Cube
VTKExamples/Python/DataManipulation/Cube
Description
This is a transliteration of the C++ example Examples/DataManipulation/Cxx/Cube.cxx in the VTK source distribution.
It illustrates the manual use of {{VTKDoxygenURL|vtkPolyData}} to construct a cube and differs from the Wiki examples [and [VTK/Examples/Cxx/GeometricObjects/Cube], which use {{VTKDoxygenURL|vtkCube}}.
Code
Cube.py
#!/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
def main():
# x = array of 8 3-tuples of float representing the vertices of a cube:
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
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
# 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(1,1,1)
renWin.SetSize(300,300)
# interact with data
renWin.Render()
iren.Start()
# Clean up
del cube
del cubeMapper
del cubeActor
del camera
del renderer
del renWin
del iren
main()