IsoparametricCellsDemo
VTKExamples/Python/GeometricObjects/IsoparametricCellsDemo
Description¶
This example shows the isoparametric cells supported by the VTK. These cells are nonlinear and contain one or more mid-side vertices. Isoparametric elements are typically used in finite element analysis. The term isoparametric is derived from the use of the same shape functions (or interpolation functions) to define the element's geometric shape as are used to define the displacements within the element.
This example illustrates each cell's representation using its parametric coordinates (pcoords) as the vertices of the cell. In practice, the vertices will correspond to physical points in a finite element model. Use vtkTessellatorFilter to better see the shape of the cell. See for example, QuadraticHexahedronDemo and QuadraticTetraDemo.
Code¶
IsoparametricCellsDemo.py
#!/usr/bin/env python # -*- coding: utf-8 -*- import vtk def main(): titles = list() textMappers = list() textActors = list() uGrids = list() mappers = list() actors = list() renderers = list() uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticEdge())) titles.append("VTK_QUADRATIC_EDGE (= 21)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticTriangle())) titles.append("VTK_QUADRATIC_TRIANGLE (= 22)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticQuad())) titles.append("VTK_QUADRATIC_QUAD (= 23)") uGrids.append(MakeQuadraticPolygon()) titles.append("VTK_QUADRATIC_POLYGON (= 36)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticTetra())) titles.append("VTK_QUADRATIC_TETRA (= 24)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticHexahedron())) titles.append("VTK_QUADRATIC_HEXAHEDRON (= 25)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticWedge())) titles.append("VTK_QUADRATIC_WEDGE (= 26)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticPyramid())) titles.append("VTK_QUADRATIC_PYRAMID (= 27)") uGrids.append(MakeUnstructuredGrid( vtk.vtkBiQuadraticQuad())) titles.append("VTK_BIQUADRATIC_QUAD (= 28)") uGrids.append(MakeUnstructuredGrid( vtk.vtkTriQuadraticHexahedron())) titles.append("VTK_TRIQUADRATIC_HEXAHEDRON (= 29)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticLinearQuad())) titles.append("VTK_QUADRATIC_LINEAR_QUAD (= 30)") uGrids.append(MakeUnstructuredGrid( vtk.vtkQuadraticLinearWedge())) titles.append("VTK_QUADRATIC_LINEAR_WEDGE (= 31)") uGrids.append(MakeUnstructuredGrid( vtk.vtkBiQuadraticQuadraticWedge())) titles.append("VTK_BIQUADRATIC_QUADRATIC_WEDGE (= 32)") uGrids.append(MakeUnstructuredGrid( vtk.vtkBiQuadraticQuadraticHexahedron())) titles.append("VTK_BIQUADRATIC_QUADRATIC_HEXAHEDRON (= 33)") uGrids.append(MakeUnstructuredGrid( vtk.vtkBiQuadraticTriangle())) titles.append("VTK_BIQUADRATIC_TRIANGLE (= 34)") uGrids.append(MakeUnstructuredGrid( vtk.vtkCubicLine())) titles.append("VTK_CUBIC_LINE (= 35)") colors = vtk.vtkNamedColors() renWin = vtk.vtkRenderWindow() renWin.SetSize(600, 600) renWin.SetWindowName("Isoparametric Cell") iRen = vtk.vtkRenderWindowInteractor() iRen.SetRenderWindow(renWin) # Create one sphere for all sphere = vtk.vtkSphereSource() sphere.SetPhiResolution(21) sphere.SetThetaResolution(21) sphere.SetRadius(.08) # Create one text property for all textProperty = vtk.vtkTextProperty() textProperty.SetFontSize(10) textProperty.SetJustificationToCentered() # Create and link the mappers actors and renderers together. for i in range(0, len(uGrids)): print("Creating:", titles[i]) textMappers.append(vtk.vtkTextMapper()) textActors.append(vtk.vtkActor2D()) textMappers[i].GetTextProperty().SetFontSize(10) textMappers[i].GetTextProperty().ShadowOn() 