vtkrender.py

from __future__ import print_function
import sys
import vtk

ren = vtk.vtkRenderer()
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
renWin.SetSize(512,512)

reader = vtk.vtkOBJReader()
reader.SetFileName(sys.argv[1])
reader.Update()
obj = reader.GetOutput()

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputConnection(reader.GetOutputPort())

# Create actor and set the mapper and the texture
actor = vtk.vtkActor()
actor.GetProperty().SetOpacity(0.7)
actor.SetMapper(mapper)

if len(sys.argv)==4:
  import xml.etree.ElementTree
  e = xml.etree.ElementTree.parse(sys.argv[3]).getroot()
  camera = vtk.vtkCamera()
  props = e[0]
  pos = props[0]

  def at(p, i):
    return float(p[i].attrib['value'])

  camera.SetPosition(at(props[0],0), at(props[0],1), at(props[0],2))
  camera.SetFocalPoint(at(props[1],0), at(props[1],1), at(props[1],2))
  camera.SetViewUp(at(props[2],0), at(props[2],1), at(props[2],2))

  ren.SetActiveCamera(camera)

ren.AddActor(actor)
# paraview default color
ren.SetBackground(81/255.0,87/255.0,110/255.0,);
renWin.Render()

# # screenshot code:
w2if = vtk.vtkWindowToImageFilter()
w2if.SetInput(renWin)
w2if.Update()

writer = vtk.vtkPNGWriter()
writer.SetFileName(sys.argv[2])
writer.SetInputConnection(w2if.GetOutputPort())
writer.Write()