Clipper c;
c.AddPaths(myPath, ptSubject, true);
ClearVector(myPath);
c.AddPaths(myPathMinus, ptClip, true);
c.Execute(ctDifference, myPath, pftEvenOdd, pftEvenOdd);
myPath.reserve(myPath.size() + non_HitPaths.size() + 1);
myPath.insert(myPath.end(), non_HitPaths.begin(), non_HitPaths.end());
ClearVector(non_HitPaths);
ClearVector(myPathMinus)
mypath代表正图元的size大概是2W,myPathMinus代表负图元size大概100多,实在是太慢了