[vtkusers] Saving multiple time steps in a vtkXMLStructuredGrid file ...

[Meehan, Bernard]

I was hoping to be able to write a scalar field that changed over time to
a vtkXMLStructuredGridFile, following the example on this thread:
http://public.kitware.com/pipermail/vtkusers/2012-November/077262.html

But when I examined my ³*vts² file, the scalar function wasn¹t written to
a different time step. I¹d be happy to turn this into an example on the
wiki if I could get it to work Š

import vtk

NX = 10
NY = 10
NZ = 10

#-------------------------------Create your
Grid-------------------------------#
pts = vtk.vtkPoints()
for i in range(NX):
  for j in range(NY):
    for k in range(NZ):
      pts.InsertNextPoint(i, j, k)

sg = vtk.vtkStructuredGrid()
sg.SetDimensions(NX, NY, NZ)
sg.SetPoints(pts)

f1 = vtk.vtkDoubleArray()
f1.SetName("Function 1")
for i in range(NX):
  for j in range(NY):
    for k in range(NZ):
      f1.InsertNextValue(i+j+k)
sg.GetPointData().AddArray(f1)

#----------------------------------Save
File-----------------------------------#
w = vtk.vtkXMLStructuredGridWriter()
w.SetFileName("test.vts")
w.SetInputData(sg)
w.SetDataModeToAscii()
w.SetCompressorTypeToNone()
w.SetNumberOfTimeSteps(3)

w.Start()
w.WriteNextTime(0.0)
w.WriteNextTime(0.1)

# I wanted to see if I could change "Function 1" at the third time step,
but
# when I look at the file that is written, the time step for this never
seems
# to change?

f1 = vtk.vtkDoubleArray()
f1.SetName("Function 1")
for i in range(NX):
  for j in range(NY):
    for k in range(NZ):
      f1.InsertNextValue(-(i+j+k))
sg.GetPointData().AddArray(f1)
sg.Modified()

w.WriteNextTime(0.2)
w.Stop()