Cell3DDemonstration
vtk-examples/Python/GeometricObjects/Cell3DDemonstration
Description¶
This is a demonstration of how to construct and display geometric objects using the classes derived from vtkCell3D. For each object we specify the points and cell Ids.
From this we create an unstructured grid. In some cases a vtkCellArray is used and the result is added to the unstructured grid, see: MakePolyhedron() and MakeTetrahedron().
Also demonstrated is the use of vectors to hold the unstructured grids, mappers, actors and renderers.
The resultant objects are then displayed in a grid.
Other languages
See (Cxx)
Question
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Code¶
Cell3DDemonstration.py
#!/usr/bin/env python
# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingFreeType
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkCommonCore import (
vtkIdList,
vtkPoints
)
from vtkmodules.vtkCommonDataModel import (
VTK_POLYHEDRON,
VTK_TETRA,
vtkCellArray,
vtkHexagonalPrism,
vtkHexahedron,
vtkPentagonalPrism,
vtkPyramid,
vtkTetra,
vtkUnstructuredGrid,
vtkVoxel,
vtkWedge
)
from vtkmodules.vtkIOImage import vtkPNGWriter
from vtkmodules.vtkRenderingCore import (
vtkActor,
vtkActor2D,
vtkDataSetMapper,
vtkRenderWindow,
vtkRenderWindowInteractor,
vtkRenderer,
vtkTextMapper,
vtkTextProperty,
vtkWindowToImageFilter
)
def main():
colors = vtkNamedColors()
# Set the background color.
colors.SetColor('BkgColor', [51, 77, 102, 255])
titles = list()
textMappers = list()
textActors = list()
uGrids = list()
mappers = list()
actors = list()
renderers = list()
uGrids.append(MakeHexagonalPrism())
titles.append('Hexagonal Prism')
uGrids.append(MakeHexahedron())
titles.append('Hexahedron')
uGrids.append(MakePentagonalPrism())
titles.append('Pentagonal Prism')
uGrids.append(MakePolyhedron())
titles.append('Polyhedron')
uGrids.append(MakePyramid())
titles.append('Pyramid')
uGrids.append(MakeTetrahedron())
titles.append('Tetrahedron')
uGrids.append(MakeVoxel())
titles.append('Voxel')
uGrids.append(MakeWedge())
titles.append('Wedge')
renWin = vtkRenderWindow()
renWin.SetWindowName('Cell3DDemonstration')
iRen = vtkRenderWindowInteractor()
iRen.SetRenderWindow(renWin)
# Create one text property for all
textProperty = vtkTextProperty()
textProperty.SetFontSize(16)
textProperty.SetJustificationToCentered()
textProperty.SetColor(colors.GetColor3d('LightGoldenrodYellow'))
# Create and link the mappers actors and renderers together.
for i in range(0, len(uGrids)):
textMappers.append(vtkTextMapper())
textActors.append(vtkActor2D())
mappers.append(vtkDataSetMapper())
actors.append(vtkActor())
renderers.append(vtkRenderer())
mappers[i].SetInputData(uGrids[i])
actors[i].SetMapper(mappers[i])
actors[i].GetProperty().SetColor(colors.GetColor3d('PeachPuff'))
renderers[i].AddViewProp(actors[i])
textMappers[i].SetInput(titles[i])
textMappers[i].SetTextProperty(textProperty)
textActors[i].SetMapper(textMappers[i])
textActors[i].SetPosition(120, 16)
renderers[i].AddViewProp(textActors[i])
renWin.AddRenderer(renderers[i])
gridDimensions = 3
rendererSize = 300
renWin.SetSize(rendererSize * gridDimensions,
rendererSize * gridDimensions)
for row in range(0, gridDimensions):
for col in range(0, gridDimensions):
index = row * gridDimensions + col
# (xmin, ymin, xmax, ymax)
viewport = [
float(col) * rendererSize /
(gridDimensions * rendererSize),
float(gridDimensions - (row + 1)) * rendererSize /
(gridDimensions * rendererSize),
float(col + 1) * rendererSize /
(gridDimensions * rendererSize),
float(gridDimensions - row) * rendererSize /
(gridDimensions * rendererSize)]
if index > len(actors) - 1:
