Dear community,

We recently got a non-public support request about handling drag and drop events for a custom image control in a dialog. And while we have shown this, drag event handling, multiple times before, I thought it does not hurt to answer this publicly, as this very case - an image control - is quite common, and it does not hurt having a bit more verbose public example for it.

edit: I have updated this topic with new code and a new video, to also handle outgoing asset drag events, and talk a bit about the pros and cons of different approaches, and what you could do when not implementing a code example as I did here, and therefore have a bit more leverage room when it comes to complexity.

In general, doing all this is possible. It is just that not everything is a ready-made solution for you, where you just call a function. At some point you have to "swim" here yourself, as we cannot write your code for you, but I hope the example helps shedding some light on the probably uncessarily complicated drag handling in Cinema 4D.

Cheers,
Ferdinand

Result

Code

"""Provides an example for implementing a custom control that can generate and receive drag events.

The example implements a dialog which holds multiple "cards" (BitmapCard) that display an image
and can receive drag events. The user can drag images from the file system into these cards (file
paths) or drag texture assets from the Asset Browser into these cards. The cards can also generate
drag events themselves, e.g., when the user drags from a card, it will generate a drag event. 
Showcased (selectable via the combo box in the menu of the dialog) are three drag types:

1. File paths: Dragging a card will generate an image file path drag event, which for example could 
   be dragged into a file path field of a shader, onto an object in the viewport, or onto other 
   BitmapCard controls. The advantage of this approach is that we do not have to create
   materials or assets, but can just use the file path directly.

2. Materials: Dragging a card will generate an atom drag event, here populated with a Redshift
   material that has the texture of the card as an input. This material can then be dragged onto
   anything that accepts materials, like objects in the viewport. The disadvantage of this
   approach is that we have to create a material, and that we have to exactly define how the 
   material is constructed.

3. Assets: Dragging a card will generate an asset drag event, here populated with a texture asset
   that has the texture of the card as an input. This asset can then be dragged onto anything that
   texture accepts assets, such as an object in the viewport. The disadvantage of this
   approach is that we have to create an asset.

   - The example also showcases a variation oof this approach, where we exploit a bit how the
     texture asset drag handling works, to avoid having to create an asset.


Overview:

- BitmapCard: A user area control that can receive drag events and generate drag events itself. Here
              you will find almost all the relevant code for drag and drop handling
- BitmapStackDialog: A dialog that holds multiple BitmapCard controls and allows the user to select
                the drag type via a combo box. This dialog is the main entry point of the example
                but does not contain much relevant code itself.
"""
__author__ = "Ferdinand Hoppe"
__copyright__ = "Copyright 2025 Maxon Computer GmbH"

import os
import re

import c4d
import maxon
import mxutils

# The file types that are supported to be dragged into a BitmapCard control.
DRAG_IN_FILE_TYPES: list[str] = [".png", ".jpg", ".jpeg", ".tif"]

# A regex to check of a string (which is meant to be a path/url) already as a scheme (like file:///
# or http:///). The protocol we are mostly checking for is "asset:///", but we keep this regex generic
# to allow for other schemes as well.
RE_URL_HAS_SCHEME = re.compile("^[a-zA-Z][a-zA-Z\d+\-.]*:\/\/\/")

# A non-public core message which need when we want to properly generate asset drag events.
COREMSG_SETCOMMANDEDITMODE: int = 300001000


class BitmapCard(c4d.gui.GeUserArea):
    """Implements a control that can receive bitmap path drag events and generates drag events itself.
    """

    def __init__(self, host: "BitmapStackDialog") -> None:
        """Constructs a new BitmapCard object.
        """
        # The host dialog that holds this card. This is used to access the drag type selected in the
        # combo box of the dialog.
        self._host: BitmapStackDialog = host

        # The image file path and the bitmap that is displayed in this card.
        self._path: str | None = ""
        self._bitmap: c4d.bitmaps.BaseBitmap | None = None

    def GetMinSize(self) -> tuple[int, int]:
        """Called by Cinema 4d to evaluate the minimum size of the user area.
        """
        return 250, 100

    def DrawMsg(self, x1, y1, x2, y2, msg_ref):
        """Called by Cinema 4D to let the user area draw itself.
        """
        self.OffScreenOn()
        self.SetClippingRegion(x1, y1, x2, y2)

        # Draw the background and then the bitmap if it exists. In the real world, we would have to
        # either adapt #GetMinSize to the size of the bitmap, or draw the bitmap in a way that it
        # fits into the user area, e.g., by scaling it down. Here we just draw it at a fixed size.
        self.DrawSetPen(c4d.gui.GetGuiWorldColor(c4d.COLOR_BGGADGET))
        self.DrawRectangle(x1, y1, x2, y2)
        if self._bitmap:
            w, h = self._bitmap.GetSize()
            self.DrawBitmap(self._bitmap, 5, 5, 240, 90, 0,
                            0, w, h, c4d.BMP_NORMALSCALED)

    def Message(self, msg: c4d.BaseContainer, result: c4d.BaseContainer) -> int:
        """Called by Cinema 4D to handle messages sent to the user area.

        Here we implement receiving drag events when the user drags something onto this user area.
        """
        # A drag event is coming in.
        if msg.GetId() == c4d.BFM_DRAGRECEIVE:
            # Get out when the drag event has been discarded.
            if msg.GetInt32(c4d.BFM_DRAG_LOST) or msg.GetInt32(c4d.BFM_DRAG_ESC):
                return self.SetDragDestination(c4d.MOUSE_FORBIDDEN)

            # Get out when this is not a drag type we support (we just support images). Note that we
            # cannot make up drag types ourselves, so when we want to send/receive complex data, we
            # must use the DRAGTYPE_ATOMARRAY type and pack our data into a BaseContainer attached
            # to the nodes we drag/send.
            data: dict = self.GetDragObject(msg)
            dragType: int = data.get("type", 0)
            if dragType not in [c4d.DRAGTYPE_FILENAME_IMAGE, maxon.DRAGTYPE_ASSET]:
                return self.SetDragDestination(c4d.MOUSE_FORBIDDEN)

            # Here we could optionally check the drag event hitting some target area.
            # yPos: float = self.GetDragPosition(msg).get('y', 0.0)
            # if not 0 < yPos < 50 or not self.CheckDropArea(msg, True, True):
            #     return self.SetDragDestination(c4d.MOUSE_FORBIDDEN)

            # After this point, we are dealing with a valid drag event.

            # The drag is still going on, we just set the mouse cursor to indicate that we are
            # ready to receive the drag event.
            if msg.GetInt32(c4d.BFM_DRAG_FINISHED) == 0:
                return self.SetDragDestination(c4d.MOUSE_MOVE)
            # The drag event is finished, we can now process the data.
            else:
                # Unpack a file being dragged directly.
                path: str | None = None
                if dragType == c4d.DRAGTYPE_FILENAME_IMAGE:
                    path = data.get("object", None)
                # Unpack an asset being dragged.
                elif dragType == maxon.DRAGTYPE_ASSET:
                    array: maxon.DragAndDropDataAssetArray = data.get(
                        "object", None)
                    descriptions: tuple[tuple[maxon.AssetDescription, maxon.Url, maxon.String]] = (
                        array.GetAssetDescriptions())
                    if not descriptions:
                        # Invalid asset but we are not in an error state.
                        return True

                    # Check that we are dealing with an image asset.
                    asset: maxon.AssetDescription = descriptions[0][0]
                    metadata: maxon.BaseContainer = asset.GetMetaData()
                    subType: maxon.Id = metadata.Get(
                        maxon.ASSETMETADATA.SubType, maxon.Id())
                    if (subType != maxon.ASSETMETADATA.SubType_ENUM_MediaImage):
                        # Invalid asset but we are not in an error state.
                        return True

                    path = str(maxon.AssetInterface.GetAssetUrl(asset, True))

                if not isinstance(path, str):
                    return False  # Critical failure.

                if (dragType == c4d.DRAGTYPE_FILENAME_IMAGE and
                    (not os.path.exists(path) or
                     os.path.splitext(path)[1].lower() not in DRAG_IN_FILE_TYPES)):
                    # Invalid file type but we are not in an error state.
                    return True

                self._path = path
                self._bitmap = c4d.bitmaps.BaseBitmap()
                if self._bitmap.InitWith(path)[0] != c4d.IMAGERESULT_OK:
                    return False  # Critical failure.

                self.Redraw()  # Redraw the user area to show the new bitmap.

                return True

        # Process other messages, doing this is very important, as we otherwise break the
        # message chain.
        return c4d.gui.GeUserArea.Message(self, msg, result)

    def InputEvent(self, msg: c4d.BaseContainer) -> bool:
        """Called by Cinema 4D when the user area receives input events.

