渲染在 vtkCommand 中创建的 actor（回调）

Question

我正在尝试编写一个程序，该程序在按下箭头键时显示和循环显示不同文件格式的图像。我发现设置我的 reader->mapper->actor 管道然后启动我的 RenderWindowInteractor 允许渲染 actor，但是将此代码移动到 RenderWindowInteractor 的 KeyPressEvent 的回调不允许渲染 actor。一旦事件循环开始，是否需要额外的步骤来设置新的actor，或者我犯了其他错误？

import vtk

#Create the renderer that will display our actors

ren = vtk.vtkRenderer()

actor = None

#Maps the data from the Nifti file 'filename' onto a vtkImageSlice actor

def LoadNifti():

    # load head MRI in NIFTI format

    reader = vtk.vtkNIFTIImageReader()

    reader.SetFileName("head.nii")

    reader.Update()

    # Add an ImageSliceMapper, which maps data to an ImageSlice Actor

    mapper = vtk.vtkImageSliceMapper()

    #Set the slice position to the camera focal point

    mapper.SliceAtFocalPointOn()

    mapper.SetInputConnection(reader.GetOutputPort())

    # Add an ImageSlice actor, which represents a slice as an image

    global actor

    actor = vtk.vtkImageSlice()

    actor.SetMapper(mapper)

#Placeholder for when I have DICOM working

def ShowDICOM(filename):

    pass

#Create a RenderWindow to display images from the Renderer

renWin = vtk.vtkRenderWindow()

renWin.AddRenderer(ren)

#Wrap the RenderWindow in a RenderWindowInteractor to catch key and mouse events

iren = vtk.vtkRenderWindowInteractor()

iren.SetRenderWindow(renWin)

def foo():

    LoadNifti()

    ren.AddActor(actor)

##Extend the default functionality of the interactor and its style with custom listeners

def KeyPressEvent(obj, ev):

    foo()

    print("This verifies that the callback is triggered")

iren.AddObserver("KeyPressEvent", KeyPressEvent)        

#Start the program

###########################################################################

# WHEN foo() IS PRESENT BELOW, THE ACTOR WILL RENDER IMMEDIATELY.

# WHEN foo() IS ABSENT BELOW, CALLING foo() BY TRIGGERING THE KeyPressEvent

# IS NOT SUFFICIENT TO HAVE THE ACTOR RENDER.

###########################################################################

foo()

#According to the docs, the Start method will initialize iren and render renWin automatically

iren.Start()

Answer 1

好吧，您绝对可以在回调中添加或删除角色。要立即再次渲染场景，只需调用iren.Render()。当您在没有任何可见演员和明确定义的相机的情况下启动渲染器时，ResetCamera通常需要。AutomaticResetCamera在初始化期间只调用一次，这就是为什么调用foo()beforeiren.Start()使对象可见的原因。def foo():    LoadNifti()    ren.AddActor(actor)    ren.ResetCamera() # should that be necessary    iren.Render()