[vtkusers] BlankCell for UnstructuredGrid not working

[Hui Zhou]

I am learning VTK and I am adapting some example code of VTK to experiment
with it.  A simple tast I am doing is to blank some cells of a
structuredgrid, but somehow could not get it work.  I printed the
IsCellVisible flag for those cells I try to blank, and all are zero.  So it
really puzzeled me why those cells are always visible on the visualization.
 I appreciate your input very much.

Best Regards!

'''
    My first vtk code
    Manually generate a structured grid
'''

import vtk
from math import sin,  cos
from random import random

dims = [30,  20,  11]
nd = dims[0] * dims[1] * dims[2]

sgrid = vtk.vtkStructuredGrid()
sgrid.SetDimensions(dims)
for i in range(40,  50):
    sgrid.BlankCell(i)
    s = sgrid.IsCellVisible(i)
    print s


pts = vtk.vtkPoints()
pts.Allocate(nd)
vectors = vtk.vtkFloatArray()
vectors.SetNumberOfComponents(1)
vectors.SetNumberOfTuples(nd)

dz = 2.0 / (dims[2] - 1)
rmin = 0.5
rmax = 1.0
dr = (rmax - rmin) / (dims[1] - 1)
x = [0,  0,  0]
v = [0,  0,  0]

for k in range(0,  dims[2]) :
    x[2] = -1.0 + k * dz
    kOffset = k * dims[0] * dims[1]
    for j in range(0,  dims[1]):
        r = rmin + j * dr
        jOffset = j * dims[0]
        for i in range(0,  dims[0]):
            theta = i * vtk.vtkMath.RadiansFromDegrees(180.0 / (dims[0]-1))
            x[0] = r * cos(theta)
            x[1] = r * sin(theta)
            v[0] = -x[1]
            v[1] = x[0]

            offset = i + jOffset + kOffset
            pts.InsertPoint(offset,  x)
            #vectors.InsertTuple(offset,  v)
            #vectors.SetValue(offset,  random())

cnt = 0
for k in range(0,  dims[2]-1):
    for j in range(0,  dims[1]-1):
        for i in range(0,  dims[0]-1):
            vectors.SetValue(cnt,  cnt)
            cnt += 1

sgrid.SetPoints(pts)
#sgrid.GetPointData().SetVectors(vectors)
vectors.SetName("HU")
#sgrid.GetPointData().AddArray(vectors)
sgrid.GetCellData().AddArray(vectors)

for i in range(40,  50):
    s = sgrid.IsCellVisible(i)
    print s

#hedgehog = vtk.vtkHedgeHog();
#hedgehog.SetInput(sgrid)
#hedgehog.SetScaleFactor(0.1)

sgridOutline = vtk.vtkOutlineFilter()
sgridOutline.SetInput(sgrid)

lut = vtk.vtkLookupTable()
#lut.SetNumberOfColors(256)
#lut.SetHueRange(0, 1)

def CreateSgridActor(imin,  imax,  jmin,  jmax,  kmin,  kmax):
    sgridFilter = vtk.vtkStructuredGridGeometryFilter()
    sgridFilter.SetInput(sgrid)
    sgridFilter.SetExtent(imin,  imax,  jmin,  jmax,  kmin,  kmax)

    sgridMapper = vtk.vtkPolyDataMapper()
    sgridMapper.SetLookupTable(lut)
    sgridMapper.SetInput(sgridFilter.GetOutput())
    sgridMapper.SetScalarModeToUseCellFieldData()
    sgridMapper.SelectColorArray("HU")
    sgridMapper.SetScalarRange(0,  dims[0]*dims[1]*dims[2])

    sgridActor = vtk.vtkActor()
    sgridActor.SetMapper(sgridMapper)

    return sgridActor

ren = vtk.vtkRenderer()
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)

ren.AddActor(CreateSgridActor(0,  0,  0,  dims[1],  0,  dims[2]))
ren.AddActor(CreateSgridActor(0,  dims[0],  0,  0,  0,  dims[2]))
ren.AddActor(CreateSgridActor(0,  dims[0],  0,  dims[1],  0,  0))
ren.AddActor(CreateSgridActor(dims[0]-1,  dims[0]-1,  0,  dims[1],  0,
 dims[2]))
ren.AddActor(CreateSgridActor(0,  dims[0],  dims[1]-1,  dims[1]-1,  0,
 dims[2]))
ren.AddActor(CreateSgridActor(0,  dims[0],  0,  dims[1],  dims[2]-1,
 dims[2]-1))

# colorbar
colorbar = vtk.vtkScalarBarActor()
colorbar.SetLookupTable(lut)
colorbar.SetTitle("HU")
colorbar.SetNumberOfLabels(4)


ren.AddActor2D(colorbar)


#ren.SetBackground(1,  1,  1)
ren.ResetCamera()
ren.GetActiveCamera().Elevation(60)
ren.GetActiveCamera().Azimuth(30)
ren.GetActiveCamera().Zoom(0.8)
renWin.SetSize(500,  500)

iren.Initialize()
renWin.Render()
iren.Start()
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