TypeError: GeListNode_ass_subscript when creating a new object

John_Do

Hello,

I have the following error message in one of my script ( which is iteraring over shaders) when I perfom these steps :

running the script over the materials
performing an undo
running the script again > error

TypeError: GeListNode_ass_subscript expected Description identifier, not None

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "scriptmanager", line 198, in <module>
  File "scriptmanager", line 171, in main
  File "scriptmanager", line 84, in convert_c4d_bitmap
  File "scriptmanager", line 116, in create_cr_bitmap_shader
SystemError: <class 'c4d.BaseShader'> returned a result with an exception set

I've seen another topic where the same error was reported, but in this case the error is happening on the line responsible for creating a new BaseShader object ( first line of the function below ). Undo / Redo commands are working perfectly fine, so I really don't see how I could fix this one.

def create_cr_bitmap_shader(filepath, colorspc, basename, exposure, shader):
    cr_bitmap = c4d.BaseShader(1036473)
    cr_bitmap_bc = cr_bitmap.GetDataInstance()
    cr_bitmap_bc.SetFilename(c4d.CORONA_BITMAP_FILENAME, filepath)
    cr_bitmap_bc.SetInt32(c4d.CORONA_BITMAP_COLORPROFILE, colorspc)
    cr_bitmap_bc.SetString(c4d.ID_BASELIST_NAME, basename)
    cr_bitmap_bc.SetFloat(c4d.CORONA_BITMAP_EXPOSURE, exposure)
    return cr_bitmap  # Return the bitmap shader object for further material insertion

The result of the error is a messed up shader tree, with some shaders missing file path, others completely removed from the scene.

Thank you

m_adam

Hi, please post a reproducible example, because with the information you posted we can't help you much since the code you posted does not contain any use of GeListNode_ass_subscript

Cheers,
Maxime.

John_Do

Hi Maxime,

It's a script for Corona for Cinema 4D so I don't know if it'll be of any use to you. But from what I've understood materials and shaders structure are identical to the Standard C4D Material, so I've reduced the script to its essentials by removing few parameters, code below.

import c4d
import time



def iter_shaders(node):
    """Credits go to @ferdinand and @HerrMay over 
    at https://developers.maxon.net/ for the tree-traversal method

    Yields all descendants of ``node`` in a truly iterative fashion.

    The passed node itself is yielded as the first node and the node graph is
    being traversed in depth first fashion.

    This will not fail even on the most complex scenes due to truly
    hierarchical iteration. The lookup table to do this, is here solved with
    a dictionary which yields favorable look-up times in especially larger
    scenes but results in a more convoluted code. The look-up could
    also be solved with a list and then searching in the form ``if node in
    lookupTable`` in it, resulting in cleaner code but worse runtime metrics
    due to the difference in lookup times between list and dict collections.
    """
    if not node:
        return

    # The lookup dictionary and a terminal node which is required due to the
    # fact that this is truly iterative, and we otherwise would leak into the
    # ancestors and siblings of the input node. The terminal node could be
    # set to a different node, for example ``node.GetUp()`` to also include
    # siblings of the passed in node.
    visited = {}
    terminator = node

    while node:

        if isinstance(node, c4d.BaseMaterial) and not node.GetFirstShader():
            break

        if isinstance(node, c4d.BaseMaterial) and node.GetFirstShader():
            node = node.GetFirstShader()

        # C4DAtom is not natively hashable, i.e., cannot be stored as a key
        # in a dict, so we have to hash them by their unique id.
        node_uuid = node.FindUniqueID(c4d.MAXON_CREATOR_ID)
        if not node_uuid:
            raise RuntimeError("Could not retrieve UUID for {}.".format(node))

        # Yield the node when it has not been encountered before.
        if not visited.get(bytes(node_uuid)):
            yield node
            visited[bytes(node_uuid)] = True

        # Attempt to get the first child of the node and hash it.
        child = node.GetDown()

        if child:
            child_uuid = child.FindUniqueID(c4d.MAXON_CREATOR_ID)
            if not child_uuid:
                raise RuntimeError(
                    "Could not retrieve UUID for {}.".format(child))

        # Walk the graph in a depth first fashion.
        if child and not visited.get(bytes(child_uuid)):
            node = child

        elif node == terminator:
            break

        elif node.GetNext():
            node = node.GetNext()

        else:
            node = node.GetUp()


