vtkXMLUnstructuredGridReader Summary (updated from time to time)

About vtkXMLUnstructuredGridReader

class reference https://vtk.org/doc/nightly/html/classvtkXMLUnstructuredGridReader.html If you don't have the functionality you want, you may also want to investigate the parent class vtkXMLUnstructuredDataReader.

By using vtkXMLUnstructuredGridReader, you can read vtm format files with vtk library.

This time we will create a vtu file using the result of OpenFOAM

terminal

$ git clone https://github.com/matsubaraDaisuke/vtk-data-set.git
$ cd openfoam_case
$ foamTovkt -ascii

VTK is created directly under ʻopenfoam_case, and a folder is created every output time of ʻOpenFOAM. The vtm file is in that folder.

Basic code

import vtk

# reader
reader = vtk.vtkXMLUnstructuredGridReader () 
reader.SetFileName("VTK/src_283/internal.vtu"); #vtu file path
reader.Update()

# filter
filter = vtk.vtkGeometryFilter()
filter.SetInputConnection(reader.GetOutputPort())
filter.Update()

# mapper
mapper = vtk.vtkCompositePolyDataMapper2()
mapper.SetInputConnection(filter.GetOutputPort()) #Set filter in mapper

# actor
actor = vtk.vtkActor()
actor.SetMapper(mapper)             #Set mapper for actor
actor.GetProperty().EdgeVisibilityOn()

# renderer
renderer = vtk.vtkRenderer()
renderer.AddActor(actor)            #Set actor in renderer

##Background color setting
renderer.GradientBackgroundOn()      #Set gradient background
renderer.SetBackground2(0.2,0.4,0.6) #Top color
renderer.SetBackground(1,1,1)        #Bottom color

#Window
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(renderer)         #Set renderer in Window
iren = vtk.vtkRenderWindowInteractor();
iren.SetRenderWindow(renWin);
renWin.SetSize(850, 850)
renWin.Render()
iren.Start();

You can see the information with print

print(reader)
>>
vtkXMLUnstructuredGridReader (0x7ff031cf9b50)
  Debug: Off
  Modified Time: 9623
  Reference Count: 2
  Registered Events: (none)
  Executive: 0x7ff031cf3c90
  ErrorCode: Undefined error: 0
  Information: 0x7ff031ce3700
  AbortExecute: Off
  Progress: 1
  Progress Text: (None)
  FileName: VTK/src_283/internal.vtu
  CellDataArraySelection: 0x7ff031ce3b20
  PointDataArraySelection: 0x7ff031cef0e0
  ColumnArraySelection: 0x7ff031cef0e0
  Stream: (none)
  TimeStep:0
  NumberOfTimeSteps:0
  TimeStepRange:(0,0)

Method

It is actually implemented in vtkXMLUnstructuredDataReader.

GetNumberOfPoints Number of parts? Get

reader.GetNumberOfPoints() 
>> 1

GetNumberOfCells Get the number of cells

reader.GetNumberOfCells () 
>> 12225

GetNumberOfPoints Get the number of nodes

GetNumberOfPoints 
>> 25012