ObjectARX study notes (21) ----- how to get current view vector

Acad:: ErrorStatus
getSysVar(LPCTSTR varName, AcGePoint3d& val)
{
resbuf rb;
if (acedGetVar(varName, &rb) == RTNORM) {
ASSERT(rb.restype == RT3DPOINT);
val. set(rb.resval.rpoint[X], rb.resval.rpoint[Y], rb.resval.rpoint[Z]);
return (Acad :: Eok);
}
else
return (Acad :: eInvalidInput);
}

// cheat and get viewdir for current viewport from the system variable

 AcGeVector3d viewdir;
AcGePoint3d tmpPt;
getSysVar(_T( "viewdir"), tmpPt);
viewDir = tmpPt.asVector();