# Add a renderer even if there is no actor.
# This makes the render window background all the same color.
ren = vtkRenderer()
ren.SetBackground(colors.GetColor3d('BkgColor'))
ren.SetViewport(viewport)
renWin.AddRenderer(ren)
continue
renderers[index].SetViewport(viewport)
renderers[index].SetBackground(colors.GetColor3d('BkgColor'))
renderers[index].ResetCamera()
renderers[index].GetActiveCamera().Azimuth(30)
renderers[index].GetActiveCamera().Elevation(-30)
renderers[index].GetActiveCamera().Zoom(0.85)
renderers[index].ResetCameraClippingRange()
iRen.Initialize()
renWin.SetWindowName('Cell3DDemonstration')
renWin.Render()
iRen.Start()
def MakeHexagonalPrism():
"""
3D: hexagonal prism: a wedge with an hexagonal base.
Be careful, the base face ordering is different from wedge.
"""
numberOfVertices = 12
points = vtkPoints()
points.InsertNextPoint(0.0, 0.0, 1.0)
points.InsertNextPoint(1.0, 0.0, 1.0)
points.InsertNextPoint(1.5, 0.5, 1.0)
points.InsertNextPoint(1.0, 1.0, 1.0)
points.InsertNextPoint(0.0, 1.0, 1.0)
points.InsertNextPoint(-0.5, 0.5, 1.0)
points.InsertNextPoint(0.0, 0.0, 0.0)
points.InsertNextPoint(1.0, 0.0, 0.0)
points.InsertNextPoint(1.5, 0.5, 0.0)
points.InsertNextPoint(1.0, 1.0, 0.0)
points.InsertNextPoint(0.0, 1.0, 0.0)
points.InsertNextPoint(-0.5, 0.5, 0.0)
hexagonalPrism = vtkHexagonalPrism()
for i in range(0, numberOfVertices):
hexagonalPrism.GetPointIds().SetId(i, i)
ug = vtkUnstructuredGrid()
ug.InsertNextCell(hexagonalPrism.GetCellType(),
hexagonalPrism.GetPointIds())
ug.SetPoints(points)
return ug
def MakeHexahedron():
"""
A regular hexagon (cube) with all faces square and three squares around
each vertex is created below.
Setup the coordinates of eight points
(the two faces must be in counter clockwise
order as viewed from the outside).
As an exercise you can modify the coordinates of the points to create
seven topologically distinct convex hexahedras.