def convert_c4d_bitmap(doc, c4d_bitmap, remove=True):
    # Create the bitmap object in memory
    cr_bitmap = create_cr_bitmap_shader(
        c4d_bitmap[c4d.BITMAPSHADER_FILENAME])
    if isinstance(c4d_bitmap.GetUp(), c4d.BaseShader):
        parent = c4d_bitmap.GetUp()
        # Looking for the slot in the parent base
        # container where the shader is inserted
        parent_shader_slot = get_bc_id(parent.GetDataInstance(), c4d_bitmap)
        cr_bitmap.InsertUnder(parent)  # Insert the bitmap in the shader
        doc.AddUndo(c4d.UNDOTYPE_NEW, cr_bitmap)
        doc.AddUndo(c4d.UNDOTYPE_CHANGE, parent)
        # Linking the bitmap in the right slot
        parent[parent_shader_slot] = cr_bitmap
    elif isinstance(c4d_bitmap.GetMain(), c4d.BaseMaterial):
        parent = c4d_bitmap.GetMain()
        parent_shader_slot = get_bc_id(parent.GetDataInstance(), c4d_bitmap)
        parent.InsertShader(cr_bitmap)
        doc.AddUndo(c4d.UNDOTYPE_NEW, cr_bitmap)
        doc.AddUndo(c4d.UNDOTYPE_CHANGE, parent)
        parent[parent_shader_slot] = cr_bitmap
    # Removing the old bitmap
    if remove:
        doc.AddUndo(c4d.UNDOTYPE_DELETEOBJ, c4d_bitmap)
        c4d_bitmap.Remove()
    return cr_bitmap


def create_cr_bitmap_shader(filepath):
    cr_bitmap = c4d.BaseShader(1036473)
    cr_bitmap_bc = cr_bitmap.GetDataInstance()
    cr_bitmap_bc.SetFilename(c4d.CORONA_BITMAP_FILENAME, filepath)
    return cr_bitmap  # Return the bitmap shader object for further material insertion


def get_bc_id(target_bc, target_value):
    for index, value in target_bc:
        if value == target_value:
            return index


def main():

    doc = c4d.documents.GetActiveDocument()

    materials = doc.GetActiveMaterials()

    doc.StartUndo()

    # Performance measurements
    tic = time.perf_counter()
    c = 0

    # Main loop
    for material in materials:

        mtl_shaders = []

        # Step over non Corona Physical materials or Corona Legacy materials.
        if material.GetType() not in (1056306, 1032100):
            continue

        print(f"{material = }")

        for shader in iter_shaders(material):
            if shader.GetRealType() == c4d.Xbitmap:
                mtl_shaders.append(shader)

        if mtl_shaders:
            for i in mtl_shaders:
                c += 1
                convert_c4d_bitmap(doc, i)

        print(end="\n")

    # Performance measurements
    toc = time.perf_counter()
    print(
        f"Bitmap conversion successful: {c} shaders converted in {toc - tic:0.4f} seconds ")

    doc.EndUndo()

    c4d.EventAdd()


if __name__ == '__main__':
    main()

One thing worth mentionning : with this version, I've got the also a TypeError but the Traceback is different, now the AddUndo method raises an exception.

Traceback (most recent call last):
  File "scriptmanager", line 162, in <module>
  File "scriptmanager", line 147, in main
  File "scriptmanager", line 99, in convert_c4d_bitmap
SystemError: <method 'AddUndo' of 'c4d.documents.BaseDocument' objects> returned a result with an exception set

Thank you

m_adam

Hey, sadly I can't reproduce your issue, can you provide a test scene?

John_Do

Hi Maxime,

Thank for looking into this, I'll send you my test scene by DM since it contains some 3rd party textures.

m_adam

Hi the issue is that there some shaders that are shared between multiple instances. So meaning when you change one you also change the others.
So you have to take into account that in your convert_c4d_bitmap method, since you are deleting the original things in any case.

So with that's said in order to not have this exception you need to adapt your code to not to try to delete a node that have been already deleted:

def convert_c4d_bitmap(doc, c4d_bitmap, remove=True):
    # Create the bitmap object in memory
    cr_bitmap = create_cr_bitmap_shader(c4d_bitmap[c4d.BITMAPSHADER_FILENAME])
    cr_bitmap_added = True
    if isinstance(c4d_bitmap.GetUp(), c4d.BaseShader):
        parent = c4d_bitmap.GetUp()
        # Looking for the slot in the parent base
        # container where the shader is inserted
        parent_shader_slot = get_bc_id(parent.GetDataInstance(), c4d_bitmap)
        cr_bitmap.InsertUnder(parent)  # Insert the bitmap in the shader
        doc.AddUndo(c4d.UNDOTYPE_NEW, cr_bitmap)
        doc.AddUndo(c4d.UNDOTYPE_CHANGE, parent)
        # Linking the bitmap in the right slot
        parent[parent_shader_slot] = cr_bitmap
    
    elif isinstance(c4d_bitmap.GetMain(), c4d.BaseMaterial):
        parent = c4d_bitmap.GetMain()
        parent_shader_slot = get_bc_id(parent.GetDataInstance(), c4d_bitmap)
        parent.InsertShader(cr_bitmap)
        doc.AddUndo(c4d.UNDOTYPE_NEW, cr_bitmap)
        doc.AddUndo(c4d.UNDOTYPE_CHANGE, parent)
        parent[parent_shader_slot] = cr_bitmap

    else:
        cr_bitmap_added = False

    # Removing the old bitmap
    if remove and cr_bitmap_added:
        doc.AddUndo(c4d.UNDOTYPE_DELETEOBJ, c4d_bitmap)
        c4d_bitmap.Remove()

    return cr_bitmap

Cheers,
Maxime.

John_Do

Hi Maxime,

Thank you very much for looking at my issue.
Did you try the new function ? I've added it in my code and unfortunately I get the same result as before.