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("Tomato")) actors[i].GetProperty().EdgeVisibilityOn() actors[i].GetProperty().SetLineWidth(3) actors[i].GetProperty().SetOpacity(.5) renderers[i].AddViewProp(actors[i]) textMappers[i].SetInput(titles[i]) textActors[i].SetMapper(textMappers[i]) textActors[i].SetPosition(50, 10) renderers[i].AddViewProp(textActors[i]) # Label the points labelMapper = vtk.vtkLabeledDataMapper() labelMapper.SetInputData(uGrids[i]) labelActor = vtk.vtkActor2D() labelActor.SetMapper(labelMapper) renderers[i].AddViewProp(labelActor) # Glyph the points pointMapper = vtk.vtkGlyph3DMapper() pointMapper.SetInputData(uGrids[i]) pointMapper.SetSourceConnection(sphere.GetOutputPort()) pointMapper.ScalingOff() pointMapper.ScalarVisibilityOff() pointActor = vtk.vtkActor() pointActor.SetMapper(pointMapper) pointActor.GetProperty().SetDiffuseColor(colors.GetColor3d("Banana")) pointActor.GetProperty().SetSpecular(.6) pointActor.GetProperty().SetSpecularColor(1.0, 1.0, 1.0) pointActor.GetProperty().SetSpecularPower(100) renderers[i].AddViewProp(pointActor) renWin.AddRenderer(renderers[i]) # Setup the viewports xGridDimensions = 4 yGridDimensions = 4 rendererSize = 240 renWin.SetSize(rendererSize * xGridDimensions, rendererSize * yGridDimensions) for row in range(0, yGridDimensions): for col in range(0, xGridDimensions): index = row * xGridDimensions + col # (xmin, ymin, xmax, ymax) viewport = [float(col) / xGridDimensions, float(yGridDimensions - (row + 1)) / yGridDimensions, float(col + 1) / xGridDimensions, float(yGridDimensions - row) / yGridDimensions] 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("SlateGray")) ren.SetViewport(viewport) renWin.AddRenderer(ren) continue renderers[index].SetViewport(viewport) renderers[index].SetBackground(colors.GetColor3d("SlateGray")) renderers[index].ResetCamera() renderers[index].GetActiveCamera().Azimuth(30) renderers[index].GetActiveCamera().Elevation(-30) renderers[index].ResetCameraClippingRange() iRen.Initialize() renWin.Render() iRen.Start() # These functions return a vtkUnstructured grid corresponding to the object. def MakeUnstructuredGrid(aCell): pcoords = aCell.GetParametricCoords() for i in range(0, aCell.GetNumberOfPoints()): aCell.GetPointIds().SetId(i, i) aCell.GetPoints().SetPoint(i, (pcoords[3 * i]), (pcoords[3 * i + 1]), (pcoords[3 * i + 2])) ug = vtk.vtkUnstructuredGrid() ug.SetPoints(aCell.GetPoints()) ug.InsertNextCell(aCell.GetCellType(), aCell.GetPointIds()) return ug def MakeQuadraticPolygon(): quadraticPolygon = vtk.vtkQuadraticPolygon() quadraticPolygon.GetPointIds().SetNumberOfIds(8) quadraticPolygon.GetPointIds().SetId(0, 0) quadraticPolygon.GetPointIds().SetId(1, 1) quadraticPolygon.GetPointIds().SetId(2, 2) quadraticPolygon.GetPointIds().SetId(3, 3) quadraticPolygon.GetPointIds().SetId(4, 4) quadraticPolygon.GetPointIds().SetId(5, 5) quadraticPolygon.GetPointIds().SetId(6, 6) quadraticPolygon.GetPointIds().SetId(7, 7) quadraticPolygon.GetPoints().SetNumberOfPoints(8) quadraticPolygon.GetPoints().SetPoint(0, 0.0, 0.0, 0.0) quadraticPolygon.GetPoints().SetPoint(1, 2.0, 0.0, 0.0) quadraticPolygon.GetPoints().SetPoint(2, 2.0, 2.0, 0.0) quadraticPolygon.GetPoints().SetPoint(3, 0.0, 2.0, 0.0) quadraticPolygon.GetPoints().SetPoint(4, 1.0, 0.0, 0.0) quadraticPolygon.GetPoints().SetPoint(5, 2.0, 1.0, 0.0) quadraticPolygon.GetPoints().SetPoint(6, 1.0, 2.0, 0.0) quadraticPolygon.GetPoints().SetPoint(7, 0.0, 1.0, 0.0) quadraticPolygon.GetPoints().SetPoint(5, 3.0, 1.0, 0.0) ug = vtk.vtkUnstructuredGrid() ug.SetPoints(quadraticPolygon.GetPoints()) ug.InsertNextCell(quadraticPolygon.GetCellType(), quadraticPolygon.GetPointIds()) return ug if __name__ == '__main__': main()