"""
numberOfVertices = 8
# Create the points
points = vtkPoints()
points.InsertNextPoint(0.0, 0.0, 0.0)
points.InsertNextPoint(1.0, 0.0, 0.0)
points.InsertNextPoint(1.0, 1.0, 0.0)
points.InsertNextPoint(0.0, 1.0, 0.0)
points.InsertNextPoint(0.0, 0.0, 1.0)
points.InsertNextPoint(1.0, 0.0, 1.0)
points.InsertNextPoint(1.0, 1.0, 1.0)
points.InsertNextPoint(0.0, 1.0, 1.0)
# Create a hexahedron from the points
hex_ = vtkHexahedron()
for i in range(0, numberOfVertices):
hex_.GetPointIds().SetId(i, i)
# Add the points and hexahedron to an unstructured grid
uGrid = vtkUnstructuredGrid()
uGrid.SetPoints(points)
uGrid.InsertNextCell(hex_.GetCellType(), hex_.GetPointIds())
return uGrid
def MakePentagonalPrism():
numberOfVertices = 10
# Create the points
points = vtkPoints()
points.InsertNextPoint(11, 10, 10)
points.InsertNextPoint(13, 10, 10)
points.InsertNextPoint(14, 12, 10)
points.InsertNextPoint(12, 14, 10)
points.InsertNextPoint(10, 12, 10)
points.InsertNextPoint(11, 10, 14)
points.InsertNextPoint(13, 10, 14)
points.InsertNextPoint(14, 12, 14)
points.InsertNextPoint(12, 14, 14)
points.InsertNextPoint(10, 12, 14)
# Pentagonal Prism
pentagonalPrism = vtkPentagonalPrism()
for i in range(0, numberOfVertices):
pentagonalPrism.GetPointIds().SetId(i, i)
# Add the points and hexahedron to an unstructured grid
uGrid = vtkUnstructuredGrid()
uGrid.SetPoints(points)
uGrid.InsertNextCell(pentagonalPrism.GetCellType(),
pentagonalPrism.GetPointIds())
return uGrid
def MakePolyhedron():
"""
Make a regular dodecahedron. It consists of twelve regular pentagonal
faces with three faces meeting at each vertex.
"""
# numberOfVertices = 20
numberOfFaces = 12
# numberOfFaceVertices = 5
points = vtkPoints()
points.InsertNextPoint(1.21412, 0, 1.58931)
points.InsertNextPoint(0.375185, 1.1547, 1.58931)
points.InsertNextPoint(-0.982247, 0.713644, 1.58931)
points.InsertNextPoint(-0.982247, -0.713644, 1.58931)
points.InsertNextPoint(0.375185, -1.1547, 1.58931)
points.InsertNextPoint(1.96449, 0, 0.375185)
points.InsertNextPoint(0.607062, 1.86835, 0.375185)
points.InsertNextPoint(-1.58931, 1.1547, 0.375185)
points.InsertNextPoint(-1.58931, -1.1547, 0.375185)
points.InsertNextPoint(0.607062, -1.86835, 0.375185)
points.InsertNextPoint(1.58931, 1.1547, -0.375185)
points.InsertNextPoint(-0.607062, 1.86835, -0.375185)
points.InsertNextPoint(-1.96449, 0, -0.375185)
points.InsertNextPoint(-0.607062, -1.86835, -0.375185)
points.InsertNextPoint(1.58931, -1.1547, -0.375185)
points.InsertNextPoint(0.982247, 0.713644, -1.58931)
points.InsertNextPoint(-0.375185, 1.1547, -1.58931)
points.InsertNextPoint(-1.21412, 0, -1.58931)
points.InsertNextPoint(-0.375185, -1.1547, -1.58931)
points.InsertNextPoint(0.982247, -0.713644, -1.58931)
# Dimensions are [numberOfFaces][numberOfFaceVertices]
dodechedronFace = [
[0, 1, 2, 3, 4],
[0, 5, 10, 6, 1],
[1, 6, 11, 7, 2],
[2, 7, 12, 8, 3],
[3, 8, 13, 9, 4],
[4, 9, 14, 5, 0],
[15, 10, 5, 14, 19],
[16, 11, 6, 10, 15],
[17, 12, 7, 11, 16],
[18, 13, 8, 12, 17],
[19, 14, 9, 13, 18],
[19, 18, 17, 16, 15]
]
dodechedronFacesIdList = vtkIdList()
# Number faces that make up the cell.
dodechedronFacesIdList.InsertNextId(numberOfFaces)
for face in dodechedronFace:
# Number of points in the face == numberOfFaceVertices
dodechedronFacesIdList.InsertNextId(len(face))
# Insert the pointIds for that face.
[dodechedronFacesIdList.InsertNextId(i) for i in face]
uGrid = vtkUnstructuredGrid()
uGrid.InsertNextCell(VTK_POLYHEDRON, dodechedronFacesIdList)
uGrid.SetPoints(points)
return uGrid
def MakePyramid():
"""
Make a regular square pyramid.
