#!/usr/bin/env python
 
# This is (almost) a direct C++ to Python transliteration of
# <VTK-root>/Examples/DataManipulation/Cxx/Cube.cxx from the VTK
# source distribution, which "shows how to manually create vtkPolyData"
#
# A convenience function, mkVtkIdList(), has been added and one if/else
# so the example also works in version 6 or later.
#
# Lines like `obj->Delete()` have been transliterated as `del obj` to,
# preserve the resemblance to the original C++ example, although I
# doubt this achieves anything beyond what Python's garbage collection
# would do anyway.
 
import vtk
 
# Makes a vtkIdList from a Python iterable. I'm kinda surprised that
# this is necessary, since I assumed that this kind of thing would
# have been built into the wrapper and happen transparently, but it
# seems not.
 
 
def mkVtkIdList(it):
 vil = vtk.vtkIdList()
 for i in it:
  vil.InsertNextId(int(i))
 return vil
 
# 繪制通用方法
def myShow(cube):
 # Now we'll look at it.
 cubeMapper = vtk.vtkPolyDataMapper()
 if vtk.VTK_MAJOR_VERSION <= 5:
  cubeMapper.SetInput(cube)
 else:
  cubeMapper.SetInputData(cube)
 cubeMapper.SetScalarRange(0, 7)
 cubeActor = vtk.vtkActor()
 cubeActor.SetMapper(cubeMapper)
 
 # The usual rendering stuff.
 camera = vtk.vtkCamera()
 camera.SetPosition(1, 1, 1)
 camera.SetFocalPoint(0, 0, 0)
 
 renderer = vtk.vtkRenderer()
 renWin = vtk.vtkRenderWindow()
 renWin.AddRenderer(renderer)
 
 iren = vtk.vtkRenderWindowInteractor()
 iren.SetRenderWindow(renWin)
 
 renderer.AddActor(cubeActor)
 renderer.SetActiveCamera(camera)
 renderer.ResetCamera()
 renderer.SetBackground(0, 0, 0)
 
 renWin.SetSize(300, 300)
 
 # interact with data
 renWin.Render()
 iren.Start()
 del cubeMapper
 del cubeActor
 del camera
 del renderer
 del renWin
 del iren
 
def main():
 # x = array of 8 3-tuples of float representing the vertices of a cube:
 # 8個三維值代表長方體的8個頂點
 x = [(0.0, 0.0, 0.0), (1.0, 0.0, 0.0), (1.0, 1.0, 0.0), (0.0, 1.0, 0.0),
   (0.0, 0.0, 1.0), (1.0, 0.0, 1.0), (1.0, 1.0, 1.0), (0.0, 1.0, 1.0)]
 
 # pts = array of 6 4-tuples of vtkIdType (int) representing the faces
 #  of the cube in terms of the above vertices
 # 點的編號0-7，每個面由4個點組成
 pts = [(0, 1, 2, 3), (4, 5, 6, 7), (0, 1, 5, 4),
   (1, 2, 6, 5), (2, 3, 7, 6), (3, 0, 4, 7)]
 
 # We'll create the building blocks of polydata including data attributes.
 cube = vtk.vtkPolyData()
 points = vtk.vtkPoints()
 polys = vtk.vtkCellArray()
 scalars = vtk.vtkFloatArray()
 
 # Load the point, cell, and data attributes.
 for i in range(8):
  points.InsertPoint(i, x[i])
 for i in range(6):
  polys.InsertNextCell(mkVtkIdList(pts[i]))
 for i in range(8):
  scalars.InsertTuple1(i, i)
 
 # We now assign the pieces to the vtkPolyData.
 cube.SetPoints(points)
 del points
 cube.SetPolys(polys)
 del polys
 cube.GetPointData().SetScalars(scalars)
 del scalars
 
 myShow(cube)
 # Clean up
 del cube
 
main()