Cell3DDemonstration

VTKExamples/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.

Code

Cell3DDemonstration.py

#!/usr/bin/env python

import vtk


def main():
    colors = vtk.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 = vtk.vtkRenderWindow()
    renWin.SetWindowName('Cell3D Demonstration')

    iRen = vtk.vtkRenderWindowInteractor()
    iRen.SetRenderWindow(renWin)

    # Create one text property for all
    textProperty = vtk.vtkTextProperty()
    textProperty.SetFontSize(16)
    textProperty.SetJustificationToCentered()

    # Create and link the mappers actors and renderers together.
    for i in range(0, len(uGrids)):
        textMappers.append(vtk.vtkTextMapper())
        textActors.append(vtk.vtkActor2D())

        mappers.append(vtk.vtkDataSetMapper())
        actors.append(vtk.vtkActor())
        renderers.append(vtk.vtkRenderer())

        mappers[i].SetInputData(uGrids[i])
        actors[i].SetMapper(mappers[i])
        actors[i].GetProperty().SetColor(
            colors.GetColor3d("Seashell"))
        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 = vtk.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.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 = vtk.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 = vtk.vtkHexagonalPrism()
    for i in range(0, numberOfVertices):
        hexagonalPrism.GetPointIds().SetId(i, i)

    ug = vtk.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 = vtk.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_ = vtk.vtkHexahedron()
    for i in range(0, numberOfVertices):
        hex_.GetPointIds().SetId(i, i)

    # Add the points and hexahedron to an unstructured grid
    uGrid = vtk.vtkUnstructuredGrid()
    uGrid.SetPoints(points)
    uGrid.InsertNextCell(hex_.GetCellType(), hex_.GetPointIds())

    return uGrid


def MakePentagonalPrism():
    numberOfVertices = 10

    # Create the points
    points = vtk.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 = vtk.vtkPentagonalPrism()
    for i in range(0, numberOfVertices):
        pentagonalPrism.GetPointIds().SetId(i, i)

    # Add the points and hexahedron to an unstructured grid
    uGrid = vtk.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 = vtk.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 = vtk.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 = vtk.vtkUnstructuredGrid()
    uGrid.InsertNextCell(vtk.VTK_POLYHEDRON, dodechedronFacesIdList)
    uGrid.SetPoints(points)

    return uGrid


def MakePyramid():
    """
      Make a regular square pyramid.
    """
    numberOfVertices = 5

    points = vtk.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 = vtk.vtkPyramid()
    for i in range(0, numberOfVertices):
        pyramid.GetPointIds().SetId(i, i)

    ug = vtk.vtkUnstructuredGrid()
    ug.SetPoints(points)
    ug.InsertNextCell(pyramid.GetCellType(), pyramid.GetPointIds())

    return ug


def MakeTetrahedron():
    """
      Make a tetrahedron.
    """
    numberOfVertices = 4

    points = vtk.vtkPoints()
    points.InsertNextPoint(0, 0, 0)
    points.InsertNextPoint(1, 0, 0)
    points.InsertNextPoint(1, 1, 0)
    points.InsertNextPoint(0, 1, 1)

    tetra = vtk.vtkTetra()
    for i in range(0, numberOfVertices):
        tetra.GetPointIds().SetId(i, i)

    cellArray = vtk.vtkCellArray()
    cellArray.InsertNextCell(tetra)

    unstructuredGrid = vtk.vtkUnstructuredGrid()
    unstructuredGrid.SetPoints(points)
    unstructuredGrid.SetCells(vtk.VTK_TETRA, cellArray)

    return unstructuredGrid


def MakeVoxel():
    """
      A voxel is a representation of a regular grid in 3-D space.
    """
    numberOfVertices = 8

    points = vtk.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 = vtk.vtkVoxel()
    for i in range(0, numberOfVertices):
        voxel.GetPointIds().SetId(i, i)

    ug = vtk.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 = vtk.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 = vtk.vtkWedge()
    for i in range(0, numberOfVertices):
        wedge.GetPointIds().SetId(i, i)

    ug = vtk.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 = vtk.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 = vtk.vtkPNGWriter()
    writer.SetFileName(fn)
    writer.SetInputConnection(windowToImageFilter.GetOutputPort())
    writer.Write()


if __name__ == '__main__':
    main()