"""
numberOfVertices = 5
points = vtkPoints()
p = [
[1.0, 1.0, 0.0],
[-1.0, 1.0, 0.0],
[-1.0, -1.0, 0.0],
[1.0, -1.0, 0.0],
[0.0, 0.0, 1.0]
]
for pt in p:
points.InsertNextPoint(pt)
pyramid = vtkPyramid()
for i in range(0, numberOfVertices):
pyramid.GetPointIds().SetId(i, i)
ug = vtkUnstructuredGrid()
ug.SetPoints(points)
ug.InsertNextCell(pyramid.GetCellType(), pyramid.GetPointIds())
return ug
def MakeTetrahedron():
"""
Make a tetrahedron.
"""
numberOfVertices = 4
points = vtkPoints()
points.InsertNextPoint(0, 0, 0)
points.InsertNextPoint(1, 0, 0)
points.InsertNextPoint(1, 1, 0)
points.InsertNextPoint(0, 1, 1)
tetra = vtkTetra()
for i in range(0, numberOfVertices):
tetra.GetPointIds().SetId(i, i)
cellArray = vtkCellArray()
cellArray.InsertNextCell(tetra)
unstructuredGrid = vtkUnstructuredGrid()
unstructuredGrid.SetPoints(points)
unstructuredGrid.SetCells(VTK_TETRA, cellArray)
return unstructuredGrid
def MakeVoxel():
"""
A voxel is a representation of a regular grid in 3-D space.
"""
numberOfVertices = 8
points = vtkPoints()
points.InsertNextPoint(0, 0, 0)
points.InsertNextPoint(1, 0, 0)
points.InsertNextPoint(0, 1, 0)
points.InsertNextPoint(1, 1, 0)
points.InsertNextPoint(0, 0, 1)
points.InsertNextPoint(1, 0, 1)
points.InsertNextPoint(0, 1, 1)
points.InsertNextPoint(1, 1, 1)
voxel = vtkVoxel()
for i in range(0, numberOfVertices):
voxel.GetPointIds().SetId(i, i)
ug = vtkUnstructuredGrid()
ug.SetPoints(points)
ug.InsertNextCell(voxel.GetCellType(), voxel.GetPointIds())
return ug
def MakeWedge():
"""
A wedge consists of two triangular ends and three rectangular faces.
"""
numberOfVertices = 6
points = vtkPoints()
points.InsertNextPoint(0, 1, 0)
points.InsertNextPoint(0, 0, 0)
points.InsertNextPoint(0, .5, .5)
points.InsertNextPoint(1, 1, 0)
points.InsertNextPoint(1, 0.0, 0.0)
points.InsertNextPoint(1, .5, .5)
wedge = vtkWedge()
for i in range(0, numberOfVertices):
wedge.GetPointIds().SetId(i, i)
ug = vtkUnstructuredGrid()
ug.SetPoints(points)
ug.InsertNextCell(wedge.GetCellType(), wedge.GetPointIds())
return ug
def WritePNG(renWin, fn, magnification=1):
"""
Screenshot
Write out a png corresponding to the render window.
:param: renWin - the render window.
:param: fn - the file name.
:param: magnification - the magnification.
"""
windowToImageFilter = vtkWindowToImageFilter()
windowToImageFilter.SetInput(renWin)
windowToImageFilter.SetMagnification(magnification)
# Record the alpha (transparency) channel
# windowToImageFilter.SetInputBufferTypeToRGBA()
windowToImageFilter.SetInputBufferTypeToRGB()
# Read from the back buffer
windowToImageFilter.ReadFrontBufferOff()
windowToImageFilter.Update()
writer = vtkPNGWriter()
writer.SetFileName(fn)
writer.SetInputConnection(windowToImageFilter.GetOutputPort())
writer.Write()
if __name__ == '__main__':
main()