python custom render pass

Support
1

Hi, I’m trying to create a custom render pass using just python. It seems that it’s impossible create a subclass in python using vtkRenderDelegate

class myPass(vtk.vtkRendererDelegate):
    # def __init__(self, *args, **kwargs):
    #     super().__init__(*args, **kwargs)
    def Render(self, s):
        """
        s: vtkRenderState
        """
        pass
myPass()
# TypeError: this is an abstract class and cannot be instantiated

I think it’s the same issue explained here http://vtk.1045678.n5.nabble.com/vtkParametricFunction-sub-classes-in-Python-td5740029.html

In addition, as explained here
https://gitlab.kitware.com/vtk/vtk/blob/master/Wrapping/Python/README.md

It is possible to subclass a VTK class from within Python, but it
is NOT possible to properly override the virtual methods of the class.

Therefore, there is no reason to peform the following approach

class myPass(vtk.vtkGaussianBlurPass):
....
  def Render( renderState):
     pass

Is there any way to create a custom render pass in python?

Thanks

2

is this still not possible?

3

There may be several solutions, but a simple one is to create a vtkScriptedRenderPass in C++ and in all the methods that you want to implement in Python, add a little code snippet that calls a Python object’s corresponding method. We use this approach in 3D Slicer for several classes that we want our users to be able to implement in Python. You can see an example here. In Python, all you need to do is to create a vtkScriptedRenderPass object and set your Python render pass implementation’s .py file in the SetPythonSource method.