EllipticalCylinderDemo
VTKExamples/Python/GeometricObjects/EllipticalCylinderDemo
Description¶
The example shows the vtkPolyLine that forms the base of the elliptical cylinder and an oriented arrow that represents the vector that vtkLinearExtrusionFilter uses to create the cylinder. The example takes an optional triple that defines the vector for the filter. The length of the vector is the height of the cylinder.
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Question
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Code¶
EllipticalCylinderDemo.py
#!/usr/bin/env python # -*- coding: utf-8 -*- import math import vtk def main(): nx, ny, nz = get_program_parameters() colors = vtk.vtkNamedColors() angle = 0 r1 = 50 r2 = 30 centerX = 10.0 centerY = 5.0 points = vtk.vtkPoints() idx = 0 while angle <= 2.0 * vtk.vtkMath.Pi() + (vtk.vtkMath.Pi() / 60.0): points.InsertNextPoint(r1 * math.cos(angle) + centerX, r2 * math.sin(angle) + centerY, 0.0) angle = angle + (vtk.vtkMath.Pi() / 60.0) idx += 1 line = vtk.vtkPolyLine() line.GetPointIds().SetNumberOfIds(idx) for i in range(0, idx): line.GetPointIds().SetId(i, i) lines = vtk.vtkCellArray() lines.InsertNextCell(line) polyData = vtk.vtkPolyData() polyData.SetPoints(points) polyData.SetLines(lines) extrude = vtk.vtkLinearExtrusionFilter() extrude.SetInputData(polyData) extrude.SetExtrusionTypeToNormalExtrusion() extrude.SetVector(nx, ny, nz) extrude.Update() # Create an oriented arrow startPoint = [0.0] * 3 endPoint = [0.0] * 3 startPoint[0] = centerX startPoint[1] = centerY startPoint[2] = 0.0 endPoint[0] = startPoint[0] + extrude.GetVector()[0] endPoint[1] = startPoint[1] + extrude.GetVector()[1] endPoint[2] = startPoint[2] + extrude.GetVector()[2] # Compute a basis normalizedX = [0.0] * 3 normalizedY = [0.0] * 3 normalizedZ = [0.0] * 3 # The X axis is a vector from start to end vtk.vtkMath.Subtract(endPoint, startPoint, normalizedX) length = vtk.vtkMath.Norm(normalizedX) vtk.vtkMath.Normalize(normalizedX) # The Z axis is an arbitrary vector cross X arbitrary = [0.0] * 3 arbitrary[0] = vtk.vtkMath.Random(-10, 10) arbitrary[1] = vtk.vtkMath.Random(-10, 10) arbitrary[2] = vtk.vtkMath.Random(-10, 10) vtk.vtkMath.Cross(normalizedX, arbitrary, normalizedZ) vtk.vtkMath.Normalize(normalizedZ) # The Y axis is Z cross X vtk.vtkMath.Cross(normalizedZ, normalizedX, normalizedY) matrix = vtk.vtkMatrix4x4() # Create the direction cosine matrix matrix.Identity() for i in range(0, 3): matrix.SetElement(i, 0, normalizedX[i]) matrix.SetElement(i, 1, normalizedY[i]) matrix.SetElement(i, 2, normalizedZ[i]) # Apply the transforms transform = vtk.vtkTransform() transform.Translate(startPoint) transform.Concatenate(matrix) transform.Scale(length, length, length) arrowSource = vtk.vtkArrowSource() arrowSource.SetTipResolution(31) arrowSource.SetShaftResolution(21) # Transform the polydata transformPD = vtk.vtkTransformPolyDataFilter() transformPD.SetTransform(transform) transformPD.SetInputConnection(arrowSource.GetOutputPort()) # Create a mapper and actor for the arrow arrowMapper = vtk.vtkPolyDataMapper() arrowMapper.SetInputConnection(transformPD.GetOutputPort()) arrowActor = vtk.vtkActor() arrowActor.SetMapper(arrowMapper) arrowActor.GetProperty().SetColor(colors.GetColor3d("Tomato")) tubes = vtk.vtkTubeFilter() tubes.SetInputData(polyData) tubes.SetRadius(2.0) tubes.SetNumberOfSides(21) lineMapper = vtk.vtkPolyDataMapper() lineMapper.SetInputConnection(tubes.GetOutputPort()) lineActor = vtk.vtkActor() lineActor.SetMapper(lineMapper) lineActor.GetProperty().SetColor(colors.GetColor3d("Peacock")) mapper = vtk.vtkPolyDataMapper() mapper.SetInputConnection(extrude.GetOutputPort()) actor = vtk.vtkActor() actor.SetMapper(mapper) actor.GetProperty().SetColor(colors.GetColor3d("Banana")) actor.GetProperty().SetOpacity(.7) ren = vtk.vtkRenderer() ren.SetBackground(colors.GetColor3d("SlateGray")) ren.AddActor(actor) ren.AddActor(lineActor) ren.AddActor(arrowActor) renWin = vtk.vtkRenderWindow() renWin.SetWindowName("Elliptical Cylinder Demo") renWin.AddRenderer(ren) renWin.SetSize(600, 600) iren = vtk.vtkRenderWindowInteractor() iren.SetRenderWindow(renWin) style = vtk.vtkInteractorStyleTrackballCamera() iren.SetInteractorStyle(style) camera = vtk.vtkCamera() camera.SetPosition(0, 1, 0) camera.SetFocalPoint(0, 0, 0) camera.SetViewUp(0, 0, 1) camera.Azimuth(30) camera.Elevation(30) ren.SetActiveCamera(camera) ren.ResetCamera() ren.ResetCameraClippingRange() renWin.Render() iren.Start() def get_program_parameters(): import argparse description = 'Elliptical Cylinder Demo.' epilogue = ''' The example shows the vtkPolyLine that forms the base of the elliptical cylinder and an oriented arrow that represents the vector that vtkLinearExtrusionFilter uses to create the cylinder. The example takes an optional triple that defines the vector for the filter. The length of the vector is the height of the cylinder. ''' parser = argparse.ArgumentParser(description=description, epilog=epilogue, formatter_class=argparse.RawDescriptionHelpFormatter) parser.add_argument('-nx', nargs='?', const=0.0, default=0.0, type=float) parser.add_argument('-ny', nargs='?', const=0.0, default=0.0, type=float) parser.add_argument('-nz', nargs='?', const=100.0, default=100.0, type=float) args = parser.parse_args() return args.nx, args.ny, args.nz if __name__ == '__main__': main()