vtk面积

vtkSmartPointer triangle = vtkSmartPointer::New();
triangle->GetPointIds()->SetId(0, numPts + elem[0]);
triangle->GetPointIds()->SetId(1, numPts + elem[1]);
triangle->GetPointIds()->SetId(2, numPts + elem[2]);
cells->InsertNextCell(triangle);

triangle->GetPoints()->DeepCopy(pts);
double area = triangle->ComputeArea();