AcDbCurve::extend 延长指定多义线的前后长度

转载:http://blog.csdn.net/wanglihua312/article/details/7593392

int myExtendPolyline(AcDbPolyline* pl,double sOff,double eOff)

{

ASSERT(pl);

if (pl->numVerts() < 2)

{

return 0;

}

if (sOff > 0)

{

AcGePoint3d sPt,sPt2;

pl->getStartPoint(sPt);

pl->getPointAt(1,sPt2);

 

double td1,td2;

pl->getDistAtPoint(sPt,td1);

pl->getDistAtPoint(sPt2,td2);

double off = td2 – td1;

 

double sParam = fabs(sOff) / off;

 

if(pl->extend(-sParam) != Acad::eOk)

{

ASSERT(0);

return 0;

}

}

if (eOff > 0)

{

AcGePoint3d ePt,ePt2;

pl->getEndPoint(ePt);

pl->getPointAt(pl->numVerts() – 2,ePt2);

 

double td1,td2;

pl->getDistAtPoint(ePt2,td1);

pl->getDistAtPoint(ePt,td2);

double off = td2 – td1;

 

double eparam = fabs(eOff) / off;

if(pl->extend(eparam) != Acad::eOk)

{

ASSERT(0);

return 0;

}

}

 

return 1;

}