        Here we implement creating drag events when the user drags from this user area. The type of
        drag event which is initiated is determined by the drag type selected in the combo box
        of the dialog.
        """
        # When this is not a left mouse button event on this user area, we just get out without
        # consuming the event (by returning False).
        if (msg.GetInt32(c4d.BFM_INPUT_DEVICE) != c4d.BFM_INPUT_MOUSE or
                msg.GetInt32(c4d.BFM_INPUT_CHANNEL) != c4d.BFM_INPUT_MOUSELEFT):
            return False

        # Get the type of drag event that should be generated, and handle it.
        dragType: int = self._host.GetInt32(self._host.ID_DRAG_TYPE)
        return self.HandleDragEvent(msg, dragType)
    
    # --- Custom drag handling methods -------------------------------------------------------------

    # I have split up thing into three methods for readability, this all could also be done directly
    # in the InputEvent method.

    def HandleDragEvent(self, event: c4d.BaseContainer, dragType: int) -> bool:
        """Handles starting a drag event by generating the drag data and sending it to the system.

        This is called when the user starts dragging from this user area.
        """
        # This requires us to modify the document, so we must be on the main thread (technically
        # not true when the type is DRAGTYPE_FILENAME_IMAGE, but that would be for you to optimize).
        if not c4d.threading.GeIsMainThread():
            raise False

        # Generate our drag data, either a file path, a material, or an asset.
        doc: c4d.documents.BaseDocument = c4d.documents.GetActiveDocument()
        data: object = self.GenerateDragData(doc, dragType)

        # Now we set off the drag event. When we are dragging assets, we have to sandwich the event
        # in these core message calls, as otherwise the palette edit mode toggling will not work
        # correctly.
        if dragType == maxon.DRAGTYPE_ASSET:
            bc: c4d.BaseContainer = c4d.BaseContainer(
                COREMSG_SETCOMMANDEDITMODE)
            bc.SetInt32(1, True)
            c4d.SendCoreMessage(c4d.COREMSG_CINEMA, bc, 0)

        # When #HandleMouseDrag returns #False, this means that the user has cancelled the drag
        # event, one case could be that the user actually did not intend to drag, but just
        # clicked on the user area.
        #
        # In this case we remove the drag data we generated, as it is not needed anymore. Note that
        # this will NOT catch the case that the drag event is cancelled by the recipient, e.g., the
        # user drags a material onto something that does not accept materials.
        if not self.HandleMouseDrag(event, dragType, data, 0):
            self.RemoveDragData(doc, data)
            return True

        # Other half of the sandwich, we toggle the palette edit mode back to normal.
        if dragType == maxon.DRAGTYPE_ASSET:
            bc: c4d.BaseContainer = c4d.BaseContainer(
                COREMSG_SETCOMMANDEDITMODE)
            bc.SetInt32(1, False)
            c4d.SendCoreMessage(c4d.COREMSG_CINEMA, bc, 0)

        return True

    def GenerateDragData(self, doc: c4d.documents.BaseDocument, dragType
                         ) -> str | c4d.BaseMaterial | maxon.DragAndDropDataAssetArray:
        """Generates the drag data for the given drag type.

        Each tile just encapsulates a file path, but we realize dragging them as file paths,
        materials, or assets. So, when the type is material or asset, the drag data must be
        generated from the file path. Which is why we have this method here.
        """
        if not c4d.threading.GeIsMainThread():
            raise RuntimeError(
                "GenerateDragData must be called from the main thread.")

        # The user has selected "File" as the drag type, we just return the file path.
        if dragType == c4d.DRAGTYPE_FILENAME_IMAGE:
            return self._path
        # The user has selected "Material" as the drag type, we create a Redshift material with the
        # texture as input and return that material.
        elif dragType == c4d.DRAGTYPE_ATOMARRAY:
            material: c4d.BaseMaterial = mxutils.CheckType(
                c4d.BaseMaterial(c4d.Mmaterial))

            # Create a simple graph using that texture, and insert the material into the
            # active document.
            maxon.GraphDescription.ApplyDescription(
                maxon.GraphDescription.GetGraph(
                    material, maxon.NodeSpaceIdentifiers.RedshiftMaterial),
                {
                    "$type": "Output",
                    "Surface": {
                        "$type": "Standard Material",
                        "Base/Color": {
                            "$type": "Texture",
                            # Set the texture. When our source is a file we will just have a plain
                            # path, e.g. "C:/path/to/file.png" and we have to prefix with a scheme
                            # (file) to make it a valid URL. When we are dealing with an asset, the
                            # texture path will already be a valid URL in the "asset:///" scheme.
                            "Image/Filename/Path": (maxon.Url(f"{self._path}")
                                                    if RE_URL_HAS_SCHEME.match(self._path) else
                                                    maxon.Url(f"file:///{self._path}"))
                        }
                    }
                })
            doc.InsertMaterial(material)
            return [material]
        # The user has selected "Asset" as the drag type, we create a texture asset and return that.
        elif dragType == maxon.DRAGTYPE_ASSET:
            # So we have to cases here, either that we want truly want to generate an asset drag
            # event or that we just want to piggy-back onto the texture asset drag and drop
            # mechanism of Cinema 4D, which is what we do here.

            # Code for truly generating an asset drag event, where we would store the asset in the
            # scene repository.
            generateAssets: bool = False
            if generateAssets:
                # Get the scene repository and create an asset storage structure for the asset.
                repo: maxon.AssetRepository = doc.GetSceneRepository(True)
                store: maxon.StoreAssetStruct = maxon.StoreAssetStruct(
                    maxon.Id(), repo, repo)

                # Now save the texture asset to the repository.
                url: maxon.Url = maxon.Url(self._path)
                name: str = url.GetName()
                asset, _ = maxon.AssetCreationInterface.SaveTextureAsset(
                    url, name, store, (), True)

                # Create a drag array for that asset. It is important that we use the URL of the
                # asset (maxon.AssetInterface.GetAssetUrl) and not #url or asset.GetUrl(), as both
                # are physical file paths, and will then cause the drag and drop handling to use
                # these physical files, including the popup asking for wether the file should be
                # copied. We will exploit exactly this behavior in the second case.
                dragArray: maxon.DragAndDropDataAssetArray = maxon.DragAndDropDataAssetArray()
                dragArray.SetLookupRepository(repo)
                dragArray.SetAssetDescriptions((
                    (asset, maxon.AssetInterface.GetAssetUrl(asset, True), maxon.String(name)),
                ))

                return dragArray
            # With this case we can piggy-back onto the existing drag and drop texture asset
            # handling of Cinema 4D, without actually having to create an asset. THIS IS A
            # WORKAROUND, we could decide at any moment to change how the drag and drop
            # handling of assets works, possibly rendering this approach obsolete.
            else:
                # The slight disadvantage of this approach (besides it being a hack and us possibly
                # removing it at some point) is that we have to pay the download cost of
                # #self._host._dummyAssetId once. I.e., the user has to download that texture once
                # either by using it in the Asset Browser or by running this code. Once the asset has
                # been cached, this will not happen again.
                #
                # But since we search below in a 'whoever comes first' manner, what is the first
                # texture asset could change, and this could then be an asset which has not been
                # downloaded yet. So, in a more robust world we would pick a fixed asset below. But
                # this comes then with the burden of maintenance, as we could remove one of the
                # builtin texture assets at any time. So, the super advanced solution would be to
                # ship the plugin with its own asset database, and mount and use that. Here we could
                # use a hard-coded asset ID, and would have to have never pay download costs, as
                # the repository would be local.

