Ported GradientFilter from Cxx to Python

src/Python/PolyData/GradientFilter.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import vtk
+
+def main(filename):
+    print("Loading", filename)
+    reader = vtk.vtkUnstructuredGridReader()
+    reader.SetFileName(filename)
+
+    edges = vtk.vtkExtractEdges()
+    edges.SetInputConnection(reader.GetOutputPort())
+
+    tubes = vtk.vtkTubeFilter()
+    tubes.SetInputConnection(edges.GetOutputPort())
+    tubes.SetRadius(0.0625)
+    tubes.SetVaryRadiusToVaryRadiusOff()
+    tubes.SetNumberOfSides(32)
+
+    tubesMapper = vtk.vtkPolyDataMapper()
+    tubesMapper.SetInputConnection(tubes.GetOutputPort())
+    tubesMapper.SetScalarRange(0.0, 26.0)
+
+    tubesActor = vtk.vtkActor()
+    tubesActor.SetMapper(tubesMapper)
+
+    gradients = vtk.vtkGradientFilter()
+    gradients.SetInputConnection(reader.GetOutputPort())
+
+    vectors = vtk.vtkAssignAttribute()
+    vectors.SetInputConnection(gradients.GetOutputPort())
+    vectors.Assign("Gradients", vtk.vtkDataSetAttributes.VECTORS, \
+        vtk.vtkAssignAttribute.POINT_DATA)
+
+    arrow = vtk.vtkArrowSource()
+
+    glyphs = vtk.vtkGlyph3D()
+    glyphs.SetInputConnection(0, vectors.GetOutputPort())
+    glyphs.SetInputConnection(1, arrow.GetOutputPort())
+    glyphs.ScalingOn()
+    glyphs.SetScaleModeToScaleByVector()
+    glyphs.SetScaleFactor(0.25)
+    glyphs.OrientOn()
+    glyphs.ClampingOff()
+    glyphs.SetVectorModeToUseVector()
+    glyphs.SetIndexModeToOff()
+
+    glyphMapper = vtk.vtkPolyDataMapper()
+    glyphMapper.SetInputConnection(glyphs.GetOutputPort())
+    glyphMapper.ScalarVisibilityOff()
+
+    glyphActor = vtk.vtkActor()
+    glyphActor.SetMapper(glyphMapper)
+
+    renderer = vtk.vtkRenderer()
+    renderer.AddActor(tubesActor)
+    renderer.AddActor(glyphActor)
+    renderer.SetBackground(0.328125, 0.347656, 0.425781)
+
+    renwin = vtk.vtkRenderWindow()
+    renwin.AddRenderer(renderer)
+    renwin.SetSize(350, 500)
+
+    renderer.ResetCamera()
+    camera = renderer.GetActiveCamera()
+    camera.Elevation(-80.0)
+    camera.OrthogonalizeViewUp()
+    camera.Azimuth(135.0)
+
+    iren = vtk.vtkRenderWindowInteractor()
+    iren.SetRenderWindow(renwin)
+    iren.Initialize()
+    iren.Start()
+    return 1
+
+def get_program_parameters():
+    import argparse
+    description = 'Computes the gradient of a scalar field defined on the points of a data set.'
+    epilogue = '''
+    filename=./src/Testing/Data/uGridEx.vtk
+    '''
+    parser = argparse.ArgumentParser(description=description, epilog=epilogue,
+                                     formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('filename', help='Filename.vtk')
+    args = parser.parse_args()
+    return args.filename
+
+if __name__ == "__main__":
+    main(get_program_parameters())