ExtractSelectionUsingCells选择和提取三维模型中的特定单元（Cell）

一：主要的知识点

1、说明
本文只是教程内容的一小段，因博客字数限制，故进行拆分。主教程链接：vtk教程------逐行解析官网所有Python示例-CSDN博客
2、知识点纪要
本段代码主要涉及的有①通过特定索引取得网格面模型
二：代码及注释

python 复制代码
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkCommonCore import vtkIdTypeArray
from vtkmodules.vtkCommonDataModel import vtkSelection, vtkSelectionNode, vtkUnstructuredGrid
from vtkmodules.vtkFiltersExtraction import vtkExtractSelection
from vtkmodules.vtkFiltersSources import vtkSphereSource
from vtkmodules.vtkRenderingCore import (
    vtkActor,
    vtkCamera,
    vtkDataSetMapper,
    vtkProperty,
    vtkRenderWindow,
    vtkRenderWindowInteractor,
    vtkRenderer
)


def main():
    colors = vtkNamedColors()

    sphereSource = vtkSphereSource()
    sphereSource.Update()

    ids = vtkIdTypeArray()
    ids.SetNumberOfComponents(1)
    for i in range(10, 20):
        ids.InsertNextValue(i)

    selectionNode = vtkSelectionNode()
    selectionNode.SetFieldType(vtkSelectionNode.CELL)
    selectionNode.SetSelectionList(ids)
    selectionNode.SetContentType(vtkSelectionNode.INDICES)

    selection = vtkSelection()
    selection.AddNode(selectionNode)

    extractSelection = vtkExtractSelection()
    extractSelection.SetInputConnection(0, sphereSource.GetOutputPort())
    extractSelection.SetInputData(1, selection)
    extractSelection.Update()

    selected = vtkUnstructuredGrid()
    selected.ShallowCopy(extractSelection.GetOutput())

    selectionNode.GetProperties().Set(vtkSelectionNode.INVERSE(), 1) #取反，1表示取反状态启用？
    extractSelection.Update()

    notSelected = vtkUnstructuredGrid()
    notSelected.ShallowCopy(extractSelection.GetOutput())

    backfaces = vtkProperty()
    backfaces.SetColor(colors.GetColor3d("Gold"))

    inputMapper = vtkDataSetMapper()
    inputMapper.SetInputConnection(sphereSource.GetOutputPort())
    inputActor = vtkActor()
    inputActor.SetMapper(inputMapper)
    inputActor.GetProperty().SetColor(colors.GetColor3d("MistyRose"))
    inputActor.SetBackfaceProperty(backfaces)

    selectedMapper = vtkDataSetMapper()
    selectedMapper.SetInputData(selected)

    selectedActor = vtkActor()
    selectedActor.SetMapper(selectedMapper)
    selectedActor.SetBackfaceProperty(backfaces)
    selectedActor.GetProperty().SetColor(colors.GetColor3d('MistyRose'))

    notSelectedMapper = vtkDataSetMapper()
    notSelectedMapper.SetInputData(notSelected)

    notSelectedActor = vtkActor()
    notSelectedActor.SetMapper(notSelectedMapper)
    notSelectedActor.SetBackfaceProperty(backfaces)
    notSelectedActor.GetProperty().SetColor(colors.GetColor3d('MistyRose'))

    # There will be one render window
    renderWindow = vtkRenderWindow()
    renderWindow.SetSize(900, 300)
    renderWindow.SetWindowName('ExtractSelectionCells')

    # And one interactor
    interactor = vtkRenderWindowInteractor()
    interactor.SetRenderWindow(renderWindow)

    # Define viewport ranges
    # (xmin, ymin, xmax, ymax)
    leftViewport = [0.0, 0.0, 0.33, 1.0]
    centerViewport = [0.33, 0.0, 0.66, 1.0]
    rightViewport = [0.66, 0.0, 1.0, 1.0]

    # Create a camera for all renderers
    camera = vtkCamera()

    # Setup the renderers
    leftRenderer = vtkRenderer()
    renderWindow.AddRenderer(leftRenderer)
    leftRenderer.SetViewport(leftViewport)
    leftRenderer.SetBackground(colors.GetColor3d('BurlyWood'))
    leftRenderer.SetActiveCamera(camera)

    centerRenderer = vtkRenderer()
    renderWindow.AddRenderer(centerRenderer)
    centerRenderer.SetViewport(centerViewport)
    centerRenderer.SetBackground(colors.GetColor3d('orchid_dark'))
    centerRenderer.SetActiveCamera(camera)

    rightRenderer = vtkRenderer()
    renderWindow.AddRenderer(rightRenderer)
    rightRenderer.SetViewport(rightViewport)
    rightRenderer.SetBackground(colors.GetColor3d('CornflowerBlue'))
    rightRenderer.SetActiveCamera(camera)

    leftRenderer.AddActor(inputActor)
    centerRenderer.AddActor(selectedActor)
    rightRenderer.AddActor(notSelectedActor)

    leftRenderer.ResetCamera()

    renderWindow.Render()
    interactor.Start()



if __name__ == '__main__':
    main()