# ImplicitPolyDataDistance

VTKExamples/Python/PolyData/ImplicitPolyDataDistance

### Description

Shows how to use vtkImplicitPolyDataDistance.

Other Languages

See (Cxx)

### Code

ImplicitPolyDataDistance.py

    import numpy as np
    import vtk

    def main():
        sphereSource = vtk.vtkSphereSource()
        sphereSource.SetCenter(0.0, 0.0, 0.0)
        sphereSource.SetRadius(1.0)
        sphereSource.Update()

        sphereMapper = vtk.vtkPolyDataMapper()
        sphereMapper.SetInputConnection(sphereSource.GetOutputPort())
        sphereMapper.ScalarVisibilityOff()

        sphereActor = vtk.vtkActor()
        sphereActor.SetMapper(sphereMapper)
        sphereActor.GetProperty().SetOpacity(.3)
        sphereActor.GetProperty().SetColor(1, 0, 0)

        implicitPolyDataDistance = vtk.vtkImplicitPolyDataDistance()
        implicitPolyDataDistance.SetInput(sphereSource.GetOutput())

        # Setup a grid
        points = vtk.vtkPoints()
        step = 0.1
        for x in np.arange(-2, 2, step):
            for y in np.arange(-2, 2, step):
                for z in np.arange(-2, 2, step):
                    points.InsertNextPoint(x, y, z)

        # Add distances to each point
        signedDistances = vtk.vtkFloatArray()
        signedDistances.SetNumberOfComponents(1)
        signedDistances.SetName("SignedDistances")

        # Evaluate the signed distance function at all of the grid points
        for pointId in range(points.GetNumberOfPoints()):
            p = points.GetPoint(pointId)
            signedDistance = implicitPolyDataDistance.EvaluateFunction(p)
            signedDistances.InsertNextValue(signedDistance)

        polyData = vtk.vtkPolyData()
        polyData.SetPoints(points)
        polyData.GetPointData().SetScalars(signedDistances)

        vertexGlyphFilter = vtk.vtkVertexGlyphFilter()
        vertexGlyphFilter.SetInputData(polyData)
        vertexGlyphFilter.Update()

        signedDistanceMapper = vtk.vtkPolyDataMapper()
        signedDistanceMapper.SetInputConnection(vertexGlyphFilter.GetOutputPort())
        signedDistanceMapper.ScalarVisibilityOn()

        signedDistanceActor = vtk.vtkActor()
        signedDistanceActor.SetMapper(signedDistanceMapper)

        renderer = vtk.vtkRenderer()
        renderer.AddViewProp(sphereActor)
        renderer.AddViewProp(signedDistanceActor)

        renderWindow = vtk.vtkRenderWindow()
        renderWindow.AddRenderer(renderer)

        renWinInteractor = vtk.vtkRenderWindowInteractor()
        renWinInteractor.SetRenderWindow(renderWindow)

        renderWindow.Render()
        renWinInteractor.Start()

    if __name__ == '__main__':
        main()