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.
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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()