                # Find the asset by its Id, which we have stored in the dialog.
                repo: maxon.AssetRepositoryInterface = maxon.AssetInterface.GetUserPrefsRepository()
                dummy: maxon.AssetDescription = repo.FindLatestAsset(
                    maxon.AssetTypes.File().GetId(), self._host._dummyAssetId, maxon.Id(),
                    maxon.ASSET_FIND_MODE.LATEST)

                # Setup the drag array with the asset. Note that #asset must be a valid texture
                # asset, so just passing maxon.AssetDescription() will not work. But the backend
                # for drag and drop handling will actually ignore the asset except for type checking
                # it, and use the URL we provided instead.
                dragArray: maxon.DragAndDropDataAssetArray = maxon.DragAndDropDataAssetArray()
                dragArray.SetLookupRepository(repo)
                dragArray.SetAssetDescriptions((
                    (dummy, maxon.Url(self._path), maxon.String(os.path.basename(self._path))),
                ))
            return dragArray
        else:
            raise ValueError(f"Unsupported drag type: {dragType}")

    def RemoveDragData(self, doc: c4d.documents.BaseDocument,
                       data: str | list[c4d.BaseMaterial] | maxon.DragAndDropDataAssetArray) -> bool:
        """Removes generated content when the user cancels a drag event.

        Sometimes the user starts a drag event, but then cancels it, e.g., by pressing the
        escape key. In this case, we have to remove the generated content, e.g., the material or
        asset that we created for the drag event.
        """
        if not c4d.threading.GeIsMainThread():
            return False

        if isinstance(data, list):
            # Remove the dragged materials from the document. Since we are always generating a new
            # material, we can just remove them. That is in general probably not the best design,
            # and a real world application should avoid duplicating materials.
            for item in data:
                if isinstance(item, c4d.BaseList2D):
                    item.Remove()
        elif isinstance(data, str):
            # Here we could technically remove a file.
            pass
        elif isinstance(data, maxon.DragAndDropDataAssetArray):
            # We could remove the asset, but other than for the material, there is no guarantee
            # that we are the only user of it, as the Asset API has a duplicate preventing
            # mechanism. So, the #SaveTextureAsset call above could have returned an already
            # existing asset. Since we could operate with a document bound repository, we could
            # search the whole document for asset references and only when we find none, remove
            # the asset.
            #
            # We use here the little hack that we actually do not create an asset, to just to piggy-
            # back onto the material drag and drop mechanism of assets, so we can just ignore
            # this case.
            pass

        return True


class BitmapStackDialog(c4d.gui.GeDialog):
    """Implements a a simple dialog that stacks multiple BitmapCard controls.
    """
    ID_DRAG_TYPE: int = 1002

    def __init__(self):
        """Constructs a new ExampleDialog object.
        """
        # The user area controls that will generate and receive drag events.
        self._cards: list[BitmapCard] = [
            BitmapCard(host=self) for _ in range(4)]

        # The id for the dummy asset that used to generate 'fake' texture asset drag events. We
        # search for it here once, so that we do not have to do it in the __init__ of each
        # BitmapCard, or even worse, in the HandleDragEvent of each BitmapCard.

        # We could technically also store here the AssetDescription instead of the Id, but that
        # reference can go stale, so we just store the Id and then grab with it the asset when we
        # need it. Which is much faster than searching asset broadly as we do here. In the end, we
        # could probably also do all this in the drag handling of the BitmapCard, but a little bit
        # of optimization does not hurt.
        self._dummyAssetId: maxon.Id | None = None
        if not maxon.AssetDataBasesInterface.WaitForDatabaseLoading():
            raise RuntimeError("Could not initialize the asset databases.")

        def findTexture(asset: maxon.AssetDescription) -> bool:
            """Finds the first texture asset in the user preferences repository.
            """
            # When this is not a texture asset, we just continue searching.
            meta: maxon.AssetMetaData = asset.GetMetaData()
            if (meta.Get(maxon.ASSETMETADATA.SubType, maxon.Id()) !=
                    maxon.ASSETMETADATA.SubType_ENUM_MediaImage):
                return True

            # When it is a texture asset, we store it as the dummy asset and stop searching.
            self._dummyAssetId = asset.GetId()
            return False

        # Search for our dummy asset in the user preferences repository.
        repo: maxon.AssetRepositoryInterface = maxon.AssetInterface.GetUserPrefsRepository()
        repo.FindAssets(maxon.AssetTypes.File().GetId(), maxon.Id(), maxon.Id(),
                        maxon.ASSET_FIND_MODE.LATEST, findTexture)

    def CreateLayout(self):
        """Called by Cinema 4D to populate the dialog with controls.
        """
        self.SetTitle("Drag and Drop Example")
        self.GroupSpace(5, 5)
        self.GroupBorderSpace(5, 5, 5, 5)

        # Build the combo box in the menu bar of the dialog.
        self.GroupBeginInMenuLine()
        self.GroupBegin(1000, c4d.BFH_LEFT | c4d.BFV_TOP, cols=2)
        self.GroupBorderSpace(5, 5, 5, 5)
        self.GroupSpace(5, 5)
        self.AddStaticText(1001, c4d.BFH_LEFT |
                           c4d.BFV_CENTER, name="Drag Events as:")
        self.AddComboBox(1002, c4d.BFH_RIGHT | c4d.BFV_TOP)
        self.GroupEnd()
        self.GroupEnd()

        # Add the BitmapCard controls to the dialog.
        for i, card in enumerate(self._cards):
            self.AddUserArea(2000 + i, c4d.BFH_LEFT | c4d.BFV_TOP)
            self.AttachUserArea(card, 2000 + i)

        # Add items to the combo box to select the drag type.
        self.AddChild(self.ID_DRAG_TYPE, c4d.DRAGTYPE_FILENAME_IMAGE, "Files")
        self.AddChild(self.ID_DRAG_TYPE, c4d.DRAGTYPE_ATOMARRAY, "Materials")
        self.AddChild(self.ID_DRAG_TYPE, maxon.DRAGTYPE_ASSET, "Assets")
        self.SetInt32(self.ID_DRAG_TYPE, c4d.DRAGTYPE_FILENAME_IMAGE)

        return True


# Define a global variable of the dialog to keep it alive in a Script Manager script. ASYNC dialogs
# should not be opened in production code from a Script Manager script, as this results in a
# dangling dialog. Implement a command plugin when you need async dialogs in production.
dlg: BitmapStackDialog = BitmapStackDialog()
if __name__ == "__main__":
    dlg.Open(dlgtype=c4d.DLG_TYPE_ASYNC, defaultw=150, defaulth=250)

Hi,

thanks for the kind words both from Maxon and the community. I am looking forward to my upcoming adventures with the SDK Team and Cinema community.

Cheers,
Ferdinand

Hello @holgerbiebrach,

please excuse the wait. So, this is possible in Python and quite easy to do. This new behavior is just the old dialog folding which has been reworked a little bit. I have provided a simple example at the end of the posting. There is one problem regarding title bars which is sort of an obstacle for plugin developers which want to distribute their plugins, it is explained in the example below.

I hope this helps and cheers,
Ferdinand

The result:

The code:

"""Example for a command plugin with a foldable dialog as provided with the
Asset Browser or Coordinate Manger in Cinema 4D R25.

The core of this is just the old GeDialog folding mechanic which has been
changed slightly with R25 as it will now also hide the title bar of a folded
dialog, i.e., the dialog will be hidden completely.

The structure shown here mimics relatively closely what the Coordinate Manger
does. There is however one caveat: Even our internal implementations do not
hide the title bar of a dialog when unfolded. Instead, this is done via 
layouts, i.e., by clicking onto the ≡ icon of the dialog and unchecking the
"Show Window Title" option and then saving such layout. If you would want
to provide a plugin which exactly mimics one of the folding managers, you
would have to either ask your users to take these steps or provide a layout.

