添加多个单元对象

---

开发环境：

1. Windows 11 家庭中文版
2. Microsoft Visual Studio Community 2019
3. VTK-9.3.0.rc0
4. vtk-example
5. 参考代码

---

demo解决问题：不同阶段添加多个单元对象。 定义一个点集和一个单元集合，单元的类型可以是点、三角形、矩形、多边形等基本图形。只有定义了单元数据才能显示该图形数据。
关键类：vtkPoints、vtkCellArray、vtkPolyData

vtkPolyData可以看看知乎这位老兄的总结：https://zhuanlan.zhihu.com/p/336743251

---

prj name: AddCell

#include 
#include 
#include 
#include 

int main(int, char*[])
{
  // Create a triangle
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(1.0, 0.0, 0.0);
  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(0.0, 1.0, 0.0);

  vtkNew<vtkTriangle> triangle;
  triangle->GetPointIds()->SetId(0, 0);
  triangle->GetPointIds()->SetId(1, 1);
  triangle->GetPointIds()->SetId(2, 2);

  //构造cell array 并插入一个单元对象的索引，插入操作是深拷贝
  vtkNew<vtkCellArray> triangles;
  triangles->InsertNextCell(triangle);

  // Create a polydata object
  vtkNew<vtkPolyData> polyData;

  // Add the geometry and topology to the polydata
  polyData->SetPoints(points);
  polyData->SetPolys(triangles);

  std::cout << "There are " << polyData->GetNumberOfCells() << " cells."
            << std::endl;

  polyData->GetPolys()->InsertNextCell(triangle);//获取到cell array后再插入一个单元对象

  std::cout << "There are " << polyData->GetNumberOfCells() << " cells."
            << std::endl;

  return EXIT_SUCCESS;
}