# Motor

VTKExamples/Python/VisualizationAlgorithms/Motor

### Description

This is an example of texture clipping using a transparent texture map. The motor shown consists of five complex parts, some of which are hidden by the outer casing. To see the inside of the motor, we define an implicit clipping function. This function is simply the intersection of two planes to form a clipping "corner". The object * vtkImplicitTextureCoords** is used in combination with this implicit function to generate texture coordinates. These objects are then rendered with the appropriate texture map and the internal parts of the motor can be seen.

The texture map consists of three regions (as described previously in the chapter). The concealed region is transparent. The transition region is opaque but with a black (zero intensity) color. The highlighted region is full intensity and opaque. As can be seen from the result , the boundaries appear as black borders giving a nice visual effect.

Note the use of vectors in the C++ version and lists in the Python version to reduce repetitious code.

### Code

Motor.py

    #!/usr/bin/env python

    # This code is based on the VTK file: /IO/Geometry/Testing/Python/motor.py.

    import vtk

    def main():
        colors = vtk.vtkNamedColors()

        textureFile, motorFile = get_program_parameters()

        # Create the Renderer, RenderWindow and RenderWindowInteractor.
        ren = vtk.vtkRenderer()
        renWin = vtk.vtkRenderWindow()
        renWin.AddRenderer(ren)
        iren = vtk.vtkRenderWindowInteractor()
        iren.SetRenderWindow(renWin)

        # Create the cutting planes.
        planes = vtk.vtkPlanes()
        points = vtk.vtkPoints()
        norms = vtk.vtkFloatArray()

        norms.SetNumberOfComponents(3)
        points.InsertPoint(0, 0.0, 0.0, 0.0)
        norms.InsertTuple3(0, 0.0, 0.0, 1.0)
        points.InsertPoint(1, 0.0, 0.0, 0.0)
        norms.InsertTuple3(1, -1.0, 0.0, 0.0)
        planes.SetPoints(points)
        planes.SetNormals(norms)

        # Get the texture.
        texReader = vtk.vtkStructuredPointsReader()
        texReader.SetFileName(textureFile)
        texture = vtk.vtkTexture()
        texture.SetInputConnection(texReader.GetOutputPort())
        texture.InterpolateOff()
        texture.RepeatOff()

        # Set up the pipelines for the parts of the motor.
        # We will use lists of pipeline objects.
        numberOfParts = 5
        byu = list()
        normals = list()
        tex = list()
        byuMapper = list()
        byuActor = list()
        partColours = ['cold_grey', 'peacock', 'raw_sienna', 'banana', 'peach_puff']
        # Use this to control which parts to display.
        displayParts = [True] * numberOfParts
        # If displayParts[2] = False then an image like that in the VTK tests is produced.

        # Build the pipelines.
        for i in range(0, numberOfParts):
            byu.append(vtk.vtkBYUReader())
            byu[i].SetGeometryFileName(motorFile)
            byu[i].SetPartNumber(i + 1)

            normals.append(vtk.vtkPolyDataNormals())
            normals[i].SetInputConnection(byu[i].GetOutputPort())

            tex.append(vtk.vtkImplicitTextureCoords())
            tex[i].SetInputConnection(normals[i].GetOutputPort())
            tex[i].SetRFunction(planes)
            # tex[i].FlipTextureOn()

            byuMapper.append(vtk.vtkDataSetMapper())
            byuMapper[i].SetInputConnection(tex[i].GetOutputPort())

            byuActor.append(vtk.vtkActor())
            byuActor[i].SetMapper(byuMapper[i])
            byuActor[i].SetTexture(texture)
            byuActor[i].GetProperty().SetColor(colors.GetColor3d(partColours[i]))

            ren.AddActor(byuActor[i])
            if displayParts[i]:
                byuActor[i].VisibilityOn()
            else:
                byuActor[i].VisibilityOff()

        ren.SetBackground(colors.GetColor3d('AliceBlue'))

        renWin.SetSize(512, 512)

        camera = vtk.vtkCamera()
        camera.SetFocalPoint(0.0286334, 0.0362996, 0.0379685)
        camera.SetPosition(1.37067, 1.08629, -1.30349)
        camera.SetViewAngle(17.673)
        camera.SetClippingRange(1, 10)
        camera.SetViewUp(-0.376306, -0.5085, -0.774482)
        ren.SetActiveCamera(camera)

        # Render the image.
        iren.Initialize()
        iren.Start()

    def get_program_parameters():
        import argparse
        description = 'Texture clipping using a transparent texture map.'
        epilogue = '''
            Texture clipping using a transparent texture map.
       '''
        parser = argparse.ArgumentParser(description=description, epilog=epilogue,
                                         formatter_class=argparse.RawDescriptionHelpFormatter)
        parser.add_argument('textureFile', help='The texture file: texThres2.vtk.')
        parser.add_argument('motorFile', help='The motor file: motor.g.')
        args = parser.parse_args()
        return args.textureFile, args.motorFile

    if __name__ == '__main__':
        main()