Which is not ideal, but I currently do not see a sane way to hide the title
bar of a dialog. What you could do, is open the dialog as an async popup which 
would hide the title bar. But that would also remove the ability to dock the 
dialog. You could then invoke `GeDialog.AddGadegt(c4d.DIALOG_PIN, SOME_ID)`to 
manually add a pin back to your dialog, so that you can dock it. But that is 
not how it is done internally by us, as we simply rely on layouts for that.
"""

import c4d


class ExampleDialog (c4d.gui.GeDialog):
    """Example dialog that does nothing.

    The dialog itself has nothing to do with the implementation of the
    folding.
    """
    ID_GADGETS_START = 1000
    ID_GADGET_GROUP = 0
    ID_GADGET_LABEL = 1
    ID_GADGET_TEXT = 2

    GADGET_STRIDE = 10
    GADEGT_COUNT = 5

    def CreateLayout(self) -> bool:
        """Creates dummy gadgets.
        """
        self.SetTitle("ExampleDialog")
        flags = c4d.BFH_SCALEFIT

        for i in range(self.GADEGT_COUNT):
            gid = self.ID_GADGETS_START + i * self.GADGET_STRIDE
            name = f"Item {i}"

            self.GroupBegin(gid + self.ID_GADGET_GROUP, flags, cols=2)
            self.GroupBorderSpace(5, 5, 5, 5)
            self.GroupSpace(2, 2)
            self.AddStaticText(gid + self.ID_GADGET_LABEL, flags, name=name)
            self.AddEditText(gid + self.ID_GADGET_TEXT, flags)
            self.GroupEnd()
        return True


class FoldingManagerCommand (c4d.plugins.CommandData):
    """Provides the implementation for a command with a foldable dialog.
    """
    ID_PLUGIN = 1058525
    REF_DIALOG = None

    @property
    def Dialog(self) -> ExampleDialog:
        """Returns a class bound ExampleDialog instance.
        """
        if FoldingManagerCommand.REF_DIALOG is None:
            FoldingManagerCommand.REF_DIALOG = ExampleDialog()

        return FoldingManagerCommand.REF_DIALOG

    def Execute(self, doc: c4d.documents.BaseDocument) -> bool:
        """Folds or unfolds the dialog.

        The core of the folding logic as employed by the Asset Browser
        or the Coordinate manager in R25.
        """
        # Get the class bound dialog reference.
        dlg = self.Dialog
        # Fold the dialog, i.e., hide it if it is open and unfolded. In C++
        # you would also want to test for the dialog being visible with
        # GeDialog::IsVisible, but we cannot do that in Python.
        if dlg.IsOpen() and not dlg.GetFolding():
            dlg.SetFolding(True)
        # Open or unfold the dialog. The trick here is that calling
        # GeDialog::Open will also unfold the dialog.
        else:
            dlg.Open(c4d.DLG_TYPE_ASYNC, FoldingManagerCommand.ID_PLUGIN)

        return True

    def RestoreLayout(self, secret: any) -> bool:
        """Restores the dialog on layout changes.
        """
        return self.Dialog.Restore(FoldingManagerCommand.ID_PLUGIN, secret)

    def GetState(self, doc: c4d.documents.BaseDocument) -> int:
        """Sets the command icon state of the plugin.

        This is not required, but makes it a bit nicer, as it will indicate
        in the command icon when the dialog is folded and when not.
        """
        dlg = self.Dialog
        result = c4d.CMD_ENABLED
        if dlg.IsOpen() and not dlg.GetFolding():
            result |= c4d.CMD_VALUE

        return result


def RegisterFoldingManagerCommand() -> bool:
    """Registers the example.
    """
    return c4d.plugins.RegisterCommandPlugin(
        id=FoldingManagerCommand.ID_PLUGIN,
        str="FoldingManagerCommand",
        info=c4d.PLUGINFLAG_SMALLNODE,
        icon=None,
        help="FoldingManagerCommand",
        dat=FoldingManagerCommand())


if __name__ == '__main__':
    if not RegisterFoldingManagerCommand():
        raise RuntimeError(
            f"Failed to register {FoldingManagerCommand} plugin.")

Dear Community,

this question reached us via email-support in the context of C++, but I thought the answer might be interesting for other users too.

The underlying question in this case was how to project points from object or world space into the texture space of an object with UV data. I am showing here deliberately an approach that can be followed both in C++ and Python, so that all users can benefit from this. In C++ one has also the option of using VolumeData and its methods VolumeData::GetUvw or VolumeData::ProjectPoint but must then either implement a volume shader (as otherwise the volume data attached to the ChannelData passed to ShaderData::Output will be nullptr), or use VolumeData:: AttachVolumeDataFake to access ::ProjectPoint. There is however no inherent necessity to take this shader bound route as shown by the example.

Cheers,
Ferdinand

Result

The script has created a texture with red pixels for the intersection points of the rays cast from each vertex of the spline towards the origin of the polygon object. The script also created the null object rays to visualize the rays which have been cast.

raycast_texture.c4d : The scene file.

Code

You must save the script to disk before running it, as the script infers from the script location the place to save the generated texture to.

"""Demonstrates how to project points from world or object space to UV space.

This script assumes that the user has selected a polygon object and a spline object in the order
mentioned. The script projects the points of the spline object onto the polygon object and creates
a texture from the UV coordinates of the projected points. The texture is then applied to the
polygon object.

The script uses the `GeRayCollider` class to find the intersection of rays cast from the points of
the spline object to the polygon object. The UV coordinates of the intersection points are then
calculated using the `HairLibrary` class. In the C++ API, one should use maxon::
GeometryUtilsInterface::CalculatePolygonPointST() instead.

Finally, using GeRayCollider is only an example for projecting points onto the mesh. In practice,
any other method can be used as long as it provides points that lie in the plane(s) of a polygon.

The meat of the example is in the `main()` function. The other functions are just fluff.
"""

import os
import c4d
import mxutils
import uuid

from mxutils import CheckType

doc: c4d.documents.BaseDocument  # The currently active document.
op: c4d.BaseObject | None  # The primary selected object in `doc`. Can be `None`.

def CreateTexture(points: list[c4d.Vector], path: str, resolution: int = 1000) -> None:
    """Creates a texture from the given `points` and saves it to the given `path`.

    Parameters:
        path (str): The path to save the texture to.
        points (list[c4d.Vector]): The points to create the texture from.
    """
    # Check the input values for validity.
    if os.path.exists(path):
        raise FileExistsError(f"File already exists at path: {path}")
    if not path.endswith(".png"):
        raise ValueError("The path must end with '.png'.")

    # Create a drawing canvas to draw the points on.
    canvas: c4d.bitmaps.GeClipMap = CheckType(c4d.bitmaps.GeClipMap())
    if not canvas.Init(resolution, resolution, 24):
        raise MemoryError("Failed to initialize GeClipMap.")

