如何在VTK中直接访问多边形？

import vtk

# 创建多边形数据对象
polyData = vtk.vtkPolyData()

# 定义多边形的顶点坐标
points = vtk.vtkPoints()
points.InsertNextPoint(0, 0, 0)
points.InsertNextPoint(1, 0, 0)
points.InsertNextPoint(1, 1, 0)
points.InsertNextPoint(0, 1, 0)

# 定义多边形的拓扑结构
polygons = vtk.vtkCellArray()
polygon = vtk.vtkPolygon()
polygon.GetPointIds().SetNumberOfIds(4)
polygon.GetPointIds().SetId(0, 0)
polygon.GetPointIds().SetId(1, 1)
polygon.GetPointIds().SetId(2, 2)
polygon.GetPointIds().SetId(3, 3)
polygons.InsertNextCell(polygon)

# 将顶点和拓扑结构添加到多边形数据中
polyData.SetPoints(points)
polyData.SetPolys(polygons)

# 访问多边形数据
points = polyData.GetPoints()
polys = polyData.GetPolys()

# 输出多边形的顶点坐标
for i in range(points.GetNumberOfPoints()):
    point = points.GetPoint(i)
    print("顶点", i, "坐标：", point)

# 输出多边形的拓扑结构
polys.InitTraversal()
while True:
    cell = vtk.vtkIdList()
    if polys.GetNextCell(cell) == 0:
        break
    print("多边形顶点索引：", end="")
    for i in range(cell.GetNumberOfIds()):
        print(cell.GetId(i), end=" ")
    print()