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121 lines
4.2 KiB
121 lines
4.2 KiB
2 years ago
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#!/usr/bin/env python
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# In this example vtkClipPolyData is used to cut a polygonal model
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# of a cow in half. In addition, the open clip is closed by triangulating
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# the resulting complex polygons.
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import vtk
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from vtk.util.misc import vtkGetDataRoot
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from vtk.util.colors import peacock, tomato
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VTK_DATA_ROOT = vtkGetDataRoot()
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# First start by reading a cow model. We also generate surface normals for
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# prettier rendering.
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cow = vtk.vtkBYUReader()
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cow.SetGeometryFileName(VTK_DATA_ROOT + "/Data/Viewpoint/cow.g")
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cowNormals = vtk.vtkPolyDataNormals()
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cowNormals.SetInputConnection(cow.GetOutputPort())
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# We clip with an implicit function. Here we use a plane positioned near
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# the center of the cow model and oriented at an arbitrary angle.
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plane = vtk.vtkPlane()
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plane.SetOrigin(0.25, 0, 0)
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plane.SetNormal(-1, -1, 0)
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# vtkClipPolyData requires an implicit function to define what it is to
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# clip with. Any implicit function, including complex boolean combinations
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# can be used. Notice that we can specify the value of the implicit function
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# with the SetValue method.
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clipper = vtk.vtkClipPolyData()
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clipper.SetInputConnection(cowNormals.GetOutputPort())
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clipper.SetClipFunction(plane)
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clipper.GenerateClipScalarsOn()
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clipper.GenerateClippedOutputOn()
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clipper.SetValue(0.5)
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clipMapper = vtk.vtkPolyDataMapper()
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clipMapper.SetInputConnection(clipper.GetOutputPort())
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clipMapper.ScalarVisibilityOff()
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backProp = vtk.vtkProperty()
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backProp.SetDiffuseColor(tomato)
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clipActor = vtk.vtkActor()
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clipActor.SetMapper(clipMapper)
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clipActor.GetProperty().SetColor(peacock)
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clipActor.SetBackfaceProperty(backProp)
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# Here we are cutting the cow. Cutting creates lines where the cut
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# function intersects the model. (Clipping removes a portion of the
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# model but the dimension of the data does not change.)
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#
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# The reason we are cutting is to generate a closed polygon at the
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# boundary of the clipping process. The cutter generates line
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# segments, the stripper then puts them together into polylines. We
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# then pull a trick and define polygons using the closed line
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# segements that the stripper created.
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cutEdges = vtk.vtkCutter()
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cutEdges.SetInputConnection(cowNormals.GetOutputPort())
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cutEdges.SetCutFunction(plane)
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cutEdges.GenerateCutScalarsOn()
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cutEdges.SetValue(0, 0.5)
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cutStrips = vtk.vtkStripper()
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cutStrips.SetInputConnection(cutEdges.GetOutputPort())
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cutStrips.Update()
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cutPoly = vtk.vtkPolyData()
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cutPoly.SetPoints(cutStrips.GetOutput().GetPoints())
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cutPoly.SetPolys(cutStrips.GetOutput().GetLines())
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# Triangle filter is robust enough to ignore the duplicate point at
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# the beginning and end of the polygons and triangulate them.
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cutTriangles = vtk.vtkTriangleFilter()
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cutTriangles.SetInput(cutPoly)
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cutMapper = vtk.vtkPolyDataMapper()
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cutMapper.SetInput(cutPoly)
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cutMapper.SetInputConnection(cutTriangles.GetOutputPort())
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cutActor = vtk.vtkActor()
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cutActor.SetMapper(cutMapper)
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cutActor.GetProperty().SetColor(peacock)
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# The clipped part of the cow is rendered wireframe.
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restMapper = vtk.vtkPolyDataMapper()
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restMapper.SetInput(clipper.GetClippedOutput())
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restMapper.ScalarVisibilityOff()
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restActor = vtk.vtkActor()
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restActor.SetMapper(restMapper)
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restActor.GetProperty().SetRepresentationToWireframe()
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# Create graphics stuff
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ren = vtk.vtkRenderer()
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renWin = vtk.vtkRenderWindow()
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renWin.AddRenderer(ren)
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iren = vtk.vtkRenderWindowInteractor()
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iren.SetRenderWindow(renWin)
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# Add the actors to the renderer, set the background and size
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ren.AddActor(clipActor)
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ren.AddActor(cutActor)
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ren.AddActor(restActor)
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ren.SetBackground(1, 1, 1)
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ren.ResetCamera()
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ren.GetActiveCamera().Azimuth(30)
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ren.GetActiveCamera().Elevation(30)
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ren.GetActiveCamera().Dolly(1.5)
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ren.ResetCameraClippingRange()
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renWin.SetSize(300, 300)
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iren.Initialize()
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# Lets you move the cut plane back and forth by invoking the function
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# Cut with the appropriate plane value (essentially a distance from
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# the original plane). This is not used in this code but should give
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# you an idea of how to define a function to do this.
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def Cut(v):
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clipper.SetValue(v)
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cutEdges.SetValue(0, v)
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cutStrips.Update()
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cutPoly.SetPoints(cutStrips.GetOutput().GetPoints())
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cutPoly.SetPolys(cutStrips.GetOutput().GetLines())
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cutMapper.Update()
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renWin.Render()
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renWin.Render()
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iren.Start()
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