    # Fill the canvas with white.
    canvas.BeginDraw()
    canvas.SetColor(255, 255, 255)
    canvas.FillRect(0, 0, resolution, resolution)

    # Draw the points on the canvas.
    canvas.SetColor(255, 0, 0)
    for p in points:
        x: int = int(p.x * resolution)
        y: int = int(p.y * resolution)
        x0: int = max(0, x - 1)
        y0: int = max(0, y - 1)
        x1: int = min(resolution, x + 1)
        y1: int = min(resolution, y + 1)
        canvas.FillRect(x0, y0, x1, y1)

    canvas.EndDraw()

    # Save the canvas to the given path.
    bitmap: c4d.bitmaps.BaseBitmap = CheckType(canvas.GetBitmap())
    bitmap.Save(path, c4d.FILTER_PNG)

    c4d.bitmaps.ShowBitmap(bitmap)

def ApplyTexture(obj: c4d.BaseObject, path: str) -> None:
    """Applies the texture at the given `path` to the given `obj`.
    """
    CheckType(obj, c4d.BaseObject)

    # Check the input values for validity.
    if not os.path.exists(path):
        raise FileNotFoundError(f"File does not exist at path: {path}")

    # Create a material and apply the texture to it.
    material: c4d.BaseMaterial = CheckType(c4d.BaseMaterial(c4d.Mmaterial), c4d.BaseMaterial)
    obj.GetDocument().InsertMaterial(material)

    shader: c4d.BaseShader = CheckType(c4d.BaseShader(c4d.Xbitmap), c4d.BaseShader)
    shader[c4d.BITMAPSHADER_FILENAME] = path
    material.InsertShader(shader)
    material[c4d.MATERIAL_COLOR_SHADER] = shader
    material[c4d.MATERIAL_PREVIEWSIZE] = c4d.MATERIAL_PREVIEWSIZE_1024

    # Apply the material to the object.
    tag: c4d.TextureTag = CheckType(obj.MakeTag(c4d.Ttexture))
    tag[c4d.TEXTURETAG_PROJECTION] = c4d.TEXTURETAG_PROJECTION_UVW
    tag[c4d.TEXTURETAG_MATERIAL] = material

def CreateDebugRays(spline: c4d.SplineObject, p: c4d.Vector) -> None:
    """Adds spline objects to the document to visualize the rays from the given `p` to the points of
    the given `spline`.
    """
    doc: c4d.documents.BaseDocument = CheckType(spline.GetDocument(), c4d.documents.BaseDocument)
    rays: c4d.BaseObject = c4d.BaseObject(c4d.Onull)
    rays.SetName("Rays")
    doc.InsertObject(rays)

    for q in spline.GetAllPoints():
        ray: c4d.SplineObject = c4d.SplineObject(2, c4d.SPLINETYPE_LINEAR)
        ray.SetPoint(0, p)
        ray.SetPoint(1, q * spline.GetMg())
        ray.Message(c4d.MSG_UPDATE)
        ray.InsertUnder(rays)

def main() -> None:
    """Carries out the main logic of the script.
    """
    # Check the object selection for being meaningful input.
    selected: list[c4d.BaseObject] = doc.GetActiveObjects(c4d.GETACTIVEOBJECTFLAGS_SELECTIONORDER)
    if (len(selected) != 2 or not selected[0].CheckType(c4d.Opolygon) or
        not selected[1].CheckType(c4d.Ospline)):
        raise ValueError("Please select a polygon object and a spline object.")

    polygonObject, splineObject = selected

    # Get the uvw tag, the points, and the polygons of the polygon object.
    uvwTag: c4d.UvwTag = mxutils.CheckType(polygonObject.GetTag(c4d.Tuvw))
    points: list[c4d.Vector] = [polygonObject.GetMg() * p for p in polygonObject.GetAllPoints()]
    polys: list[c4d.CPolygon] = polygonObject.GetAllPolygons()

    # We are casting here in a dumb manner towards the center of the polygon object. In practice,
    # one should cast rays towards the plane of the polygon object. Or even better, use another
    # method to project the points onto the polygon object, as GeRayCollider is not the most 
    # efficient thing in the world.
    rayTarget: c4d.Vector = polygonObject.GetMg().off
    CreateDebugRays(splineObject, rayTarget)

    # Initialize the GeRayCollider to find the intersection of rays cast from the points of the
    # spline object to the polygon object.
    collider: c4d.utils.GeRayCollider = c4d.utils.GeRayCollider()
    if not collider.Init(polygonObject):
        raise MemoryError("Failed to initialize GeRayCollider.")


    # Init our output list and iterate over the points of the spline object.
    uvPoints: list[c4d.Vector] = []
    for p in splineObject.GetAllPoints():

        # Transform the point from object to world space (q) and then to the polygon object's space
        # (ro). Our ray direction always points towards the center of the polygon object.
        q: c4d.Vector = splineObject.GetMg() * p
        ro: c4d.Vector = ~polygonObject.GetMg() * q
        rd: c4d.Vector = rayTarget - ro

        # Cast the ray and check if it intersects with the polygon object.
        if not collider.Intersect(ro, rd, 1E6) or collider.GetIntersectionCount() < 1:
            continue
        
        # Get the hit position and the polygon ID of the intersection.
        hit: dict = collider.GetNearestIntersection()
        pos: c4d.Vector = mxutils.CheckType(hit.get("hitpos", None), c4d.Vector)
        pid: int = mxutils.CheckType(hit.get("face_id", None), int)

        # One mistake would be now to use the barycentric coordinates that are in the intersection
        # data, as Cinema uses an optimized algorithm to interpolate in a quad and not the standard
        # cartesian-barycentric conversion. In Python these polygon weights are only exposed in a 
        # bit weird place, the hair library. In C++ these barycentric coordinates make sense because
        # there exist methods to convert them to weights. In Python the barycentric coordinates are
        # pretty much useless as we do not have such a conversion function here.

        # Compute the weights s, t for the intersection point in the polygon.
        s, t = c4d.modules.hair.HairLibrary().GetPolyPointST(
            pos, points[polys[pid].a], points[polys[pid].b],
                 points[polys[pid].c], points[polys[pid].d], True)

        # Get the uv polygon and bilinearly interpolate the coordinates using the weights. It would
        # be better to use the more low-level variable tag data access functions in VariableTag 
        # than UvwTag.GetSlow() in a real-world scenario.
        uvw: list[c4d.Vector] = list(uvwTag.GetSlow(pid).values())
        t0: c4d.Vector = c4d.utils.MixVec(uvw[0], uvw[1], s)
        t1: c4d.Vector = c4d.utils.MixVec(uvw[3], uvw[2], s)
        uv: c4d.Vector = c4d.utils.MixVec(t0, t1, t)

        # Append the UV coordinates to the output list.
        uvPoints.append(uv)

    # Write the UV coordinates to a texture and apply it to the polygon object.
    path: str = os.path.join(os.path.dirname(__file__), f"image-{uuid.uuid4()}.png")
    CreateTexture(uvPoints, path, resolution=1024)
    ApplyTexture(polygonObject, path)

    c4d.EventAdd()


if __name__ == '__main__':
    main()

Hi,

that your script is not working has not anything to do with pseudo decimals, but the fact that you are treating numbers as strings (which is generally a bad idea) in a not very careful manner. When you truncate the string representation of a number which is represented in scientific notation (with an exponent), then you also truncate that exponent and therefor change the value of the number.

To truncate a float you can either take the floor of my_float * 10 ** digits and then divide by 10 ** digits again or use the keyword round.

data = [0.03659665587738824,
        0.00018878623163019122,
        1.1076812650509394e-03,
        1.3882258325566638e-06]

for n in data:
    rounded = round(n, 4)
    floored = int(n * 10000) / 10000
    print(n, rounded, floored)

0.03659665587738824 0.0366 0.0365
0.00018878623163019122 0.0002 0.0001
0.0011076812650509394 0.0011 0.0011
1.3882258325566637e-06 0.0 0.0
[Finished in 0.1s]

Cheers
zipit

Dear community,

We will have to touch multiple parts of developers.maxon.net on the 18.01.2024 and 19.01.2024 22.01.2024. This will result in outages of our documentation and the forum these days. I will try to keep the outage times to a minimum and it will certainly not span the whole two days. But especially one task I will do on Friday might take hours to complete and I can only do that on a forum which is in maintenance mode.

Please make sure to download a recent offline documentation in case you plan to do extended development work the next two days. As a result, forum support might also be delayed on these days.

Cheers,
Ferdinand

Hi,

sorry for all the confusion. You have to pass actual instances of objects. The following code does what you want (and this time I actually tried it myself ;)).

import c4d

def main():
    """
    """
    bc = doc.GetAllTextures(ar=doc.GetMaterials())
    for cid, value in bc:
        print cid, value

if __name__=='__main__':
   main()

Cheers,
zipit

Hi,

technically this is possible via c4d.utils.SendModellingCommand(). However, the related specific command ID (c4d.ID_MODELING_OUTLINE_SELECTION_TOOL) is marked as private. So there is no documentation on how to use this properly.

