Python中的vtk用户类

Question

I'd like to extend vtkActor with my own stuff in Python. I cannot find the way to call the base class __init__ , it looks there is no __init__ . Maybe the vtk/Python wrapping does not allow such a user specialization, the super fails saying vtkActor is not a type... hmmm ...

how can I do something like :

class MyVtkActor(vtk.vtkActor):
  def __init__(self,*args):
    vtk.vtkActor.__init__(self,*args)
    # my stuff here

?

Answer 1

The Python-wrappers for VTK-classes are somewhat different. Have a look at this ipython-session:

In [1]: import vtk

In [2]: type(vtk.vtkActor)
Out[2]: <type 'vtkclass'>

In [3]: type(vtk.vtkActor())
Out[3]: vtkobject

Basically, you can still inherit from vtkActor, but you cannot depend on the object-initialization that is used in Python. You can still call the "normal" methods of this super-class explicitly, with self as first argument.

You must set all properties manually that a call to the contructor (in a C-meaning) would do.

Remember: object construction is performed before initialization, so if you inherit from vtkActor, the normal vtkActor constructor is being called. So by defining

class MyActor(vtk.vtkActor):
    pass

you also get an vtkobject:

In [8]: type(MyActor())
Out[9]: vtkobject

If you are in need of a real-life sample, you could look at this class . It's part of my PyLocator program. Each marker (blue/green balls on the screenshots) is such an object.