EllipseToPline 椭圆转多段线Pline

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AcDbPolyline* ConvertEllipseToPline(AcDbEllipse* pEllipse)
{
        if(!pEllipse)
                return NULL;

        double dParam;
        double dLength;
        double dStep;
        BOOL bClosed=TRUE;
        AcGePoint3d pt3d;
        std::vector<AcGePoint3d> arPt3;
        pEllipse->getEndParam(dParam);
        pEllipse->getDistAtParam(dParam,dLength);

        const unsigned dSegments=100;//divide ellipse into 100 segments
        dStep=(dLength/dSegments)>1?(dLength/dSegments):1;

        if(!pEllipse->isClosed())
                bClosed=FALSE;

        for(double dDist=0.0;dDist<dLength;dDist=dDist+dStep)
        {
                pEllipse->getPointAtDist(dDist,pt3d);
                arPt3.push_back(pt3d);
        }

        pEllipse->getEndPoint(pt3d);
        if(pt3d.distanceTo(arPt3.back())>0.0001)
                arPt3.push_back(pt3d);

        AcDbPolyline* pPline=new AcDbPolyline();
        for(size_t i=0;i<arPt3.size();i++)
                pPline->addVertexAt(i,AcGePoint2d(arPt3[i].x,arPt3[i].y));

        pPline->setClosed(bClosed);
        pPline->setPropertiesFrom(pEllipse);

        return pPline;
}


                double dParamStart;
                es = pEllipse->getStartParam(dParamStart);
                dStep = (dParam - dParamStart) / dSegments;
                for (double par = dParamStart; par<= dParam; par+=dStep)
                {
                        es = pEllipse->getPointAtParam(par, pt3d);
                        arPt3.push_back(pt3d);
                }