But it is not to hard to figure out the edges that are border edges. The example below will find all outlines, mimicing c4ds functionality of letting you select a specific loop is just a matter of additional filtering I left out to keep things short.

import c4d
# Welcome to the world of Python


def set_outline_seleection(op):
    """ Sets the outline edge selection for op.

    Args:
        op (c4d.PolygonObject): The object to perform an outline selection on.
    """
    # Return if op is not a polygon object.
    if not isinstance(op, c4d.PolygonObject):
        return

    # This is Cinema's version of an edge neighbor data structure
    nbr = c4d.utils.Neighbor()
    nbr.Init(op)

    # Get the edge selection for our object.
    selection = op.GetEdgeS()
    selection.DeselectAll()

    # Loop over all polygons in our object.
    for pid, cpoly in enumerate(op.GetAllPolygons()):
        # All edge point pair indices of our polygon as a list of tuples with
        # their local edge index.
        edge_point_pairs = [(0, cpoly.a, cpoly.b), (1, cpoly.b, cpoly.c),
                            (2, cpoly.c, cpoly.d), (3, cpoly.d, cpoly.a)]
        # Loop over all edge point pairs in a polygon:
        for eid, a, b in edge_point_pairs:
            # Skip over "empty" triangle edges - c4d presents triangles as four
            # point polygons
            if a == b:
                continue
            # Test if the current polygon ID is the only ID associated with
            # with the current edge, i. e. if the edge is an outline edge.
            if nbr.GetNeighbor(a, b, pid) == c4d.NOTOK:
                # Global edge indices in Cinema are indexed as polygon
                # ID * 4 + edge index in the polygon.

                # Select the edge in our BaseSelect
                selection.Select(pid * 4 + eid)
    # Update Cinema
    c4d.EventAdd()


# Main function
def main():
    """
    """
    set_outline_seleection(op)


# Execute main()
if __name__ == '__main__':
    main()

Cheers
zipit

Dear development community,

On September the 10th, 2024, Maxon Computer released Cinema 4D 2025.0.0. For an overview of the new features of Cinema 4D 2025.0, please refer to the release announcement. Alongside this release, a new Cinema 4D SDK and SDK documentation have been released, reflecting the API changes for 2025.0.0. The major changes are:

C++ API

• What was formerly has been know as the Classic API has been deprecated in favour of the Cinema API. Alongside this a new cinema namespace has been introduced which contains all the entities which were formerly in the anonymous global namespace known as the Classic API. Plugin authors must adopt their code to this new API, although the changes are not nearly as extensive as for 2024. See the 2025 migration guide for details. Code examples and documentation have been updated to now refer to a Cinema API.
• 2025 uses OCIO as the default color management mode, brings an improved color picker, and made general improvements to the consistency of the OCIO implementation. This had some effects on the underlying OCIO API which are reflected in two new code examples in the OCIO Manual and a new plugin in the SDK.

Python API

• Python also received the update from Classic to Cinema API. But here the change was more of a cosmetic nature confined to the documentation. The c4d package remains the home for all formerly Classic and now Cinema API entities.
• The mxutils package received updates around standardized scene traversal, random number generation, and more.
• Graph descriptions now support variadic ports of arbitrary complexity and explicit port references.

Head to our download section for the newest SDK downloads, or the C++ and Python API change notes for an in detail overview of the changes.

We discovered late in the cycle bugs in the Asset API code examples and OCIO code in the Python SDK. Which is why the publication of the Python SDK and GitHub code examples has been postponed until these bugs are fixed. They should be ready latest by Friday the 13th of September. But the Python online documentation is accessible and error free (to our knowledge).

We had to make some last minute changes to the C++ SDK regarding OCIO code examples. Only the extended C++ SDK contains these changes. The application provided sdk.zip will catch up with the next release of Cinema 4D.

Happy rendering and coding,
the Maxon SDK Team

Cloudflare unfortunately still does interfere with our server cache. And you might have to refresh your cache manually.

When you are not automatically redirected to the new versions, and also do not see 2024.5 in the version selector, please press CTRL + F5 or press CTRL and click on the reload icon of your browser anywhere on developers.maxon.net/docs/ to refresh your cache. You only have to do this once and it will apply to all documentations at once. Otherwise your cache will automatically update latest by 19/07/2024 00:00.

Hi,

you use GetActiveDocument() in a NodeData environment. You cannot do this, since nodes are also executed when their document is not the active document (while rendering for example - documents get cloned for rendering).

Cheers
zipit

Hey @spedler,

I did give this a shot. I cannot reproduce this after even quite a few attempts, but one of my colleagues (Fritz) could. There is probably some undo code missing in the color chip dialog. I assume that was what you did, Steve, right? You set the color via the popup color chip dialog and not with the inline control? Fritz could reproduce this without your plugin. So, my hunch was right, your plugin is not the culprit.

Since I cannot fix what I cannot reproduce on my machine, I have created a bug ticket for this and sent it off to the owners of the COLOR control. The ticket is ITEM#652737 Parameters of type COLOR do not always correctly invoke UNDOs in descriptions.

Out of curiosity: Can you also reproduce this on your machine with a a builtin object, e.g., the Cube object? Fritz and I were both on macOS while testing. But this being OS-specific seems a bit unlikely.

Cheers,
Ferdinand

I have moved this topic into "bugs".

edit: As always with these things now I can reproduce it too

Hey @ThomasB,

so I did a clean writing of your plugin demo code in preparation to debug the output and I cannot reproduce the issue you report. For me the light works. There were some issues with your code, but none of them should cause the light to malfunction as your reported on LoadDocument. What you did there with self.container was a bit dicey and could have caused the issue but it seems somewhat unlikely.

I am today on my Mac, it seems quite unlikely that this is an OS related issue.

The object after pressing the button in your plugin:

And the object after collapsing it:

Cheers,
Ferdinand

from c4d import plugins, bitmaps, BaseObject, GeListNode

import c4d
import mxutils
import os


PLUGIN_ID: int = 1000200
PY_ADD_LIGHTS: int = 10000


class RedshiftLightsTest(plugins.ObjectData):
    """
    """
    HOUSE_PATH: str = os.path.join(os.path.dirname(__file__), "res", "models", "build_1.c4d")

    def __init__(self) -> None:
        """
        """
        self.SetOptimizeCache(True)
        self._asset_doc: c4d.documents.BaseDocument | None = None

        # No, never store a reference to what you return as your cache in GVO!
        # self.container = None

    def Init(self, op, isCloneInit: bool = False) -> bool:
        """
        """
        if not os.path.exists(self.HOUSE_PATH):
            raise FileNotFoundError(f"House model not found at {self.HOUSE_PATH}")
        
        # For cloning it would be better to copy over the document to avoid reloading it, but since
        # we do not implement NodeData.CopyTo() we will just reload it for now.
        self._asset_doc = mxutils.CheckType(
            c4d.documents.LoadDocument(self.HOUSE_PATH, c4d.SCENEFILTER_OBJECTS | c4d.SCENEFILTER_MATERIALS))

        return True
    
    def GetAssetPayload(self) -> c4d.BaseObject | None:
        """Returns a copy of the asset payload for the plugin.
        """
        if not isinstance(self._asset_doc, c4d.documents.BaseDocument):
            raise RuntimeError("Asset not loaded correctly.") # Should not happen, but just in case.
        
        root: c4d.BaseObject = self._asset_doc.GetFirstObject()
        if not root:
            raise RuntimeError("Asset document has no root object.")
        
        payload: c4d.BaseObject = root.GetDown()
        if not payload:
            raise RuntimeError("Asset document has no payload object.")
        
        return payload.GetClone()
    

    def GetVirtualObjects(self, op: BaseObject, hh: object) -> BaseObject | None:
        """
        """
        # Return the cached object if it is not dirty, otherwise rebuild it.
        dirty: bool = op.CheckCache(hh) or op.IsDirty(c4d.DIRTYFLAGS_DATA | c4d.DIRTYFLAGS_ALL)
        if not dirty:
            return op.GetCache(hh)
        
