[osg-users] Why are the two osg::Polytope results different when using the transform method?

[mirr...@gmail.com]

        win10&osg3.6.4
        //        
        osg::Matrixd proj = osg::Matrixd::identity();
proj.makePerspective(60, frustumAspectWidth/frustumAspectHeight, 
frustumNear, frustumFar);
//
const double mynear = proj(3, 2) / (proj(2, 2) - 1.0);
const double myfar = proj(3, 2) / (1.0 + proj(2, 2));
//
const double nLeft = mynear * (proj(2, 0) - 1.0) / proj(0, 0);
const double nRight = mynear * (1.0 + proj(2, 0)) / proj(0, 0);
const double nTop = mynear * (1.0 + proj(2, 1)) / proj(1, 1);
const double nBottom = mynear * (proj(2, 1) - 1.0) / proj(1, 1);
const double fLeft = myfar * (proj(2, 0) - 1.0) / proj(0, 0);
const double fRight = myfar * (1.0 + proj(2, 0)) / proj(0, 0);
const double fTop = myfar * (1.0 + proj(2, 1)) / proj(1, 1);
const double fBottom = myfar * (proj(2, 1) - 1.0) / proj(1, 1);
//
        osg::Matrixd ViewM = _view->getCamera()->getInverseViewMatrix();
        {
       osg::Polytope viewFrstumPoly;
osg::Vec3d pt[9];
pt[1] = osg::Vec3d(nLeft, nBottom,  -mynear)*ViewM ;
pt[2] = osg::Vec3d(nRight, nBottom, -mynear)*ViewM ;
pt[3] = osg::Vec3d(nRight, nTop, -mynear)*ViewM ;
        viewFrstumPoly.add(osg::Plane(pt[1],pt[2],pt[3]));
        }

        {
         osg::Polytope viewFrstumPoly2;
         osg::Vec3d pt[9];
         pt[1] = osg::Vec3d(nLeft, nBottom,  -mynear);
         pt[2] = osg::Vec3d(nRight, nBottom, -mynear) ;
         pt[3] = osg::Vec3d(nRight, nTop, -mynear);
         viewFrstumPoly2.add(osg::Plane(pt[1],pt[2],pt[3]));
          viewFrstumPoly2 .transform(ViewM);
        }
        

         

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