrix());

           osg::Vec3 ptEye= osg::Vec3(  0, 0, 0) * _inverseMV;

*/

 

参考代码如下：

/*OSG中的HUD实时显示视点坐标*/

#include <osgDB/ReadFile>

#include <osgViewer/Viewer>

#include <osg/Geode>

#include <osg/Depth>

#include <osg/CameraNode>

#include <osgText/Text>

#include <osgGA/TrackballManipulator>

#include <osg/LineWidth>

#include <osg/Point>

#include <osg/ShapeDrawable>

#include <osg/MatrixTransform>

 

 

 

#include <iostream>

#include <sstream>

 

#pragma comment( lib, "osgd.lib"); //.在Debug版本下的库名都加d,如"osgd.lib"

#pragma comment( lib,