        # Returning None in an ObjectData.GetVirtualObjects() call will tell Cinema that a memory error
        # occurred, and with that cause Cinema to stop calling/building the object. This is almost never
        # what we want, return a Null object instead.
        null: c4d.BaseObject | None = c4d.BaseObject(c4d.Onull)
        if not null:
            return c4d.BaseObject(c4d.Onull)
        
        payload: c4d.BaseObject | None = self.GetAssetPayload()
        if payload:
            payload.InsertUnder(null)

        return null

    def Message(self, node: GeListNode, type: int, data: object) -> bool:
        """
        """
        if type == c4d.MSG_DESCRIPTION_COMMAND:
            if data["id"][0].id == PY_ADD_LIGHTS:
                self.ImportLights(node)
                return True

        return True
    
    def ImportLights(self, node: GeListNode) -> bool:
        """
        """
        if not isinstance(node, c4d.BaseObject) or not c4d.threading.GeIsMainThreadAndNoDrawThread():
            return False
        
        # This is a bit tedious but each of these calls can fail, and you cannot, or better, should
        # not just do chain calls such as GetDown().GetDown().GetNext().GetNext(). One could abstract
        # this away with a function such as Traverse(node, "DDNN") where D = Down, N = Next, but for 
        # this example I just did it manually.
        doc: c4d.documents.BaseDocument = node.GetDocument()
        if not doc:
            return False
        
        payload: c4d.BaseObject | None = self.GetAssetPayload()
        if not payload:
            return False
        
        down: c4d.BaseObject | None = payload.GetDown()
        if not down:
            return False
        
        item: c4d.BaseObject | None = down.GetNext()
        if not item:
            return False
        
        light: c4d.BaseObject | None = item.GetNext()
        if not light:
            return False
        
        clone: c4d.BaseObject | None = light.GetClone()
        if not clone:
            return False

        doc.InsertObject(clone)
        c4d.EventAdd()
        return True

if __name__ == "__main__":
    path, file = os.path.split(__file__)
    file = "icon.tif"
    new_path = os.path.join(path, "res", file)
    bitmap = bitmaps.BaseBitmap()
    bitmap.InitWith(new_path)
    plugins.RegisterObjectPlugin(id=PLUGIN_ID, str="redshift_lights_test", g=RedshiftLightsTest, description="redshift_lights_test", icon=bitmap,
                                 info=c4d.OBJECT_GENERATOR)

Hey @Anlv,

thank you for the confirmation and for the precise debug report.

Cheers,
Ferdinand

Hey, could you please try again

POST https://developers.maxon.net/forum/api/post/upload 403 (Forbidden)

That is the culprit. That is the data upload endpoint and something is not letting you even talk with it. Could be NodeBB misbehaving or some shenanigans by Cloudflare. I will see if I can find out more.

edit: now I see it too, this is some cloudflare misfire

Thanks for the info @Anlv

Hey Steve,

The toast messages of NodeBB are often not very helpful. What I meant was the JS console.

I do not even see the failed upload attempts in my server logs; which in combination with "Error. Something went wrong while parsing server response" sounds a bit like a severed session? I.e., the client is sending and server does not even consider looking at the data, resulting in a timeout?

E.g. this. Here it fails because I am using an unsupported filetype.

Just right click on the page, select inspect and then go to the console tab (which is usually the selected default). All modern browsers have this.

Cheers,
Ferdinand

PS: Please also expand the call stack like so:

Hey Steve,

Something with the forum uploads is buggy. For some people it works and for some it does not, it is rather mysterious. Could you share the console output of when the upload fails? I neither see something in the server logs nor can I reproduce this from my work machines or private machines. We will replace the forum soon, so I will not put too much work into this, but maybe there is a quick fix.

Regarding your issue: That sounds indeed like a bug, I will have a look. At first glance I do neither see anything in your code that stands out, such as dangerous NodeData::SetParameter code, nor are there issues like giving multiple elements the same ID in odiamond.h. We did touch the color picker a while ago (2025.X), so I would not rule out that we added some kind of bug.

Cheers,
Ferdinand

Hey,

sorry for the delay, I did read your reply. When I set the parameter in your scene the issue disappears. I did not check the LoadDocument/MergeDocument aspect yet. But I am 99.99% sure that there is no bug in Orslight in the conventional sense, it is just that the Orslight::GetVirtualObjects method is a bit of a fever dream.

The issue is Orslight::GetVirtualObjects returns a null object in some cases and a null with a light attached in other cases. LoadDocument/MergeDocument having a significant enough impact on the scene graph that causes Orslight::GetVirtualObjects to change its cache building behaviour from "null + light" to "null" sounds a bit unlikely but is not impossible (that would mean the scene importer is buggy).

I will try to have another look tomorrow or next week. When you want to help yourself, you could just do what I did: Diff the light from the loaded scene with a light your have already in the document which you know that works.

Cheers,
Ferdinand

Hello @leah.hayes,

Welcome to the Maxon developers forum and its community, it is great to have you with us!

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About your First Question

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Where is the Python code of the built-in character templates ...

They are stored in {c4d installation folder}/library.zip/characters.

Is there a supported way to extract or view a built-in template (for example through c4d.modules.character.builder.Template) so I can study how the auto-adjustment is implemented?

I am not quite sure that I follow. All these rigs are just our standard CA component system decorated with some Xpresso and Python. Since there can be literally hundreds of nodes in a rig, I attached below a little helper script to scan for specific Python content or just the scripts in general that are embedded somewhere in the rig.

Is there a public API entry point to trigger or implement this kind of auto-adjustment for other templates?

That auto adjustment seems to be some kind of Python script which the authors of this rig provided. These CA rigs have been created by (technical) artists and not the members of the Maxon development team. See the print out below for details on the artist code for "auto-adjustment".

Cheers,
Ferdinand

Result

====================================================================================================
Node: Character Component (Character Component) | Attribute: (2158, 130, 1022113)

Value:

import c4d
from c4d import gui
import c4d.modules.character as ca
import c4d.utils as utils
#Welcome to the world of Python

def Bl2DIterator(bl2D):
    while bl2D:
        yield bl2D
        for bl2DChild in Bl2DIterator(bl2D.GetDown()):
            yield bl2DChild
        bl2D = bl2D.GetNext()

def SearchInHierarchy(obj, name):
    allChildrenWithName = [bl2D for bl2D in Bl2DIterator(obj.GetDown()) if bl2D.GetName() == name]
    return allChildrenWithName[0]

def ShowLayer(layersList, showName):
    for layer in layersList:
        layerName = layer[c4d.ID_BASELIST_NAME]
        if showName in layerName:
            layer[c4d.ID_LAYER_VIEW] = True
            layer[c4d.ID_LAYER_MANAGER] = True

def HideLayer(layersList, hideName):
    for layer in layersList:
        layerName = layer[c4d.ID_BASELIST_NAME]
        if hideName in layerName:
            layer[c4d.ID_LAYER_VIEW] = False
            layer[c4d.ID_LAYER_MANAGER] = False

def CharacterAnimateMode(characterObject):
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_HIGHLIGHT_OVER] = 4
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_MOUSEOVER] = 0
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_VISIBLE] = 2
    characterObject[c4d.ID_CA_CHARACTER_OM_DISPLAY] = 5
    characterObject[c4d.ID_CA_CHARACTER_LOCK_AM] = False

def CharacterEditMode(characterObject):
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_HIGHLIGHT_OVER] = 3
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_MOUSEOVER] = 4
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_VISIBLE] = 3
    characterObject[c4d.ID_CA_CHARACTER_OM_DISPLAY] = 1
    characterObject[c4d.ID_CA_CHARACTER_LOCK_AM] = True

def CharacterBindMode(characterObject):
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_HIGHLIGHT_OVER] = 4
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_MOUSEOVER] = 4
    characterObject[c4d.ID_CA_CHARACTER_COMPONENT_VISIBLE] = 1
    characterObject[c4d.ID_CA_CHARACTER_OM_DISPLAY] = 5
    characterObject[c4d.ID_CA_CHARACTER_LOCK_AM] = True

def CatchEmAll(obj, stop, listy):
    if obj is None: return

    #Actions go here
    if obj.GetType()==1019362:
        listy.append(obj)
    if not stop:
        if obj.GetDown():
            CatchEmAll(obj.GetDown(), stop, listy)
        if obj.GetNext():
            CatchEmAll(obj.GetNext(), stop, listy)

    return listy

def SetGlobalRotation(obj, rot):
    """
    Please remember, Cinema 4D handles rotation in radians.

