vtk自定义一个带箭头的直线actor，可设置方向和长度

以下是一个vtk自定义的带箭头的直线actor的示例代码，可以设置方向和长度。

import vtk

class ArrowLineActor(vtk.vtkActor):
    
    def __init__(self, length=1.0, direction=(1,0,0)):
        super().__init__()
        
        # create line source
        self.lineSource = vtk.vtkLineSource()
        self.lineSource.SetPoint1(0,0,0)
        self.lineSource.SetPoint2(length*direction[0],length*direction[1],length*direction[2])
        
        # create arrow source
        self.arrowSource = vtk.vtkArrowSource()
        self.arrowSource.SetTipLength(0.3)
        self.arrowSource.SetTipRadius(0.1)
        self.arrowSource.SetShaftRadius(0.05)
        
        # create glyph3D
        self.glyph3D = vtk.vtkGlyph3D()
        self.glyph3D.SetInputConnection(self.lineSource.GetOutputPort())
        self.glyph3D.SetSourceConnection(self.arrowSource.GetOutputPort())
        self.glyph3D.SetVectorModeToUseNormal()
        self.glyph3D.SetScaleFactor(length)
        
        # create mapper
        self.mapper = vtk.vtkPolyDataMapper()
        self.mapper.SetInputConnection(self.glyph3D.GetOutputPort())
        
        # create actor
        self.SetMapper(self.mapper)
        
    def SetLength(self, length):
        self.lineSource.SetPoint2(length*self.lineSource.GetPoint2())
        self.glyph3D.SetScaleFactor(length)
        
    def SetDirection(self, direction):
        self.lineSource.SetPoint2(self.lineSource.GetPoint1() + self.glyph3D.GetScaleFactor()*vtk.vtkVector3d(direction))
        

使用示例：

# create a renderer and window
renderer = vtk.vtkRenderer()
renderWindow = vtk.vtkRenderWindow()
renderWindow.AddRenderer(renderer)

# create a interactor
interactor = vtk.vtkRenderWindowInteractor()
interactor.SetRenderWindow(renderWindow)

# create an arrow line actor
arrowLineActor = ArrowLineActor(length=5.0, direction=(1,1,1))
arrowLineActor.GetProperty().SetColor(0,1,0)
renderer.AddActor(arrowLineActor)

# set camera position and focal point
camera = renderer.GetActiveCamera()
camera.SetPosition(10, 10, 10)
camera.SetFocalPoint(0, 0, 0)
camera.Zoom(0.8)

# start interaction
interactor.Initialize()
renderWindow.Render()
interactor.Start()

在这个示例中，我们创建了一个长度为5.0，方向为(1,1,1)的箭头直线actor，并将其添加到renderer中。你可以使用SetLength方法来改变线段的长度，使用SetDirection方法来改变线段的方向。