    Example for H=10, P=20, B=30:

    import c4d
    from c4d import utils
    #...
    hpb = c4d.Vector(utils.Rad(10), utils.Rad(20), utils.Rad(30))
    SetGlobalRotation(obj, hpb) #object's rotation is 10, 20, 30
    """
    m = obj.GetMg()
    pos = m.off
    scale = c4d.Vector( m.v1.GetLength(),
                        m.v2.GetLength(),
                        m.v3.GetLength())

    m = utils.HPBToMatrix(rot)

    m.off = pos
    m.v1 = m.v1.GetNormalized() * scale.x
    m.v2 = m.v2.GetNormalized() * scale.y
    m.v3 = m.v3.GetNormalized() * scale.z

    obj.SetMg(m)

def SetGlobalScale(obj, scale):
    m = obj.GetMg()

    m.v1 = m.v1.GetNormalized() * scale.x
    m.v2 = m.v2.GetNormalized() * scale.y
    m.v3 = m.v3.GetNormalized() * scale.z

    obj.SetMg(m)

def ModeChanged():
    characterObject = charop.GetObject()
    #Turning Off the Annotation
    # Main function

    leftAnnotationTag = SearchInHierarchy(characterObject, "LeftLeg_bind").GetLastTag()
    print(leftAnnotationTag)
    if leftAnnotationTag.GetType() == c4d.Tannotation:
        leftAnnotationTag[c4d.ANNOTATIONTAG_VIEWPORT_SHOW] = False

    #Hiding the Rig's Layers
    root = doc.GetLayerObjectRoot() #Gets the layer manager
    layersList = root.GetChildren() #Get Layer list
    for layer in layersList:
        layerName = layer[c4d.ID_BASELIST_NAME]
        if "Mixamo_Rig" in layerName:
            layer[c4d.ID_LAYER_VIEW] = False
            layer[c4d.ID_LAYER_MANAGER] = False
            mixamoLayers = layer.GetChildren()
            for layer in mixamoLayers:
                layerName = layer[c4d.ID_BASELIST_NAME]
                if "Retarget_Hierarchy" in layerName or \
                "ANIMDATA_Nulls" in layerName or \
                "Control Hierarchy" in layerName:
                    layer[c4d.ID_LAYER_VIEW] = False
                    layer[c4d.ID_LAYER_MANAGER] = False

    masterControl = SearchInHierarchy(characterObject, "Master_con+")
    hips = SearchInHierarchy(characterObject, "Hips")
    if nmode==c4d.ID_CA_CHARACTER_MODE_BUILD or \
    nmode==c4d.ID_CA_CHARACTER_MODE_ADJUST:
        CharacterEditMode(characterObject)

    if nmode==c4d.ID_CA_CHARACTER_MODE_BIND:
        CharacterBindMode(characterObject)

    if nmode==c4d.ID_CA_CHARACTER_MODE_ADJUST and omode==c4d.ID_CA_CHARACTER_MODE_BUILD:
        #Changed search method to only search in Character Object
        #hips=doc.SearchObject("Hips")
        #masterControl=doc.SearchObject("Master_con+")
        #added Namespace Code
        nameSpace=masterControl[c4d.ID_USERDATA,16]

        results=CatchEmAll(hips, hips.GetNext(), [])
        for result in results:
            mixamo=doc.SearchObject(nameSpace+result.GetName())
            if mixamo:
                matR = result.GetMg()
                matM = mixamo.GetMg()
                matR.off = matM.off
                matR.v1 = matM.v1.GetNormalized()
                matR.v2 = matM.v2.GetNormalized()
                matR.v3 = matM.v3.GetNormalized()
                result.SetMg(matR)


            if result.GetName()=='Neck1':
                #neck=doc.SearchObject(nameSpace+'Neck')
                #head=doc.SearchObject(nameSpace+'Head')
                neck = SearchInHierarchy(characterObject, nameSpace+'Neck')
                head = SearchInHierarchy(characterObject, nameSpace+'Head')
                if head and neck:
                    result.SetMg((neck.GetMg()+head.GetMg())/2)

        print("Auto-Adjustment Complete")

        #Turning On the Annotation
        if leftAnnotationTag.GetType() == c4d.Tannotation:
            leftAnnotationTag[c4d.ANNOTATIONTAG_VIEWPORT_SHOW] = True

    if omode==c4d.ID_CA_CHARACTER_MODE_ADJUST and nmode!=c4d.ID_CA_CHARACTER_MODE_BUILD:
        L_Leg=doc.SearchObject("Left_IK_parent_rot_algn")
        #L_Leg = charop.FindObject("Left_IK_parent_rot_algn")
        if L_Leg:
            conTag=L_Leg.GetFirstTag()
            conTag[c4d.EXPRESSION_ENABLE]=False
        R_Leg=doc.SearchObject("Right_IK_parent_rot_algn")
        #R_Leg = charop.FindObject("Right_IK_parent_rot_algn")
        if R_Leg:
            conTag=R_Leg.GetFirstTag()
            conTag[c4d.EXPRESSION_ENABLE]=False

    if nmode==c4d.ID_CA_CHARACTER_MODE_ANIMATE:
        CharacterAnimateMode(characterObject)
        doc.SetActiveObject(masterControl, c4d.SELECTION_NEW)
    c4d.EventAdd()

Code

"""Scans the document for all nodes that have multi-line string parameters that contain the word "adjustment" 
(case-insensitive) and prints the node name, type, parameter ID, and value to the console.
"""

import c4d
import mxutils

doc: c4d.documents.BaseDocument

def main() -> None:
    """
    """
    node: c4d.BaseList2D
    pid: c4d.DescID

    # Iterate over all objects and tags in the document that live outside of caches and within the 
    # object branch of the document.
    for node in mxutils.RecurseGraph(doc.GetFirstObject(), yieldBranches=True, yieldHierarchy=True, 
                                     branchFilter=[c4d.Obase, c4d.Tbase]):
        # Iterate over the description, i.e., parameters of the node.
        for data, pid, _ in node.GetDescription(c4d.DESCFLAGS_DESC_NONE):
            # The first level of this parameter is not of type string or does not use the
            # multi-line string GUI, so  we skip it.
            if pid[0].dtype != c4d.DTYPE_STRING or data[c4d.DESC_CUSTOMGUI] != c4d.CUSTOMGUI_STRINGMULTI:
                continue
            
            # Try to read the value, the exception block is needed as not all parameter types are 
            # accessible in Python (and this could be some kind of exotic multi level string data type).
            try:
                value: str | None = str(node[pid]).strip()
                if not isinstance(value, str) or not value:
                    continue
            except Exception:
                continue

            # Check if the value contains the word "adjustment" (case-insensitive), if not, skip it.
            if "adjustment" not in value.lower():
                continue
            
            # Print the match.
            print ("\n\n" + ("=" * 100))
            print (f"Node: {node.GetName()} ({node.GetTypeName()}) | Attribute: {pid}\n\nValue:\n\n{value}")

            # For good measure, select the node and break the loop.
            (doc.SetActiveObject(node, c4d.SELECTION_NEW) 
             if isinstance(node, c4d.BaseObject) else 
             doc.SetActiveTag(node, c4d.SELECTION_NEW))
            break
        c4d.EventAdd()


if __name__ == '__main__':
    main()

Hey, good news, this is fixed in the upcoming hotfix (2026.3.2).